gdb_server -- subroutinize memory map logic

[openocd.git] / src / server / gdb_server.c

/***************************************************************************
 *   Copyright (C) 2005 by Dominic Rath                                    *
 *   Dominic.Rath@gmx.de                                                   *
 *                                                                         *
 *   Copyright (C) 2007-2009 Øyvind Harboe                                 *
 *   oyvind.harboe@zylin.com                                               *
 *                                                                         *
 *   Copyright (C) 2008 by Spencer Oliver                                  *
 *   spen@spen-soft.co.uk                                                  *
 *                                                                         *
 *   This program is free software; you can redistribute it and/or modify  *
 *   it under the terms of the GNU General Public License as published by  *
 *   the Free Software Foundation; either version 2 of the License, or     *
 *   (at your option) any later version.                                   *
 *                                                                         *
 *   This program is distributed in the hope that it will be useful,       *
 *   but WITHOUT ANY WARRANTY; without even the implied warranty of        *
 *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the         *
 *   GNU General Public License for more details.                          *
 *                                                                         *
 *   You should have received a copy of the GNU General Public License     *
 *   along with this program; if not, write to the                         *
 *   Free Software Foundation, Inc.,                                       *
 *   59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.             *
 ***************************************************************************/
#ifdef HAVE_CONFIG_H
#include "config.h"
#endif

#include <target/breakpoints.h>
#include <target/target_request.h>
#include <target/register.h>
#include "server.h"
#include <flash/nor/core.h>
#include "gdb_server.h"
#include <target/image.h>
#include <jtag/jtag.h>


/**
 * @file
 * GDB server implementation.
 *
 * This implements the GDB Remote Serial Protocol, over TCP connections,
 * giving GDB access to the JTAG or other hardware debugging facilities
 * found in most modern embedded processors.
 */

/* private connection data for GDB */
struct gdb_connection
{
        char buffer[GDB_BUFFER_SIZE];
        char *buf_p;
        int buf_cnt;
        int ctrl_c;
        enum target_state frontend_state;
        struct image *vflash_image;
        int closed;
        int busy;
        int noack_mode;
        bool sync;      /* set flag to true if you want the next stepi to return immediately.
                       allowing GDB to pick up a fresh set of register values from the target
                       without modifying the target state. */

};


#if 0
#define _DEBUG_GDB_IO_
#endif

static struct gdb_connection *current_gdb_connection;

static int gdb_breakpoint_override;
static enum breakpoint_type gdb_breakpoint_override_type;

static int gdb_error(struct connection *connection, int retval);
static unsigned short gdb_port = 3333;
static unsigned short gdb_port_next = 0;
static const char DIGITS[16] = "0123456789abcdef";

static void gdb_log_callback(void *priv, const char *file, unsigned line,
                const char *function, const char *string);

/* number of gdb connections, mainly to suppress gdb related debugging spam
 * in helper/log.c when no gdb connections are actually active */
int gdb_actual_connections;

/* set if we are sending a memory map to gdb
 * via qXfer:memory-map:read packet */
/* enabled by default*/
static int gdb_use_memory_map = 1;
/* enabled by default*/
static int gdb_flash_program = 1;

/* if set, data aborts cause an error to be reported in memory read packets
 * see the code in gdb_read_memory_packet() for further explanations.
 * Disabled by default.
 */
static int gdb_report_data_abort;

static int gdb_last_signal(struct target *target)
{
        switch (target->debug_reason)
        {
                case DBG_REASON_DBGRQ:
                        return 0x2; /* SIGINT */
                case DBG_REASON_BREAKPOINT:
                case DBG_REASON_WATCHPOINT:
                case DBG_REASON_WPTANDBKPT:
                        return 0x05; /* SIGTRAP */
                case DBG_REASON_SINGLESTEP:
                        return 0x05; /* SIGTRAP */
                case DBG_REASON_NOTHALTED:
                        return 0x0; /* no signal... shouldn't happen */
                default:
                        LOG_USER("undefined debug reason %d - target needs reset", target->debug_reason);
                        return 0x0;
        }
}

static int check_pending(struct connection *connection,
                int timeout_s, int *got_data)
{
        /* a non-blocking socket will block if there is 0 bytes available on the socket,
         * but return with as many bytes as are available immediately
         */
        struct timeval tv;
        fd_set read_fds;
        struct gdb_connection *gdb_con = connection->priv;
        int t;
        if (got_data == NULL)
                got_data=&t;
        *got_data = 0;

        if (gdb_con->buf_cnt > 0)
        {
                *got_data = 1;
                return ERROR_OK;
        }

        FD_ZERO(&read_fds);
        FD_SET(connection->fd, &read_fds);

        tv.tv_sec = timeout_s;
        tv.tv_usec = 0;
        if (socket_select(connection->fd + 1, &read_fds, NULL, NULL, &tv) == 0)
        {
                /* This can typically be because a "monitor" command took too long
                 * before printing any progress messages
                 */
                if (timeout_s > 0)
                {
                        return ERROR_GDB_TIMEOUT;
                } else
                {
                        return ERROR_OK;
                }
        }
        *got_data = FD_ISSET(connection->fd, &read_fds) != 0;
        return ERROR_OK;
}

static int gdb_get_char_inner(struct connection *connection, int* next_char)
{
        struct gdb_connection *gdb_con = connection->priv;
        int retval = ERROR_OK;

        for (;;)
        {
                if (connection->service->type == CONNECTION_PIPE)
                {
                        gdb_con->buf_cnt = read(connection->fd, gdb_con->buffer, GDB_BUFFER_SIZE);
                }
                else
                {
                        retval = check_pending(connection, 1, NULL);
                        if (retval != ERROR_OK)
                                return retval;
                        gdb_con->buf_cnt = read_socket(connection->fd, gdb_con->buffer, GDB_BUFFER_SIZE);
                }

                if (gdb_con->buf_cnt > 0)
                {
                        break;
                }
                if (gdb_con->buf_cnt == 0)
                {
                        gdb_con->closed = 1;
                        return ERROR_SERVER_REMOTE_CLOSED;
                }

#ifdef _WIN32
                errno = WSAGetLastError();

                switch (errno)
                {
                        case WSAEWOULDBLOCK:
                                usleep(1000);
                                break;
                        case WSAECONNABORTED:
                                gdb_con->closed = 1;
                                return ERROR_SERVER_REMOTE_CLOSED;
                        case WSAECONNRESET:
                                gdb_con->closed = 1;
                                return ERROR_SERVER_REMOTE_CLOSED;
                        default:
                                LOG_ERROR("read: %d", errno);
                                exit(-1);
                }
#else
                switch (errno)
                {
                        case EAGAIN:
                                usleep(1000);
                                break;
                        case ECONNABORTED:
                                gdb_con->closed = 1;
                                return ERROR_SERVER_REMOTE_CLOSED;
                        case ECONNRESET:
                                gdb_con->closed = 1;
                                return ERROR_SERVER_REMOTE_CLOSED;
                        default:
                                LOG_ERROR("read: %s", strerror(errno));
                                gdb_con->closed = 1;
                                return ERROR_SERVER_REMOTE_CLOSED;
                }
#endif
        }

#ifdef _DEBUG_GDB_IO_
        debug_buffer = malloc(gdb_con->buf_cnt + 1);
        memcpy(debug_buffer, gdb_con->buffer, gdb_con->buf_cnt);
        debug_buffer[gdb_con->buf_cnt] = 0;
        LOG_DEBUG("received '%s'", debug_buffer);
        free(debug_buffer);
#endif

        gdb_con->buf_p = gdb_con->buffer;
        gdb_con->buf_cnt--;
        *next_char = *(gdb_con->buf_p++);
        if (gdb_con->buf_cnt > 0)
                connection->input_pending = 1;
        else
                connection->input_pending = 0;
#ifdef _DEBUG_GDB_IO_
        LOG_DEBUG("returned char '%c' (0x%2.2x)", *next_char, *next_char);
#endif

        return retval;
}

/**
 * The cool thing about this fn is that it allows buf_p and buf_cnt to be
 * held in registers in the inner loop.
 *
 * For small caches and embedded systems this is important!
 */
static inline int gdb_get_char_fast(struct connection *connection, int* next_char, char **buf_p, int *buf_cnt)
{
        int retval = ERROR_OK;

        if ((*buf_cnt)-- > 0)
        {
                *next_char = **buf_p;
                (*buf_p)++;
                if (*buf_cnt > 0)
                        connection->input_pending = 1;
                else
                        connection->input_pending = 0;

#ifdef _DEBUG_GDB_IO_
                LOG_DEBUG("returned char '%c' (0x%2.2x)", *next_char, *next_char);
#endif

                return ERROR_OK;
        }

        struct gdb_connection *gdb_con = connection->priv;
        gdb_con->buf_p = *buf_p;
        gdb_con->buf_cnt = *buf_cnt;
        retval = gdb_get_char_inner(connection, next_char);
        *buf_p = gdb_con->buf_p;
        *buf_cnt = gdb_con->buf_cnt;

        return retval;
}


static int gdb_get_char(struct connection *connection, int* next_char)
{
        struct gdb_connection *gdb_con = connection->priv;
        return gdb_get_char_fast(connection, next_char, &gdb_con->buf_p, &gdb_con->buf_cnt);
}


static int gdb_putback_char(struct connection *connection, int last_char)
{
        struct gdb_connection *gdb_con = connection->priv;

        if (gdb_con->buf_p > gdb_con->buffer)
        {
                *(--gdb_con->buf_p) = last_char;
                gdb_con->buf_cnt++;
        }
        else
        {
                LOG_ERROR("BUG: couldn't put character back");
        }

        return ERROR_OK;
}

/* The only way we can detect that the socket is closed is the first time
 * we write to it, we will fail. Subsequent write operations will
 * succeed. Shudder! */
static int gdb_write(struct connection *connection, void *data, int len)
{
        struct gdb_connection *gdb_con = connection->priv;
        if (gdb_con->closed)
                return ERROR_SERVER_REMOTE_CLOSED;

        if (connection->service->type == CONNECTION_PIPE)
        {
                /* write to stdout */
                if (write(STDOUT_FILENO, data, len) == len)
                {
                        return ERROR_OK;
                }
        }
        else
        {
                if (write_socket(connection->fd, data, len) == len)
                {
                        return ERROR_OK;
                }
        }
        gdb_con->closed = 1;
        return ERROR_SERVER_REMOTE_CLOSED;
}

static int gdb_put_packet_inner(struct connection *connection,
                char *buffer, int len)
{
        int i;
        unsigned char my_checksum = 0;
#ifdef _DEBUG_GDB_IO_
        char *debug_buffer;
#endif
        int reply;
        int retval;
        struct gdb_connection *gdb_con = connection->priv;

        for (i = 0; i < len; i++)
                my_checksum += buffer[i];

#ifdef _DEBUG_GDB_IO_
        /*
         * At this point we should have nothing in the input queue from GDB,
         * however sometimes '-' is sent even though we've already received
         * an ACK (+) for everything we've sent off.
         */
        int gotdata;
        for (;;)
        {
                retval = check_pending(connection, 0, &gotdata);
                if (retval != ERROR_OK)
                        return retval;
                if (!gotdata)
                        break;
                if ((retval = gdb_get_char(connection, &reply)) != ERROR_OK)
                        return retval;
                if (reply == '$') {
                        /* fix a problem with some IAR tools */
                        gdb_putback_char(connection, reply);
                        LOG_DEBUG("Unexpected start of new packet");
                        break;
                }

                LOG_WARNING("Discard unexpected char %c", reply);
        }
#endif

        while (1)
        {
#ifdef _DEBUG_GDB_IO_
                debug_buffer = malloc(len + 1);
                memcpy(debug_buffer, buffer, len);
                debug_buffer[len] = 0;
                LOG_DEBUG("sending packet '$%s#%2.2x'", debug_buffer, my_checksum);
                free(debug_buffer);
#endif

                char local_buffer[1024];
                local_buffer[0] = '$';
                if ((size_t)len + 4 <= sizeof(local_buffer))
                {
                        /* performance gain on smaller packets by only a single call to gdb_write() */
                        memcpy(local_buffer + 1, buffer, len++);
                        local_buffer[len++] = '#';
                        local_buffer[len++] = DIGITS[(my_checksum >> 4) & 0xf];
                        local_buffer[len++] = DIGITS[my_checksum & 0xf];
                        if ((retval = gdb_write(connection, local_buffer, len)) != ERROR_OK)
                        {
                                return retval;
                        }
                }
                else
                {
                        /* larger packets are transmitted directly from caller supplied buffer
                           by several calls to gdb_write() to avoid dynamic allocation */
                        local_buffer[1] = '#';
                        local_buffer[2] = DIGITS[(my_checksum >> 4) & 0xf];
                        local_buffer[3] = DIGITS[my_checksum & 0xf];
                        if ((retval = gdb_write(connection, local_buffer, 1)) != ERROR_OK)
                        {
                                return retval;
                        }
                        if ((retval = gdb_write(connection, buffer, len)) != ERROR_OK)
                        {
                                return retval;
                        }
                        if ((retval = gdb_write(connection, local_buffer + 1, 3)) != ERROR_OK)
                        {
                                return retval;
                        }
                }

                if (gdb_con->noack_mode)
                        break;

                if ((retval = gdb_get_char(connection, &reply)) != ERROR_OK)
                        return retval;

                if (reply == '+')
                        break;
                else if (reply == '-')
                {
                        /* Stop sending output packets for now */
                        log_remove_callback(gdb_log_callback, connection);
                        LOG_WARNING("negative reply, retrying");
                }
                else if (reply == 0x3)
                {
                        gdb_con->ctrl_c = 1;
                        if ((retval = gdb_get_char(connection, &reply)) != ERROR_OK)
                                return retval;
                        if (reply == '+')
                                break;
                        else if (reply == '-')
                        {
                                /* Stop sending output packets for now */
                                log_remove_callback(gdb_log_callback, connection);
                                LOG_WARNING("negative reply, retrying");
                        }
                        else if (reply == '$') {
                                LOG_ERROR("GDB missing ack(1) - assumed good");
                                gdb_putback_char(connection, reply);
                                return ERROR_OK;
                        } else {

                                LOG_ERROR("unknown character(1) 0x%2.2x in reply, dropping connection", reply);
                                gdb_con->closed = 1;
                                return ERROR_SERVER_REMOTE_CLOSED;
                        }
                }
                else if (reply == '$') {
                        LOG_ERROR("GDB missing ack(2) - assumed good");
                        gdb_putback_char(connection, reply);
                        return ERROR_OK;
                }
                else
                {
                        LOG_ERROR("unknown character(2) 0x%2.2x in reply, dropping connection", reply);
                        gdb_con->closed = 1;
                        return ERROR_SERVER_REMOTE_CLOSED;
                }
        }
        if (gdb_con->closed)
                return ERROR_SERVER_REMOTE_CLOSED;

        return ERROR_OK;
}

static int gdb_put_packet(struct connection *connection, char *buffer, int len)
{
        struct gdb_connection *gdb_con = connection->priv;
        gdb_con->busy = 1;
        int retval = gdb_put_packet_inner(connection, buffer, len);
        gdb_con->busy = 0;

        /* we sent some data, reset timer for keep alive messages */
        kept_alive();

        return retval;
}

static __inline__ int fetch_packet(struct connection *connection, int *checksum_ok, int noack, int *len, char *buffer)
{
        unsigned char my_checksum = 0;
        char checksum[3];
        int character;
        int retval = ERROR_OK;

        struct gdb_connection *gdb_con = connection->priv;
        my_checksum = 0;
        int count = 0;
        count = 0;

        /* move this over into local variables to use registers and give the
         * more freedom to optimize */
        char *buf_p = gdb_con->buf_p;
        int buf_cnt = gdb_con->buf_cnt;

        for (;;)
        {
                /* The common case is that we have an entire packet with no escape chars.
                 * We need to leave at least 2 bytes in the buffer to have
                 * gdb_get_char() update various bits and bobs correctly.
                 */
                if ((buf_cnt > 2) && ((buf_cnt + count) < *len))
                {
                        /* The compiler will struggle a bit with constant propagation and
                         * aliasing, so we help it by showing that these values do not
                         * change inside the loop
                         */
                        int i;
                        char *buf = buf_p;
                        int run = buf_cnt - 2;
                        i = 0;
                        int done = 0;
                        while (i < run)
                        {
                                character = *buf++;
                                i++;
                                if (character == '#')
                                {
                                        /* Danger! character can be '#' when esc is
                                         * used so we need an explicit boolean for done here.
                                         */
                                        done = 1;
                                        break;
                                }

                                if (character == '}')
                                {
                                        /* data transmitted in binary mode (X packet)
                                         * uses 0x7d as escape character */
                                        my_checksum += character & 0xff;
                                        character = *buf++;
                                        i++;
                                        my_checksum += character & 0xff;
                                        buffer[count++] = (character ^ 0x20) & 0xff;
                                }
                                else
                                {
                                        my_checksum += character & 0xff;
                                        buffer[count++] = character & 0xff;
                                }
                        }
                        buf_p += i;
                        buf_cnt -= i;
                        if (done)
                                break;
                }
                if (count > *len)
                {
                        LOG_ERROR("packet buffer too small");
                        retval = ERROR_GDB_BUFFER_TOO_SMALL;
                        break;
                }

                retval = gdb_get_char_fast(connection, &character, &buf_p, &buf_cnt);
                if (retval != ERROR_OK)
                        break;

                if (character == '#')
                        break;

                if (character == '}')
                {
                        /* data transmitted in binary mode (X packet)
                         * uses 0x7d as escape character */
                        my_checksum += character & 0xff;

                        retval = gdb_get_char_fast(connection, &character, &buf_p, &buf_cnt);
                        if (retval != ERROR_OK)
                                break;

                        my_checksum += character & 0xff;
                        buffer[count++] = (character ^ 0x20) & 0xff;
                }
                else
                {
                        my_checksum += character & 0xff;
                        buffer[count++] = character & 0xff;
                }
        }

        gdb_con->buf_p = buf_p;
        gdb_con->buf_cnt = buf_cnt;

        if (retval != ERROR_OK)
                return retval;

        *len = count;

        if ((retval = gdb_get_char(connection, &character)) != ERROR_OK)
                return retval;
        checksum[0] = character;
        if ((retval = gdb_get_char(connection, &character)) != ERROR_OK)
                return retval;
        checksum[1] = character;
        checksum[2] = 0;

        if (!noack)
        {
                *checksum_ok = (my_checksum == strtoul(checksum, NULL, 16));
        }

        return ERROR_OK;
}

static int gdb_get_packet_inner(struct connection *connection,
                char *buffer, int *len)
{
        int character;
        int retval;
        struct gdb_connection *gdb_con = connection->priv;

        while (1)
        {
                do
                {
                        if ((retval = gdb_get_char(connection, &character)) != ERROR_OK)
                                return retval;

#ifdef _DEBUG_GDB_IO_
                        LOG_DEBUG("character: '%c'", character);
#endif

                        switch (character)
                        {
                                case '$':
                                        break;
                                case '+':
                                        /* gdb sends a dummy ack '+' at every remote connect - see remote_start_remote (remote.c)
                                         * in case anyone tries to debug why they receive this warning every time */
                                        LOG_WARNING("acknowledgment received, but no packet pending");
                                        break;
                                case '-':
                                        LOG_WARNING("negative acknowledgment, but no packet pending");
                                        break;
                                case 0x3:
                                        gdb_con->ctrl_c = 1;
                                        *len = 0;
                                        return ERROR_OK;
                                default:
                                        LOG_WARNING("ignoring character 0x%x", character);
                                        break;
                        }
                } while (character != '$');



                int checksum_ok = 0;
                /* explicit code expansion here to get faster inlined code in -O3 by not
                 * calculating checksum
                 */
                if (gdb_con->noack_mode)
                {
                        if ((retval = fetch_packet(connection, &checksum_ok, 1, len, buffer)) != ERROR_OK)
                                return retval;
                } else
                {
                        if ((retval = fetch_packet(connection, &checksum_ok, 0, len, buffer)) != ERROR_OK)
                                return retval;
                }

                if (gdb_con->noack_mode)
                {
                        /* checksum is not checked in noack mode */
                        break;
                }
                if (checksum_ok)
                {
                        if ((retval = gdb_write(connection, "+", 1)) != ERROR_OK)
                        {
                                return retval;
                        }
                        break;
                }
        }
        if (gdb_con->closed)
                return ERROR_SERVER_REMOTE_CLOSED;

        return ERROR_OK;
}

static int gdb_get_packet(struct connection *connection, char *buffer, int *len)
{
        struct gdb_connection *gdb_con = connection->priv;
        gdb_con->busy = 1;
        int retval = gdb_get_packet_inner(connection, buffer, len);
        gdb_con->busy = 0;
        return retval;
}

static int gdb_output_con(struct connection *connection, const char* line)
{
        char *hex_buffer;
        int i, bin_size;

        bin_size = strlen(line);

        hex_buffer = malloc(bin_size*2 + 2);
        if (hex_buffer == NULL)
                return ERROR_GDB_BUFFER_TOO_SMALL;

        hex_buffer[0] = 'O';
        for (i = 0; i < bin_size; i++)
                snprintf(hex_buffer + 1 + i*2, 3, "%2.2x", line[i]);
        hex_buffer[bin_size*2 + 1] = 0;

        int retval = gdb_put_packet(connection, hex_buffer, bin_size*2 + 1);

        free(hex_buffer);
        return retval;
}

static int gdb_output(struct command_context *context, const char* line)
{
        /* this will be dumped to the log and also sent as an O packet if possible */
        LOG_USER_N("%s", line);
        return ERROR_OK;
}


static void gdb_frontend_halted(struct target *target, struct connection *connection)
{
        struct gdb_connection *gdb_connection = connection->priv;

        /* In the GDB protocol when we are stepping or continuing execution,
         * we have a lingering reply. Upon receiving a halted event
         * when we have that lingering packet, we reply to the original
         * step or continue packet.
         *
         * Executing monitor commands can bring the target in and
         * out of the running state so we'll see lots of TARGET_EVENT_XXX
         * that are to be ignored.
         */
        if (gdb_connection->frontend_state == TARGET_RUNNING)
        {
                char sig_reply[4];
                int signal;

                /* stop forwarding log packets! */
                log_remove_callback(gdb_log_callback, connection);

                if (gdb_connection->ctrl_c)
                {
                        signal = 0x2;
                        gdb_connection->ctrl_c = 0;
                }
                else
                {
                        signal = gdb_last_signal(target);
                }

                snprintf(sig_reply, 4, "T%2.2x", signal);
                gdb_put_packet(connection, sig_reply, 3);
                gdb_connection->frontend_state = TARGET_HALTED;
        }
}

static int gdb_target_callback_event_handler(struct target *target,
                enum target_event event, void *priv)
{
        int retval;
        struct connection *connection = priv;

        target_handle_event(target, event);
        switch (event)
        {
                case TARGET_EVENT_GDB_HALT:
                        gdb_frontend_halted(target, connection);
                        break;
                case TARGET_EVENT_HALTED:
                        target_call_event_callbacks(target, TARGET_EVENT_GDB_END);
                        break;
                case TARGET_EVENT_GDB_FLASH_ERASE_START:
                        target_handle_event(target, TARGET_EVENT_OLD_gdb_program_config);
                        if ((retval = jtag_execute_queue()) != ERROR_OK)
                        {
                                return retval;
                        }
                        break;
                default:
                        break;
        }

        return ERROR_OK;
}

static int gdb_new_connection(struct connection *connection)
{
        struct gdb_connection *gdb_connection = malloc(sizeof(struct gdb_connection));
        struct gdb_service *gdb_service = connection->service->priv;
        int retval;
        int initial_ack;

        connection->priv = gdb_connection;

        /* initialize gdb connection information */
        gdb_connection->buf_p = gdb_connection->buffer;
        gdb_connection->buf_cnt = 0;
        gdb_connection->ctrl_c = 0;
        gdb_connection->frontend_state = TARGET_HALTED;
        gdb_connection->vflash_image = NULL;
        gdb_connection->closed = 0;
        gdb_connection->busy = 0;
        gdb_connection->noack_mode = 0;
        gdb_connection->sync = true;

        /* send ACK to GDB for debug request */
        gdb_write(connection, "+", 1);

        /* output goes through gdb connection */
        command_set_output_handler(connection->cmd_ctx, gdb_output, connection);

        /* we must remove all breakpoints registered to the target as a previous
         * GDB session could leave dangling breakpoints if e.g. communication
         * timed out.
         */
        breakpoint_clear_target(gdb_service->target);
        watchpoint_clear_target(gdb_service->target);

        /* register callback to be informed about target events */
        target_register_event_callback(gdb_target_callback_event_handler, connection);

        /* remove the initial ACK from the incoming buffer */
        if ((retval = gdb_get_char(connection, &initial_ack)) != ERROR_OK)
                return retval;

        /* FIX!!!??? would we actually ever receive a + here???
         * Not observed.
         */
        if (initial_ack != '+')
                gdb_putback_char(connection, initial_ack);
        target_call_event_callbacks(gdb_service->target, TARGET_EVENT_GDB_ATTACH);

        gdb_actual_connections++;
        LOG_DEBUG("New GDB Connection: %d, Target %s, state: %s",
                  gdb_actual_connections,
                  target_name(gdb_service->target),
                  target_state_name(gdb_service->target));

        return ERROR_OK;
}

static int gdb_connection_closed(struct connection *connection)
{
        struct gdb_service *gdb_service = connection->service->priv;
        struct gdb_connection *gdb_connection = connection->priv;

        /* we're done forwarding messages. Tear down callback before
         * cleaning up connection.
         */
        log_remove_callback(gdb_log_callback, connection);

        gdb_actual_connections--;
        LOG_DEBUG("GDB Close, Target: %s, state: %s, gdb_actual_connections=%d",
                  target_name(gdb_service->target),
                  target_state_name(gdb_service->target),
                  gdb_actual_connections);

        /* see if an image built with vFlash commands is left */
        if (gdb_connection->vflash_image)
        {
                image_close(gdb_connection->vflash_image);
                free(gdb_connection->vflash_image);
                gdb_connection->vflash_image = NULL;
        }

        /* if this connection registered a debug-message receiver delete it */
        delete_debug_msg_receiver(connection->cmd_ctx, gdb_service->target);

        if (connection->priv)
        {
                free(connection->priv);
                connection->priv = NULL;
        }
        else
        {
                LOG_ERROR("BUG: connection->priv == NULL");
        }


        target_unregister_event_callback(gdb_target_callback_event_handler, connection);

        target_call_event_callbacks(gdb_service->target, TARGET_EVENT_GDB_END);

        target_call_event_callbacks(gdb_service->target, TARGET_EVENT_GDB_DETACH);

        return ERROR_OK;
}

static void gdb_send_error(struct connection *connection, uint8_t the_error)
{
        char err[4];
        snprintf(err, 4, "E%2.2X", the_error);
        gdb_put_packet(connection, err, 3);
}

static int gdb_last_signal_packet(struct connection *connection,
                struct target *target, char* packet, int packet_size)
{
        char sig_reply[4];
        int signal;

        signal = gdb_last_signal(target);

        snprintf(sig_reply, 4, "S%2.2x", signal);
        gdb_put_packet(connection, sig_reply, 3);

        return ERROR_OK;
}

static int gdb_reg_pos(struct target *target, int pos, int len)
{
        if (target->endianness == TARGET_LITTLE_ENDIAN)
                return pos;
        else
                return len - 1 - pos;
}

/* Convert register to string of bytes. NB! The # of bits in the
 * register might be non-divisible by 8(a byte), in which
 * case an entire byte is shown.
 *
 * NB! the format on the wire is the target endianness
 *
 * The format of reg->value is little endian
 *
 */
static void gdb_str_to_target(struct target *target,
                char *tstr, struct reg *reg)
{
        int i;

        uint8_t *buf;
        int buf_len;
        buf = reg->value;
        buf_len = DIV_ROUND_UP(reg->size, 8);

        for (i = 0; i < buf_len; i++)
        {
                int j = gdb_reg_pos(target, i, buf_len);
                tstr[i*2]   = DIGITS[(buf[j]>>4) & 0xf];
                tstr[i*2 + 1] = DIGITS[buf[j]&0xf];
        }
}

static int hextoint(int c)
{
        if (c>='0'&&c<='9')
        {
                return c-'0';
        }
        c = toupper(c);
        if (c>='A'&&c<='F')
        {
                return c-'A'+10;
        }
        LOG_ERROR("BUG: invalid register value %08x", c);
        return 0;
}

/* copy over in register buffer */
static void gdb_target_to_reg(struct target *target,
                char *tstr, int str_len, uint8_t *bin)
{
        if (str_len % 2)
        {
                LOG_ERROR("BUG: gdb value with uneven number of characters encountered");
                exit(-1);
        }

        int i;
        for (i = 0; i < str_len; i += 2)
        {
                uint8_t t = hextoint(tstr[i]) << 4;
                t |= hextoint(tstr[i + 1]);

                int j = gdb_reg_pos(target, i/2, str_len/2);
                bin[j] = t;
        }
}

static int gdb_get_registers_packet(struct connection *connection,
                struct target *target, char* packet, int packet_size)
{
        struct reg **reg_list;
        int reg_list_size;
        int retval;
        int reg_packet_size = 0;
        char *reg_packet;
        char *reg_packet_p;
        int i;

#ifdef _DEBUG_GDB_IO_
        LOG_DEBUG("-");
#endif

        if ((retval = target_get_gdb_reg_list(target, &reg_list, &reg_list_size)) != ERROR_OK)
        {
                return gdb_error(connection, retval);
        }

        for (i = 0; i < reg_list_size; i++)
        {
                reg_packet_size += reg_list[i]->size;
        }

        reg_packet = malloc(DIV_ROUND_UP(reg_packet_size, 8) * 2);
        reg_packet_p = reg_packet;

        for (i = 0; i < reg_list_size; i++)
        {
                gdb_str_to_target(target, reg_packet_p, reg_list[i]);
                reg_packet_p += DIV_ROUND_UP(reg_list[i]->size, 8) * 2;
        }

#ifdef _DEBUG_GDB_IO_
        {
                char *reg_packet_p;
                reg_packet_p = strndup(reg_packet, DIV_ROUND_UP(reg_packet_size, 8) * 2);
                LOG_DEBUG("reg_packet: %s", reg_packet_p);
                free(reg_packet_p);
        }
#endif

        gdb_put_packet(connection, reg_packet, DIV_ROUND_UP(reg_packet_size, 8) * 2);
        free(reg_packet);

        free(reg_list);

        return ERROR_OK;
}

static int gdb_set_registers_packet(struct connection *connection,
                struct target *target, char *packet, int packet_size)
{
        int i;
        struct reg **reg_list;
        int reg_list_size;
        int retval;
        char *packet_p;

#ifdef _DEBUG_GDB_IO_
        LOG_DEBUG("-");
#endif

        /* skip command character */
        packet++;
        packet_size--;

        if (packet_size % 2)
        {
                LOG_WARNING("GDB set_registers packet with uneven characters received, dropping connection");
                return ERROR_SERVER_REMOTE_CLOSED;
        }

        if ((retval = target_get_gdb_reg_list(target, &reg_list, &reg_list_size)) != ERROR_OK)
        {
                return gdb_error(connection, retval);
        }

        packet_p = packet;
        for (i = 0; i < reg_list_size; i++)
        {
                uint8_t *bin_buf;
                int chars = (DIV_ROUND_UP(reg_list[i]->size, 8) * 2);

                if (packet_p + chars > packet + packet_size)
                {
                        LOG_ERROR("BUG: register packet is too small for registers");
                }

                bin_buf = malloc(DIV_ROUND_UP(reg_list[i]->size, 8));
                gdb_target_to_reg(target, packet_p, chars, bin_buf);

                reg_list[i]->type->set(reg_list[i], bin_buf);

                /* advance packet pointer */
                packet_p += chars;


                free(bin_buf);
        }

        /* free struct reg *reg_list[] array allocated by get_gdb_reg_list */
        free(reg_list);

        gdb_put_packet(connection, "OK", 2);

        return ERROR_OK;
}

static int gdb_get_register_packet(struct connection *connection,
                struct target *target, char *packet, int packet_size)
{
        char *reg_packet;
        int reg_num = strtoul(packet + 1, NULL, 16);
        struct reg **reg_list;
        int reg_list_size;
        int retval;

#ifdef _DEBUG_GDB_IO_
        LOG_DEBUG("-");
#endif

        if ((retval = target_get_gdb_reg_list(target, &reg_list, &reg_list_size)) != ERROR_OK)
        {
                return gdb_error(connection, retval);
        }

        if (reg_list_size <= reg_num)
        {
                LOG_ERROR("gdb requested a non-existing register");
                exit(-1);
        }

        reg_packet = malloc(DIV_ROUND_UP(reg_list[reg_num]->size, 8) * 2);

        gdb_str_to_target(target, reg_packet, reg_list[reg_num]);

        gdb_put_packet(connection, reg_packet, DIV_ROUND_UP(reg_list[reg_num]->size, 8) * 2);

        free(reg_list);
        free(reg_packet);

        return ERROR_OK;
}

static int gdb_set_register_packet(struct connection *connection,
                struct target *target, char *packet, int packet_size)
{
        char *separator;
        uint8_t *bin_buf;
        int reg_num = strtoul(packet + 1, &separator, 16);
        struct reg **reg_list;
        int reg_list_size;
        int retval;

        LOG_DEBUG("-");

        if ((retval = target_get_gdb_reg_list(target, &reg_list, &reg_list_size)) != ERROR_OK)
        {
                return gdb_error(connection, retval);
        }

        if (reg_list_size < reg_num)
        {
                LOG_ERROR("gdb requested a non-existing register");
                return ERROR_SERVER_REMOTE_CLOSED;
        }

        if (*separator != '=')
        {
                LOG_ERROR("GDB 'set register packet', but no '=' following the register number");
                return ERROR_SERVER_REMOTE_CLOSED;
        }

        /* convert from GDB-string (target-endian) to hex-string (big-endian) */
        bin_buf = malloc(DIV_ROUND_UP(reg_list[reg_num]->size, 8));
        int chars = (DIV_ROUND_UP(reg_list[reg_num]->size, 8) * 2);

        /* fix!!! add some sanity checks on packet size here */

        gdb_target_to_reg(target, separator + 1, chars, bin_buf);

        reg_list[reg_num]->type->set(reg_list[reg_num], bin_buf);

        gdb_put_packet(connection, "OK", 2);

        free(bin_buf);
        free(reg_list);

        return ERROR_OK;
}

static int gdb_error(struct connection *connection, int retval)
{
        switch (retval)
        {
                case ERROR_TARGET_DATA_ABORT:
                        gdb_send_error(connection, EIO);
                        break;
                case ERROR_TARGET_TRANSLATION_FAULT:
                        gdb_send_error(connection, EFAULT);
                        break;
                case ERROR_TARGET_UNALIGNED_ACCESS:
                        gdb_send_error(connection, EFAULT);
                        break;
                case ERROR_TARGET_NOT_HALTED:
                        gdb_send_error(connection, EFAULT);
                        break;
                default:
                        /* This could be that the target reset itself. */
                        LOG_ERROR("unexpected error %i", retval);
                        gdb_send_error(connection, EFAULT);
                        break;
        }

        return ERROR_OK;
}

/* We don't have to worry about the default 2 second timeout for GDB packets,
 * because GDB breaks up large memory reads into smaller reads.
 *
 * 8191 bytes by the looks of it. Why 8191 bytes instead of 8192?????
 */
static int gdb_read_memory_packet(struct connection *connection,
                struct target *target, char *packet, int packet_size)
{
        char *separator;
        uint32_t addr = 0;
        uint32_t len = 0;

        uint8_t *buffer;
        char *hex_buffer;

        int retval = ERROR_OK;

        /* skip command character */
        packet++;

        addr = strtoul(packet, &separator, 16);

        if (*separator != ',')
        {
                LOG_ERROR("incomplete read memory packet received, dropping connection");
                return ERROR_SERVER_REMOTE_CLOSED;
        }

        len = strtoul(separator + 1, NULL, 16);

        buffer = malloc(len);

        LOG_DEBUG("addr: 0x%8.8" PRIx32 ", len: 0x%8.8" PRIx32 "", addr, len);

        retval = target_read_buffer(target, addr, len, buffer);

        if ((retval != ERROR_OK)&&!gdb_report_data_abort)
        {
                /* TODO : Here we have to lie and send back all zero's lest stack traces won't work.
                 * At some point this might be fixed in GDB, in which case this code can be removed.
                 *
                 * OpenOCD developers are acutely aware of this problem, but there is nothing
                 * gained by involving the user in this problem that hopefully will get resolved
                 * eventually
                 *
                 * http://sourceware.org/cgi-bin/gnatsweb.pl?cmd = view%20audit-trail&database = gdb&pr = 2395
                 *
                 * For now, the default is to fix up things to make current GDB versions work.
                 * This can be overwritten using the gdb_report_data_abort <'enable'|'disable'> command.
                 */
                memset(buffer, 0, len);
                retval = ERROR_OK;
        }

        if (retval == ERROR_OK)
        {
                hex_buffer = malloc(len * 2 + 1);

                uint32_t i;
                for (i = 0; i < len; i++)
                {
                        uint8_t t = buffer[i];
                        hex_buffer[2 * i] = DIGITS[(t >> 4) & 0xf];
                        hex_buffer[2 * i + 1] = DIGITS[t & 0xf];
                }

                gdb_put_packet(connection, hex_buffer, len * 2);

                free(hex_buffer);
        }
        else
        {
                retval = gdb_error(connection, retval);
        }

        free(buffer);

        return retval;
}

static int gdb_write_memory_packet(struct connection *connection,
                struct target *target, char *packet, int packet_size)
{
        char *separator;
        uint32_t addr = 0;
        uint32_t len = 0;

        uint8_t *buffer;

        uint32_t i;
        int retval;

        /* skip command character */
        packet++;

        addr = strtoul(packet, &separator, 16);

        if (*separator != ',')
        {
                LOG_ERROR("incomplete write memory packet received, dropping connection");
                return ERROR_SERVER_REMOTE_CLOSED;
        }

        len = strtoul(separator + 1, &separator, 16);

        if (*(separator++) != ':')
        {
                LOG_ERROR("incomplete write memory packet received, dropping connection");
                return ERROR_SERVER_REMOTE_CLOSED;
        }

        buffer = malloc(len);

        LOG_DEBUG("addr: 0x%8.8" PRIx32 ", len: 0x%8.8" PRIx32 "", addr, len);

        for (i = 0; i < len; i++)
        {
                uint32_t tmp;
                sscanf(separator + 2*i, "%2" SCNx32 , &tmp);
                buffer[i] = tmp;
        }

        retval = target_write_buffer(target, addr, len, buffer);

        if (retval == ERROR_OK)
        {
                gdb_put_packet(connection, "OK", 2);
        }
        else
        {
                retval = gdb_error(connection, retval);
        }

        free(buffer);

        return retval;
}

static int gdb_write_memory_binary_packet(struct connection *connection,
                struct target *target, char *packet, int packet_size)
{
        char *separator;
        uint32_t addr = 0;
        uint32_t len = 0;

        int retval;

        /* skip command character */
        packet++;

        addr = strtoul(packet, &separator, 16);

        if (*separator != ',')
        {
                LOG_ERROR("incomplete write memory binary packet received, dropping connection");
                return ERROR_SERVER_REMOTE_CLOSED;
        }

        len = strtoul(separator + 1, &separator, 16);

        if (*(separator++) != ':')
        {
                LOG_ERROR("incomplete write memory binary packet received, dropping connection");
                return ERROR_SERVER_REMOTE_CLOSED;
        }

        retval = ERROR_OK;
        if (len)
        {
                LOG_DEBUG("addr: 0x%8.8" PRIx32 ", len: 0x%8.8" PRIx32 "", addr, len);

                retval = target_write_buffer(target, addr, len, (uint8_t*)separator);
        }

        if (retval == ERROR_OK)
        {
                gdb_put_packet(connection, "OK", 2);
        }
        else
        {
                if ((retval = gdb_error(connection, retval)) != ERROR_OK)
                        return retval;
        }

        return ERROR_OK;
}

static int gdb_step_continue_packet(struct connection *connection,
                struct target *target, char *packet, int packet_size)
{
        int current = 0;
        uint32_t address = 0x0;
        int retval = ERROR_OK;

        LOG_DEBUG("-");

        if (packet_size > 1)
        {
                packet[packet_size] = 0;
                address = strtoul(packet + 1, NULL, 16);
        }
        else
        {
                current = 1;
        }

        if (packet[0] == 'c')
        {
                LOG_DEBUG("continue");
                target_handle_event(target, TARGET_EVENT_OLD_pre_resume);
                retval = target_resume(target, current, address, 0, 0); /* resume at current address, don't handle breakpoints, not debugging */
        }
        else if (packet[0] == 's')
        {
                LOG_DEBUG("step");
                /* step at current or address, don't handle breakpoints */
                retval = target_step(target, current, address, 0);
        }
        return retval;
}

static int gdb_breakpoint_watchpoint_packet(struct connection *connection,
                struct target *target, char *packet, int packet_size)
{
        int type;
        enum breakpoint_type bp_type = BKPT_SOFT /* dummy init to avoid warning */;
        enum watchpoint_rw wp_type = WPT_READ /* dummy init to avoid warning */;
        uint32_t address;
        uint32_t size;
        char *separator;
        int retval;

        LOG_DEBUG("-");

        type = strtoul(packet + 1, &separator, 16);

        if (type == 0)  /* memory breakpoint */
                bp_type = BKPT_SOFT;
        else if (type == 1) /* hardware breakpoint */
                bp_type = BKPT_HARD;
        else if (type == 2) /* write watchpoint */
                wp_type = WPT_WRITE;
        else if (type == 3) /* read watchpoint */
                wp_type = WPT_READ;
        else if (type == 4) /* access watchpoint */
                wp_type = WPT_ACCESS;
        else
        {
                LOG_ERROR("invalid gdb watch/breakpoint type(%d), dropping connection", type);
                return ERROR_SERVER_REMOTE_CLOSED;
        }


        if (gdb_breakpoint_override && ((bp_type == BKPT_SOFT)||(bp_type == BKPT_HARD)))
        {
                bp_type = gdb_breakpoint_override_type;
        }

        if (*separator != ',')
        {
                LOG_ERROR("incomplete breakpoint/watchpoint packet received, dropping connection");
                return ERROR_SERVER_REMOTE_CLOSED;
        }

        address = strtoul(separator + 1, &separator, 16);

        if (*separator != ',')
        {
                LOG_ERROR("incomplete breakpoint/watchpoint packet received, dropping connection");
                return ERROR_SERVER_REMOTE_CLOSED;
        }

        size = strtoul(separator + 1, &separator, 16);

        switch (type)
        {
                case 0:
                case 1:
                        if (packet[0] == 'Z')
                        {
                                if ((retval = breakpoint_add(target, address, size, bp_type)) != ERROR_OK)
                                {
                                        if ((retval = gdb_error(connection, retval)) != ERROR_OK)
                                                return retval;
                                }
                                else
                                {
                                        gdb_put_packet(connection, "OK", 2);
                                }
                        }
                        else
                        {
                                breakpoint_remove(target, address);
                                gdb_put_packet(connection, "OK", 2);
                        }
                        break;
                case 2:
                case 3:
                case 4:
                {
                        if (packet[0] == 'Z')
                        {
                                if ((retval = watchpoint_add(target, address, size, wp_type, 0, 0xffffffffu)) != ERROR_OK)
                                {
                                        if ((retval = gdb_error(connection, retval)) != ERROR_OK)
                                                return retval;
                                }
                                else
                                {
                                        gdb_put_packet(connection, "OK", 2);
                                }
                        }
                        else
                        {
                                watchpoint_remove(target, address);
                                gdb_put_packet(connection, "OK", 2);
                        }
                        break;
                }
                default:
                        break;
        }

        return ERROR_OK;
}

/* print out a string and allocate more space as needed,
 * mainly used for XML at this point
 */
static void xml_printf(int *retval, char **xml, int *pos, int *size,
                const char *fmt, ...)
{
        if (*retval != ERROR_OK)
        {
                return;
        }
        int first = 1;

        for (;;)
        {
                if ((*xml == NULL) || (!first))
                {
                        /* start by 0 to exercise all the code paths.
                         * Need minimum 2 bytes to fit 1 char and 0 terminator. */

                        *size = *size * 2 + 2;
                        char *t = *xml;
                        *xml = realloc(*xml, *size);
                        if (*xml == NULL)
                        {
                                if (t)
                                        free(t);
                                *retval = ERROR_SERVER_REMOTE_CLOSED;
                                return;
                        }
                }

                va_list ap;
                int ret;
                va_start(ap, fmt);
                ret = vsnprintf(*xml + *pos, *size - *pos, fmt, ap);
                va_end(ap);
                if ((ret > 0) && ((ret + 1) < *size - *pos))
                {
                        *pos += ret;
                        return;
                }
                /* there was just enough or not enough space, allocate more. */
                first = 0;
        }
}

static int decode_xfer_read(char *buf, char **annex, int *ofs, unsigned int *len)
{
        char *separator;

        /* Extract and NUL-terminate the annex. */
        *annex = buf;
        while (*buf && *buf != ':')
                buf++;
        if (*buf == '\0')
                return -1;
        *buf++ = 0;

        /* After the read marker and annex, qXfer looks like a
         * traditional 'm' packet. */

        *ofs = strtoul(buf, &separator, 16);

        if (*separator != ',')
                return -1;

        *len = strtoul(separator + 1, NULL, 16);

        return 0;
}

static int gdb_calc_blocksize(struct flash_bank *bank)
{
        uint32_t i;
        uint32_t block_size = 0xffffffff;

        /* loop through all sectors and return smallest sector size */

        for (i = 0; i < (uint32_t)bank->num_sectors; i++)
        {
                if (bank->sectors[i].size < block_size)
                        block_size = bank->sectors[i].size;
        }

        return block_size;
}

static int compare_bank (const void * a, const void * b)
{
        struct flash_bank *b1, *b2;
        b1=*((struct flash_bank **)a);
        b2=*((struct flash_bank **)b);

        if (b1->base == b2->base)
        {
                return 0;
        } else if (b1->base > b2->base)
        {
                return 1;
        } else
        {
                return -1;
        }
}

static int gdb_memory_map(struct connection *connection,
                struct target *target, char *packet, int packet_size)
{
        /* We get away with only specifying flash here. Regions that are not
         * specified are treated as if we provided no memory map(if not we
         * could detect the holes and mark them as RAM).
         * Normally we only execute this code once, but no big deal if we
         * have to regenerate it a couple of times.
         */

        struct flash_bank *p;
        char *xml = NULL;
        int size = 0;
        int pos = 0;
        int retval = ERROR_OK;
        struct flash_bank **banks;
        int offset;
        int length;
        char *separator;
        int blocksize;
        uint32_t ram_start = 0;
        int i;

        /* skip command character */
        packet += 23;

        offset = strtoul(packet, &separator, 16);
        length = strtoul(separator + 1, &separator, 16);

        xml_printf(&retval, &xml, &pos, &size, "<memory-map>\n");

        /* Sort banks in ascending order.  We need to report non-flash
         * memory as ram (or rather read/write) by default for GDB, since
         * it has no concept of non-cacheable read/write memory (i/o etc).
         *
         * FIXME Most non-flash addresses are *NOT* RAM!  Don't lie.
         */
        banks = malloc(sizeof(struct flash_bank *)*flash_get_bank_count());

        for (i = 0; i < flash_get_bank_count(); i++) {
                p = get_flash_bank_by_num(i);
                if (p == NULL) {
                        free(banks);
                        retval = ERROR_FAIL;
                        gdb_send_error(connection, retval);
                        return retval;
                }
                banks[i] = p;
        }

        qsort(banks, flash_get_bank_count(), sizeof(struct flash_bank *),
                        compare_bank);

        for (i = 0; i < flash_get_bank_count(); i++) {
                p = banks[i];

                if (ram_start < p->base)
                        xml_printf(&retval, &xml, &pos, &size,
                                "<memory type=\"ram\" start=\"0x%x\" "
                                        "length=\"0x%x\"/>\n",
                                ram_start, p->base-ram_start);

                /* If device has uneven sector sizes, eg. str7, lpc
                 * we pass the smallest sector size to gdb memory map
                 *
                 * FIXME Don't lie about flash regions with different
                 * sector sizes; just tell GDB about each region as
                 * if it were a separate flash device.
                 */
                blocksize = gdb_calc_blocksize(p);

                xml_printf(&retval, &xml, &pos, &size,
                        "<memory type=\"flash\" start=\"0x%x\" "
                                "length=\"0x%x\">\n" \
                        "<property name=\"blocksize\">0x%x</property>\n" \
                        "</memory>\n", \
                        p->base, p->size, blocksize);
                ram_start = p->base + p->size;
        }

        if (ram_start != 0)
                xml_printf(&retval, &xml, &pos, &size,
                        "<memory type=\"ram\" start=\"0x%x\" "
                                "length=\"0x%x\"/>\n",
                        ram_start, 0-ram_start);
        /* ELSE a flash chip could be at the very end of the 32 bit address
         * space, in which case ram_start will be precisely 0
         */

        free(banks);
        banks = NULL;

        xml_printf(&retval, &xml, &pos, &size, "</memory-map>\n");

        if (retval != ERROR_OK) {
                gdb_send_error(connection, retval);
                return retval;
        }

        if (offset + length > pos)
                length = pos - offset;

        char *t = malloc(length + 1);
        t[0] = 'l';
        memcpy(t + 1, xml + offset, length);
        gdb_put_packet(connection, t, length + 1);

        free(t);
        free(xml);
        return ERROR_OK;
}

static int gdb_query_packet(struct connection *connection,
        struct target *target, char *packet, int packet_size)
{
        struct command_context *cmd_ctx = connection->cmd_ctx;
        struct gdb_connection *gdb_connection = connection->priv;

        if (strstr(packet, "qRcmd,"))
        {
                if (packet_size > 6)
                {
                        char *cmd;
                        int i;
                        cmd = malloc((packet_size - 6)/2 + 1);
                        for (i = 0; i < (packet_size - 6)/2; i++)
                        {
                                uint32_t tmp;
                                sscanf(packet + 6 + 2*i, "%2" SCNx32 , &tmp);
                                cmd[i] = tmp;
                        }
                        cmd[(packet_size - 6)/2] = 0x0;

                        /* We want to print all debug output to GDB connection */
                        log_add_callback(gdb_log_callback, connection);
                        target_call_timer_callbacks_now();
                        /* some commands need to know the GDB connection, make note of current
                         * GDB connection. */
                        current_gdb_connection = gdb_connection;
                        command_run_line(cmd_ctx, cmd);
                        current_gdb_connection = NULL;
                        target_call_timer_callbacks_now();
                        log_remove_callback(gdb_log_callback, connection);
                        free(cmd);
                }
                gdb_put_packet(connection, "OK", 2);
                return ERROR_OK;
        }
        else if (strstr(packet, "qCRC:"))
        {
                if (packet_size > 5)
                {
                        int retval;
                        char gdb_reply[10];
                        char *separator;
                        uint32_t checksum;
                        uint32_t addr = 0;
                        uint32_t len = 0;

                        /* skip command character */
                        packet += 5;

                        addr = strtoul(packet, &separator, 16);

                        if (*separator != ',')
                        {
                                LOG_ERROR("incomplete read memory packet received, dropping connection");
                                return ERROR_SERVER_REMOTE_CLOSED;
                        }

                        len = strtoul(separator + 1, NULL, 16);

                        retval = target_checksum_memory(target, addr, len, &checksum);

                        if (retval == ERROR_OK)
                        {
                                snprintf(gdb_reply, 10, "C%8.8" PRIx32 "", checksum);
                                gdb_put_packet(connection, gdb_reply, 9);
                        }
                        else
                        {
                                if ((retval = gdb_error(connection, retval)) != ERROR_OK)
                                        return retval;
                        }

                        return ERROR_OK;
                }
        }
        else if (strstr(packet, "qSupported"))
        {
                /* we currently support packet size and qXfer:memory-map:read (if enabled)
                 * disable qXfer:features:read for the moment */
                int retval = ERROR_OK;
                char *buffer = NULL;
                int pos = 0;
                int size = 0;

                xml_printf(&retval, &buffer, &pos, &size,
                                "PacketSize=%x;qXfer:memory-map:read%c;qXfer:features:read-;QStartNoAckMode+",
                                (GDB_BUFFER_SIZE - 1), ((gdb_use_memory_map == 1) && (flash_get_bank_count() > 0)) ? '+' : '-');

                if (retval != ERROR_OK)
                {
                        gdb_send_error(connection, 01);
                        return ERROR_OK;
                }

                gdb_put_packet(connection, buffer, strlen(buffer));
                free(buffer);

                return ERROR_OK;
        }
        else if (strstr(packet, "qXfer:memory-map:read::")
                        && (flash_get_bank_count() > 0))
                return gdb_memory_map(connection, target, packet, packet_size);
        else if (strstr(packet, "qXfer:features:read:"))
        {
                char *xml = NULL;
                int size = 0;
                int pos = 0;
                int retval = ERROR_OK;

                int offset;
                unsigned int length;
                char *annex;

                /* skip command character */
                packet += 20;

                if (decode_xfer_read(packet, &annex, &offset, &length) < 0)
                {
                        gdb_send_error(connection, 01);
                        return ERROR_OK;
                }

                if (strcmp(annex, "target.xml") != 0)
                {
                        gdb_send_error(connection, 01);
                        return ERROR_OK;
                }

                xml_printf(&retval, &xml, &pos, &size, \
                        "l < target version=\"1.0\">\n < architecture > arm</architecture>\n</target>\n");

                if (retval != ERROR_OK)
                {
                        gdb_send_error(connection, retval);
                        return retval;
                }

                gdb_put_packet(connection, xml, strlen(xml));

                free(xml);
                return ERROR_OK;
        }
        else if (strstr(packet, "QStartNoAckMode"))
        {
                gdb_connection->noack_mode = 1;
                gdb_put_packet(connection, "OK", 2);
                return ERROR_OK;
        }

        gdb_put_packet(connection, "", 0);
        return ERROR_OK;
}

static int gdb_v_packet(struct connection *connection,
                struct target *target, char *packet, int packet_size)
{
        struct gdb_connection *gdb_connection = connection->priv;
        struct gdb_service *gdb_service = connection->service->priv;
        int result;

        /* if flash programming disabled - send a empty reply */

        if (gdb_flash_program == 0)
        {
                gdb_put_packet(connection, "", 0);
                return ERROR_OK;
        }

        if (strstr(packet, "vFlashErase:"))
        {
                unsigned long addr;
                unsigned long length;

                char *parse = packet + 12;
                if (*parse == '\0')
                {
                        LOG_ERROR("incomplete vFlashErase packet received, dropping connection");
                        return ERROR_SERVER_REMOTE_CLOSED;
                }

                addr = strtoul(parse, &parse, 16);

                if (*(parse++) != ',' || *parse == '\0')
                {
                        LOG_ERROR("incomplete vFlashErase packet received, dropping connection");
                        return ERROR_SERVER_REMOTE_CLOSED;
                }

                length = strtoul(parse, &parse, 16);

                if (*parse != '\0')
                {
                        LOG_ERROR("incomplete vFlashErase packet received, dropping connection");
                        return ERROR_SERVER_REMOTE_CLOSED;
                }

                /* assume all sectors need erasing - stops any problems
                 * when flash_write is called multiple times */
                flash_set_dirty();

                /* perform any target specific operations before the erase */
                target_call_event_callbacks(gdb_service->target,
                                TARGET_EVENT_GDB_FLASH_ERASE_START);

                /* vFlashErase:addr,length messages require region start and
                 * end to be "block" aligned ... if padding is ever needed,
                 * GDB will have become dangerously confused.
                 */
                result = flash_erase_address_range(gdb_service->target,
                                false, addr, length);

                /* perform any target specific operations after the erase */
                target_call_event_callbacks(gdb_service->target,
                                TARGET_EVENT_GDB_FLASH_ERASE_END);

                /* perform erase */
                if (result != ERROR_OK)
                {
                        /* GDB doesn't evaluate the actual error number returned,
                         * treat a failed erase as an I/O error
                         */
                        gdb_send_error(connection, EIO);
                        LOG_ERROR("flash_erase returned %i", result);
                }
                else
                        gdb_put_packet(connection, "OK", 2);

                return ERROR_OK;
        }

        if (strstr(packet, "vFlashWrite:"))
        {
                int retval;
                unsigned long addr;
                unsigned long length;
                char *parse = packet + 12;

                if (*parse == '\0')
                {
                        LOG_ERROR("incomplete vFlashErase packet received, dropping connection");
                        return ERROR_SERVER_REMOTE_CLOSED;
                }
                addr = strtoul(parse, &parse, 16);
                if (*(parse++) != ':')
                {
                        LOG_ERROR("incomplete vFlashErase packet received, dropping connection");
                        return ERROR_SERVER_REMOTE_CLOSED;
                }
                length = packet_size - (parse - packet);

                /* create a new image if there isn't already one */
                if (gdb_connection->vflash_image == NULL)
                {
                        gdb_connection->vflash_image = malloc(sizeof(struct image));
                        image_open(gdb_connection->vflash_image, "", "build");
                }

                /* create new section with content from packet buffer */
                if ((retval = image_add_section(gdb_connection->vflash_image, addr, length, 0x0, (uint8_t*)parse)) != ERROR_OK)
                {
                        return retval;
                }

                gdb_put_packet(connection, "OK", 2);

                return ERROR_OK;
        }

        if (!strcmp(packet, "vFlashDone"))
        {
                uint32_t written;

                /* process the flashing buffer. No need to erase as GDB
                 * always issues a vFlashErase first. */
                target_call_event_callbacks(gdb_service->target, TARGET_EVENT_GDB_FLASH_WRITE_START);
                result = flash_write(gdb_service->target, gdb_connection->vflash_image, &written, 0);
                target_call_event_callbacks(gdb_service->target, TARGET_EVENT_GDB_FLASH_WRITE_END);
                if (result != ERROR_OK)
                {
                        if (result == ERROR_FLASH_DST_OUT_OF_BANK)
                                gdb_put_packet(connection, "E.memtype", 9);
                        else
                                gdb_send_error(connection, EIO);
                        }
                else
                {
                        LOG_DEBUG("wrote %u bytes from vFlash image to flash", (unsigned)written);
                        gdb_put_packet(connection, "OK", 2);
                }

                image_close(gdb_connection->vflash_image);
                free(gdb_connection->vflash_image);
                gdb_connection->vflash_image = NULL;

                return ERROR_OK;
        }

        gdb_put_packet(connection, "", 0);
        return ERROR_OK;
}

static int gdb_detach(struct connection *connection, struct target *target)
{
        struct gdb_service *gdb_service = connection->service->priv;

        target_call_event_callbacks(gdb_service->target,
                        TARGET_EVENT_GDB_DETACH);

        return gdb_put_packet(connection, "OK", 2);
}

static void gdb_log_callback(void *priv, const char *file, unsigned line,
                const char *function, const char *string)
{
        struct connection *connection = priv;
        struct gdb_connection *gdb_con = connection->priv;

        if (gdb_con->busy)
        {
                /* do not reply this using the O packet */
                return;
        }

        gdb_output_con(connection, string);
}

static void gdb_sig_halted(struct connection *connection)
{
        char sig_reply[4];
        snprintf(sig_reply, 4, "T%2.2x", 2);
        gdb_put_packet(connection, sig_reply, 3);

}

static int gdb_input_inner(struct connection *connection)
{
        /* Do not allocate this on the stack */
        static char gdb_packet_buffer[GDB_BUFFER_SIZE];

        struct gdb_service *gdb_service = connection->service->priv;
        struct target *target = gdb_service->target;
        char *packet = gdb_packet_buffer;
        int packet_size;
        int retval;
        struct gdb_connection *gdb_con = connection->priv;
        static int extended_protocol = 0;

        /* drain input buffer */
        do
        {
                packet_size = GDB_BUFFER_SIZE-1;
                retval = gdb_get_packet(connection, packet, &packet_size);
                if (retval != ERROR_OK)
                        return retval;

                /* terminate with zero */
                packet[packet_size] = 0;

                if (LOG_LEVEL_IS(LOG_LVL_DEBUG)) {
                        if (packet[0] == 'X') {
                                // binary packets spew junk into the debug log stream
                                char buf[ 50 ];
                                int x;
                                for (x = 0 ; (x < 49) && (packet[x] != ':') ; x++) {
                                        buf[x] = packet[x];
                                }
                                buf[x] = 0;
                                LOG_DEBUG("received packet: '%s:<binary-data>'", buf);
                        } else {
                                LOG_DEBUG("received packet: '%s'", packet);
                        }
                }

                if (packet_size > 0)
                {
                        retval = ERROR_OK;
                        switch (packet[0])
                        {
                                case 'H':
                                        /* Hct... -- set thread
                                         * we don't have threads, send empty reply */
                                        gdb_put_packet(connection, NULL, 0);
                                        break;
                                case 'q':
                                case 'Q':
                                        retval = gdb_query_packet(connection,
                                                        target, packet,
                                                        packet_size);
                                        break;
                                case 'g':
                                        retval = gdb_get_registers_packet(
                                                        connection, target,
                                                        packet, packet_size);
                                        break;
                                case 'G':
                                        retval = gdb_set_registers_packet(
                                                        connection, target,
                                                        packet, packet_size);
                                        break;
                                case 'p':
                                        retval = gdb_get_register_packet(
                                                        connection, target,
                                                        packet, packet_size);
                                        break;
                                case 'P':
                                        retval = gdb_set_register_packet(
                                                        connection, target,
                                                        packet, packet_size);
                                        break;
                                case 'm':
                                        retval = gdb_read_memory_packet(
                                                        connection, target,
                                                        packet, packet_size);
                                        break;
                                case 'M':
                                        retval = gdb_write_memory_packet(
                                                        connection, target,
                                                        packet, packet_size);
                                        break;
                                case 'z':
                                case 'Z':
                                        retval = gdb_breakpoint_watchpoint_packet(connection, target, packet, packet_size);
                                        break;
                                case '?':
                                        gdb_last_signal_packet(
                                                        connection, target,
                                                        packet, packet_size);
                                        break;
                                case 'c':
                                case 's':
                                        {
                                                int retval = ERROR_OK;

                                                struct gdb_connection *gdb_con = connection->priv;
                                                log_add_callback(gdb_log_callback, connection);

                                                bool nostep = false;
                                                if (target->state == TARGET_RUNNING)
                                                {
                                                        LOG_WARNING("The target is already running. Halt target before stepi/continue.");
                                                        retval = target_halt(target);
                                                        if (retval == ERROR_OK)
                                                                retval = target_wait_state(target, TARGET_HALTED, 100);
                                                } else if (target->state != TARGET_HALTED)
                                                {
                                                        LOG_WARNING("The target is not in the halted nor running stated, stepi/continue ignored.");
                                                        nostep = true;
                                                } else if ((packet[0] == 's') && gdb_con->sync)
                                                {
                                                        /* Hmm..... when you issue a continue in GDB, then a "stepi" is
                                                         * sent by GDB first to OpenOCD, thus defeating the check to
                                                         * make only the single stepping have the sync feature...
                                                         */
                                                        nostep = true;
                                                        LOG_WARNING("stepi ignored. GDB will now fetch the register state from the target.");
                                                }
                                                gdb_con->sync = false;

                                                if ((retval!=ERROR_OK) || nostep)
                                                {
                                                        /* Either the target isn't in the halted state, then we can't
                                                         * step/continue. This might be early setup, etc.
                                                         *
                                                         * Or we want to allow GDB to pick up a fresh set of
                                                         * register values without modifying the target state.
                                                         *
                                                         */
                                                        gdb_sig_halted(connection);

                                                        /* stop forwarding log packets! */
                                                        log_remove_callback(gdb_log_callback, connection);
                                                } else
                                                {
                                                        /* We're running/stepping, in which case we can
                                                         * forward log output until the target is halted
                                                         */
                                                        gdb_con->frontend_state = TARGET_RUNNING;
                                                        target_call_event_callbacks(target, TARGET_EVENT_GDB_START);
                                                        int retval = gdb_step_continue_packet(connection, target, packet, packet_size);
                                                        if (retval != ERROR_OK)
                                                        {
                                                                /* we'll never receive a halted condition... issue a false one.. */
                                                                gdb_frontend_halted(target, connection);
                                                        }
                                                }
                                        }
                                        break;
                                case 'v':
                                        retval = gdb_v_packet(
                                                        connection, target,
                                                        packet, packet_size);
                                        break;
                                case 'D':
                                        retval = gdb_detach(connection, target);
                                        extended_protocol = 0;
                                        break;
                                case 'X':
                                        retval = gdb_write_memory_binary_packet(
                                                        connection, target,
                                                        packet, packet_size);
                                        if (retval != ERROR_OK)
                                                return retval;
                                        break;
                                case 'k':
                                        if (extended_protocol != 0)
                                                break;
                                        gdb_put_packet(connection, "OK", 2);
                                        return ERROR_SERVER_REMOTE_CLOSED;
                                case '!':
                                        /* handle extended remote protocol */
                                        extended_protocol = 1;
                                        gdb_put_packet(connection, "OK", 2);
                                        break;
                                case 'R':
                                        /* handle extended restart packet */
                                        breakpoint_clear_target(gdb_service->target);
                                        watchpoint_clear_target(gdb_service->target);
                                        command_run_linef(connection->cmd_ctx,
                                                        "ocd_gdb_restart %s",
                                                        target_name(target));
                                        break;
                                default:
                                        /* ignore unknown packets */
                                        LOG_DEBUG("ignoring 0x%2.2x packet", packet[0]);
                                        gdb_put_packet(connection, NULL, 0);
                                        break;
                        }

                        /* if a packet handler returned an error, exit input loop */
                        if (retval != ERROR_OK)
                                return retval;
                }

                if (gdb_con->ctrl_c)
                {
                        if (target->state == TARGET_RUNNING)
                        {
                                retval = target_halt(target);
                                if (retval != ERROR_OK)
                                {
                                        target_call_event_callbacks(target, TARGET_EVENT_GDB_HALT);
                                }
                                gdb_con->ctrl_c = 0;
                        } else
                        {
                                LOG_INFO("The target is not running when halt was requested, stopping GDB.");
                                target_call_event_callbacks(target, TARGET_EVENT_GDB_HALT);
                        }
                }

        } while (gdb_con->buf_cnt > 0);

        return ERROR_OK;
}

static int gdb_input(struct connection *connection)
{
        int retval = gdb_input_inner(connection);
        struct gdb_connection *gdb_con = connection->priv;
        if (retval == ERROR_SERVER_REMOTE_CLOSED)
                return retval;

        /* logging does not propagate the error, yet can set the gdb_con->closed flag */
        if (gdb_con->closed)
                return ERROR_SERVER_REMOTE_CLOSED;

        /* we'll recover from any other errors(e.g. temporary timeouts, etc.) */
        return ERROR_OK;
}

static int gdb_target_start(struct target *target, uint16_t port)
{
        bool use_pipes = 0 == port;
        struct gdb_service *gdb_service = malloc(sizeof(struct gdb_service));
        if (NULL == gdb_service)
                return -ENOMEM;

        gdb_service->target = target;

        add_service("gdb", use_pipes ? CONNECTION_PIPE : CONNECTION_TCP,
                        port, 1, &gdb_new_connection, &gdb_input,
                        &gdb_connection_closed, gdb_service);

        const char *name = target_name(target);
        if (use_pipes)
                LOG_DEBUG("gdb service for target '%s' using pipes", name);
        else
                LOG_DEBUG("gdb service for target '%s' on TCP port %u", name, port);
        return ERROR_OK;
}

static int gdb_target_add_one(struct target *target)
{
        if (gdb_port == 0 && server_use_pipes == 0)
        {
                LOG_INFO("gdb port disabled");
                return ERROR_OK;
        }
        if (0 == gdb_port_next)
                gdb_port_next = gdb_port;

        bool use_pipes = server_use_pipes;
        static bool server_started_with_pipes = false;
        if (server_started_with_pipes)
        {
                LOG_WARNING("gdb service permits one target when using pipes");
                if (0 == gdb_port)
                        return ERROR_OK;

                use_pipes = false;
        }

        int e = gdb_target_start(target, use_pipes ? 0 : gdb_port_next);
        if (ERROR_OK == e)
        {
                server_started_with_pipes |= use_pipes;
                gdb_port_next++;
        }
        return e;
}

int gdb_target_add_all(struct target *target)
{
        if (NULL == target)
        {
                LOG_WARNING("gdb services need one or more targets defined");
                return ERROR_OK;
        }

        while (NULL != target)
        {
                int retval = gdb_target_add_one(target);
                if (ERROR_OK != retval)
                        return retval;

                target = target->next;
        }

        return ERROR_OK;
}

COMMAND_HANDLER(handle_gdb_sync_command)
{
        if (CMD_ARGC != 0)
        {
                return ERROR_COMMAND_SYNTAX_ERROR;
        }

        if (current_gdb_connection == NULL)
        {
                command_print(CMD_CTX,
                                "gdb_sync command can only be run from within gdb using \"monitor gdb_sync\"");
                return ERROR_FAIL;
        }

        current_gdb_connection->sync = true;

        return ERROR_OK;
}

/* daemon configuration command gdb_port */
COMMAND_HANDLER(handle_gdb_port_command)
{
        int retval = CALL_COMMAND_HANDLER(server_port_command, &gdb_port);
        if (ERROR_OK == retval)
                gdb_port_next = gdb_port;
        return retval;
}

COMMAND_HANDLER(handle_gdb_memory_map_command)
{
        if (CMD_ARGC == 1)
                COMMAND_PARSE_ENABLE(CMD_ARGV[0], gdb_use_memory_map);

        return ERROR_COMMAND_SYNTAX_ERROR;
}

COMMAND_HANDLER(handle_gdb_flash_program_command)
{
        if (CMD_ARGC == 1)
                COMMAND_PARSE_ENABLE(CMD_ARGV[0], gdb_flash_program);

        return ERROR_COMMAND_SYNTAX_ERROR;
}

COMMAND_HANDLER(handle_gdb_report_data_abort_command)
{
        if (CMD_ARGC == 1)
                COMMAND_PARSE_ENABLE(CMD_ARGV[0], gdb_report_data_abort);

        return ERROR_COMMAND_SYNTAX_ERROR;
}

/* gdb_breakpoint_override */
COMMAND_HANDLER(handle_gdb_breakpoint_override_command)
{
        if (CMD_ARGC == 0)
        {

        } else if (CMD_ARGC == 1)
        {
                gdb_breakpoint_override = 1;
                if (strcmp(CMD_ARGV[0], "hard") == 0)
                {
                        gdb_breakpoint_override_type = BKPT_HARD;
                } else if (strcmp(CMD_ARGV[0], "soft") == 0)
                {
                        gdb_breakpoint_override_type = BKPT_SOFT;
                } else if (strcmp(CMD_ARGV[0], "disable") == 0)
                {
                        gdb_breakpoint_override = 0;
                }
        } else
        {
                return ERROR_COMMAND_SYNTAX_ERROR;
        }
        if (gdb_breakpoint_override)
        {
                LOG_USER("force %s breakpoints", (gdb_breakpoint_override_type == BKPT_HARD)?"hard":"soft");
        } else
        {
                LOG_USER("breakpoint type is not overridden");
        }

        return ERROR_OK;
}

static const struct command_registration gdb_command_handlers[] = {
        {
                .name = "gdb_sync",
                .handler = handle_gdb_sync_command,
                .mode = COMMAND_ANY,
                .help = "next stepi will return immediately allowing "
                        "GDB to fetch register state without affecting "
                        "target state",
        },
        {
                .name = "gdb_port",
                .handler = handle_gdb_port_command,
                .mode = COMMAND_ANY,
                .help = "Display or specify base port on which to listen "
                        "for incoming GDB connections.  "
                        "No arguments reports GDB port; zero disables.",
                .usage = "[port_num]",
        },
        {
                .name = "gdb_memory_map",
                .handler = handle_gdb_memory_map_command,
                .mode = COMMAND_CONFIG,
                .help = "enable or disable memory map",
                .usage = "('enable'|'disable')"
        },
        {
                .name = "gdb_flash_program",
                .handler = handle_gdb_flash_program_command,
                .mode = COMMAND_CONFIG,
                .help = "enable or disable flash program",
                .usage = "('enable'|'disable')"
        },
        {
                .name = "gdb_report_data_abort",
                .handler = handle_gdb_report_data_abort_command,
                .mode = COMMAND_CONFIG,
                .help = "enable or disable reporting data aborts",
                .usage = "('enable'|'disable')"
        },
        {
                .name = "gdb_breakpoint_override",
                .handler = handle_gdb_breakpoint_override_command,
                .mode = COMMAND_ANY,
                .help = "Display or specify type of breakpoint "
                        "to be used by gdb 'break' commands.",
                .usage = "('hard'|'soft'|'disable')"
        },
        COMMAND_REGISTRATION_DONE
};

int gdb_register_commands(struct command_context *cmd_ctx)
{
        return register_commands(cmd_ctx, NULL, gdb_command_handlers);
}