Archipelago » qemu

/*

 * QEMU System Emulator

 *

 * Copyright (c) 2003-2008 Fabrice Bellard

 *

 * Permission is hereby granted, free of charge, to any person obtaining a copy

 * of this software and associated documentation files (the "Software"), to deal

 * in the Software without restriction, including without limitation the rights

 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell

 * copies of the Software, and to permit persons to whom the Software is

 * furnished to do so, subject to the following conditions:

 *

 * The above copyright notice and this permission notice shall be included in

 * all copies or substantial portions of the Software.

 *

 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR

 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,

 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL

 * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER

 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,

 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN

 * THE SOFTWARE.

 */

#include <unistd.h>

#include <fcntl.h>

#include <signal.h>

#include <time.h>

#include <errno.h>

#include <sys/time.h>

#include <zlib.h>

/* Needed early for CONFIG_BSD etc. */

#include "config-host.h"

#ifndef _WIN32

#include <sys/times.h>

#include <sys/wait.h>

#include <termios.h>

#include <sys/mman.h>

#include <sys/ioctl.h>

#include <sys/resource.h>

#include <sys/socket.h>

#include <netinet/in.h>

#include <net/if.h>

#if defined(__NetBSD__)

#include <net/if_tap.h>

#endif

#ifdef __linux__

#include <linux/if_tun.h>

#endif

#include <arpa/inet.h>

#include <dirent.h>

#include <netdb.h>

#include <sys/select.h>

#ifdef CONFIG_BSD

#include <sys/stat.h>

#if defined(__FreeBSD__) || defined(__DragonFly__)

#include <libutil.h>

#else

#include <util.h>

#endif

#elif defined (__GLIBC__) && defined (__FreeBSD_kernel__)

#include <freebsd/stdlib.h>

#else

#ifdef __linux__

#include <pty.h>

#include <malloc.h>

#include <linux/rtc.h>

#endif

#endif

#endif

#ifdef _WIN32

#include <windows.h>

#include <malloc.h>

#include <sys/timeb.h>

#include <mmsystem.h>

#define getopt_long_only getopt_long

#define memalign(align, size) malloc(size)

#endif

#include "qemu-common.h"

#include "hw/hw.h"

#include "net.h"

#include "monitor.h"

#include "sysemu.h"

#include "qemu-timer.h"

#include "qemu-char.h"

#include "block.h"

#include "audio/audio.h"

#include "migration.h"

#include "qemu_socket.h"

/* point to the block driver where the snapshots are managed */

static BlockDriverState *bs_snapshots;

#define SELF_ANNOUNCE_ROUNDS 5

#define ETH_P_EXPERIMENTAL 0x01F1 /* just a number */

//#define ETH_P_EXPERIMENTAL 0x0012 /* make it the size of the packet */

#define EXPERIMENTAL_MAGIC 0xf1f23f4f

static int announce_self_create(uint8_t *buf, 

                                uint8_t *mac_addr)

{

    uint32_t magic = EXPERIMENTAL_MAGIC;

    uint16_t proto = htons(ETH_P_EXPERIMENTAL);

    /* FIXME: should we send a different packet (arp/rarp/ping)? */

    memset(buf, 0, 64);

    memset(buf, 0xff, 6);         /* h_dst */

    memcpy(buf + 6, mac_addr, 6); /* h_src */

    memcpy(buf + 12, &proto, 2);  /* h_proto */

    memcpy(buf + 14, &magic, 4);  /* magic */

    return 64; /* len */

}

static void qemu_announce_self_once(void *opaque)

{

    int i, len;

    VLANState *vlan;

    VLANClientState *vc;

    uint8_t buf[256];

    static int count = SELF_ANNOUNCE_ROUNDS;

    QEMUTimer *timer = *(QEMUTimer **)opaque;

    for (i = 0; i < MAX_NICS; i++) {

        if (!nd_table[i].used)

            continue;

        len = announce_self_create(buf, nd_table[i].macaddr);

        vlan = nd_table[i].vlan;

        for(vc = vlan->first_client; vc != NULL; vc = vc->next) {

            vc->receive(vc, buf, len);

        }

    }

    if (count--) {

            qemu_mod_timer(timer, qemu_get_clock(rt_clock) + 100);

    } else {

            qemu_del_timer(timer);

            qemu_free_timer(timer);

    }

}

void qemu_announce_self(void)

{

        static QEMUTimer *timer;

        timer = qemu_new_timer(rt_clock, qemu_announce_self_once, &timer);

        qemu_announce_self_once(&timer);

}

/***********************************************************/

/* savevm/loadvm support */

#define IO_BUF_SIZE 32768

struct QEMUFile {

    QEMUFilePutBufferFunc *put_buffer;

    QEMUFileGetBufferFunc *get_buffer;

    QEMUFileCloseFunc *close;

    QEMUFileRateLimit *rate_limit;

    QEMUFileSetRateLimit *set_rate_limit;

    void *opaque;

    int is_write;

    int64_t buf_offset; /* start of buffer when writing, end of buffer

                           when reading */

    int buf_index;

    int buf_size; /* 0 when writing */

    uint8_t buf[IO_BUF_SIZE];

    int has_error;

};

typedef struct QEMUFileStdio

{

    FILE *stdio_file;

    QEMUFile *file;

} QEMUFileStdio;

typedef struct QEMUFileSocket

{

    int fd;

    QEMUFile *file;

} QEMUFileSocket;

static int socket_get_buffer(void *opaque, uint8_t *buf, int64_t pos, int size)

{

    QEMUFileSocket *s = opaque;

    ssize_t len;

    do {

        len = recv(s->fd, (void *)buf, size, 0);

    } while (len == -1 && socket_error() == EINTR);

    if (len == -1)

        len = -socket_error();

    return len;

}

static int socket_close(void *opaque)

{

    QEMUFileSocket *s = opaque;

    qemu_free(s);

    return 0;

}

static int stdio_put_buffer(void *opaque, const uint8_t *buf, int64_t pos, int size)

{

    QEMUFileStdio *s = opaque;

    return fwrite(buf, 1, size, s->stdio_file);

}

static int stdio_get_buffer(void *opaque, uint8_t *buf, int64_t pos, int size)

{

    QEMUFileStdio *s = opaque;

    FILE *fp = s->stdio_file;

    int bytes;

    do {

        clearerr(fp);

        bytes = fread(buf, 1, size, fp);

    } while ((bytes == 0) && ferror(fp) && (errno == EINTR));

    return bytes;

}

static int stdio_pclose(void *opaque)

{

    QEMUFileStdio *s = opaque;

    pclose(s->stdio_file);

    qemu_free(s);

    return 0;

}

static int stdio_fclose(void *opaque)

{

    QEMUFileStdio *s = opaque;

    fclose(s->stdio_file);

    qemu_free(s);

    return 0;

}

QEMUFile *qemu_popen(FILE *stdio_file, const char *mode)

{

    QEMUFileStdio *s;

    if (stdio_file == NULL || mode == NULL || (mode[0] != 'r' && mode[0] != 'w') || mode[1] != 0) {

        fprintf(stderr, "qemu_popen: Argument validity check failed\n");

        return NULL;

    }

    s = qemu_mallocz(sizeof(QEMUFileStdio));

    s->stdio_file = stdio_file;

    if(mode[0] == 'r') {

        s->file = qemu_fopen_ops(s, NULL, stdio_get_buffer, stdio_pclose, NULL, NULL);

    } else {

        s->file = qemu_fopen_ops(s, stdio_put_buffer, NULL, stdio_pclose, NULL, NULL);

    }

    return s->file;

}

QEMUFile *qemu_popen_cmd(const char *command, const char *mode)

{

    FILE *popen_file;

    popen_file = popen(command, mode);

    if(popen_file == NULL) {

        return NULL;

    }

    return qemu_popen(popen_file, mode);

}

int qemu_stdio_fd(QEMUFile *f)

{

    QEMUFileStdio *p;

    int fd;

    p = (QEMUFileStdio *)f->opaque;

    fd = fileno(p->stdio_file);

    return fd;

}

QEMUFile *qemu_fdopen(int fd, const char *mode)

{

    QEMUFileStdio *s;

    if (mode == NULL ||

        (mode[0] != 'r' && mode[0] != 'w') ||

        mode[1] != 'b' || mode[2] != 0) {

        fprintf(stderr, "qemu_fdopen: Argument validity check failed\n");

        return NULL;

    }

    s = qemu_mallocz(sizeof(QEMUFileStdio));

    s->stdio_file = fdopen(fd, mode);

    if (!s->stdio_file)

        goto fail;

    if(mode[0] == 'r') {

        s->file = qemu_fopen_ops(s, NULL, stdio_get_buffer, stdio_fclose, NULL, NULL);

    } else {

        s->file = qemu_fopen_ops(s, stdio_put_buffer, NULL, stdio_fclose, NULL, NULL);

    }

    return s->file;

fail:

    qemu_free(s);

    return NULL;

}

QEMUFile *qemu_fopen_socket(int fd)

{

    QEMUFileSocket *s = qemu_mallocz(sizeof(QEMUFileSocket));

    s->fd = fd;

    s->file = qemu_fopen_ops(s, NULL, socket_get_buffer, socket_close, NULL, NULL);

    return s->file;

}

static int file_put_buffer(void *opaque, const uint8_t *buf,

                            int64_t pos, int size)

{

    QEMUFileStdio *s = opaque;

    fseek(s->stdio_file, pos, SEEK_SET);

    fwrite(buf, 1, size, s->stdio_file);

    return size;

}

static int file_get_buffer(void *opaque, uint8_t *buf, int64_t pos, int size)

{

    QEMUFileStdio *s = opaque;

    fseek(s->stdio_file, pos, SEEK_SET);

    return fread(buf, 1, size, s->stdio_file);

}

QEMUFile *qemu_fopen(const char *filename, const char *mode)

{

    QEMUFileStdio *s;

    if (mode == NULL ||

        (mode[0] != 'r' && mode[0] != 'w') ||

        mode[1] != 'b' || mode[2] != 0) {

        fprintf(stderr, "qemu_fdopen: Argument validity check failed\n");

        return NULL;

    }

    s = qemu_mallocz(sizeof(QEMUFileStdio));

    s->stdio_file = fopen(filename, mode);

    if (!s->stdio_file)

        goto fail;

    if(mode[0] == 'w') {

        s->file = qemu_fopen_ops(s, file_put_buffer, NULL, stdio_fclose, NULL, NULL);

    } else {

        s->file = qemu_fopen_ops(s, NULL, file_get_buffer, stdio_fclose, NULL, NULL);

    }

    return s->file;

fail:

    qemu_free(s);

    return NULL;

}

static int block_put_buffer(void *opaque, const uint8_t *buf,

                           int64_t pos, int size)

{

    bdrv_save_vmstate(opaque, buf, pos, size);

    return size;

}

static int block_get_buffer(void *opaque, uint8_t *buf, int64_t pos, int size)

{

    return bdrv_load_vmstate(opaque, buf, pos, size);

}

static int bdrv_fclose(void *opaque)

{

    return 0;

}

static QEMUFile *qemu_fopen_bdrv(BlockDriverState *bs, int is_writable)

{

    if (is_writable)

        return qemu_fopen_ops(bs, block_put_buffer, NULL, bdrv_fclose, NULL, NULL);

    return qemu_fopen_ops(bs, NULL, block_get_buffer, bdrv_fclose, NULL, NULL);

}

QEMUFile *qemu_fopen_ops(void *opaque, QEMUFilePutBufferFunc *put_buffer,

                         QEMUFileGetBufferFunc *get_buffer,

                         QEMUFileCloseFunc *close,

                         QEMUFileRateLimit *rate_limit,

                         QEMUFileSetRateLimit *set_rate_limit)

{

    QEMUFile *f;

    f = qemu_mallocz(sizeof(QEMUFile));

    f->opaque = opaque;

    f->put_buffer = put_buffer;

    f->get_buffer = get_buffer;

    f->close = close;

    f->rate_limit = rate_limit;

    f->set_rate_limit = set_rate_limit;

    f->is_write = 0;

    return f;

}

int qemu_file_has_error(QEMUFile *f)

{

    return f->has_error;

}

void qemu_file_set_error(QEMUFile *f)

{

    f->has_error = 1;

}

void qemu_fflush(QEMUFile *f)

{

    if (!f->put_buffer)

        return;

    if (f->is_write && f->buf_index > 0) {

        int len;

        len = f->put_buffer(f->opaque, f->buf, f->buf_offset, f->buf_index);

        if (len > 0)

            f->buf_offset += f->buf_index;

        else

            f->has_error = 1;

        f->buf_index = 0;

    }

}

static void qemu_fill_buffer(QEMUFile *f)

{

    int len;

    if (!f->get_buffer)

        return;

    if (f->is_write)

        abort();

    len = f->get_buffer(f->opaque, f->buf, f->buf_offset, IO_BUF_SIZE);

    if (len > 0) {

        f->buf_index = 0;

        f->buf_size = len;

        f->buf_offset += len;

    } else if (len != -EAGAIN)

        f->has_error = 1;

}

int qemu_fclose(QEMUFile *f)

{

    int ret = 0;

    qemu_fflush(f);

    if (f->close)

        ret = f->close(f->opaque);

    qemu_free(f);

    return ret;

}

void qemu_file_put_notify(QEMUFile *f)

{

    f->put_buffer(f->opaque, NULL, 0, 0);

}

void qemu_put_buffer(QEMUFile *f, const uint8_t *buf, int size)

{

    int l;

    if (!f->has_error && f->is_write == 0 && f->buf_index > 0) {

        fprintf(stderr,

                "Attempted to write to buffer while read buffer is not empty\n");

        abort();

    }

    while (!f->has_error && size > 0) {

        l = IO_BUF_SIZE - f->buf_index;

        if (l > size)

            l = size;

        memcpy(f->buf + f->buf_index, buf, l);

        f->is_write = 1;

        f->buf_index += l;

        buf += l;

        size -= l;

        if (f->buf_index >= IO_BUF_SIZE)

            qemu_fflush(f);

    }

}

void qemu_put_byte(QEMUFile *f, int v)

{

    if (!f->has_error && f->is_write == 0 && f->buf_index > 0) {

        fprintf(stderr,

                "Attempted to write to buffer while read buffer is not empty\n");

        abort();

    }

    f->buf[f->buf_index++] = v;

    f->is_write = 1;

    if (f->buf_index >= IO_BUF_SIZE)

        qemu_fflush(f);

}

int qemu_get_buffer(QEMUFile *f, uint8_t *buf, int size1)

{

    int size, l;

    if (f->is_write)

        abort();

    size = size1;

    while (size > 0) {

        l = f->buf_size - f->buf_index;

        if (l == 0) {

            qemu_fill_buffer(f);

            l = f->buf_size - f->buf_index;

            if (l == 0)

                break;

        }

        if (l > size)

            l = size;

        memcpy(buf, f->buf + f->buf_index, l);

        f->buf_index += l;

        buf += l;

        size -= l;

    }

    return size1 - size;

}

int qemu_get_byte(QEMUFile *f)

{

    if (f->is_write)

        abort();

    if (f->buf_index >= f->buf_size) {

        qemu_fill_buffer(f);

        if (f->buf_index >= f->buf_size)

            return 0;

    }

    return f->buf[f->buf_index++];

}

int64_t qemu_ftell(QEMUFile *f)

{

    return f->buf_offset - f->buf_size + f->buf_index;

}

int64_t qemu_fseek(QEMUFile *f, int64_t pos, int whence)

{

    if (whence == SEEK_SET) {

        /* nothing to do */

    } else if (whence == SEEK_CUR) {

        pos += qemu_ftell(f);

    } else {

        /* SEEK_END not supported */

        return -1;

    }

    if (f->put_buffer) {

        qemu_fflush(f);

        f->buf_offset = pos;

    } else {

        f->buf_offset = pos;

        f->buf_index = 0;

        f->buf_size = 0;

    }

    return pos;

}

int qemu_file_rate_limit(QEMUFile *f)

{

    if (f->rate_limit)

        return f->rate_limit(f->opaque);

    return 0;

}

size_t qemu_file_set_rate_limit(QEMUFile *f, size_t new_rate)

{

    /* any failed or completed migration keeps its state to allow probing of

     * migration data, but has no associated file anymore */

    if (f && f->set_rate_limit)

        return f->set_rate_limit(f->opaque, new_rate);

    return 0;

}

void qemu_put_be16(QEMUFile *f, unsigned int v)

{

    qemu_put_byte(f, v >> 8);

    qemu_put_byte(f, v);

}

void qemu_put_be32(QEMUFile *f, unsigned int v)

{

    qemu_put_byte(f, v >> 24);

    qemu_put_byte(f, v >> 16);

    qemu_put_byte(f, v >> 8);

    qemu_put_byte(f, v);

}

void qemu_put_be64(QEMUFile *f, uint64_t v)

{

    qemu_put_be32(f, v >> 32);

    qemu_put_be32(f, v);

}

unsigned int qemu_get_be16(QEMUFile *f)

{

    unsigned int v;

    v = qemu_get_byte(f) << 8;

    v |= qemu_get_byte(f);

    return v;

}

unsigned int qemu_get_be32(QEMUFile *f)

{

    unsigned int v;

    v = qemu_get_byte(f) << 24;

    v |= qemu_get_byte(f) << 16;

    v |= qemu_get_byte(f) << 8;

    v |= qemu_get_byte(f);

    return v;

}

uint64_t qemu_get_be64(QEMUFile *f)

{

    uint64_t v;

    v = (uint64_t)qemu_get_be32(f) << 32;

    v |= qemu_get_be32(f);

    return v;

}

typedef struct SaveStateEntry {

    char idstr[256];

    int instance_id;

    int version_id;

    int section_id;

    SaveLiveStateHandler *save_live_state;

    SaveStateHandler *save_state;

    LoadStateHandler *load_state;

    void *opaque;

    struct SaveStateEntry *next;

} SaveStateEntry;

static SaveStateEntry *first_se;

/* TODO: Individual devices generally have very little idea about the rest

   of the system, so instance_id should be removed/replaced.

   Meanwhile pass -1 as instance_id if you do not already have a clearly

   distinguishing id for all instances of your device class. */

int register_savevm_live(const char *idstr,

                         int instance_id,

                         int version_id,

                         SaveLiveStateHandler *save_live_state,

                         SaveStateHandler *save_state,

                         LoadStateHandler *load_state,

                         void *opaque)

{

    SaveStateEntry *se, **pse;

    static int global_section_id;

    se = qemu_malloc(sizeof(SaveStateEntry));

    pstrcpy(se->idstr, sizeof(se->idstr), idstr);

    se->instance_id = (instance_id == -1) ? 0 : instance_id;

    se->version_id = version_id;

    se->section_id = global_section_id++;

    se->save_live_state = save_live_state;

    se->save_state = save_state;

    se->load_state = load_state;

    se->opaque = opaque;

    se->next = NULL;

    /* add at the end of list */

    pse = &first_se;

    while (*pse != NULL) {

        if (instance_id == -1

                && strcmp(se->idstr, (*pse)->idstr) == 0

                && se->instance_id <= (*pse)->instance_id)

            se->instance_id = (*pse)->instance_id + 1;

        pse = &(*pse)->next;

    }

    *pse = se;

    return 0;

}

int register_savevm(const char *idstr,

                    int instance_id,

                    int version_id,

                    SaveStateHandler *save_state,

                    LoadStateHandler *load_state,

                    void *opaque)

{

    return register_savevm_live(idstr, instance_id, version_id,

                                NULL, save_state, load_state, opaque);

}

void unregister_savevm(const char *idstr, void *opaque)

{

    SaveStateEntry **pse;

    pse = &first_se;

    while (*pse != NULL) {

        if (strcmp((*pse)->idstr, idstr) == 0 && (*pse)->opaque == opaque) {

            SaveStateEntry *next = (*pse)->next;

            qemu_free(*pse);

            *pse = next;

            continue;

        }

        pse = &(*pse)->next;

    }

}

#define QEMU_VM_FILE_MAGIC           0x5145564d

#define QEMU_VM_FILE_VERSION_COMPAT  0x00000002

#define QEMU_VM_FILE_VERSION         0x00000003

#define QEMU_VM_EOF                  0x00

#define QEMU_VM_SECTION_START        0x01

#define QEMU_VM_SECTION_PART         0x02

#define QEMU_VM_SECTION_END          0x03

#define QEMU_VM_SECTION_FULL         0x04

int qemu_savevm_state_begin(QEMUFile *f)

{

    SaveStateEntry *se;

    qemu_put_be32(f, QEMU_VM_FILE_MAGIC);

    qemu_put_be32(f, QEMU_VM_FILE_VERSION);

    for (se = first_se; se != NULL; se = se->next) {

        int len;

        if (se->save_live_state == NULL)

            continue;

        /* Section type */

        qemu_put_byte(f, QEMU_VM_SECTION_START);

        qemu_put_be32(f, se->section_id);

        /* ID string */

        len = strlen(se->idstr);

        qemu_put_byte(f, len);

        qemu_put_buffer(f, (uint8_t *)se->idstr, len);

        qemu_put_be32(f, se->instance_id);

        qemu_put_be32(f, se->version_id);

        se->save_live_state(f, QEMU_VM_SECTION_START, se->opaque);

    }

    if (qemu_file_has_error(f))

        return -EIO;

    return 0;

}

int qemu_savevm_state_iterate(QEMUFile *f)

{

    SaveStateEntry *se;

    int ret = 1;

    for (se = first_se; se != NULL; se = se->next) {

        if (se->save_live_state == NULL)

            continue;

        /* Section type */

        qemu_put_byte(f, QEMU_VM_SECTION_PART);

        qemu_put_be32(f, se->section_id);

        ret &= !!se->save_live_state(f, QEMU_VM_SECTION_PART, se->opaque);

    }

    if (ret)

        return 1;

    if (qemu_file_has_error(f))

        return -EIO;

    return 0;

}

int qemu_savevm_state_complete(QEMUFile *f)

{

    SaveStateEntry *se;

    for (se = first_se; se != NULL; se = se->next) {

        if (se->save_live_state == NULL)

            continue;

        /* Section type */

        qemu_put_byte(f, QEMU_VM_SECTION_END);

        qemu_put_be32(f, se->section_id);

        se->save_live_state(f, QEMU_VM_SECTION_END, se->opaque);

    }

    for(se = first_se; se != NULL; se = se->next) {

        int len;

        if (se->save_state == NULL)

            continue;

        /* Section type */

        qemu_put_byte(f, QEMU_VM_SECTION_FULL);

        qemu_put_be32(f, se->section_id);

        /* ID string */

        len = strlen(se->idstr);

        qemu_put_byte(f, len);

        qemu_put_buffer(f, (uint8_t *)se->idstr, len);

        qemu_put_be32(f, se->instance_id);

        qemu_put_be32(f, se->version_id);

        se->save_state(f, se->opaque);

    }

    qemu_put_byte(f, QEMU_VM_EOF);

    if (qemu_file_has_error(f))

        return -EIO;

    return 0;

}

int qemu_savevm_state(QEMUFile *f)

{

    int saved_vm_running;

    int ret;

    saved_vm_running = vm_running;

    vm_stop(0);

    bdrv_flush_all();

    ret = qemu_savevm_state_begin(f);

    if (ret < 0)

        goto out;

    do {

        ret = qemu_savevm_state_iterate(f);

        if (ret < 0)

            goto out;

    } while (ret == 0);

    ret = qemu_savevm_state_complete(f);

out:

    if (qemu_file_has_error(f))

        ret = -EIO;

    if (!ret && saved_vm_running)

        vm_start();

    return ret;

}

static SaveStateEntry *find_se(const char *idstr, int instance_id)

{

    SaveStateEntry *se;

    for(se = first_se; se != NULL; se = se->next) {

        if (!strcmp(se->idstr, idstr) &&

            instance_id == se->instance_id)

            return se;

    }

    return NULL;

}

typedef struct LoadStateEntry {

    SaveStateEntry *se;

    int section_id;

    int version_id;

    struct LoadStateEntry *next;

} LoadStateEntry;

static int qemu_loadvm_state_v2(QEMUFile *f)

{

    SaveStateEntry *se;

    int len, ret, instance_id, record_len, version_id;

    int64_t total_len, end_pos, cur_pos;

    char idstr[256];

    total_len = qemu_get_be64(f);

    end_pos = total_len + qemu_ftell(f);

    for(;;) {

        if (qemu_ftell(f) >= end_pos)

            break;

        len = qemu_get_byte(f);

        qemu_get_buffer(f, (uint8_t *)idstr, len);

        idstr[len] = '\0';

        instance_id = qemu_get_be32(f);

        version_id = qemu_get_be32(f);