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/*

 * QEMU buffered QEMUFile

 *

 * Copyright IBM, Corp. 2008

 *

 * Authors:

 *  Anthony Liguori   <aliguori@us.ibm.com>

 *

 * This work is licensed under the terms of the GNU GPL, version 2.  See

 * the COPYING file in the top-level directory.

 *

 * Contributions after 2012-01-13 are licensed under the terms of the

 * GNU GPL, version 2 or (at your option) any later version.

 */

#include "qemu-common.h"

#include "hw/hw.h"

#include "qemu/timer.h"

#include "buffered_file.h"

//#define DEBUG_BUFFERED_FILE

typedef struct QEMUFileBuffered

{

    MigrationState *migration_state;

    QEMUFile *file;

    int freeze_output;

    size_t bytes_xfer;

    size_t xfer_limit;

    uint8_t *buffer;

    size_t buffer_size;

    size_t buffer_capacity;

    QEMUTimer *timer;

} QEMUFileBuffered;

#ifdef DEBUG_BUFFERED_FILE

#define DPRINTF(fmt, ...) \

    do { printf("buffered-file: " fmt, ## __VA_ARGS__); } while (0)

#else

#define DPRINTF(fmt, ...) \

    do { } while (0)

#endif

static void buffered_append(QEMUFileBuffered *s,

                            const uint8_t *buf, size_t size)

{

    if (size > (s->buffer_capacity - s->buffer_size)) {

        DPRINTF("increasing buffer capacity from %zu by %zu\n",

                s->buffer_capacity, size + 1024);

        s->buffer_capacity += size + 1024;

        s->buffer = g_realloc(s->buffer, s->buffer_capacity);

    }

    memcpy(s->buffer + s->buffer_size, buf, size);

    s->buffer_size += size;

}

static ssize_t buffered_flush(QEMUFileBuffered *s)

{

    size_t offset = 0;

    ssize_t ret = 0;

    DPRINTF("flushing %zu byte(s) of data\n", s->buffer_size);

    while (s->bytes_xfer < s->xfer_limit && offset < s->buffer_size) {

        ret = migrate_fd_put_buffer(s->migration_state, s->buffer + offset,

                                    s->buffer_size - offset);

        if (ret == -EAGAIN) {

            DPRINTF("backend not ready, freezing\n");

            ret = 0;

            s->freeze_output = 1;

            break;

        }

        if (ret <= 0) {

            DPRINTF("error flushing data, %zd\n", ret);

            break;

        } else {

            DPRINTF("flushed %zd byte(s)\n", ret);

            offset += ret;

            s->bytes_xfer += ret;

        }

    }

    DPRINTF("flushed %zu of %zu byte(s)\n", offset, s->buffer_size);

    memmove(s->buffer, s->buffer + offset, s->buffer_size - offset);

    s->buffer_size -= offset;

    if (ret < 0) {

        return ret;

    }

    return offset;

}

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

{

    QEMUFileBuffered *s = opaque;

    ssize_t error;

    DPRINTF("putting %d bytes at %" PRId64 "\n", size, pos);

    error = qemu_file_get_error(s->file);

    if (error) {

        DPRINTF("flush when error, bailing: %s\n", strerror(-error));

        return error;

    }

    DPRINTF("unfreezing output\n");

    s->freeze_output = 0;

    if (size > 0) {

        DPRINTF("buffering %d bytes\n", size - offset);

        buffered_append(s, buf, size);

    }

    error = buffered_flush(s);

    if (error < 0) {

        DPRINTF("buffered flush error. bailing: %s\n", strerror(-error));

        return error;

    }

    if (pos == 0 && size == 0) {

        DPRINTF("file is ready\n");

        if (!s->freeze_output && s->bytes_xfer < s->xfer_limit) {

            DPRINTF("notifying client\n");

            migrate_fd_put_ready(s->migration_state);

        }

    }

    return size;

}

static int buffered_close(void *opaque)

{

    QEMUFileBuffered *s = opaque;

    ssize_t ret = 0;

    int ret2;

    DPRINTF("closing\n");

    s->xfer_limit = INT_MAX;

    while (!qemu_file_get_error(s->file) && s->buffer_size) {

        ret = buffered_flush(s);

        if (ret < 0) {

            break;

        }

        if (s->freeze_output) {

            ret = migrate_fd_wait_for_unfreeze(s->migration_state);

            if (ret < 0) {

                break;

            }

        }

    }

    ret2 = migrate_fd_close(s->migration_state);

    if (ret >= 0) {

        ret = ret2;

    }

    qemu_del_timer(s->timer);

    qemu_free_timer(s->timer);

    g_free(s->buffer);

    g_free(s);

    return ret;

}

/*

 * The meaning of the return values is:

 *   0: We can continue sending

 *   1: Time to stop

 *   negative: There has been an error

 */

static int buffered_get_fd(void *opaque)

{

    QEMUFileBuffered *s = opaque;

    return qemu_get_fd(s->file);

}

static int buffered_rate_limit(void *opaque)

{

    QEMUFileBuffered *s = opaque;

    int ret;

    ret = qemu_file_get_error(s->file);

    if (ret) {

        return ret;

    }

    if (s->freeze_output)

        return 1;

    if (s->bytes_xfer > s->xfer_limit)

        return 1;

    return 0;

}

static int64_t buffered_set_rate_limit(void *opaque, int64_t new_rate)

{

    QEMUFileBuffered *s = opaque;

    if (qemu_file_get_error(s->file)) {

        goto out;

    }

    if (new_rate > SIZE_MAX) {

        new_rate = SIZE_MAX;

    }

    s->xfer_limit = new_rate / 10;

out:

    return s->xfer_limit;

}

static int64_t buffered_get_rate_limit(void *opaque)

{

    QEMUFileBuffered *s = opaque;

    return s->xfer_limit;

}

static void buffered_rate_tick(void *opaque)

{

    QEMUFileBuffered *s = opaque;

    if (qemu_file_get_error(s->file)) {

        buffered_close(s);

        return;

    }

    qemu_mod_timer(s->timer, qemu_get_clock_ms(rt_clock) + 100);

    if (s->freeze_output)

        return;

    s->bytes_xfer = 0;

    buffered_put_buffer(s, NULL, 0, 0);

}

static const QEMUFileOps buffered_file_ops = {

    .get_fd =         buffered_get_fd,

    .put_buffer =     buffered_put_buffer,

    .close =          buffered_close,

    .rate_limit =     buffered_rate_limit,

    .get_rate_limit = buffered_get_rate_limit,

    .set_rate_limit = buffered_set_rate_limit,

};

QEMUFile *qemu_fopen_ops_buffered(MigrationState *migration_state)

{

    QEMUFileBuffered *s;

    s = g_malloc0(sizeof(*s));

    s->migration_state = migration_state;

    s->xfer_limit = migration_state->bandwidth_limit / 10;

    s->file = qemu_fopen_ops(s, &buffered_file_ops);

    s->timer = qemu_new_timer_ms(rt_clock, buffered_rate_tick, s);

    qemu_mod_timer(s->timer, qemu_get_clock_ms(rt_clock) + 100);

    return s->file;

}