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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.

 *

 */

#include "qemu-common.h"

#include "hw/hw.h"

#include "qemu-timer.h"

#include "qemu-char.h"

#include "buffered_file.h"

//#define DEBUG_BUFFERED_FILE

typedef struct QEMUFileBuffered

{

    BufferedPutFunc *put_buffer;

    BufferedPutReadyFunc *put_ready;

    BufferedWaitForUnfreezeFunc *wait_for_unfreeze;

    BufferedCloseFunc *close;

    void *opaque;

    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)) {

        void *tmp;

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

                s->buffer_capacity, size + 1024);

        s->buffer_capacity += size + 1024;

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

        if (tmp == NULL) {

            fprintf(stderr, "qemu file buffer expansion failed\n");

            exit(1);

        }

        s->buffer = tmp;

    }

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

    s->buffer_size += size;

}

static void buffered_flush(QEMUFileBuffered *s)

{

    size_t offset = 0;

    int error;

    error = qemu_file_get_error(s->file);

    if (error != 0) {

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

        return;

    }

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

    while (offset < s->buffer_size) {

        ssize_t ret;

        ret = s->put_buffer(s->opaque, s->buffer + offset,

                            s->buffer_size - offset);

        if (ret == -EAGAIN) {

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

            s->freeze_output = 1;

            break;

        }

        if (ret <= 0) {

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

            qemu_file_set_error(s->file, ret);

            break;

        } else {

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

            offset += 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;

}

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

{

    QEMUFileBuffered *s = opaque;

    int offset = 0, error;

    ssize_t ret;

    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;

    buffered_flush(s);

    while (!s->freeze_output && offset < size) {

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

            DPRINTF("transfer limit exceeded when putting\n");

            break;

        }

        ret = s->put_buffer(s->opaque, buf + offset, size - offset);

        if (ret == -EAGAIN) {

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

            s->freeze_output = 1;

            break;

        }

        if (ret <= 0) {

            DPRINTF("error putting\n");

            qemu_file_set_error(s->file, ret);

            offset = -EINVAL;

            break;

        }

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

        offset += ret;

        s->bytes_xfer += ret;

    }

    if (offset >= 0) {

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

        buffered_append(s, buf + offset, size - offset);

        offset = size;

    }

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

        DPRINTF("file is ready\n");

        if (s->bytes_xfer <= s->xfer_limit) {

            DPRINTF("notifying client\n");

            s->put_ready(s->opaque);

        }

    }

    return offset;

}

static int buffered_close(void *opaque)

{

    QEMUFileBuffered *s = opaque;

    int ret;

    DPRINTF("closing\n");

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

        buffered_flush(s);

        if (s->freeze_output)

            s->wait_for_unfreeze(s->opaque);

    }

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

    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_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_flush(s);

    /* Add some checks around this */

    s->put_ready(s->opaque);

}

QEMUFile *qemu_fopen_ops_buffered(void *opaque,

                                  size_t bytes_per_sec,

                                  BufferedPutFunc *put_buffer,

                                  BufferedPutReadyFunc *put_ready,

                                  BufferedWaitForUnfreezeFunc *wait_for_unfreeze,

                                  BufferedCloseFunc *close)

{

    QEMUFileBuffered *s;

    s = g_malloc0(sizeof(*s));

    s->opaque = opaque;

    s->xfer_limit = bytes_per_sec / 10;

    s->put_buffer = put_buffer;

    s->put_ready = put_ready;

    s->wait_for_unfreeze = wait_for_unfreeze;

    s->close = close;

    s->file = qemu_fopen_ops(s, buffered_put_buffer, NULL,

                             buffered_close, buffered_rate_limit,

                             buffered_set_rate_limit,

                             buffered_get_rate_limit);

    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;

}