diff options
Diffstat (limited to 'buffered_file.c')
| -rw-r--r-- | buffered_file.c | 250 |
1 files changed, 250 insertions, 0 deletions
diff --git a/buffered_file.c b/buffered_file.c new file mode 100644 index 0000000000..1d72b4637a --- /dev/null +++ b/buffered_file.c @@ -0,0 +1,250 @@ +/* + * 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 "sysemu.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 has_error; + 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 %ld by %ld\n", + s->buffer_capacity, size + 1024); + + s->buffer_capacity += size + 1024; + + tmp = qemu_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; + + if (s->has_error) { + dprintf("flush when error, bailing\n"); + return; + } + + dprintf("flushing %ld 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, %ld\n", ret); + s->has_error = 1; + break; + } else { + dprintf("flushed %ld byte(s)\n", ret); + offset += ret; + } + } + + dprintf("flushed %ld of %ld 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; + ssize_t ret; + + dprintf("putting %ld bytes at %Ld\n", size, pos); + + if (s->has_error) { + dprintf("flush when error, bailing\n"); + return -EINVAL; + } + + 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"); + s->has_error = 1; + offset = -EINVAL; + break; + } + + dprintf("put %ld byte(s)\n", ret); + offset += ret; + s->bytes_xfer += ret; + } + + if (offset >= 0) { + dprintf("buffering %ld bytes\n", size - offset); + buffered_append(s, buf + offset, size - offset); + offset = size; + } + + return offset; +} + +static int buffered_close(void *opaque) +{ + QEMUFileBuffered *s = opaque; + int ret; + + dprintf("closing\n"); + + while (!s->has_error && s->buffer_size) { + buffered_flush(s); + if (s->freeze_output) + s->wait_for_unfreeze(s); + } + + ret = s->close(s->opaque); + + qemu_del_timer(s->timer); + qemu_free_timer(s->timer); + qemu_free(s->buffer); + qemu_free(s); + + return ret; +} + +static int buffered_rate_limit(void *opaque) +{ + QEMUFileBuffered *s = opaque; + + if (s->has_error) + return 0; + + if (s->freeze_output) + return 1; + + if (s->bytes_xfer > s->xfer_limit) + return 1; + + return 0; +} + +static void buffered_rate_tick(void *opaque) +{ + QEMUFileBuffered *s = opaque; + + if (s->has_error) + return; + + qemu_mod_timer(s->timer, qemu_get_clock(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 = qemu_mallocz(sizeof(*s)); + if (s == NULL) + return NULL; + + 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); + + s->timer = qemu_new_timer(rt_clock, buffered_rate_tick, s); + + qemu_mod_timer(s->timer, qemu_get_clock(rt_clock) + 100); + + return s->file; +} + |