buffered_file.c

   1 /*
   2  * QEMU buffered QEMUFile
   3  *
   4  * Copyright IBM, Corp. 2008
   5  *
   6  * Authors:
   7  *  Anthony Liguori   <aliguori@us.ibm.com>
   8  *
   9  * This work is licensed under the terms of the GNU GPL, version 2.  See
  10  * the COPYING file in the top-level directory.
  11  *
  12  */
  13
  14 #include "qemu-common.h"
  15 #include "hw/hw.h"
  16 #include "qemu-timer.h"
  17 #include "sysemu.h"
  18 #include "qemu-char.h"
  19 #include "buffered_file.h"
  20
  21 //#define DEBUG_BUFFERED_FILE
  22
  23 typedef struct QEMUFileBuffered
  24 {
  25     BufferedPutFunc *put_buffer;
  26     BufferedPutReadyFunc *put_ready;
  27     BufferedWaitForUnfreezeFunc *wait_for_unfreeze;
  28     BufferedCloseFunc *close;
  29     void *opaque;
  30     QEMUFile *file;
  31     int has_error;
  32     int freeze_output;
  33     size_t bytes_xfer;
  34     size_t xfer_limit;
  35     uint8_t *buffer;
  36     size_t buffer_size;
  37     size_t buffer_capacity;
  38     QEMUTimer *timer;
  39 } QEMUFileBuffered;
  40
  41 #ifdef DEBUG_BUFFERED_FILE
  42 #define dprintf(fmt, ...) \
  43     do { printf("buffered-file: " fmt, ## __VA_ARGS__); } while (0)
  44 #else
  45 #define dprintf(fmt, ...) \
  46     do { } while (0)
  47 #endif
  48
  49 static void buffered_append(QEMUFileBuffered *s,
  50                             const uint8_t *buf, size_t size)
  51 {
  52     if (size > (s->buffer_capacity - s->buffer_size)) {
  53         void *tmp;
  54
  55         dprintf("increasing buffer capacity from %ld by %ld\n",
  56                 s->buffer_capacity, size + 1024);
  57
  58         s->buffer_capacity += size + 1024;
  59
  60         tmp = qemu_realloc(s->buffer, s->buffer_capacity);
  61         if (tmp == NULL) {
  62             fprintf(stderr, "qemu file buffer expansion failed\n");
  63             exit(1);
  64         }
  65
  66         s->buffer = tmp;
  67     }
  68
  69     memcpy(s->buffer + s->buffer_size, buf, size);
  70     s->buffer_size += size;
  71 }
  72
  73 static void buffered_flush(QEMUFileBuffered *s)
  74 {
  75     size_t offset = 0;
  76
  77     if (s->has_error) {
  78         dprintf("flush when error, bailing\n");
  79         return;
  80     }
  81
  82     dprintf("flushing %ld byte(s) of data\n", s->buffer_size);
  83
  84     while (offset < s->buffer_size) {
  85         ssize_t ret;
  86
  87         ret = s->put_buffer(s->opaque, s->buffer + offset,
  88                             s->buffer_size - offset);
  89         if (ret == -EAGAIN) {
  90             dprintf("backend not ready, freezing\n");
  91             s->freeze_output = 1;
  92             break;
  93         }
  94
  95         if (ret <= 0) {
  96             dprintf("error flushing data, %ld\n", ret);
  97             s->has_error = 1;
  98             break;
  99         } else {
 100             dprintf("flushed %ld byte(s)\n", ret);
 101             offset += ret;
 102         }
 103     }
 104
 105     dprintf("flushed %ld of %ld byte(s)\n", offset, s->buffer_size);
 106     memmove(s->buffer, s->buffer + offset, s->buffer_size - offset);
 107     s->buffer_size -= offset;
 108 }
 109
 110 static int buffered_put_buffer(void *opaque, const uint8_t *buf, int64_t pos, int size)
 111 {
 112     QEMUFileBuffered *s = opaque;
 113     int offset = 0;
 114     ssize_t ret;
 115
 116     dprintf("putting %ld bytes at %Ld\n", size, pos);
 117
 118     if (s->has_error) {
 119         dprintf("flush when error, bailing\n");
 120         return -EINVAL;
 121     }
 122
 123     dprintf("unfreezing output\n");
 124     s->freeze_output = 0;
 125
 126     buffered_flush(s);
 127
 128     while (!s->freeze_output && offset < size) {
 129         if (s->bytes_xfer > s->xfer_limit) {
 130             dprintf("transfer limit exceeded when putting\n");
 131             break;
 132         }
 133
 134         ret = s->put_buffer(s->opaque, buf + offset, size - offset);
 135         if (ret == -EAGAIN) {
 136             dprintf("backend not ready, freezing\n");
 137             s->freeze_output = 1;
 138             break;
 139         }
 140
 141         if (ret <= 0) {
 142             dprintf("error putting\n");
 143             s->has_error = 1;
 144             offset = -EINVAL;
 145             break;
 146         }
 147
 148         dprintf("put %ld byte(s)\n", ret);
 149         offset += ret;
 150         s->bytes_xfer += ret;
 151     }
 152
 153     if (offset >= 0) {
 154         dprintf("buffering %ld bytes\n", size - offset);
 155         buffered_append(s, buf + offset, size - offset);
 156         offset = size;
 157     }
 158
 159     return offset;
 160 }
 161
 162 static int buffered_close(void *opaque)
 163 {
 164     QEMUFileBuffered *s = opaque;
 165     int ret;
 166
 167     dprintf("closing\n");
 168
 169     while (!s->has_error && s->buffer_size) {
 170         buffered_flush(s);
 171         if (s->freeze_output)
 172             s->wait_for_unfreeze(s);
 173     }
 174
 175     ret = s->close(s->opaque);
 176
 177     qemu_del_timer(s->timer);
 178     qemu_free_timer(s->timer);
 179     qemu_free(s->buffer);
 180     qemu_free(s);
 181
 182     return ret;
 183 }
 184
 185 static int buffered_rate_limit(void *opaque)
 186 {
 187     QEMUFileBuffered *s = opaque;
 188
 189     if (s->has_error)
 190         return 0;
 191
 192     if (s->freeze_output)
 193         return 1;
 194
 195     if (s->bytes_xfer > s->xfer_limit)
 196         return 1;
 197
 198     return 0;
 199 }
 200
 201 static void buffered_rate_tick(void *opaque)
 202 {
 203     QEMUFileBuffered *s = opaque;
 204
 205     if (s->has_error)
 206         return;
 207
 208     qemu_mod_timer(s->timer, qemu_get_clock(rt_clock) + 100);
 209
 210     if (s->freeze_output)
 211         return;
 212
 213     s->bytes_xfer = 0;
 214
 215     buffered_flush(s);
 216
 217     /* Add some checks around this */
 218     s->put_ready(s->opaque);
 219 }
 220
 221 QEMUFile *qemu_fopen_ops_buffered(void *opaque,
 222                                   size_t bytes_per_sec,
 223                                   BufferedPutFunc *put_buffer,
 224                                   BufferedPutReadyFunc *put_ready,
 225                                   BufferedWaitForUnfreezeFunc *wait_for_unfreeze,
 226                                   BufferedCloseFunc *close)
 227 {
 228     QEMUFileBuffered *s;
 229
 230     s = qemu_mallocz(sizeof(*s));
 231     if (s == NULL)
 232         return NULL;
 233
 234     s->opaque = opaque;
 235     s->xfer_limit = bytes_per_sec / 10;
 236     s->put_buffer = put_buffer;
 237     s->put_ready = put_ready;
 238     s->wait_for_unfreeze = wait_for_unfreeze;
 239     s->close = close;
 240
 241     s->file = qemu_fopen_ops(s, buffered_put_buffer, NULL,
 242                              buffered_close, buffered_rate_limit);
 243
 244     s->timer = qemu_new_timer(rt_clock, buffered_rate_tick, s);
 245
 246     qemu_mod_timer(s->timer, qemu_get_clock(rt_clock) + 100);
 247
 248     return s->file;
 249 }
 250