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  * Contributions after 2012-01-13 are licensed under the terms of the
  13  * GNU GPL, version 2 or (at your option) any later version.
  14  */
  15
  16 #include "qemu-common.h"
  17 #include "hw/hw.h"
  18 #include "qemu-timer.h"
  19 #include "qemu-char.h"
  20 #include "buffered_file.h"
  21
  22 //#define DEBUG_BUFFERED_FILE
  23
  24 typedef struct QEMUFileBuffered
  25 {
  26     BufferedPutFunc *put_buffer;
  27     BufferedPutReadyFunc *put_ready;
  28     BufferedWaitForUnfreezeFunc *wait_for_unfreeze;
  29     BufferedCloseFunc *close;
  30     void *opaque;
  31     QEMUFile *file;
  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 %zu by %zu\n",
  56                 s->buffer_capacity, size + 1024);
  57
  58         s->buffer_capacity += size + 1024;
  59
  60         tmp = g_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     int error;
  77
  78     error = qemu_file_get_error(s->file);
  79     if (error != 0) {
  80         DPRINTF("flush when error, bailing: %s\n", strerror(-error));
  81         return;
  82     }
  83
  84     DPRINTF("flushing %zu byte(s) of data\n", s->buffer_size);
  85
  86     while (offset < s->buffer_size) {
  87         ssize_t ret;
  88
  89         ret = s->put_buffer(s->opaque, s->buffer + offset,
  90                             s->buffer_size - offset);
  91         if (ret == -EAGAIN) {
  92             DPRINTF("backend not ready, freezing\n");
  93             s->freeze_output = 1;
  94             break;
  95         }
  96
  97         if (ret <= 0) {
  98             DPRINTF("error flushing data, %zd\n", ret);
  99             qemu_file_set_error(s->file, ret);
 100             break;
 101         } else {
 102             DPRINTF("flushed %zd byte(s)\n", ret);
 103             offset += ret;
 104         }
 105     }
 106
 107     DPRINTF("flushed %zu of %zu byte(s)\n", offset, s->buffer_size);
 108     memmove(s->buffer, s->buffer + offset, s->buffer_size - offset);
 109     s->buffer_size -= offset;
 110 }
 111
 112 static int buffered_put_buffer(void *opaque, const uint8_t *buf, int64_t pos, int size)
 113 {
 114     QEMUFileBuffered *s = opaque;
 115     int offset = 0, error;
 116     ssize_t ret;
 117
 118     DPRINTF("putting %d bytes at %" PRId64 "\n", size, pos);
 119
 120     error = qemu_file_get_error(s->file);
 121     if (error) {
 122         DPRINTF("flush when error, bailing: %s\n", strerror(-error));
 123         return error;
 124     }
 125
 126     DPRINTF("unfreezing output\n");
 127     s->freeze_output = 0;
 128
 129     buffered_flush(s);
 130
 131     while (!s->freeze_output && offset < size) {
 132         if (s->bytes_xfer > s->xfer_limit) {
 133             DPRINTF("transfer limit exceeded when putting\n");
 134             break;
 135         }
 136
 137         ret = s->put_buffer(s->opaque, buf + offset, size - offset);
 138         if (ret == -EAGAIN) {
 139             DPRINTF("backend not ready, freezing\n");
 140             s->freeze_output = 1;
 141             break;
 142         }
 143
 144         if (ret <= 0) {
 145             DPRINTF("error putting\n");
 146             qemu_file_set_error(s->file, ret);
 147             offset = -EINVAL;
 148             break;
 149         }
 150
 151         DPRINTF("put %zd byte(s)\n", ret);
 152         offset += ret;
 153         s->bytes_xfer += ret;
 154     }
 155
 156     if (offset >= 0) {
 157         DPRINTF("buffering %d bytes\n", size - offset);
 158         buffered_append(s, buf + offset, size - offset);
 159         offset = size;
 160     }
 161
 162     if (pos == 0 && size == 0) {
 163         DPRINTF("file is ready\n");
 164         if (s->bytes_xfer <= s->xfer_limit) {
 165             DPRINTF("notifying client\n");
 166             s->put_ready(s->opaque);
 167         }
 168     }
 169
 170     return offset;
 171 }
 172
 173 static int buffered_close(void *opaque)
 174 {
 175     QEMUFileBuffered *s = opaque;
 176     int ret;
 177
 178     DPRINTF("closing\n");
 179
 180     while (!qemu_file_get_error(s->file) && s->buffer_size) {
 181         buffered_flush(s);
 182         if (s->freeze_output)
 183             s->wait_for_unfreeze(s->opaque);
 184     }
 185
 186     ret = s->close(s->opaque);
 187
 188     qemu_del_timer(s->timer);
 189     qemu_free_timer(s->timer);
 190     g_free(s->buffer);
 191     g_free(s);
 192
 193     return ret;
 194 }
 195
 196 /*
 197  * The meaning of the return values is:
 198  *   0: We can continue sending
 199  *   1: Time to stop
 200  *   negative: There has been an error
 201  */
 202 static int buffered_rate_limit(void *opaque)
 203 {
 204     QEMUFileBuffered *s = opaque;
 205     int ret;
 206
 207     ret = qemu_file_get_error(s->file);
 208     if (ret) {
 209         return ret;
 210     }
 211     if (s->freeze_output)
 212         return 1;
 213
 214     if (s->bytes_xfer > s->xfer_limit)
 215         return 1;
 216
 217     return 0;
 218 }
 219
 220 static int64_t buffered_set_rate_limit(void *opaque, int64_t new_rate)
 221 {
 222     QEMUFileBuffered *s = opaque;
 223     if (qemu_file_get_error(s->file)) {
 224         goto out;
 225     }
 226     if (new_rate > SIZE_MAX) {
 227         new_rate = SIZE_MAX;
 228     }
 229
 230     s->xfer_limit = new_rate / 10;
 231
 232 out:
 233     return s->xfer_limit;
 234 }
 235
 236 static int64_t buffered_get_rate_limit(void *opaque)
 237 {
 238     QEMUFileBuffered *s = opaque;
 239
 240     return s->xfer_limit;
 241 }
 242
 243 static void buffered_rate_tick(void *opaque)
 244 {
 245     QEMUFileBuffered *s = opaque;
 246
 247     if (qemu_file_get_error(s->file)) {
 248         buffered_close(s);
 249         return;
 250     }
 251
 252     qemu_mod_timer(s->timer, qemu_get_clock_ms(rt_clock) + 100);
 253
 254     if (s->freeze_output)
 255         return;
 256
 257     s->bytes_xfer = 0;
 258
 259     buffered_flush(s);
 260
 261     /* Add some checks around this */
 262     s->put_ready(s->opaque);
 263 }
 264
 265 QEMUFile *qemu_fopen_ops_buffered(void *opaque,
 266                                   size_t bytes_per_sec,
 267                                   BufferedPutFunc *put_buffer,
 268                                   BufferedPutReadyFunc *put_ready,
 269                                   BufferedWaitForUnfreezeFunc *wait_for_unfreeze,
 270                                   BufferedCloseFunc *close)
 271 {
 272     QEMUFileBuffered *s;
 273
 274     s = g_malloc0(sizeof(*s));
 275
 276     s->opaque = opaque;
 277     s->xfer_limit = bytes_per_sec / 10;
 278     s->put_buffer = put_buffer;
 279     s->put_ready = put_ready;
 280     s->wait_for_unfreeze = wait_for_unfreeze;
 281     s->close = close;
 282
 283     s->file = qemu_fopen_ops(s, buffered_put_buffer, NULL,
 284                              buffered_close, buffered_rate_limit,
 285                              buffered_set_rate_limit,
 286                              buffered_get_rate_limit);
 287
 288     s->timer = qemu_new_timer_ms(rt_clock, buffered_rate_tick, s);
 289
 290     qemu_mod_timer(s->timer, qemu_get_clock_ms(rt_clock) + 100);
 291
 292     return s->file;
 293 }