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         DPRINTF("increasing buffer capacity from %zu by %zu\n",
  54                 s->buffer_capacity, size + 1024);
  55
  56         s->buffer_capacity += size + 1024;
  57
  58         s->buffer = g_realloc(s->buffer, s->buffer_capacity);
  59     }
  60
  61     memcpy(s->buffer + s->buffer_size, buf, size);
  62     s->buffer_size += size;
  63 }
  64
  65 static void buffered_flush(QEMUFileBuffered *s)
  66 {
  67     size_t offset = 0;
  68     int error;
  69
  70     error = qemu_file_get_error(s->file);
  71     if (error != 0) {
  72         DPRINTF("flush when error, bailing: %s\n", strerror(-error));
  73         return;
  74     }
  75
  76     DPRINTF("flushing %zu byte(s) of data\n", s->buffer_size);
  77
  78     while (offset < s->buffer_size) {
  79         ssize_t ret;
  80
  81         ret = s->put_buffer(s->opaque, s->buffer + offset,
  82                             s->buffer_size - offset);
  83         if (ret == -EAGAIN) {
  84             DPRINTF("backend not ready, freezing\n");
  85             s->freeze_output = 1;
  86             break;
  87         }
  88
  89         if (ret <= 0) {
  90             DPRINTF("error flushing data, %zd\n", ret);
  91             qemu_file_set_error(s->file, ret);
  92             break;
  93         } else {
  94             DPRINTF("flushed %zd byte(s)\n", ret);
  95             offset += ret;
  96         }
  97     }
  98
  99     DPRINTF("flushed %zu of %zu byte(s)\n", offset, s->buffer_size);
 100     memmove(s->buffer, s->buffer + offset, s->buffer_size - offset);
 101     s->buffer_size -= offset;
 102 }
 103
 104 static int buffered_put_buffer(void *opaque, const uint8_t *buf, int64_t pos, int size)
 105 {
 106     QEMUFileBuffered *s = opaque;
 107     int offset = 0, error;
 108     ssize_t ret;
 109
 110     DPRINTF("putting %d bytes at %" PRId64 "\n", size, pos);
 111
 112     error = qemu_file_get_error(s->file);
 113     if (error) {
 114         DPRINTF("flush when error, bailing: %s\n", strerror(-error));
 115         return error;
 116     }
 117
 118     DPRINTF("unfreezing output\n");
 119     s->freeze_output = 0;
 120
 121     buffered_flush(s);
 122
 123     while (!s->freeze_output && offset < size) {
 124         if (s->bytes_xfer > s->xfer_limit) {
 125             DPRINTF("transfer limit exceeded when putting\n");
 126             break;
 127         }
 128
 129         ret = s->put_buffer(s->opaque, buf + offset, size - offset);
 130         if (ret == -EAGAIN) {
 131             DPRINTF("backend not ready, freezing\n");
 132             s->freeze_output = 1;
 133             break;
 134         }
 135
 136         if (ret <= 0) {
 137             DPRINTF("error putting\n");
 138             qemu_file_set_error(s->file, ret);
 139             offset = -EINVAL;
 140             break;
 141         }
 142
 143         DPRINTF("put %zd byte(s)\n", ret);
 144         offset += ret;
 145         s->bytes_xfer += ret;
 146     }
 147
 148     if (offset >= 0) {
 149         DPRINTF("buffering %d bytes\n", size - offset);
 150         buffered_append(s, buf + offset, size - offset);
 151         offset = size;
 152     }
 153
 154     if (pos == 0 && size == 0) {
 155         DPRINTF("file is ready\n");
 156         if (s->bytes_xfer <= s->xfer_limit) {
 157             DPRINTF("notifying client\n");
 158             s->put_ready(s->opaque);
 159         }
 160     }
 161
 162     return offset;
 163 }
 164
 165 static int buffered_close(void *opaque)
 166 {
 167     QEMUFileBuffered *s = opaque;
 168     int ret;
 169
 170     DPRINTF("closing\n");
 171
 172     while (!qemu_file_get_error(s->file) && s->buffer_size) {
 173         buffered_flush(s);
 174         if (s->freeze_output)
 175             s->wait_for_unfreeze(s->opaque);
 176     }
 177
 178     ret = s->close(s->opaque);
 179
 180     qemu_del_timer(s->timer);
 181     qemu_free_timer(s->timer);
 182     g_free(s->buffer);
 183     g_free(s);
 184
 185     return ret;
 186 }
 187
 188 /*
 189  * The meaning of the return values is:
 190  *   0: We can continue sending
 191  *   1: Time to stop
 192  *   negative: There has been an error
 193  */
 194 static int buffered_rate_limit(void *opaque)
 195 {
 196     QEMUFileBuffered *s = opaque;
 197     int ret;
 198
 199     ret = qemu_file_get_error(s->file);
 200     if (ret) {
 201         return ret;
 202     }
 203     if (s->freeze_output)
 204         return 1;
 205
 206     if (s->bytes_xfer > s->xfer_limit)
 207         return 1;
 208
 209     return 0;
 210 }
 211
 212 static int64_t buffered_set_rate_limit(void *opaque, int64_t new_rate)
 213 {
 214     QEMUFileBuffered *s = opaque;
 215     if (qemu_file_get_error(s->file)) {
 216         goto out;
 217     }
 218     if (new_rate > SIZE_MAX) {
 219         new_rate = SIZE_MAX;
 220     }
 221
 222     s->xfer_limit = new_rate / 10;
 223
 224 out:
 225     return s->xfer_limit;
 226 }
 227
 228 static int64_t buffered_get_rate_limit(void *opaque)
 229 {
 230     QEMUFileBuffered *s = opaque;
 231
 232     return s->xfer_limit;
 233 }
 234
 235 static void buffered_rate_tick(void *opaque)
 236 {
 237     QEMUFileBuffered *s = opaque;
 238
 239     if (qemu_file_get_error(s->file)) {
 240         buffered_close(s);
 241         return;
 242     }
 243
 244     qemu_mod_timer(s->timer, qemu_get_clock_ms(rt_clock) + 100);
 245
 246     if (s->freeze_output)
 247         return;
 248
 249     s->bytes_xfer = 0;
 250
 251     buffered_flush(s);
 252
 253     /* Add some checks around this */
 254     s->put_ready(s->opaque);
 255 }
 256
 257 QEMUFile *qemu_fopen_ops_buffered(void *opaque,
 258                                   size_t bytes_per_sec,
 259                                   BufferedPutFunc *put_buffer,
 260                                   BufferedPutReadyFunc *put_ready,
 261                                   BufferedWaitForUnfreezeFunc *wait_for_unfreeze,
 262                                   BufferedCloseFunc *close)
 263 {
 264     QEMUFileBuffered *s;
 265
 266     s = g_malloc0(sizeof(*s));
 267
 268     s->opaque = opaque;
 269     s->xfer_limit = bytes_per_sec / 10;
 270     s->put_buffer = put_buffer;
 271     s->put_ready = put_ready;
 272     s->wait_for_unfreeze = wait_for_unfreeze;
 273     s->close = close;
 274
 275     s->file = qemu_fopen_ops(s, buffered_put_buffer, NULL,
 276                              buffered_close, buffered_rate_limit,
 277                              buffered_set_rate_limit,
 278                              buffered_get_rate_limit);
 279
 280     s->timer = qemu_new_timer_ms(rt_clock, buffered_rate_tick, s);
 281
 282     qemu_mod_timer(s->timer, qemu_get_clock_ms(rt_clock) + 100);
 283
 284     return s->file;
 285 }