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 }