xref: /openbmc/qemu/block/curl.c (revision 4a66d3bf)
1 /*
2  * QEMU Block driver for CURL images
3  *
4  * Copyright (c) 2009 Alexander Graf <agraf@suse.de>
5  *
6  * Permission is hereby granted, free of charge, to any person obtaining a copy
7  * of this software and associated documentation files (the "Software"), to deal
8  * in the Software without restriction, including without limitation the rights
9  * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
10  * copies of the Software, and to permit persons to whom the Software is
11  * furnished to do so, subject to the following conditions:
12  *
13  * The above copyright notice and this permission notice shall be included in
14  * all copies or substantial portions of the Software.
15  *
16  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
17  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
18  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
19  * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
20  * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
21  * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
22  * THE SOFTWARE.
23  */
24 #include "qemu-common.h"
25 #include "block/block_int.h"
26 #include <curl/curl.h>
27 
28 // #define DEBUG
29 // #define DEBUG_VERBOSE
30 
31 #ifdef DEBUG_CURL
32 #define DPRINTF(fmt, ...) do { printf(fmt, ## __VA_ARGS__); } while (0)
33 #else
34 #define DPRINTF(fmt, ...) do { } while (0)
35 #endif
36 
37 #if LIBCURL_VERSION_NUM >= 0x071000
38 /* The multi interface timer callback was introduced in 7.16.0 */
39 #define NEED_CURL_TIMER_CALLBACK
40 #endif
41 
42 #define PROTOCOLS (CURLPROTO_HTTP | CURLPROTO_HTTPS | \
43                    CURLPROTO_FTP | CURLPROTO_FTPS | \
44                    CURLPROTO_TFTP)
45 
46 #define CURL_NUM_STATES 8
47 #define CURL_NUM_ACB    8
48 #define SECTOR_SIZE     512
49 #define READ_AHEAD_SIZE (256 * 1024)
50 
51 #define FIND_RET_NONE   0
52 #define FIND_RET_OK     1
53 #define FIND_RET_WAIT   2
54 
55 struct BDRVCURLState;
56 
57 typedef struct CURLAIOCB {
58     BlockDriverAIOCB common;
59     QEMUBH *bh;
60     QEMUIOVector *qiov;
61 
62     int64_t sector_num;
63     int nb_sectors;
64 
65     size_t start;
66     size_t end;
67 } CURLAIOCB;
68 
69 typedef struct CURLState
70 {
71     struct BDRVCURLState *s;
72     CURLAIOCB *acb[CURL_NUM_ACB];
73     CURL *curl;
74     char *orig_buf;
75     size_t buf_start;
76     size_t buf_off;
77     size_t buf_len;
78     char range[128];
79     char errmsg[CURL_ERROR_SIZE];
80     char in_use;
81 } CURLState;
82 
83 typedef struct BDRVCURLState {
84     CURLM *multi;
85     QEMUTimer timer;
86     size_t len;
87     CURLState states[CURL_NUM_STATES];
88     char *url;
89     size_t readahead_size;
90     bool accept_range;
91 } BDRVCURLState;
92 
93 static void curl_clean_state(CURLState *s);
94 static void curl_multi_do(void *arg);
95 
96 #ifdef NEED_CURL_TIMER_CALLBACK
97 static int curl_timer_cb(CURLM *multi, long timeout_ms, void *opaque)
98 {
99     BDRVCURLState *s = opaque;
100 
101     DPRINTF("CURL: timer callback timeout_ms %ld\n", timeout_ms);
102     if (timeout_ms == -1) {
103         timer_del(&s->timer);
104     } else {
105         int64_t timeout_ns = (int64_t)timeout_ms * 1000 * 1000;
106         timer_mod(&s->timer,
107                   qemu_clock_get_ns(QEMU_CLOCK_REALTIME) + timeout_ns);
108     }
109     return 0;
110 }
111 #endif
112 
113 static int curl_sock_cb(CURL *curl, curl_socket_t fd, int action,
114                         void *s, void *sp)
115 {
116     DPRINTF("CURL (AIO): Sock action %d on fd %d\n", action, fd);
117     switch (action) {
118         case CURL_POLL_IN:
119             qemu_aio_set_fd_handler(fd, curl_multi_do, NULL, s);
120             break;
121         case CURL_POLL_OUT:
122             qemu_aio_set_fd_handler(fd, NULL, curl_multi_do, s);
123             break;
124         case CURL_POLL_INOUT:
125             qemu_aio_set_fd_handler(fd, curl_multi_do, curl_multi_do, s);
126             break;
127         case CURL_POLL_REMOVE:
128             qemu_aio_set_fd_handler(fd, NULL, NULL, NULL);
129             break;
130     }
131 
132     return 0;
133 }
134 
135 static size_t curl_header_cb(void *ptr, size_t size, size_t nmemb, void *opaque)
136 {
137     BDRVCURLState *s = opaque;
138     size_t realsize = size * nmemb;
139     const char *accept_line = "Accept-Ranges: bytes";
140 
141     if (realsize >= strlen(accept_line)
142         && strncmp((char *)ptr, accept_line, strlen(accept_line)) == 0) {
143         s->accept_range = true;
144     }
145 
146     return realsize;
147 }
148 
149 static size_t curl_read_cb(void *ptr, size_t size, size_t nmemb, void *opaque)
150 {
151     CURLState *s = ((CURLState*)opaque);
152     size_t realsize = size * nmemb;
153     int i;
154 
155     DPRINTF("CURL: Just reading %zd bytes\n", realsize);
156 
157     if (!s || !s->orig_buf)
158         goto read_end;
159 
160     if (s->buf_off >= s->buf_len) {
161         /* buffer full, read nothing */
162         return 0;
163     }
164     realsize = MIN(realsize, s->buf_len - s->buf_off);
165     memcpy(s->orig_buf + s->buf_off, ptr, realsize);
166     s->buf_off += realsize;
167 
168     for(i=0; i<CURL_NUM_ACB; i++) {
169         CURLAIOCB *acb = s->acb[i];
170 
171         if (!acb)
172             continue;
173 
174         if ((s->buf_off >= acb->end)) {
175             qemu_iovec_from_buf(acb->qiov, 0, s->orig_buf + acb->start,
176                                 acb->end - acb->start);
177             acb->common.cb(acb->common.opaque, 0);
178             qemu_aio_release(acb);
179             s->acb[i] = NULL;
180         }
181     }
182 
183 read_end:
184     return realsize;
185 }
186 
187 static int curl_find_buf(BDRVCURLState *s, size_t start, size_t len,
188                          CURLAIOCB *acb)
189 {
190     int i;
191     size_t end = start + len;
192 
193     for (i=0; i<CURL_NUM_STATES; i++) {
194         CURLState *state = &s->states[i];
195         size_t buf_end = (state->buf_start + state->buf_off);
196         size_t buf_fend = (state->buf_start + state->buf_len);
197 
198         if (!state->orig_buf)
199             continue;
200         if (!state->buf_off)
201             continue;
202 
203         // Does the existing buffer cover our section?
204         if ((start >= state->buf_start) &&
205             (start <= buf_end) &&
206             (end >= state->buf_start) &&
207             (end <= buf_end))
208         {
209             char *buf = state->orig_buf + (start - state->buf_start);
210 
211             qemu_iovec_from_buf(acb->qiov, 0, buf, len);
212             acb->common.cb(acb->common.opaque, 0);
213 
214             return FIND_RET_OK;
215         }
216 
217         // Wait for unfinished chunks
218         if ((start >= state->buf_start) &&
219             (start <= buf_fend) &&
220             (end >= state->buf_start) &&
221             (end <= buf_fend))
222         {
223             int j;
224 
225             acb->start = start - state->buf_start;
226             acb->end = acb->start + len;
227 
228             for (j=0; j<CURL_NUM_ACB; j++) {
229                 if (!state->acb[j]) {
230                     state->acb[j] = acb;
231                     return FIND_RET_WAIT;
232                 }
233             }
234         }
235     }
236 
237     return FIND_RET_NONE;
238 }
239 
240 static void curl_multi_read(BDRVCURLState *s)
241 {
242     int msgs_in_queue;
243 
244     /* Try to find done transfers, so we can free the easy
245      * handle again. */
246     do {
247         CURLMsg *msg;
248         msg = curl_multi_info_read(s->multi, &msgs_in_queue);
249 
250         if (!msg)
251             break;
252         if (msg->msg == CURLMSG_NONE)
253             break;
254 
255         switch (msg->msg) {
256             case CURLMSG_DONE:
257             {
258                 CURLState *state = NULL;
259                 curl_easy_getinfo(msg->easy_handle, CURLINFO_PRIVATE, (char**)&state);
260 
261                 /* ACBs for successful messages get completed in curl_read_cb */
262                 if (msg->data.result != CURLE_OK) {
263                     int i;
264                     for (i = 0; i < CURL_NUM_ACB; i++) {
265                         CURLAIOCB *acb = state->acb[i];
266 
267                         if (acb == NULL) {
268                             continue;
269                         }
270 
271                         acb->common.cb(acb->common.opaque, -EIO);
272                         qemu_aio_release(acb);
273                         state->acb[i] = NULL;
274                     }
275                 }
276 
277                 curl_clean_state(state);
278                 break;
279             }
280             default:
281                 msgs_in_queue = 0;
282                 break;
283         }
284     } while(msgs_in_queue);
285 }
286 
287 static void curl_multi_do(void *arg)
288 {
289     BDRVCURLState *s = (BDRVCURLState *)arg;
290     int running;
291     int r;
292 
293     if (!s->multi) {
294         return;
295     }
296 
297     do {
298         r = curl_multi_socket_all(s->multi, &running);
299     } while(r == CURLM_CALL_MULTI_PERFORM);
300 
301     curl_multi_read(s);
302 }
303 
304 static void curl_multi_timeout_do(void *arg)
305 {
306 #ifdef NEED_CURL_TIMER_CALLBACK
307     BDRVCURLState *s = (BDRVCURLState *)arg;
308     int running;
309 
310     if (!s->multi) {
311         return;
312     }
313 
314     curl_multi_socket_action(s->multi, CURL_SOCKET_TIMEOUT, 0, &running);
315 
316     curl_multi_read(s);
317 #else
318     abort();
319 #endif
320 }
321 
322 static CURLState *curl_init_state(BDRVCURLState *s)
323 {
324     CURLState *state = NULL;
325     int i, j;
326 
327     do {
328         for (i=0; i<CURL_NUM_STATES; i++) {
329             for (j=0; j<CURL_NUM_ACB; j++)
330                 if (s->states[i].acb[j])
331                     continue;
332             if (s->states[i].in_use)
333                 continue;
334 
335             state = &s->states[i];
336             state->in_use = 1;
337             break;
338         }
339         if (!state) {
340             g_usleep(100);
341             curl_multi_do(s);
342         }
343     } while(!state);
344 
345     if (state->curl)
346         goto has_curl;
347 
348     state->curl = curl_easy_init();
349     if (!state->curl)
350         return NULL;
351     curl_easy_setopt(state->curl, CURLOPT_URL, s->url);
352     curl_easy_setopt(state->curl, CURLOPT_TIMEOUT, 5);
353     curl_easy_setopt(state->curl, CURLOPT_WRITEFUNCTION, (void *)curl_read_cb);
354     curl_easy_setopt(state->curl, CURLOPT_WRITEDATA, (void *)state);
355     curl_easy_setopt(state->curl, CURLOPT_PRIVATE, (void *)state);
356     curl_easy_setopt(state->curl, CURLOPT_AUTOREFERER, 1);
357     curl_easy_setopt(state->curl, CURLOPT_FOLLOWLOCATION, 1);
358     curl_easy_setopt(state->curl, CURLOPT_NOSIGNAL, 1);
359     curl_easy_setopt(state->curl, CURLOPT_ERRORBUFFER, state->errmsg);
360     curl_easy_setopt(state->curl, CURLOPT_FAILONERROR, 1);
361 
362     /* Restrict supported protocols to avoid security issues in the more
363      * obscure protocols.  For example, do not allow POP3/SMTP/IMAP see
364      * CVE-2013-0249.
365      *
366      * Restricting protocols is only supported from 7.19.4 upwards.
367      */
368 #if LIBCURL_VERSION_NUM >= 0x071304
369     curl_easy_setopt(state->curl, CURLOPT_PROTOCOLS, PROTOCOLS);
370     curl_easy_setopt(state->curl, CURLOPT_REDIR_PROTOCOLS, PROTOCOLS);
371 #endif
372 
373 #ifdef DEBUG_VERBOSE
374     curl_easy_setopt(state->curl, CURLOPT_VERBOSE, 1);
375 #endif
376 
377 has_curl:
378 
379     state->s = s;
380 
381     return state;
382 }
383 
384 static void curl_clean_state(CURLState *s)
385 {
386     if (s->s->multi)
387         curl_multi_remove_handle(s->s->multi, s->curl);
388     s->in_use = 0;
389 }
390 
391 static void curl_parse_filename(const char *filename, QDict *options,
392                                 Error **errp)
393 {
394 
395     #define RA_OPTSTR ":readahead="
396     char *file;
397     char *ra;
398     const char *ra_val;
399     int parse_state = 0;
400 
401     file = g_strdup(filename);
402 
403     /* Parse a trailing ":readahead=#:" param, if present. */
404     ra = file + strlen(file) - 1;
405     while (ra >= file) {
406         if (parse_state == 0) {
407             if (*ra == ':') {
408                 parse_state++;
409             } else {
410                 break;
411             }
412         } else if (parse_state == 1) {
413             if (*ra > '9' || *ra < '0') {
414                 char *opt_start = ra - strlen(RA_OPTSTR) + 1;
415                 if (opt_start > file &&
416                     strncmp(opt_start, RA_OPTSTR, strlen(RA_OPTSTR)) == 0) {
417                     ra_val = ra + 1;
418                     ra -= strlen(RA_OPTSTR) - 1;
419                     *ra = '\0';
420                     qdict_put(options, "readahead", qstring_from_str(ra_val));
421                 }
422                 break;
423             }
424         }
425         ra--;
426     }
427 
428     qdict_put(options, "url", qstring_from_str(file));
429 
430     g_free(file);
431 }
432 
433 static QemuOptsList runtime_opts = {
434     .name = "curl",
435     .head = QTAILQ_HEAD_INITIALIZER(runtime_opts.head),
436     .desc = {
437         {
438             .name = "url",
439             .type = QEMU_OPT_STRING,
440             .help = "URL to open",
441         },
442         {
443             .name = "readahead",
444             .type = QEMU_OPT_SIZE,
445             .help = "Readahead size",
446         },
447         { /* end of list */ }
448     },
449 };
450 
451 static int curl_open(BlockDriverState *bs, QDict *options, int flags,
452                      Error **errp)
453 {
454     BDRVCURLState *s = bs->opaque;
455     CURLState *state = NULL;
456     QemuOpts *opts;
457     Error *local_err = NULL;
458     const char *file;
459     double d;
460 
461     static int inited = 0;
462 
463     if (flags & BDRV_O_RDWR) {
464         error_setg(errp, "curl block device does not support writes");
465         return -EROFS;
466     }
467 
468     opts = qemu_opts_create(&runtime_opts, NULL, 0, &error_abort);
469     qemu_opts_absorb_qdict(opts, options, &local_err);
470     if (local_err) {
471         error_propagate(errp, local_err);
472         goto out_noclean;
473     }
474 
475     s->readahead_size = qemu_opt_get_size(opts, "readahead", READ_AHEAD_SIZE);
476     if ((s->readahead_size & 0x1ff) != 0) {
477         error_setg(errp, "HTTP_READAHEAD_SIZE %zd is not a multiple of 512",
478                    s->readahead_size);
479         goto out_noclean;
480     }
481 
482     file = qemu_opt_get(opts, "url");
483     if (file == NULL) {
484         error_setg(errp, "curl block driver requires an 'url' option");
485         goto out_noclean;
486     }
487 
488     if (!inited) {
489         curl_global_init(CURL_GLOBAL_ALL);
490         inited = 1;
491     }
492 
493     DPRINTF("CURL: Opening %s\n", file);
494     s->url = g_strdup(file);
495     state = curl_init_state(s);
496     if (!state)
497         goto out_noclean;
498 
499     // Get file size
500 
501     s->accept_range = false;
502     curl_easy_setopt(state->curl, CURLOPT_NOBODY, 1);
503     curl_easy_setopt(state->curl, CURLOPT_HEADERFUNCTION,
504                      curl_header_cb);
505     curl_easy_setopt(state->curl, CURLOPT_HEADERDATA, s);
506     if (curl_easy_perform(state->curl))
507         goto out;
508     curl_easy_getinfo(state->curl, CURLINFO_CONTENT_LENGTH_DOWNLOAD, &d);
509     if (d)
510         s->len = (size_t)d;
511     else if(!s->len)
512         goto out;
513     if ((!strncasecmp(s->url, "http://", strlen("http://"))
514         || !strncasecmp(s->url, "https://", strlen("https://")))
515         && !s->accept_range) {
516         pstrcpy(state->errmsg, CURL_ERROR_SIZE,
517                 "Server does not support 'range' (byte ranges).");
518         goto out;
519     }
520     DPRINTF("CURL: Size = %zd\n", s->len);
521 
522     curl_clean_state(state);
523     curl_easy_cleanup(state->curl);
524     state->curl = NULL;
525 
526     aio_timer_init(bdrv_get_aio_context(bs), &s->timer,
527                    QEMU_CLOCK_REALTIME, SCALE_NS,
528                    curl_multi_timeout_do, s);
529 
530     // Now we know the file exists and its size, so let's
531     // initialize the multi interface!
532 
533     s->multi = curl_multi_init();
534     curl_multi_setopt(s->multi, CURLMOPT_SOCKETDATA, s);
535     curl_multi_setopt(s->multi, CURLMOPT_SOCKETFUNCTION, curl_sock_cb);
536 #ifdef NEED_CURL_TIMER_CALLBACK
537     curl_multi_setopt(s->multi, CURLMOPT_TIMERDATA, s);
538     curl_multi_setopt(s->multi, CURLMOPT_TIMERFUNCTION, curl_timer_cb);
539 #endif
540     curl_multi_do(s);
541 
542     qemu_opts_del(opts);
543     return 0;
544 
545 out:
546     error_setg(errp, "CURL: Error opening file: %s", state->errmsg);
547     curl_easy_cleanup(state->curl);
548     state->curl = NULL;
549 out_noclean:
550     g_free(s->url);
551     qemu_opts_del(opts);
552     return -EINVAL;
553 }
554 
555 static void curl_aio_cancel(BlockDriverAIOCB *blockacb)
556 {
557     // Do we have to implement canceling? Seems to work without...
558 }
559 
560 static const AIOCBInfo curl_aiocb_info = {
561     .aiocb_size         = sizeof(CURLAIOCB),
562     .cancel             = curl_aio_cancel,
563 };
564 
565 
566 static void curl_readv_bh_cb(void *p)
567 {
568     CURLState *state;
569 
570     CURLAIOCB *acb = p;
571     BDRVCURLState *s = acb->common.bs->opaque;
572 
573     qemu_bh_delete(acb->bh);
574     acb->bh = NULL;
575 
576     size_t start = acb->sector_num * SECTOR_SIZE;
577     size_t end;
578 
579     // In case we have the requested data already (e.g. read-ahead),
580     // we can just call the callback and be done.
581     switch (curl_find_buf(s, start, acb->nb_sectors * SECTOR_SIZE, acb)) {
582         case FIND_RET_OK:
583             qemu_aio_release(acb);
584             // fall through
585         case FIND_RET_WAIT:
586             return;
587         default:
588             break;
589     }
590 
591     // No cache found, so let's start a new request
592     state = curl_init_state(s);
593     if (!state) {
594         acb->common.cb(acb->common.opaque, -EIO);
595         qemu_aio_release(acb);
596         return;
597     }
598 
599     acb->start = 0;
600     acb->end = (acb->nb_sectors * SECTOR_SIZE);
601 
602     state->buf_off = 0;
603     if (state->orig_buf)
604         g_free(state->orig_buf);
605     state->buf_start = start;
606     state->buf_len = acb->end + s->readahead_size;
607     end = MIN(start + state->buf_len, s->len) - 1;
608     state->orig_buf = g_malloc(state->buf_len);
609     state->acb[0] = acb;
610 
611     snprintf(state->range, 127, "%zd-%zd", start, end);
612     DPRINTF("CURL (AIO): Reading %d at %zd (%s)\n",
613             (acb->nb_sectors * SECTOR_SIZE), start, state->range);
614     curl_easy_setopt(state->curl, CURLOPT_RANGE, state->range);
615 
616     curl_multi_add_handle(s->multi, state->curl);
617     curl_multi_do(s);
618 
619 }
620 
621 static BlockDriverAIOCB *curl_aio_readv(BlockDriverState *bs,
622         int64_t sector_num, QEMUIOVector *qiov, int nb_sectors,
623         BlockDriverCompletionFunc *cb, void *opaque)
624 {
625     CURLAIOCB *acb;
626 
627     acb = qemu_aio_get(&curl_aiocb_info, bs, cb, opaque);
628 
629     acb->qiov = qiov;
630     acb->sector_num = sector_num;
631     acb->nb_sectors = nb_sectors;
632 
633     acb->bh = qemu_bh_new(curl_readv_bh_cb, acb);
634     qemu_bh_schedule(acb->bh);
635     return &acb->common;
636 }
637 
638 static void curl_close(BlockDriverState *bs)
639 {
640     BDRVCURLState *s = bs->opaque;
641     int i;
642 
643     DPRINTF("CURL: Close\n");
644     for (i=0; i<CURL_NUM_STATES; i++) {
645         if (s->states[i].in_use)
646             curl_clean_state(&s->states[i]);
647         if (s->states[i].curl) {
648             curl_easy_cleanup(s->states[i].curl);
649             s->states[i].curl = NULL;
650         }
651         if (s->states[i].orig_buf) {
652             g_free(s->states[i].orig_buf);
653             s->states[i].orig_buf = NULL;
654         }
655     }
656     if (s->multi)
657         curl_multi_cleanup(s->multi);
658 
659     timer_del(&s->timer);
660 
661     g_free(s->url);
662 }
663 
664 static int64_t curl_getlength(BlockDriverState *bs)
665 {
666     BDRVCURLState *s = bs->opaque;
667     return s->len;
668 }
669 
670 static BlockDriver bdrv_http = {
671     .format_name            = "http",
672     .protocol_name          = "http",
673 
674     .instance_size          = sizeof(BDRVCURLState),
675     .bdrv_parse_filename    = curl_parse_filename,
676     .bdrv_file_open         = curl_open,
677     .bdrv_close             = curl_close,
678     .bdrv_getlength         = curl_getlength,
679 
680     .bdrv_aio_readv         = curl_aio_readv,
681 };
682 
683 static BlockDriver bdrv_https = {
684     .format_name            = "https",
685     .protocol_name          = "https",
686 
687     .instance_size          = sizeof(BDRVCURLState),
688     .bdrv_parse_filename    = curl_parse_filename,
689     .bdrv_file_open         = curl_open,
690     .bdrv_close             = curl_close,
691     .bdrv_getlength         = curl_getlength,
692 
693     .bdrv_aio_readv         = curl_aio_readv,
694 };
695 
696 static BlockDriver bdrv_ftp = {
697     .format_name            = "ftp",
698     .protocol_name          = "ftp",
699 
700     .instance_size          = sizeof(BDRVCURLState),
701     .bdrv_parse_filename    = curl_parse_filename,
702     .bdrv_file_open         = curl_open,
703     .bdrv_close             = curl_close,
704     .bdrv_getlength         = curl_getlength,
705 
706     .bdrv_aio_readv         = curl_aio_readv,
707 };
708 
709 static BlockDriver bdrv_ftps = {
710     .format_name            = "ftps",
711     .protocol_name          = "ftps",
712 
713     .instance_size          = sizeof(BDRVCURLState),
714     .bdrv_parse_filename    = curl_parse_filename,
715     .bdrv_file_open         = curl_open,
716     .bdrv_close             = curl_close,
717     .bdrv_getlength         = curl_getlength,
718 
719     .bdrv_aio_readv         = curl_aio_readv,
720 };
721 
722 static BlockDriver bdrv_tftp = {
723     .format_name            = "tftp",
724     .protocol_name          = "tftp",
725 
726     .instance_size          = sizeof(BDRVCURLState),
727     .bdrv_parse_filename    = curl_parse_filename,
728     .bdrv_file_open         = curl_open,
729     .bdrv_close             = curl_close,
730     .bdrv_getlength         = curl_getlength,
731 
732     .bdrv_aio_readv         = curl_aio_readv,
733 };
734 
735 static void curl_block_init(void)
736 {
737     bdrv_register(&bdrv_http);
738     bdrv_register(&bdrv_https);
739     bdrv_register(&bdrv_ftp);
740     bdrv_register(&bdrv_ftps);
741     bdrv_register(&bdrv_tftp);
742 }
743 
744 block_init(curl_block_init);
745