xref: /openbmc/qemu/qemu-img.c (revision 2993683b)
1 /*
2  * QEMU disk image utility
3  *
4  * Copyright (c) 2003-2008 Fabrice Bellard
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 "qapi-visit.h"
25 #include "qapi/qmp-output-visitor.h"
26 #include "qapi/qmp/qjson.h"
27 #include "qemu-common.h"
28 #include "qemu/option.h"
29 #include "qemu/error-report.h"
30 #include "qemu/osdep.h"
31 #include "sysemu/sysemu.h"
32 #include "block/block_int.h"
33 #include <getopt.h>
34 #include <stdio.h>
35 #include <stdarg.h>
36 
37 #ifdef _WIN32
38 #include <windows.h>
39 #endif
40 
41 typedef struct img_cmd_t {
42     const char *name;
43     int (*handler)(int argc, char **argv);
44 } img_cmd_t;
45 
46 enum {
47     OPTION_OUTPUT = 256,
48     OPTION_BACKING_CHAIN = 257,
49 };
50 
51 typedef enum OutputFormat {
52     OFORMAT_JSON,
53     OFORMAT_HUMAN,
54 } OutputFormat;
55 
56 /* Default to cache=writeback as data integrity is not important for qemu-tcg. */
57 #define BDRV_O_FLAGS BDRV_O_CACHE_WB
58 #define BDRV_DEFAULT_CACHE "writeback"
59 
60 static void format_print(void *opaque, const char *name)
61 {
62     printf(" %s", name);
63 }
64 
65 /* Please keep in synch with qemu-img.texi */
66 static void help(void)
67 {
68     const char *help_msg =
69            "qemu-img version " QEMU_VERSION ", Copyright (c) 2004-2008 Fabrice Bellard\n"
70            "usage: qemu-img command [command options]\n"
71            "QEMU disk image utility\n"
72            "\n"
73            "Command syntax:\n"
74 #define DEF(option, callback, arg_string)        \
75            "  " arg_string "\n"
76 #include "qemu-img-cmds.h"
77 #undef DEF
78 #undef GEN_DOCS
79            "\n"
80            "Command parameters:\n"
81            "  'filename' is a disk image filename\n"
82            "  'fmt' is the disk image format. It is guessed automatically in most cases\n"
83            "  'cache' is the cache mode used to write the output disk image, the valid\n"
84            "    options are: 'none', 'writeback' (default, except for convert), 'writethrough',\n"
85            "    'directsync' and 'unsafe' (default for convert)\n"
86            "  'size' is the disk image size in bytes. Optional suffixes\n"
87            "    'k' or 'K' (kilobyte, 1024), 'M' (megabyte, 1024k), 'G' (gigabyte, 1024M)\n"
88            "    and T (terabyte, 1024G) are supported. 'b' is ignored.\n"
89            "  'output_filename' is the destination disk image filename\n"
90            "  'output_fmt' is the destination format\n"
91            "  'options' is a comma separated list of format specific options in a\n"
92            "    name=value format. Use -o ? for an overview of the options supported by the\n"
93            "    used format\n"
94            "  '-c' indicates that target image must be compressed (qcow format only)\n"
95            "  '-u' enables unsafe rebasing. It is assumed that old and new backing file\n"
96            "       match exactly. The image doesn't need a working backing file before\n"
97            "       rebasing in this case (useful for renaming the backing file)\n"
98            "  '-h' with or without a command shows this help and lists the supported formats\n"
99            "  '-p' show progress of command (only certain commands)\n"
100            "  '-q' use Quiet mode - do not print any output (except errors)\n"
101            "  '-S' indicates the consecutive number of bytes that must contain only zeros\n"
102            "       for qemu-img to create a sparse image during conversion\n"
103            "  '--output' takes the format in which the output must be done (human or json)\n"
104            "\n"
105            "Parameters to check subcommand:\n"
106            "  '-r' tries to repair any inconsistencies that are found during the check.\n"
107            "       '-r leaks' repairs only cluster leaks, whereas '-r all' fixes all\n"
108            "       kinds of errors, with a higher risk of choosing the wrong fix or\n"
109            "       hiding corruption that has already occurred.\n"
110            "\n"
111            "Parameters to snapshot subcommand:\n"
112            "  'snapshot' is the name of the snapshot to create, apply or delete\n"
113            "  '-a' applies a snapshot (revert disk to saved state)\n"
114            "  '-c' creates a snapshot\n"
115            "  '-d' deletes a snapshot\n"
116            "  '-l' lists all snapshots in the given image\n"
117            "\n"
118            "Parameters to compare subcommand:\n"
119            "  '-f' first image format\n"
120            "  '-F' second image format\n"
121            "  '-s' run in Strict mode - fail on different image size or sector allocation\n";
122 
123     printf("%s\nSupported formats:", help_msg);
124     bdrv_iterate_format(format_print, NULL);
125     printf("\n");
126     exit(1);
127 }
128 
129 static int qprintf(bool quiet, const char *fmt, ...)
130 {
131     int ret = 0;
132     if (!quiet) {
133         va_list args;
134         va_start(args, fmt);
135         ret = vprintf(fmt, args);
136         va_end(args);
137     }
138     return ret;
139 }
140 
141 #if defined(WIN32)
142 /* XXX: put correct support for win32 */
143 static int read_password(char *buf, int buf_size)
144 {
145     int c, i;
146     printf("Password: ");
147     fflush(stdout);
148     i = 0;
149     for(;;) {
150         c = getchar();
151         if (c == '\n')
152             break;
153         if (i < (buf_size - 1))
154             buf[i++] = c;
155     }
156     buf[i] = '\0';
157     return 0;
158 }
159 
160 #else
161 
162 #include <termios.h>
163 
164 static struct termios oldtty;
165 
166 static void term_exit(void)
167 {
168     tcsetattr (0, TCSANOW, &oldtty);
169 }
170 
171 static void term_init(void)
172 {
173     struct termios tty;
174 
175     tcgetattr (0, &tty);
176     oldtty = tty;
177 
178     tty.c_iflag &= ~(IGNBRK|BRKINT|PARMRK|ISTRIP
179                           |INLCR|IGNCR|ICRNL|IXON);
180     tty.c_oflag |= OPOST;
181     tty.c_lflag &= ~(ECHO|ECHONL|ICANON|IEXTEN);
182     tty.c_cflag &= ~(CSIZE|PARENB);
183     tty.c_cflag |= CS8;
184     tty.c_cc[VMIN] = 1;
185     tty.c_cc[VTIME] = 0;
186 
187     tcsetattr (0, TCSANOW, &tty);
188 
189     atexit(term_exit);
190 }
191 
192 static int read_password(char *buf, int buf_size)
193 {
194     uint8_t ch;
195     int i, ret;
196 
197     printf("password: ");
198     fflush(stdout);
199     term_init();
200     i = 0;
201     for(;;) {
202         ret = read(0, &ch, 1);
203         if (ret == -1) {
204             if (errno == EAGAIN || errno == EINTR) {
205                 continue;
206             } else {
207                 ret = -1;
208                 break;
209             }
210         } else if (ret == 0) {
211             ret = -1;
212             break;
213         } else {
214             if (ch == '\r') {
215                 ret = 0;
216                 break;
217             }
218             if (i < (buf_size - 1))
219                 buf[i++] = ch;
220         }
221     }
222     term_exit();
223     buf[i] = '\0';
224     printf("\n");
225     return ret;
226 }
227 #endif
228 
229 static int print_block_option_help(const char *filename, const char *fmt)
230 {
231     BlockDriver *drv, *proto_drv;
232     QEMUOptionParameter *create_options = NULL;
233 
234     /* Find driver and parse its options */
235     drv = bdrv_find_format(fmt);
236     if (!drv) {
237         error_report("Unknown file format '%s'", fmt);
238         return 1;
239     }
240 
241     proto_drv = bdrv_find_protocol(filename);
242     if (!proto_drv) {
243         error_report("Unknown protocol '%s'", filename);
244         return 1;
245     }
246 
247     create_options = append_option_parameters(create_options,
248                                               drv->create_options);
249     create_options = append_option_parameters(create_options,
250                                               proto_drv->create_options);
251     print_option_help(create_options);
252     free_option_parameters(create_options);
253     return 0;
254 }
255 
256 static BlockDriverState *bdrv_new_open(const char *filename,
257                                        const char *fmt,
258                                        int flags,
259                                        bool require_io,
260                                        bool quiet)
261 {
262     BlockDriverState *bs;
263     BlockDriver *drv;
264     char password[256];
265     int ret;
266 
267     bs = bdrv_new("image");
268 
269     if (fmt) {
270         drv = bdrv_find_format(fmt);
271         if (!drv) {
272             error_report("Unknown file format '%s'", fmt);
273             goto fail;
274         }
275     } else {
276         drv = NULL;
277     }
278 
279     ret = bdrv_open(bs, filename, NULL, flags, drv);
280     if (ret < 0) {
281         error_report("Could not open '%s': %s", filename, strerror(-ret));
282         goto fail;
283     }
284 
285     if (bdrv_is_encrypted(bs) && require_io) {
286         qprintf(quiet, "Disk image '%s' is encrypted.\n", filename);
287         if (read_password(password, sizeof(password)) < 0) {
288             error_report("No password given");
289             goto fail;
290         }
291         if (bdrv_set_key(bs, password) < 0) {
292             error_report("invalid password");
293             goto fail;
294         }
295     }
296     return bs;
297 fail:
298     if (bs) {
299         bdrv_delete(bs);
300     }
301     return NULL;
302 }
303 
304 static int add_old_style_options(const char *fmt, QEMUOptionParameter *list,
305                                  const char *base_filename,
306                                  const char *base_fmt)
307 {
308     if (base_filename) {
309         if (set_option_parameter(list, BLOCK_OPT_BACKING_FILE, base_filename)) {
310             error_report("Backing file not supported for file format '%s'",
311                          fmt);
312             return -1;
313         }
314     }
315     if (base_fmt) {
316         if (set_option_parameter(list, BLOCK_OPT_BACKING_FMT, base_fmt)) {
317             error_report("Backing file format not supported for file "
318                          "format '%s'", fmt);
319             return -1;
320         }
321     }
322     return 0;
323 }
324 
325 static int img_create(int argc, char **argv)
326 {
327     int c;
328     uint64_t img_size = -1;
329     const char *fmt = "raw";
330     const char *base_fmt = NULL;
331     const char *filename;
332     const char *base_filename = NULL;
333     char *options = NULL;
334     Error *local_err = NULL;
335     bool quiet = false;
336 
337     for(;;) {
338         c = getopt(argc, argv, "F:b:f:he6o:q");
339         if (c == -1) {
340             break;
341         }
342         switch(c) {
343         case '?':
344         case 'h':
345             help();
346             break;
347         case 'F':
348             base_fmt = optarg;
349             break;
350         case 'b':
351             base_filename = optarg;
352             break;
353         case 'f':
354             fmt = optarg;
355             break;
356         case 'e':
357             error_report("option -e is deprecated, please use \'-o "
358                   "encryption\' instead!");
359             return 1;
360         case '6':
361             error_report("option -6 is deprecated, please use \'-o "
362                   "compat6\' instead!");
363             return 1;
364         case 'o':
365             options = optarg;
366             break;
367         case 'q':
368             quiet = true;
369             break;
370         }
371     }
372 
373     /* Get the filename */
374     if (optind >= argc) {
375         help();
376     }
377     filename = argv[optind++];
378 
379     /* Get image size, if specified */
380     if (optind < argc) {
381         int64_t sval;
382         char *end;
383         sval = strtosz_suffix(argv[optind++], &end, STRTOSZ_DEFSUFFIX_B);
384         if (sval < 0 || *end) {
385             if (sval == -ERANGE) {
386                 error_report("Image size must be less than 8 EiB!");
387             } else {
388                 error_report("Invalid image size specified! You may use k, M, "
389                       "G or T suffixes for ");
390                 error_report("kilobytes, megabytes, gigabytes and terabytes.");
391             }
392             return 1;
393         }
394         img_size = (uint64_t)sval;
395     }
396 
397     if (options && is_help_option(options)) {
398         return print_block_option_help(filename, fmt);
399     }
400 
401     bdrv_img_create(filename, fmt, base_filename, base_fmt,
402                     options, img_size, BDRV_O_FLAGS, &local_err, quiet);
403     if (error_is_set(&local_err)) {
404         error_report("%s", error_get_pretty(local_err));
405         error_free(local_err);
406         return 1;
407     }
408 
409     return 0;
410 }
411 
412 static void dump_json_image_check(ImageCheck *check, bool quiet)
413 {
414     Error *errp = NULL;
415     QString *str;
416     QmpOutputVisitor *ov = qmp_output_visitor_new();
417     QObject *obj;
418     visit_type_ImageCheck(qmp_output_get_visitor(ov),
419                           &check, NULL, &errp);
420     obj = qmp_output_get_qobject(ov);
421     str = qobject_to_json_pretty(obj);
422     assert(str != NULL);
423     qprintf(quiet, "%s\n", qstring_get_str(str));
424     qobject_decref(obj);
425     qmp_output_visitor_cleanup(ov);
426     QDECREF(str);
427 }
428 
429 static void dump_human_image_check(ImageCheck *check, bool quiet)
430 {
431     if (!(check->corruptions || check->leaks || check->check_errors)) {
432         qprintf(quiet, "No errors were found on the image.\n");
433     } else {
434         if (check->corruptions) {
435             qprintf(quiet, "\n%" PRId64 " errors were found on the image.\n"
436                     "Data may be corrupted, or further writes to the image "
437                     "may corrupt it.\n",
438                     check->corruptions);
439         }
440 
441         if (check->leaks) {
442             qprintf(quiet,
443                     "\n%" PRId64 " leaked clusters were found on the image.\n"
444                     "This means waste of disk space, but no harm to data.\n",
445                     check->leaks);
446         }
447 
448         if (check->check_errors) {
449             qprintf(quiet,
450                     "\n%" PRId64
451                     " internal errors have occurred during the check.\n",
452                     check->check_errors);
453         }
454     }
455 
456     if (check->total_clusters != 0 && check->allocated_clusters != 0) {
457         qprintf(quiet, "%" PRId64 "/%" PRId64 " = %0.2f%% allocated, "
458                 "%0.2f%% fragmented, %0.2f%% compressed clusters\n",
459                 check->allocated_clusters, check->total_clusters,
460                 check->allocated_clusters * 100.0 / check->total_clusters,
461                 check->fragmented_clusters * 100.0 / check->allocated_clusters,
462                 check->compressed_clusters * 100.0 /
463                 check->allocated_clusters);
464     }
465 
466     if (check->image_end_offset) {
467         qprintf(quiet,
468                 "Image end offset: %" PRId64 "\n", check->image_end_offset);
469     }
470 }
471 
472 static int collect_image_check(BlockDriverState *bs,
473                    ImageCheck *check,
474                    const char *filename,
475                    const char *fmt,
476                    int fix)
477 {
478     int ret;
479     BdrvCheckResult result;
480 
481     ret = bdrv_check(bs, &result, fix);
482     if (ret < 0) {
483         return ret;
484     }
485 
486     check->filename                 = g_strdup(filename);
487     check->format                   = g_strdup(bdrv_get_format_name(bs));
488     check->check_errors             = result.check_errors;
489     check->corruptions              = result.corruptions;
490     check->has_corruptions          = result.corruptions != 0;
491     check->leaks                    = result.leaks;
492     check->has_leaks                = result.leaks != 0;
493     check->corruptions_fixed        = result.corruptions_fixed;
494     check->has_corruptions_fixed    = result.corruptions != 0;
495     check->leaks_fixed              = result.leaks_fixed;
496     check->has_leaks_fixed          = result.leaks != 0;
497     check->image_end_offset         = result.image_end_offset;
498     check->has_image_end_offset     = result.image_end_offset != 0;
499     check->total_clusters           = result.bfi.total_clusters;
500     check->has_total_clusters       = result.bfi.total_clusters != 0;
501     check->allocated_clusters       = result.bfi.allocated_clusters;
502     check->has_allocated_clusters   = result.bfi.allocated_clusters != 0;
503     check->fragmented_clusters      = result.bfi.fragmented_clusters;
504     check->has_fragmented_clusters  = result.bfi.fragmented_clusters != 0;
505     check->compressed_clusters      = result.bfi.compressed_clusters;
506     check->has_compressed_clusters  = result.bfi.compressed_clusters != 0;
507 
508     return 0;
509 }
510 
511 /*
512  * Checks an image for consistency. Exit codes:
513  *
514  * 0 - Check completed, image is good
515  * 1 - Check not completed because of internal errors
516  * 2 - Check completed, image is corrupted
517  * 3 - Check completed, image has leaked clusters, but is good otherwise
518  */
519 static int img_check(int argc, char **argv)
520 {
521     int c, ret;
522     OutputFormat output_format = OFORMAT_HUMAN;
523     const char *filename, *fmt, *output;
524     BlockDriverState *bs;
525     int fix = 0;
526     int flags = BDRV_O_FLAGS | BDRV_O_CHECK;
527     ImageCheck *check;
528     bool quiet = false;
529 
530     fmt = NULL;
531     output = NULL;
532     for(;;) {
533         int option_index = 0;
534         static const struct option long_options[] = {
535             {"help", no_argument, 0, 'h'},
536             {"format", required_argument, 0, 'f'},
537             {"repair", no_argument, 0, 'r'},
538             {"output", required_argument, 0, OPTION_OUTPUT},
539             {0, 0, 0, 0}
540         };
541         c = getopt_long(argc, argv, "f:hr:q",
542                         long_options, &option_index);
543         if (c == -1) {
544             break;
545         }
546         switch(c) {
547         case '?':
548         case 'h':
549             help();
550             break;
551         case 'f':
552             fmt = optarg;
553             break;
554         case 'r':
555             flags |= BDRV_O_RDWR;
556 
557             if (!strcmp(optarg, "leaks")) {
558                 fix = BDRV_FIX_LEAKS;
559             } else if (!strcmp(optarg, "all")) {
560                 fix = BDRV_FIX_LEAKS | BDRV_FIX_ERRORS;
561             } else {
562                 help();
563             }
564             break;
565         case OPTION_OUTPUT:
566             output = optarg;
567             break;
568         case 'q':
569             quiet = true;
570             break;
571         }
572     }
573     if (optind >= argc) {
574         help();
575     }
576     filename = argv[optind++];
577 
578     if (output && !strcmp(output, "json")) {
579         output_format = OFORMAT_JSON;
580     } else if (output && !strcmp(output, "human")) {
581         output_format = OFORMAT_HUMAN;
582     } else if (output) {
583         error_report("--output must be used with human or json as argument.");
584         return 1;
585     }
586 
587     bs = bdrv_new_open(filename, fmt, flags, true, quiet);
588     if (!bs) {
589         return 1;
590     }
591 
592     check = g_new0(ImageCheck, 1);
593     ret = collect_image_check(bs, check, filename, fmt, fix);
594 
595     if (ret == -ENOTSUP) {
596         if (output_format == OFORMAT_HUMAN) {
597             error_report("This image format does not support checks");
598         }
599         ret = 1;
600         goto fail;
601     }
602 
603     if (check->corruptions_fixed || check->leaks_fixed) {
604         int corruptions_fixed, leaks_fixed;
605 
606         leaks_fixed         = check->leaks_fixed;
607         corruptions_fixed   = check->corruptions_fixed;
608 
609         if (output_format == OFORMAT_HUMAN) {
610             qprintf(quiet,
611                     "The following inconsistencies were found and repaired:\n\n"
612                     "    %" PRId64 " leaked clusters\n"
613                     "    %" PRId64 " corruptions\n\n"
614                     "Double checking the fixed image now...\n",
615                     check->leaks_fixed,
616                     check->corruptions_fixed);
617         }
618 
619         ret = collect_image_check(bs, check, filename, fmt, 0);
620 
621         check->leaks_fixed          = leaks_fixed;
622         check->corruptions_fixed    = corruptions_fixed;
623     }
624 
625     switch (output_format) {
626     case OFORMAT_HUMAN:
627         dump_human_image_check(check, quiet);
628         break;
629     case OFORMAT_JSON:
630         dump_json_image_check(check, quiet);
631         break;
632     }
633 
634     if (ret || check->check_errors) {
635         ret = 1;
636         goto fail;
637     }
638 
639     if (check->corruptions) {
640         ret = 2;
641     } else if (check->leaks) {
642         ret = 3;
643     } else {
644         ret = 0;
645     }
646 
647 fail:
648     qapi_free_ImageCheck(check);
649     bdrv_delete(bs);
650 
651     return ret;
652 }
653 
654 static int img_commit(int argc, char **argv)
655 {
656     int c, ret, flags;
657     const char *filename, *fmt, *cache;
658     BlockDriverState *bs;
659     bool quiet = false;
660 
661     fmt = NULL;
662     cache = BDRV_DEFAULT_CACHE;
663     for(;;) {
664         c = getopt(argc, argv, "f:ht:q");
665         if (c == -1) {
666             break;
667         }
668         switch(c) {
669         case '?':
670         case 'h':
671             help();
672             break;
673         case 'f':
674             fmt = optarg;
675             break;
676         case 't':
677             cache = optarg;
678             break;
679         case 'q':
680             quiet = true;
681             break;
682         }
683     }
684     if (optind >= argc) {
685         help();
686     }
687     filename = argv[optind++];
688 
689     flags = BDRV_O_RDWR;
690     ret = bdrv_parse_cache_flags(cache, &flags);
691     if (ret < 0) {
692         error_report("Invalid cache option: %s", cache);
693         return -1;
694     }
695 
696     bs = bdrv_new_open(filename, fmt, flags, true, quiet);
697     if (!bs) {
698         return 1;
699     }
700     ret = bdrv_commit(bs);
701     switch(ret) {
702     case 0:
703         qprintf(quiet, "Image committed.\n");
704         break;
705     case -ENOENT:
706         error_report("No disk inserted");
707         break;
708     case -EACCES:
709         error_report("Image is read-only");
710         break;
711     case -ENOTSUP:
712         error_report("Image is already committed");
713         break;
714     default:
715         error_report("Error while committing image");
716         break;
717     }
718 
719     bdrv_delete(bs);
720     if (ret) {
721         return 1;
722     }
723     return 0;
724 }
725 
726 /*
727  * Returns true iff the first sector pointed to by 'buf' contains at least
728  * a non-NUL byte.
729  *
730  * 'pnum' is set to the number of sectors (including and immediately following
731  * the first one) that are known to be in the same allocated/unallocated state.
732  */
733 static int is_allocated_sectors(const uint8_t *buf, int n, int *pnum)
734 {
735     bool is_zero;
736     int i;
737 
738     if (n <= 0) {
739         *pnum = 0;
740         return 0;
741     }
742     is_zero = buffer_is_zero(buf, 512);
743     for(i = 1; i < n; i++) {
744         buf += 512;
745         if (is_zero != buffer_is_zero(buf, 512)) {
746             break;
747         }
748     }
749     *pnum = i;
750     return !is_zero;
751 }
752 
753 /*
754  * Like is_allocated_sectors, but if the buffer starts with a used sector,
755  * up to 'min' consecutive sectors containing zeros are ignored. This avoids
756  * breaking up write requests for only small sparse areas.
757  */
758 static int is_allocated_sectors_min(const uint8_t *buf, int n, int *pnum,
759     int min)
760 {
761     int ret;
762     int num_checked, num_used;
763 
764     if (n < min) {
765         min = n;
766     }
767 
768     ret = is_allocated_sectors(buf, n, pnum);
769     if (!ret) {
770         return ret;
771     }
772 
773     num_used = *pnum;
774     buf += BDRV_SECTOR_SIZE * *pnum;
775     n -= *pnum;
776     num_checked = num_used;
777 
778     while (n > 0) {
779         ret = is_allocated_sectors(buf, n, pnum);
780 
781         buf += BDRV_SECTOR_SIZE * *pnum;
782         n -= *pnum;
783         num_checked += *pnum;
784         if (ret) {
785             num_used = num_checked;
786         } else if (*pnum >= min) {
787             break;
788         }
789     }
790 
791     *pnum = num_used;
792     return 1;
793 }
794 
795 /*
796  * Compares two buffers sector by sector. Returns 0 if the first sector of both
797  * buffers matches, non-zero otherwise.
798  *
799  * pnum is set to the number of sectors (including and immediately following
800  * the first one) that are known to have the same comparison result
801  */
802 static int compare_sectors(const uint8_t *buf1, const uint8_t *buf2, int n,
803     int *pnum)
804 {
805     int res, i;
806 
807     if (n <= 0) {
808         *pnum = 0;
809         return 0;
810     }
811 
812     res = !!memcmp(buf1, buf2, 512);
813     for(i = 1; i < n; i++) {
814         buf1 += 512;
815         buf2 += 512;
816 
817         if (!!memcmp(buf1, buf2, 512) != res) {
818             break;
819         }
820     }
821 
822     *pnum = i;
823     return res;
824 }
825 
826 #define IO_BUF_SIZE (2 * 1024 * 1024)
827 
828 static int64_t sectors_to_bytes(int64_t sectors)
829 {
830     return sectors << BDRV_SECTOR_BITS;
831 }
832 
833 static int64_t sectors_to_process(int64_t total, int64_t from)
834 {
835     return MIN(total - from, IO_BUF_SIZE >> BDRV_SECTOR_BITS);
836 }
837 
838 /*
839  * Check if passed sectors are empty (not allocated or contain only 0 bytes)
840  *
841  * Returns 0 in case sectors are filled with 0, 1 if sectors contain non-zero
842  * data and negative value on error.
843  *
844  * @param bs:  Driver used for accessing file
845  * @param sect_num: Number of first sector to check
846  * @param sect_count: Number of sectors to check
847  * @param filename: Name of disk file we are checking (logging purpose)
848  * @param buffer: Allocated buffer for storing read data
849  * @param quiet: Flag for quiet mode
850  */
851 static int check_empty_sectors(BlockDriverState *bs, int64_t sect_num,
852                                int sect_count, const char *filename,
853                                uint8_t *buffer, bool quiet)
854 {
855     int pnum, ret = 0;
856     ret = bdrv_read(bs, sect_num, buffer, sect_count);
857     if (ret < 0) {
858         error_report("Error while reading offset %" PRId64 " of %s: %s",
859                      sectors_to_bytes(sect_num), filename, strerror(-ret));
860         return ret;
861     }
862     ret = is_allocated_sectors(buffer, sect_count, &pnum);
863     if (ret || pnum != sect_count) {
864         qprintf(quiet, "Content mismatch at offset %" PRId64 "!\n",
865                 sectors_to_bytes(ret ? sect_num : sect_num + pnum));
866         return 1;
867     }
868 
869     return 0;
870 }
871 
872 /*
873  * Compares two images. Exit codes:
874  *
875  * 0 - Images are identical
876  * 1 - Images differ
877  * >1 - Error occurred
878  */
879 static int img_compare(int argc, char **argv)
880 {
881     const char *fmt1 = NULL, *fmt2 = NULL, *filename1, *filename2;
882     BlockDriverState *bs1, *bs2;
883     int64_t total_sectors1, total_sectors2;
884     uint8_t *buf1 = NULL, *buf2 = NULL;
885     int pnum1, pnum2;
886     int allocated1, allocated2;
887     int ret = 0; /* return value - 0 Ident, 1 Different, >1 Error */
888     bool progress = false, quiet = false, strict = false;
889     int64_t total_sectors;
890     int64_t sector_num = 0;
891     int64_t nb_sectors;
892     int c, pnum;
893     uint64_t bs_sectors;
894     uint64_t progress_base;
895 
896     for (;;) {
897         c = getopt(argc, argv, "hpf:F:sq");
898         if (c == -1) {
899             break;
900         }
901         switch (c) {
902         case '?':
903         case 'h':
904             help();
905             break;
906         case 'f':
907             fmt1 = optarg;
908             break;
909         case 'F':
910             fmt2 = optarg;
911             break;
912         case 'p':
913             progress = true;
914             break;
915         case 'q':
916             quiet = true;
917             break;
918         case 's':
919             strict = true;
920             break;
921         }
922     }
923 
924     /* Progress is not shown in Quiet mode */
925     if (quiet) {
926         progress = false;
927     }
928 
929 
930     if (optind > argc - 2) {
931         help();
932     }
933     filename1 = argv[optind++];
934     filename2 = argv[optind++];
935 
936     /* Initialize before goto out */
937     qemu_progress_init(progress, 2.0);
938 
939     bs1 = bdrv_new_open(filename1, fmt1, BDRV_O_FLAGS, true, quiet);
940     if (!bs1) {
941         error_report("Can't open file %s", filename1);
942         ret = 2;
943         goto out3;
944     }
945 
946     bs2 = bdrv_new_open(filename2, fmt2, BDRV_O_FLAGS, true, quiet);
947     if (!bs2) {
948         error_report("Can't open file %s", filename2);
949         ret = 2;
950         goto out2;
951     }
952 
953     buf1 = qemu_blockalign(bs1, IO_BUF_SIZE);
954     buf2 = qemu_blockalign(bs2, IO_BUF_SIZE);
955     bdrv_get_geometry(bs1, &bs_sectors);
956     total_sectors1 = bs_sectors;
957     bdrv_get_geometry(bs2, &bs_sectors);
958     total_sectors2 = bs_sectors;
959     total_sectors = MIN(total_sectors1, total_sectors2);
960     progress_base = MAX(total_sectors1, total_sectors2);
961 
962     qemu_progress_print(0, 100);
963 
964     if (strict && total_sectors1 != total_sectors2) {
965         ret = 1;
966         qprintf(quiet, "Strict mode: Image size mismatch!\n");
967         goto out;
968     }
969 
970     for (;;) {
971         nb_sectors = sectors_to_process(total_sectors, sector_num);
972         if (nb_sectors <= 0) {
973             break;
974         }
975         allocated1 = bdrv_is_allocated_above(bs1, NULL, sector_num, nb_sectors,
976                                              &pnum1);
977         if (allocated1 < 0) {
978             ret = 3;
979             error_report("Sector allocation test failed for %s", filename1);
980             goto out;
981         }
982 
983         allocated2 = bdrv_is_allocated_above(bs2, NULL, sector_num, nb_sectors,
984                                              &pnum2);
985         if (allocated2 < 0) {
986             ret = 3;
987             error_report("Sector allocation test failed for %s", filename2);
988             goto out;
989         }
990         nb_sectors = MIN(pnum1, pnum2);
991 
992         if (allocated1 == allocated2) {
993             if (allocated1) {
994                 ret = bdrv_read(bs1, sector_num, buf1, nb_sectors);
995                 if (ret < 0) {
996                     error_report("Error while reading offset %" PRId64 " of %s:"
997                                  " %s", sectors_to_bytes(sector_num), filename1,
998                                  strerror(-ret));
999                     ret = 4;
1000                     goto out;
1001                 }
1002                 ret = bdrv_read(bs2, sector_num, buf2, nb_sectors);
1003                 if (ret < 0) {
1004                     error_report("Error while reading offset %" PRId64
1005                                  " of %s: %s", sectors_to_bytes(sector_num),
1006                                  filename2, strerror(-ret));
1007                     ret = 4;
1008                     goto out;
1009                 }
1010                 ret = compare_sectors(buf1, buf2, nb_sectors, &pnum);
1011                 if (ret || pnum != nb_sectors) {
1012                     ret = 1;
1013                     qprintf(quiet, "Content mismatch at offset %" PRId64 "!\n",
1014                             sectors_to_bytes(
1015                                 ret ? sector_num : sector_num + pnum));
1016                     goto out;
1017                 }
1018             }
1019         } else {
1020             if (strict) {
1021                 ret = 1;
1022                 qprintf(quiet, "Strict mode: Offset %" PRId64
1023                         " allocation mismatch!\n",
1024                         sectors_to_bytes(sector_num));
1025                 goto out;
1026             }
1027 
1028             if (allocated1) {
1029                 ret = check_empty_sectors(bs1, sector_num, nb_sectors,
1030                                           filename1, buf1, quiet);
1031             } else {
1032                 ret = check_empty_sectors(bs2, sector_num, nb_sectors,
1033                                           filename2, buf1, quiet);
1034             }
1035             if (ret) {
1036                 if (ret < 0) {
1037                     ret = 4;
1038                     error_report("Error while reading offset %" PRId64 ": %s",
1039                                  sectors_to_bytes(sector_num), strerror(-ret));
1040                 }
1041                 goto out;
1042             }
1043         }
1044         sector_num += nb_sectors;
1045         qemu_progress_print(((float) nb_sectors / progress_base)*100, 100);
1046     }
1047 
1048     if (total_sectors1 != total_sectors2) {
1049         BlockDriverState *bs_over;
1050         int64_t total_sectors_over;
1051         const char *filename_over;
1052 
1053         qprintf(quiet, "Warning: Image size mismatch!\n");
1054         if (total_sectors1 > total_sectors2) {
1055             total_sectors_over = total_sectors1;
1056             bs_over = bs1;
1057             filename_over = filename1;
1058         } else {
1059             total_sectors_over = total_sectors2;
1060             bs_over = bs2;
1061             filename_over = filename2;
1062         }
1063 
1064         for (;;) {
1065             nb_sectors = sectors_to_process(total_sectors_over, sector_num);
1066             if (nb_sectors <= 0) {
1067                 break;
1068             }
1069             ret = bdrv_is_allocated_above(bs_over, NULL, sector_num,
1070                                           nb_sectors, &pnum);
1071             if (ret < 0) {
1072                 ret = 3;
1073                 error_report("Sector allocation test failed for %s",
1074                              filename_over);
1075                 goto out;
1076 
1077             }
1078             nb_sectors = pnum;
1079             if (ret) {
1080                 ret = check_empty_sectors(bs_over, sector_num, nb_sectors,
1081                                           filename_over, buf1, quiet);
1082                 if (ret) {
1083                     if (ret < 0) {
1084                         ret = 4;
1085                         error_report("Error while reading offset %" PRId64
1086                                      " of %s: %s", sectors_to_bytes(sector_num),
1087                                      filename_over, strerror(-ret));
1088                     }
1089                     goto out;
1090                 }
1091             }
1092             sector_num += nb_sectors;
1093             qemu_progress_print(((float) nb_sectors / progress_base)*100, 100);
1094         }
1095     }
1096 
1097     qprintf(quiet, "Images are identical.\n");
1098     ret = 0;
1099 
1100 out:
1101     bdrv_delete(bs2);
1102     qemu_vfree(buf1);
1103     qemu_vfree(buf2);
1104 out2:
1105     bdrv_delete(bs1);
1106 out3:
1107     qemu_progress_end();
1108     return ret;
1109 }
1110 
1111 static int img_convert(int argc, char **argv)
1112 {
1113     int c, ret = 0, n, n1, bs_n, bs_i, compress, cluster_size, cluster_sectors;
1114     int progress = 0, flags;
1115     const char *fmt, *out_fmt, *cache, *out_baseimg, *out_filename;
1116     BlockDriver *drv, *proto_drv;
1117     BlockDriverState **bs = NULL, *out_bs = NULL;
1118     int64_t total_sectors, nb_sectors, sector_num, bs_offset;
1119     uint64_t bs_sectors;
1120     uint8_t * buf = NULL;
1121     const uint8_t *buf1;
1122     BlockDriverInfo bdi;
1123     QEMUOptionParameter *param = NULL, *create_options = NULL;
1124     QEMUOptionParameter *out_baseimg_param;
1125     char *options = NULL;
1126     const char *snapshot_name = NULL;
1127     float local_progress = 0;
1128     int min_sparse = 8; /* Need at least 4k of zeros for sparse detection */
1129     bool quiet = false;
1130 
1131     fmt = NULL;
1132     out_fmt = "raw";
1133     cache = "unsafe";
1134     out_baseimg = NULL;
1135     compress = 0;
1136     for(;;) {
1137         c = getopt(argc, argv, "f:O:B:s:hce6o:pS:t:q");
1138         if (c == -1) {
1139             break;
1140         }
1141         switch(c) {
1142         case '?':
1143         case 'h':
1144             help();
1145             break;
1146         case 'f':
1147             fmt = optarg;
1148             break;
1149         case 'O':
1150             out_fmt = optarg;
1151             break;
1152         case 'B':
1153             out_baseimg = optarg;
1154             break;
1155         case 'c':
1156             compress = 1;
1157             break;
1158         case 'e':
1159             error_report("option -e is deprecated, please use \'-o "
1160                   "encryption\' instead!");
1161             return 1;
1162         case '6':
1163             error_report("option -6 is deprecated, please use \'-o "
1164                   "compat6\' instead!");
1165             return 1;
1166         case 'o':
1167             options = optarg;
1168             break;
1169         case 's':
1170             snapshot_name = optarg;
1171             break;
1172         case 'S':
1173         {
1174             int64_t sval;
1175             char *end;
1176             sval = strtosz_suffix(optarg, &end, STRTOSZ_DEFSUFFIX_B);
1177             if (sval < 0 || *end) {
1178                 error_report("Invalid minimum zero buffer size for sparse output specified");
1179                 return 1;
1180             }
1181 
1182             min_sparse = sval / BDRV_SECTOR_SIZE;
1183             break;
1184         }
1185         case 'p':
1186             progress = 1;
1187             break;
1188         case 't':
1189             cache = optarg;
1190             break;
1191         case 'q':
1192             quiet = true;
1193             break;
1194         }
1195     }
1196 
1197     if (quiet) {
1198         progress = 0;
1199     }
1200 
1201     bs_n = argc - optind - 1;
1202     if (bs_n < 1) {
1203         help();
1204     }
1205 
1206     out_filename = argv[argc - 1];
1207 
1208     /* Initialize before goto out */
1209     qemu_progress_init(progress, 2.0);
1210 
1211     if (options && is_help_option(options)) {
1212         ret = print_block_option_help(out_filename, out_fmt);
1213         goto out;
1214     }
1215 
1216     if (bs_n > 1 && out_baseimg) {
1217         error_report("-B makes no sense when concatenating multiple input "
1218                      "images");
1219         ret = -1;
1220         goto out;
1221     }
1222 
1223     qemu_progress_print(0, 100);
1224 
1225     bs = g_malloc0(bs_n * sizeof(BlockDriverState *));
1226 
1227     total_sectors = 0;
1228     for (bs_i = 0; bs_i < bs_n; bs_i++) {
1229         bs[bs_i] = bdrv_new_open(argv[optind + bs_i], fmt, BDRV_O_FLAGS, true,
1230                                  quiet);
1231         if (!bs[bs_i]) {
1232             error_report("Could not open '%s'", argv[optind + bs_i]);
1233             ret = -1;
1234             goto out;
1235         }
1236         bdrv_get_geometry(bs[bs_i], &bs_sectors);
1237         total_sectors += bs_sectors;
1238     }
1239 
1240     if (snapshot_name != NULL) {
1241         if (bs_n > 1) {
1242             error_report("No support for concatenating multiple snapshot");
1243             ret = -1;
1244             goto out;
1245         }
1246         if (bdrv_snapshot_load_tmp(bs[0], snapshot_name) < 0) {
1247             error_report("Failed to load snapshot");
1248             ret = -1;
1249             goto out;
1250         }
1251     }
1252 
1253     /* Find driver and parse its options */
1254     drv = bdrv_find_format(out_fmt);
1255     if (!drv) {
1256         error_report("Unknown file format '%s'", out_fmt);
1257         ret = -1;
1258         goto out;
1259     }
1260 
1261     proto_drv = bdrv_find_protocol(out_filename);
1262     if (!proto_drv) {
1263         error_report("Unknown protocol '%s'", out_filename);
1264         ret = -1;
1265         goto out;
1266     }
1267 
1268     create_options = append_option_parameters(create_options,
1269                                               drv->create_options);
1270     create_options = append_option_parameters(create_options,
1271                                               proto_drv->create_options);
1272 
1273     if (options) {
1274         param = parse_option_parameters(options, create_options, param);
1275         if (param == NULL) {
1276             error_report("Invalid options for file format '%s'.", out_fmt);
1277             ret = -1;
1278             goto out;
1279         }
1280     } else {
1281         param = parse_option_parameters("", create_options, param);
1282     }
1283 
1284     set_option_parameter_int(param, BLOCK_OPT_SIZE, total_sectors * 512);
1285     ret = add_old_style_options(out_fmt, param, out_baseimg, NULL);
1286     if (ret < 0) {
1287         goto out;
1288     }
1289 
1290     /* Get backing file name if -o backing_file was used */
1291     out_baseimg_param = get_option_parameter(param, BLOCK_OPT_BACKING_FILE);
1292     if (out_baseimg_param) {
1293         out_baseimg = out_baseimg_param->value.s;
1294     }
1295 
1296     /* Check if compression is supported */
1297     if (compress) {
1298         QEMUOptionParameter *encryption =
1299             get_option_parameter(param, BLOCK_OPT_ENCRYPT);
1300         QEMUOptionParameter *preallocation =
1301             get_option_parameter(param, BLOCK_OPT_PREALLOC);
1302 
1303         if (!drv->bdrv_write_compressed) {
1304             error_report("Compression not supported for this file format");
1305             ret = -1;
1306             goto out;
1307         }
1308 
1309         if (encryption && encryption->value.n) {
1310             error_report("Compression and encryption not supported at "
1311                          "the same time");
1312             ret = -1;
1313             goto out;
1314         }
1315 
1316         if (preallocation && preallocation->value.s
1317             && strcmp(preallocation->value.s, "off"))
1318         {
1319             error_report("Compression and preallocation not supported at "
1320                          "the same time");
1321             ret = -1;
1322             goto out;
1323         }
1324     }
1325 
1326     /* Create the new image */
1327     ret = bdrv_create(drv, out_filename, param);
1328     if (ret < 0) {
1329         if (ret == -ENOTSUP) {
1330             error_report("Formatting not supported for file format '%s'",
1331                          out_fmt);
1332         } else if (ret == -EFBIG) {
1333             error_report("The image size is too large for file format '%s'",
1334                          out_fmt);
1335         } else {
1336             error_report("%s: error while converting %s: %s",
1337                          out_filename, out_fmt, strerror(-ret));
1338         }
1339         goto out;
1340     }
1341 
1342     flags = BDRV_O_RDWR;
1343     ret = bdrv_parse_cache_flags(cache, &flags);
1344     if (ret < 0) {
1345         error_report("Invalid cache option: %s", cache);
1346         return -1;
1347     }
1348 
1349     out_bs = bdrv_new_open(out_filename, out_fmt, flags, true, quiet);
1350     if (!out_bs) {
1351         ret = -1;
1352         goto out;
1353     }
1354 
1355     bs_i = 0;
1356     bs_offset = 0;
1357     bdrv_get_geometry(bs[0], &bs_sectors);
1358     buf = qemu_blockalign(out_bs, IO_BUF_SIZE);
1359 
1360     if (compress) {
1361         ret = bdrv_get_info(out_bs, &bdi);
1362         if (ret < 0) {
1363             error_report("could not get block driver info");
1364             goto out;
1365         }
1366         cluster_size = bdi.cluster_size;
1367         if (cluster_size <= 0 || cluster_size > IO_BUF_SIZE) {
1368             error_report("invalid cluster size");
1369             ret = -1;
1370             goto out;
1371         }
1372         cluster_sectors = cluster_size >> 9;
1373         sector_num = 0;
1374 
1375         nb_sectors = total_sectors;
1376         if (nb_sectors != 0) {
1377             local_progress = (float)100 /
1378                 (nb_sectors / MIN(nb_sectors, cluster_sectors));
1379         }
1380 
1381         for(;;) {
1382             int64_t bs_num;
1383             int remainder;
1384             uint8_t *buf2;
1385 
1386             nb_sectors = total_sectors - sector_num;
1387             if (nb_sectors <= 0)
1388                 break;
1389             if (nb_sectors >= cluster_sectors)
1390                 n = cluster_sectors;
1391             else
1392                 n = nb_sectors;
1393 
1394             bs_num = sector_num - bs_offset;
1395             assert (bs_num >= 0);
1396             remainder = n;
1397             buf2 = buf;
1398             while (remainder > 0) {
1399                 int nlow;
1400                 while (bs_num == bs_sectors) {
1401                     bs_i++;
1402                     assert (bs_i < bs_n);
1403                     bs_offset += bs_sectors;
1404                     bdrv_get_geometry(bs[bs_i], &bs_sectors);
1405                     bs_num = 0;
1406                     /* printf("changing part: sector_num=%" PRId64 ", "
1407                        "bs_i=%d, bs_offset=%" PRId64 ", bs_sectors=%" PRId64
1408                        "\n", sector_num, bs_i, bs_offset, bs_sectors); */
1409                 }
1410                 assert (bs_num < bs_sectors);
1411 
1412                 nlow = (remainder > bs_sectors - bs_num) ? bs_sectors - bs_num : remainder;
1413 
1414                 ret = bdrv_read(bs[bs_i], bs_num, buf2, nlow);
1415                 if (ret < 0) {
1416                     error_report("error while reading sector %" PRId64 ": %s",
1417                                  bs_num, strerror(-ret));
1418                     goto out;
1419                 }
1420 
1421                 buf2 += nlow * 512;
1422                 bs_num += nlow;
1423 
1424                 remainder -= nlow;
1425             }
1426             assert (remainder == 0);
1427 
1428             if (!buffer_is_zero(buf, n * BDRV_SECTOR_SIZE)) {
1429                 ret = bdrv_write_compressed(out_bs, sector_num, buf, n);
1430                 if (ret != 0) {
1431                     error_report("error while compressing sector %" PRId64
1432                                  ": %s", sector_num, strerror(-ret));
1433                     goto out;
1434                 }
1435             }
1436             sector_num += n;
1437             qemu_progress_print(local_progress, 100);
1438         }
1439         /* signal EOF to align */
1440         bdrv_write_compressed(out_bs, 0, NULL, 0);
1441     } else {
1442         int has_zero_init = bdrv_has_zero_init(out_bs);
1443 
1444         sector_num = 0; // total number of sectors converted so far
1445         nb_sectors = total_sectors - sector_num;
1446         if (nb_sectors != 0) {
1447             local_progress = (float)100 /
1448                 (nb_sectors / MIN(nb_sectors, IO_BUF_SIZE / 512));
1449         }
1450 
1451         for(;;) {
1452             nb_sectors = total_sectors - sector_num;
1453             if (nb_sectors <= 0) {
1454                 break;
1455             }
1456             if (nb_sectors >= (IO_BUF_SIZE / 512)) {
1457                 n = (IO_BUF_SIZE / 512);
1458             } else {
1459                 n = nb_sectors;
1460             }
1461 
1462             while (sector_num - bs_offset >= bs_sectors) {
1463                 bs_i ++;
1464                 assert (bs_i < bs_n);
1465                 bs_offset += bs_sectors;
1466                 bdrv_get_geometry(bs[bs_i], &bs_sectors);
1467                 /* printf("changing part: sector_num=%" PRId64 ", bs_i=%d, "
1468                   "bs_offset=%" PRId64 ", bs_sectors=%" PRId64 "\n",
1469                    sector_num, bs_i, bs_offset, bs_sectors); */
1470             }
1471 
1472             if (n > bs_offset + bs_sectors - sector_num) {
1473                 n = bs_offset + bs_sectors - sector_num;
1474             }
1475 
1476             if (has_zero_init) {
1477                 /* If the output image is being created as a copy on write image,
1478                    assume that sectors which are unallocated in the input image
1479                    are present in both the output's and input's base images (no
1480                    need to copy them). */
1481                 if (out_baseimg) {
1482                     if (!bdrv_is_allocated(bs[bs_i], sector_num - bs_offset,
1483                                            n, &n1)) {
1484                         sector_num += n1;
1485                         continue;
1486                     }
1487                     /* The next 'n1' sectors are allocated in the input image. Copy
1488                        only those as they may be followed by unallocated sectors. */
1489                     n = n1;
1490                 }
1491             } else {
1492                 n1 = n;
1493             }
1494 
1495             ret = bdrv_read(bs[bs_i], sector_num - bs_offset, buf, n);
1496             if (ret < 0) {
1497                 error_report("error while reading sector %" PRId64 ": %s",
1498                              sector_num - bs_offset, strerror(-ret));
1499                 goto out;
1500             }
1501             /* NOTE: at the same time we convert, we do not write zero
1502                sectors to have a chance to compress the image. Ideally, we
1503                should add a specific call to have the info to go faster */
1504             buf1 = buf;
1505             while (n > 0) {
1506                 /* If the output image is being created as a copy on write image,
1507                    copy all sectors even the ones containing only NUL bytes,
1508                    because they may differ from the sectors in the base image.
1509 
1510                    If the output is to a host device, we also write out
1511                    sectors that are entirely 0, since whatever data was
1512                    already there is garbage, not 0s. */
1513                 if (!has_zero_init || out_baseimg ||
1514                     is_allocated_sectors_min(buf1, n, &n1, min_sparse)) {
1515                     ret = bdrv_write(out_bs, sector_num, buf1, n1);
1516                     if (ret < 0) {
1517                         error_report("error while writing sector %" PRId64
1518                                      ": %s", sector_num, strerror(-ret));
1519                         goto out;
1520                     }
1521                 }
1522                 sector_num += n1;
1523                 n -= n1;
1524                 buf1 += n1 * 512;
1525             }
1526             qemu_progress_print(local_progress, 100);
1527         }
1528     }
1529 out:
1530     qemu_progress_end();
1531     free_option_parameters(create_options);
1532     free_option_parameters(param);
1533     qemu_vfree(buf);
1534     if (out_bs) {
1535         bdrv_delete(out_bs);
1536     }
1537     if (bs) {
1538         for (bs_i = 0; bs_i < bs_n; bs_i++) {
1539             if (bs[bs_i]) {
1540                 bdrv_delete(bs[bs_i]);
1541             }
1542         }
1543         g_free(bs);
1544     }
1545     if (ret) {
1546         return 1;
1547     }
1548     return 0;
1549 }
1550 
1551 
1552 static void dump_snapshots(BlockDriverState *bs)
1553 {
1554     QEMUSnapshotInfo *sn_tab, *sn;
1555     int nb_sns, i;
1556     char buf[256];
1557 
1558     nb_sns = bdrv_snapshot_list(bs, &sn_tab);
1559     if (nb_sns <= 0)
1560         return;
1561     printf("Snapshot list:\n");
1562     printf("%s\n", bdrv_snapshot_dump(buf, sizeof(buf), NULL));
1563     for(i = 0; i < nb_sns; i++) {
1564         sn = &sn_tab[i];
1565         printf("%s\n", bdrv_snapshot_dump(buf, sizeof(buf), sn));
1566     }
1567     g_free(sn_tab);
1568 }
1569 
1570 static void dump_json_image_info_list(ImageInfoList *list)
1571 {
1572     Error *errp = NULL;
1573     QString *str;
1574     QmpOutputVisitor *ov = qmp_output_visitor_new();
1575     QObject *obj;
1576     visit_type_ImageInfoList(qmp_output_get_visitor(ov),
1577                              &list, NULL, &errp);
1578     obj = qmp_output_get_qobject(ov);
1579     str = qobject_to_json_pretty(obj);
1580     assert(str != NULL);
1581     printf("%s\n", qstring_get_str(str));
1582     qobject_decref(obj);
1583     qmp_output_visitor_cleanup(ov);
1584     QDECREF(str);
1585 }
1586 
1587 static void collect_snapshots(BlockDriverState *bs , ImageInfo *info)
1588 {
1589     int i, sn_count;
1590     QEMUSnapshotInfo *sn_tab = NULL;
1591     SnapshotInfoList *info_list, *cur_item = NULL;
1592     sn_count = bdrv_snapshot_list(bs, &sn_tab);
1593 
1594     for (i = 0; i < sn_count; i++) {
1595         info->has_snapshots = true;
1596         info_list = g_new0(SnapshotInfoList, 1);
1597 
1598         info_list->value                = g_new0(SnapshotInfo, 1);
1599         info_list->value->id            = g_strdup(sn_tab[i].id_str);
1600         info_list->value->name          = g_strdup(sn_tab[i].name);
1601         info_list->value->vm_state_size = sn_tab[i].vm_state_size;
1602         info_list->value->date_sec      = sn_tab[i].date_sec;
1603         info_list->value->date_nsec     = sn_tab[i].date_nsec;
1604         info_list->value->vm_clock_sec  = sn_tab[i].vm_clock_nsec / 1000000000;
1605         info_list->value->vm_clock_nsec = sn_tab[i].vm_clock_nsec % 1000000000;
1606 
1607         /* XXX: waiting for the qapi to support qemu-queue.h types */
1608         if (!cur_item) {
1609             info->snapshots = cur_item = info_list;
1610         } else {
1611             cur_item->next = info_list;
1612             cur_item = info_list;
1613         }
1614 
1615     }
1616 
1617     g_free(sn_tab);
1618 }
1619 
1620 static void dump_json_image_info(ImageInfo *info)
1621 {
1622     Error *errp = NULL;
1623     QString *str;
1624     QmpOutputVisitor *ov = qmp_output_visitor_new();
1625     QObject *obj;
1626     visit_type_ImageInfo(qmp_output_get_visitor(ov),
1627                          &info, NULL, &errp);
1628     obj = qmp_output_get_qobject(ov);
1629     str = qobject_to_json_pretty(obj);
1630     assert(str != NULL);
1631     printf("%s\n", qstring_get_str(str));
1632     qobject_decref(obj);
1633     qmp_output_visitor_cleanup(ov);
1634     QDECREF(str);
1635 }
1636 
1637 static void collect_image_info(BlockDriverState *bs,
1638                    ImageInfo *info,
1639                    const char *filename,
1640                    const char *fmt)
1641 {
1642     uint64_t total_sectors;
1643     char backing_filename[1024];
1644     char backing_filename2[1024];
1645     BlockDriverInfo bdi;
1646 
1647     bdrv_get_geometry(bs, &total_sectors);
1648 
1649     info->filename        = g_strdup(filename);
1650     info->format          = g_strdup(bdrv_get_format_name(bs));
1651     info->virtual_size    = total_sectors * 512;
1652     info->actual_size     = bdrv_get_allocated_file_size(bs);
1653     info->has_actual_size = info->actual_size >= 0;
1654     if (bdrv_is_encrypted(bs)) {
1655         info->encrypted = true;
1656         info->has_encrypted = true;
1657     }
1658     if (bdrv_get_info(bs, &bdi) >= 0) {
1659         if (bdi.cluster_size != 0) {
1660             info->cluster_size = bdi.cluster_size;
1661             info->has_cluster_size = true;
1662         }
1663         info->dirty_flag = bdi.is_dirty;
1664         info->has_dirty_flag = true;
1665     }
1666     bdrv_get_backing_filename(bs, backing_filename, sizeof(backing_filename));
1667     if (backing_filename[0] != '\0') {
1668         info->backing_filename = g_strdup(backing_filename);
1669         info->has_backing_filename = true;
1670         bdrv_get_full_backing_filename(bs, backing_filename2,
1671                                        sizeof(backing_filename2));
1672 
1673         if (strcmp(backing_filename, backing_filename2) != 0) {
1674             info->full_backing_filename =
1675                         g_strdup(backing_filename2);
1676             info->has_full_backing_filename = true;
1677         }
1678 
1679         if (bs->backing_format[0]) {
1680             info->backing_filename_format = g_strdup(bs->backing_format);
1681             info->has_backing_filename_format = true;
1682         }
1683     }
1684 }
1685 
1686 static void dump_human_image_info(ImageInfo *info)
1687 {
1688     char size_buf[128], dsize_buf[128];
1689     if (!info->has_actual_size) {
1690         snprintf(dsize_buf, sizeof(dsize_buf), "unavailable");
1691     } else {
1692         get_human_readable_size(dsize_buf, sizeof(dsize_buf),
1693                                 info->actual_size);
1694     }
1695     get_human_readable_size(size_buf, sizeof(size_buf), info->virtual_size);
1696     printf("image: %s\n"
1697            "file format: %s\n"
1698            "virtual size: %s (%" PRId64 " bytes)\n"
1699            "disk size: %s\n",
1700            info->filename, info->format, size_buf,
1701            info->virtual_size,
1702            dsize_buf);
1703 
1704     if (info->has_encrypted && info->encrypted) {
1705         printf("encrypted: yes\n");
1706     }
1707 
1708     if (info->has_cluster_size) {
1709         printf("cluster_size: %" PRId64 "\n", info->cluster_size);
1710     }
1711 
1712     if (info->has_dirty_flag && info->dirty_flag) {
1713         printf("cleanly shut down: no\n");
1714     }
1715 
1716     if (info->has_backing_filename) {
1717         printf("backing file: %s", info->backing_filename);
1718         if (info->has_full_backing_filename) {
1719             printf(" (actual path: %s)", info->full_backing_filename);
1720         }
1721         putchar('\n');
1722         if (info->has_backing_filename_format) {
1723             printf("backing file format: %s\n", info->backing_filename_format);
1724         }
1725     }
1726 
1727     if (info->has_snapshots) {
1728         SnapshotInfoList *elem;
1729         char buf[256];
1730 
1731         printf("Snapshot list:\n");
1732         printf("%s\n", bdrv_snapshot_dump(buf, sizeof(buf), NULL));
1733 
1734         /* Ideally bdrv_snapshot_dump() would operate on SnapshotInfoList but
1735          * we convert to the block layer's native QEMUSnapshotInfo for now.
1736          */
1737         for (elem = info->snapshots; elem; elem = elem->next) {
1738             QEMUSnapshotInfo sn = {
1739                 .vm_state_size = elem->value->vm_state_size,
1740                 .date_sec = elem->value->date_sec,
1741                 .date_nsec = elem->value->date_nsec,
1742                 .vm_clock_nsec = elem->value->vm_clock_sec * 1000000000ULL +
1743                                  elem->value->vm_clock_nsec,
1744             };
1745 
1746             pstrcpy(sn.id_str, sizeof(sn.id_str), elem->value->id);
1747             pstrcpy(sn.name, sizeof(sn.name), elem->value->name);
1748             printf("%s\n", bdrv_snapshot_dump(buf, sizeof(buf), &sn));
1749         }
1750     }
1751 }
1752 
1753 static void dump_human_image_info_list(ImageInfoList *list)
1754 {
1755     ImageInfoList *elem;
1756     bool delim = false;
1757 
1758     for (elem = list; elem; elem = elem->next) {
1759         if (delim) {
1760             printf("\n");
1761         }
1762         delim = true;
1763 
1764         dump_human_image_info(elem->value);
1765     }
1766 }
1767 
1768 static gboolean str_equal_func(gconstpointer a, gconstpointer b)
1769 {
1770     return strcmp(a, b) == 0;
1771 }
1772 
1773 /**
1774  * Open an image file chain and return an ImageInfoList
1775  *
1776  * @filename: topmost image filename
1777  * @fmt: topmost image format (may be NULL to autodetect)
1778  * @chain: true  - enumerate entire backing file chain
1779  *         false - only topmost image file
1780  *
1781  * Returns a list of ImageInfo objects or NULL if there was an error opening an
1782  * image file.  If there was an error a message will have been printed to
1783  * stderr.
1784  */
1785 static ImageInfoList *collect_image_info_list(const char *filename,
1786                                               const char *fmt,
1787                                               bool chain)
1788 {
1789     ImageInfoList *head = NULL;
1790     ImageInfoList **last = &head;
1791     GHashTable *filenames;
1792 
1793     filenames = g_hash_table_new_full(g_str_hash, str_equal_func, NULL, NULL);
1794 
1795     while (filename) {
1796         BlockDriverState *bs;
1797         ImageInfo *info;
1798         ImageInfoList *elem;
1799 
1800         if (g_hash_table_lookup_extended(filenames, filename, NULL, NULL)) {
1801             error_report("Backing file '%s' creates an infinite loop.",
1802                          filename);
1803             goto err;
1804         }
1805         g_hash_table_insert(filenames, (gpointer)filename, NULL);
1806 
1807         bs = bdrv_new_open(filename, fmt, BDRV_O_FLAGS | BDRV_O_NO_BACKING,
1808                            false, false);
1809         if (!bs) {
1810             goto err;
1811         }
1812 
1813         info = g_new0(ImageInfo, 1);
1814         collect_image_info(bs, info, filename, fmt);
1815         collect_snapshots(bs, info);
1816 
1817         elem = g_new0(ImageInfoList, 1);
1818         elem->value = info;
1819         *last = elem;
1820         last = &elem->next;
1821 
1822         bdrv_delete(bs);
1823 
1824         filename = fmt = NULL;
1825         if (chain) {
1826             if (info->has_full_backing_filename) {
1827                 filename = info->full_backing_filename;
1828             } else if (info->has_backing_filename) {
1829                 filename = info->backing_filename;
1830             }
1831             if (info->has_backing_filename_format) {
1832                 fmt = info->backing_filename_format;
1833             }
1834         }
1835     }
1836     g_hash_table_destroy(filenames);
1837     return head;
1838 
1839 err:
1840     qapi_free_ImageInfoList(head);
1841     g_hash_table_destroy(filenames);
1842     return NULL;
1843 }
1844 
1845 static int img_info(int argc, char **argv)
1846 {
1847     int c;
1848     OutputFormat output_format = OFORMAT_HUMAN;
1849     bool chain = false;
1850     const char *filename, *fmt, *output;
1851     ImageInfoList *list;
1852 
1853     fmt = NULL;
1854     output = NULL;
1855     for(;;) {
1856         int option_index = 0;
1857         static const struct option long_options[] = {
1858             {"help", no_argument, 0, 'h'},
1859             {"format", required_argument, 0, 'f'},
1860             {"output", required_argument, 0, OPTION_OUTPUT},
1861             {"backing-chain", no_argument, 0, OPTION_BACKING_CHAIN},
1862             {0, 0, 0, 0}
1863         };
1864         c = getopt_long(argc, argv, "f:h",
1865                         long_options, &option_index);
1866         if (c == -1) {
1867             break;
1868         }
1869         switch(c) {
1870         case '?':
1871         case 'h':
1872             help();
1873             break;
1874         case 'f':
1875             fmt = optarg;
1876             break;
1877         case OPTION_OUTPUT:
1878             output = optarg;
1879             break;
1880         case OPTION_BACKING_CHAIN:
1881             chain = true;
1882             break;
1883         }
1884     }
1885     if (optind >= argc) {
1886         help();
1887     }
1888     filename = argv[optind++];
1889 
1890     if (output && !strcmp(output, "json")) {
1891         output_format = OFORMAT_JSON;
1892     } else if (output && !strcmp(output, "human")) {
1893         output_format = OFORMAT_HUMAN;
1894     } else if (output) {
1895         error_report("--output must be used with human or json as argument.");
1896         return 1;
1897     }
1898 
1899     list = collect_image_info_list(filename, fmt, chain);
1900     if (!list) {
1901         return 1;
1902     }
1903 
1904     switch (output_format) {
1905     case OFORMAT_HUMAN:
1906         dump_human_image_info_list(list);
1907         break;
1908     case OFORMAT_JSON:
1909         if (chain) {
1910             dump_json_image_info_list(list);
1911         } else {
1912             dump_json_image_info(list->value);
1913         }
1914         break;
1915     }
1916 
1917     qapi_free_ImageInfoList(list);
1918     return 0;
1919 }
1920 
1921 #define SNAPSHOT_LIST   1
1922 #define SNAPSHOT_CREATE 2
1923 #define SNAPSHOT_APPLY  3
1924 #define SNAPSHOT_DELETE 4
1925 
1926 static int img_snapshot(int argc, char **argv)
1927 {
1928     BlockDriverState *bs;
1929     QEMUSnapshotInfo sn;
1930     char *filename, *snapshot_name = NULL;
1931     int c, ret = 0, bdrv_oflags;
1932     int action = 0;
1933     qemu_timeval tv;
1934     bool quiet = false;
1935 
1936     bdrv_oflags = BDRV_O_FLAGS | BDRV_O_RDWR;
1937     /* Parse commandline parameters */
1938     for(;;) {
1939         c = getopt(argc, argv, "la:c:d:hq");
1940         if (c == -1) {
1941             break;
1942         }
1943         switch(c) {
1944         case '?':
1945         case 'h':
1946             help();
1947             return 0;
1948         case 'l':
1949             if (action) {
1950                 help();
1951                 return 0;
1952             }
1953             action = SNAPSHOT_LIST;
1954             bdrv_oflags &= ~BDRV_O_RDWR; /* no need for RW */
1955             break;
1956         case 'a':
1957             if (action) {
1958                 help();
1959                 return 0;
1960             }
1961             action = SNAPSHOT_APPLY;
1962             snapshot_name = optarg;
1963             break;
1964         case 'c':
1965             if (action) {
1966                 help();
1967                 return 0;
1968             }
1969             action = SNAPSHOT_CREATE;
1970             snapshot_name = optarg;
1971             break;
1972         case 'd':
1973             if (action) {
1974                 help();
1975                 return 0;
1976             }
1977             action = SNAPSHOT_DELETE;
1978             snapshot_name = optarg;
1979             break;
1980         case 'q':
1981             quiet = true;
1982             break;
1983         }
1984     }
1985 
1986     if (optind >= argc) {
1987         help();
1988     }
1989     filename = argv[optind++];
1990 
1991     /* Open the image */
1992     bs = bdrv_new_open(filename, NULL, bdrv_oflags, true, quiet);
1993     if (!bs) {
1994         return 1;
1995     }
1996 
1997     /* Perform the requested action */
1998     switch(action) {
1999     case SNAPSHOT_LIST:
2000         dump_snapshots(bs);
2001         break;
2002 
2003     case SNAPSHOT_CREATE:
2004         memset(&sn, 0, sizeof(sn));
2005         pstrcpy(sn.name, sizeof(sn.name), snapshot_name);
2006 
2007         qemu_gettimeofday(&tv);
2008         sn.date_sec = tv.tv_sec;
2009         sn.date_nsec = tv.tv_usec * 1000;
2010 
2011         ret = bdrv_snapshot_create(bs, &sn);
2012         if (ret) {
2013             error_report("Could not create snapshot '%s': %d (%s)",
2014                 snapshot_name, ret, strerror(-ret));
2015         }
2016         break;
2017 
2018     case SNAPSHOT_APPLY:
2019         ret = bdrv_snapshot_goto(bs, snapshot_name);
2020         if (ret) {
2021             error_report("Could not apply snapshot '%s': %d (%s)",
2022                 snapshot_name, ret, strerror(-ret));
2023         }
2024         break;
2025 
2026     case SNAPSHOT_DELETE:
2027         ret = bdrv_snapshot_delete(bs, snapshot_name);
2028         if (ret) {
2029             error_report("Could not delete snapshot '%s': %d (%s)",
2030                 snapshot_name, ret, strerror(-ret));
2031         }
2032         break;
2033     }
2034 
2035     /* Cleanup */
2036     bdrv_delete(bs);
2037     if (ret) {
2038         return 1;
2039     }
2040     return 0;
2041 }
2042 
2043 static int img_rebase(int argc, char **argv)
2044 {
2045     BlockDriverState *bs, *bs_old_backing = NULL, *bs_new_backing = NULL;
2046     BlockDriver *old_backing_drv, *new_backing_drv;
2047     char *filename;
2048     const char *fmt, *cache, *out_basefmt, *out_baseimg;
2049     int c, flags, ret;
2050     int unsafe = 0;
2051     int progress = 0;
2052     bool quiet = false;
2053 
2054     /* Parse commandline parameters */
2055     fmt = NULL;
2056     cache = BDRV_DEFAULT_CACHE;
2057     out_baseimg = NULL;
2058     out_basefmt = NULL;
2059     for(;;) {
2060         c = getopt(argc, argv, "uhf:F:b:pt:q");
2061         if (c == -1) {
2062             break;
2063         }
2064         switch(c) {
2065         case '?':
2066         case 'h':
2067             help();
2068             return 0;
2069         case 'f':
2070             fmt = optarg;
2071             break;
2072         case 'F':
2073             out_basefmt = optarg;
2074             break;
2075         case 'b':
2076             out_baseimg = optarg;
2077             break;
2078         case 'u':
2079             unsafe = 1;
2080             break;
2081         case 'p':
2082             progress = 1;
2083             break;
2084         case 't':
2085             cache = optarg;
2086             break;
2087         case 'q':
2088             quiet = true;
2089             break;
2090         }
2091     }
2092 
2093     if (quiet) {
2094         progress = 0;
2095     }
2096 
2097     if ((optind >= argc) || (!unsafe && !out_baseimg)) {
2098         help();
2099     }
2100     filename = argv[optind++];
2101 
2102     qemu_progress_init(progress, 2.0);
2103     qemu_progress_print(0, 100);
2104 
2105     flags = BDRV_O_RDWR | (unsafe ? BDRV_O_NO_BACKING : 0);
2106     ret = bdrv_parse_cache_flags(cache, &flags);
2107     if (ret < 0) {
2108         error_report("Invalid cache option: %s", cache);
2109         return -1;
2110     }
2111 
2112     /*
2113      * Open the images.
2114      *
2115      * Ignore the old backing file for unsafe rebase in case we want to correct
2116      * the reference to a renamed or moved backing file.
2117      */
2118     bs = bdrv_new_open(filename, fmt, flags, true, quiet);
2119     if (!bs) {
2120         return 1;
2121     }
2122 
2123     /* Find the right drivers for the backing files */
2124     old_backing_drv = NULL;
2125     new_backing_drv = NULL;
2126 
2127     if (!unsafe && bs->backing_format[0] != '\0') {
2128         old_backing_drv = bdrv_find_format(bs->backing_format);
2129         if (old_backing_drv == NULL) {
2130             error_report("Invalid format name: '%s'", bs->backing_format);
2131             ret = -1;
2132             goto out;
2133         }
2134     }
2135 
2136     if (out_basefmt != NULL) {
2137         new_backing_drv = bdrv_find_format(out_basefmt);
2138         if (new_backing_drv == NULL) {
2139             error_report("Invalid format name: '%s'", out_basefmt);
2140             ret = -1;
2141             goto out;
2142         }
2143     }
2144 
2145     /* For safe rebasing we need to compare old and new backing file */
2146     if (unsafe) {
2147         /* Make the compiler happy */
2148         bs_old_backing = NULL;
2149         bs_new_backing = NULL;
2150     } else {
2151         char backing_name[1024];
2152 
2153         bs_old_backing = bdrv_new("old_backing");
2154         bdrv_get_backing_filename(bs, backing_name, sizeof(backing_name));
2155         ret = bdrv_open(bs_old_backing, backing_name, NULL, BDRV_O_FLAGS,
2156                         old_backing_drv);
2157         if (ret) {
2158             error_report("Could not open old backing file '%s'", backing_name);
2159             goto out;
2160         }
2161         if (out_baseimg[0]) {
2162             bs_new_backing = bdrv_new("new_backing");
2163             ret = bdrv_open(bs_new_backing, out_baseimg, NULL, BDRV_O_FLAGS,
2164                         new_backing_drv);
2165             if (ret) {
2166                 error_report("Could not open new backing file '%s'",
2167                              out_baseimg);
2168                 goto out;
2169             }
2170         }
2171     }
2172 
2173     /*
2174      * Check each unallocated cluster in the COW file. If it is unallocated,
2175      * accesses go to the backing file. We must therefore compare this cluster
2176      * in the old and new backing file, and if they differ we need to copy it
2177      * from the old backing file into the COW file.
2178      *
2179      * If qemu-img crashes during this step, no harm is done. The content of
2180      * the image is the same as the original one at any time.
2181      */
2182     if (!unsafe) {
2183         uint64_t num_sectors;
2184         uint64_t old_backing_num_sectors;
2185         uint64_t new_backing_num_sectors = 0;
2186         uint64_t sector;
2187         int n;
2188         uint8_t * buf_old;
2189         uint8_t * buf_new;
2190         float local_progress = 0;
2191 
2192         buf_old = qemu_blockalign(bs, IO_BUF_SIZE);
2193         buf_new = qemu_blockalign(bs, IO_BUF_SIZE);
2194 
2195         bdrv_get_geometry(bs, &num_sectors);
2196         bdrv_get_geometry(bs_old_backing, &old_backing_num_sectors);
2197         if (bs_new_backing) {
2198             bdrv_get_geometry(bs_new_backing, &new_backing_num_sectors);
2199         }
2200 
2201         if (num_sectors != 0) {
2202             local_progress = (float)100 /
2203                 (num_sectors / MIN(num_sectors, IO_BUF_SIZE / 512));
2204         }
2205 
2206         for (sector = 0; sector < num_sectors; sector += n) {
2207 
2208             /* How many sectors can we handle with the next read? */
2209             if (sector + (IO_BUF_SIZE / 512) <= num_sectors) {
2210                 n = (IO_BUF_SIZE / 512);
2211             } else {
2212                 n = num_sectors - sector;
2213             }
2214 
2215             /* If the cluster is allocated, we don't need to take action */
2216             ret = bdrv_is_allocated(bs, sector, n, &n);
2217             if (ret) {
2218                 continue;
2219             }
2220 
2221             /*
2222              * Read old and new backing file and take into consideration that
2223              * backing files may be smaller than the COW image.
2224              */
2225             if (sector >= old_backing_num_sectors) {
2226                 memset(buf_old, 0, n * BDRV_SECTOR_SIZE);
2227             } else {
2228                 if (sector + n > old_backing_num_sectors) {
2229                     n = old_backing_num_sectors - sector;
2230                 }
2231 
2232                 ret = bdrv_read(bs_old_backing, sector, buf_old, n);
2233                 if (ret < 0) {
2234                     error_report("error while reading from old backing file");
2235                     goto out;
2236                 }
2237             }
2238 
2239             if (sector >= new_backing_num_sectors || !bs_new_backing) {
2240                 memset(buf_new, 0, n * BDRV_SECTOR_SIZE);
2241             } else {
2242                 if (sector + n > new_backing_num_sectors) {
2243                     n = new_backing_num_sectors - sector;
2244                 }
2245 
2246                 ret = bdrv_read(bs_new_backing, sector, buf_new, n);
2247                 if (ret < 0) {
2248                     error_report("error while reading from new backing file");
2249                     goto out;
2250                 }
2251             }
2252 
2253             /* If they differ, we need to write to the COW file */
2254             uint64_t written = 0;
2255 
2256             while (written < n) {
2257                 int pnum;
2258 
2259                 if (compare_sectors(buf_old + written * 512,
2260                     buf_new + written * 512, n - written, &pnum))
2261                 {
2262                     ret = bdrv_write(bs, sector + written,
2263                         buf_old + written * 512, pnum);
2264                     if (ret < 0) {
2265                         error_report("Error while writing to COW image: %s",
2266                             strerror(-ret));
2267                         goto out;
2268                     }
2269                 }
2270 
2271                 written += pnum;
2272             }
2273             qemu_progress_print(local_progress, 100);
2274         }
2275 
2276         qemu_vfree(buf_old);
2277         qemu_vfree(buf_new);
2278     }
2279 
2280     /*
2281      * Change the backing file. All clusters that are different from the old
2282      * backing file are overwritten in the COW file now, so the visible content
2283      * doesn't change when we switch the backing file.
2284      */
2285     if (out_baseimg && *out_baseimg) {
2286         ret = bdrv_change_backing_file(bs, out_baseimg, out_basefmt);
2287     } else {
2288         ret = bdrv_change_backing_file(bs, NULL, NULL);
2289     }
2290 
2291     if (ret == -ENOSPC) {
2292         error_report("Could not change the backing file to '%s': No "
2293                      "space left in the file header", out_baseimg);
2294     } else if (ret < 0) {
2295         error_report("Could not change the backing file to '%s': %s",
2296             out_baseimg, strerror(-ret));
2297     }
2298 
2299     qemu_progress_print(100, 0);
2300     /*
2301      * TODO At this point it is possible to check if any clusters that are
2302      * allocated in the COW file are the same in the backing file. If so, they
2303      * could be dropped from the COW file. Don't do this before switching the
2304      * backing file, in case of a crash this would lead to corruption.
2305      */
2306 out:
2307     qemu_progress_end();
2308     /* Cleanup */
2309     if (!unsafe) {
2310         if (bs_old_backing != NULL) {
2311             bdrv_delete(bs_old_backing);
2312         }
2313         if (bs_new_backing != NULL) {
2314             bdrv_delete(bs_new_backing);
2315         }
2316     }
2317 
2318     bdrv_delete(bs);
2319     if (ret) {
2320         return 1;
2321     }
2322     return 0;
2323 }
2324 
2325 static int img_resize(int argc, char **argv)
2326 {
2327     int c, ret, relative;
2328     const char *filename, *fmt, *size;
2329     int64_t n, total_size;
2330     bool quiet = false;
2331     BlockDriverState *bs = NULL;
2332     QemuOpts *param;
2333     static QemuOptsList resize_options = {
2334         .name = "resize_options",
2335         .head = QTAILQ_HEAD_INITIALIZER(resize_options.head),
2336         .desc = {
2337             {
2338                 .name = BLOCK_OPT_SIZE,
2339                 .type = QEMU_OPT_SIZE,
2340                 .help = "Virtual disk size"
2341             }, {
2342                 /* end of list */
2343             }
2344         },
2345     };
2346 
2347     /* Remove size from argv manually so that negative numbers are not treated
2348      * as options by getopt. */
2349     if (argc < 3) {
2350         help();
2351         return 1;
2352     }
2353 
2354     size = argv[--argc];
2355 
2356     /* Parse getopt arguments */
2357     fmt = NULL;
2358     for(;;) {
2359         c = getopt(argc, argv, "f:hq");
2360         if (c == -1) {
2361             break;
2362         }
2363         switch(c) {
2364         case '?':
2365         case 'h':
2366             help();
2367             break;
2368         case 'f':
2369             fmt = optarg;
2370             break;
2371         case 'q':
2372             quiet = true;
2373             break;
2374         }
2375     }
2376     if (optind >= argc) {
2377         help();
2378     }
2379     filename = argv[optind++];
2380 
2381     /* Choose grow, shrink, or absolute resize mode */
2382     switch (size[0]) {
2383     case '+':
2384         relative = 1;
2385         size++;
2386         break;
2387     case '-':
2388         relative = -1;
2389         size++;
2390         break;
2391     default:
2392         relative = 0;
2393         break;
2394     }
2395 
2396     /* Parse size */
2397     param = qemu_opts_create_nofail(&resize_options);
2398     if (qemu_opt_set(param, BLOCK_OPT_SIZE, size)) {
2399         /* Error message already printed when size parsing fails */
2400         ret = -1;
2401         qemu_opts_del(param);
2402         goto out;
2403     }
2404     n = qemu_opt_get_size(param, BLOCK_OPT_SIZE, 0);
2405     qemu_opts_del(param);
2406 
2407     bs = bdrv_new_open(filename, fmt, BDRV_O_FLAGS | BDRV_O_RDWR, true, quiet);
2408     if (!bs) {
2409         ret = -1;
2410         goto out;
2411     }
2412 
2413     if (relative) {
2414         total_size = bdrv_getlength(bs) + n * relative;
2415     } else {
2416         total_size = n;
2417     }
2418     if (total_size <= 0) {
2419         error_report("New image size must be positive");
2420         ret = -1;
2421         goto out;
2422     }
2423 
2424     ret = bdrv_truncate(bs, total_size);
2425     switch (ret) {
2426     case 0:
2427         qprintf(quiet, "Image resized.\n");
2428         break;
2429     case -ENOTSUP:
2430         error_report("This image does not support resize");
2431         break;
2432     case -EACCES:
2433         error_report("Image is read-only");
2434         break;
2435     default:
2436         error_report("Error resizing image (%d)", -ret);
2437         break;
2438     }
2439 out:
2440     if (bs) {
2441         bdrv_delete(bs);
2442     }
2443     if (ret) {
2444         return 1;
2445     }
2446     return 0;
2447 }
2448 
2449 static const img_cmd_t img_cmds[] = {
2450 #define DEF(option, callback, arg_string)        \
2451     { option, callback },
2452 #include "qemu-img-cmds.h"
2453 #undef DEF
2454 #undef GEN_DOCS
2455     { NULL, NULL, },
2456 };
2457 
2458 int main(int argc, char **argv)
2459 {
2460     const img_cmd_t *cmd;
2461     const char *cmdname;
2462 
2463     error_set_progname(argv[0]);
2464 
2465     qemu_init_main_loop();
2466     bdrv_init();
2467     if (argc < 2)
2468         help();
2469     cmdname = argv[1];
2470     argc--; argv++;
2471 
2472     /* find the command */
2473     for(cmd = img_cmds; cmd->name != NULL; cmd++) {
2474         if (!strcmp(cmdname, cmd->name)) {
2475             return cmd->handler(argc, argv);
2476         }
2477     }
2478 
2479     /* not found */
2480     help();
2481     return 0;
2482 }
2483