lib/libzfs/libzfs_diff.c

   1 /*
   2  * CDDL HEADER START
   3  *
   4  * The contents of this file are subject to the terms of the
   5  * Common Development and Distribution License (the "License").
   6  * You may not use this file except in compliance with the License.
   7  *
   8  * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
   9  * or http://www.opensolaris.org/os/licensing.
  10  * See the License for the specific language governing permissions
  11  * and limitations under the License.
  12  *
  13  * When distributing Covered Code, include this CDDL HEADER in each
  14  * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
  15  * If applicable, add the following below this CDDL HEADER, with the
  16  * fields enclosed by brackets "[]" replaced with your own identifying
  17  * information: Portions Copyright [yyyy] [name of copyright owner]
  18  *
  19  * CDDL HEADER END
  20  */
  21
  22 /*
  23  * Copyright (c) 2010, Oracle and/or its affiliates. All rights reserved.
  24  */
  25
  26 /*
  27  * zfs diff support
  28  */
  29 #include <ctype.h>
  30 #include <errno.h>
  31 #include <libintl.h>
  32 #include <string.h>
  33 #include <sys/types.h>
  34 #include <sys/stat.h>
  35 #include <fcntl.h>
  36 #include <attr.h>
  37 #include <stddef.h>
  38 #include <unistd.h>
  39 #include <stdio.h>
  40 #include <stdlib.h>
  41 #include <stropts.h>
  42 #include <pthread.h>
  43 #include <sys/zfs_ioctl.h>
  44 #include <libzfs.h>
  45 #include "libzfs_impl.h"
  46
  47 #define ZDIFF_SNAPDIR           "/.zfs/snapshot/"
  48 #define ZDIFF_SHARESDIR         "/.zfs/shares/"
  49 #define ZDIFF_PREFIX            "zfs-diff-%d"
  50
  51 #define ZDIFF_ADDED     '+'
  52 #define ZDIFF_MODIFIED  'M'
  53 #define ZDIFF_REMOVED   '-'
  54 #define ZDIFF_RENAMED   'R'
  55
  56 static boolean_t
  57 do_name_cmp(const char *fpath, const char *tpath)
  58 {
  59         char *fname, *tname;
  60         fname = strrchr(fpath, '/') + 1;
  61         tname = strrchr(tpath, '/') + 1;
  62         return (strcmp(fname, tname) == 0);
  63 }
  64
  65 typedef struct differ_info {
  66         zfs_handle_t *zhp;
  67         char *fromsnap;
  68         char *frommnt;
  69         char *tosnap;
  70         char *tomnt;
  71         char *ds;
  72         char *dsmnt;
  73         char *tmpsnap;
  74         char errbuf[1024];
  75         boolean_t isclone;
  76         boolean_t scripted;
  77         boolean_t classify;
  78         boolean_t timestamped;
  79         uint64_t shares;
  80         int zerr;
  81         int cleanupfd;
  82         int outputfd;
  83         int datafd;
  84 } differ_info_t;
  85
  86 /*
  87  * Given a {dsname, object id}, get the object path
  88  */
  89 static int
  90 get_stats_for_obj(differ_info_t *di, const char *dsname, uint64_t obj,
  91     char *pn, int maxlen, zfs_stat_t *sb)
  92 {
  93         zfs_cmd_t zc = { 0 };
  94         int error;
  95
  96         (void) strlcpy(zc.zc_name, dsname, sizeof (zc.zc_name));
  97         zc.zc_obj = obj;
  98
  99         errno = 0;
 100         error = ioctl(di->zhp->zfs_hdl->libzfs_fd, ZFS_IOC_OBJ_TO_STATS, &zc);
 101         di->zerr = errno;
 102
 103         /* we can get stats even if we failed to get a path */
 104         (void) memcpy(sb, &zc.zc_stat, sizeof (zfs_stat_t));
 105         if (error == 0) {
 106                 ASSERT(di->zerr == 0);
 107                 (void) strlcpy(pn, zc.zc_value, maxlen);
 108                 return (0);
 109         }
 110
 111         if (di->zerr == EPERM) {
 112                 (void) snprintf(di->errbuf, sizeof (di->errbuf),
 113                     dgettext(TEXT_DOMAIN,
 114                     "The sys_config privilege or diff delegated permission "
 115                     "is needed\nto discover path names"));
 116                 return (-1);
 117         } else {
 118                 (void) snprintf(di->errbuf, sizeof (di->errbuf),
 119                     dgettext(TEXT_DOMAIN,
 120                     "Unable to determine path or stats for "
 121                     "object %lld in %s"), obj, dsname);
 122                 return (-1);
 123         }
 124 }
 125
 126 /*
 127  * stream_bytes
 128  *
 129  * Prints a file name out a character at a time.  If the character is
 130  * not in the range of what we consider "printable" ASCII, display it
 131  * as an escaped 3-digit octal value.  ASCII values less than a space
 132  * are all control characters and we declare the upper end as the
 133  * DELete character.  This also is the last 7-bit ASCII character.
 134  * We choose to treat all 8-bit ASCII as not printable for this
 135  * application.
 136  */
 137 static void
 138 stream_bytes(FILE *fp, const char *string)
 139 {
 140         while (*string) {
 141                 if (*string > ' ' && *string != '\\' && *string < '\177')
 142                         (void) fprintf(fp, "%c", *string++);
 143                 else
 144                         (void) fprintf(fp, "\\%03o", *string++);
 145         }
 146 }
 147
 148 static void
 149 print_what(FILE *fp, mode_t what)
 150 {
 151         char symbol;
 152
 153         switch (what & S_IFMT) {
 154         case S_IFBLK:
 155                 symbol = 'B';
 156                 break;
 157         case S_IFCHR:
 158                 symbol = 'C';
 159                 break;
 160         case S_IFDIR:
 161                 symbol = '/';
 162                 break;
 163         case S_IFDOOR:
 164                 symbol = '>';
 165                 break;
 166         case S_IFIFO:
 167                 symbol = '|';
 168                 break;
 169         case S_IFLNK:
 170                 symbol = '@';
 171                 break;
 172         case S_IFPORT:
 173                 symbol = 'P';
 174                 break;
 175         case S_IFSOCK:
 176                 symbol = '=';
 177                 break;
 178         case S_IFREG:
 179                 symbol = 'F';
 180                 break;
 181         default:
 182                 symbol = '?';
 183                 break;
 184         }
 185         (void) fprintf(fp, "%c", symbol);
 186 }
 187
 188 static void
 189 print_cmn(FILE *fp, differ_info_t *di, const char *file)
 190 {
 191         stream_bytes(fp, di->dsmnt);
 192         stream_bytes(fp, file);
 193 }
 194
 195 static void
 196 print_rename(FILE *fp, differ_info_t *di, const char *old, const char *new,
 197     zfs_stat_t *isb)
 198 {
 199         if (di->timestamped)
 200                 (void) fprintf(fp, "%10lld.%09lld\t",
 201                     (longlong_t)isb->zs_ctime[0],
 202                     (longlong_t)isb->zs_ctime[1]);
 203         (void) fprintf(fp, "%c\t", ZDIFF_RENAMED);
 204         if (di->classify) {
 205                 print_what(fp, isb->zs_mode);
 206                 (void) fprintf(fp, "\t");
 207         }
 208         print_cmn(fp, di, old);
 209         if (di->scripted)
 210                 (void) fprintf(fp, "\t");
 211         else
 212                 (void) fprintf(fp, " -> ");
 213         print_cmn(fp, di, new);
 214         (void) fprintf(fp, "\n");
 215 }
 216
 217 static void
 218 print_link_change(FILE *fp, differ_info_t *di, int delta, const char *file,
 219     zfs_stat_t *isb)
 220 {
 221         if (di->timestamped)
 222                 (void) fprintf(fp, "%10lld.%09lld\t",
 223                     (longlong_t)isb->zs_ctime[0],
 224                     (longlong_t)isb->zs_ctime[1]);
 225         (void) fprintf(fp, "%c\t", ZDIFF_MODIFIED);
 226         if (di->classify) {
 227                 print_what(fp, isb->zs_mode);
 228                 (void) fprintf(fp, "\t");
 229         }
 230         print_cmn(fp, di, file);
 231         (void) fprintf(fp, "\t(%+d)", delta);
 232         (void) fprintf(fp, "\n");
 233 }
 234
 235 static void
 236 print_file(FILE *fp, differ_info_t *di, char type, const char *file,
 237     zfs_stat_t *isb)
 238 {
 239         if (di->timestamped)
 240                 (void) fprintf(fp, "%10lld.%09lld\t",
 241                     (longlong_t)isb->zs_ctime[0],
 242                     (longlong_t)isb->zs_ctime[1]);
 243         (void) fprintf(fp, "%c\t", type);
 244         if (di->classify) {
 245                 print_what(fp, isb->zs_mode);
 246                 (void) fprintf(fp, "\t");
 247         }
 248         print_cmn(fp, di, file);
 249         (void) fprintf(fp, "\n");
 250 }
 251
 252 static int
 253 write_inuse_diffs_one(FILE *fp, differ_info_t *di, uint64_t dobj)
 254 {
 255         struct zfs_stat fsb, tsb;
 256         boolean_t same_name;
 257         mode_t fmode, tmode;
 258         char fobjname[MAXPATHLEN], tobjname[MAXPATHLEN];
 259         int fobjerr, tobjerr;
 260         int change;
 261
 262         if (dobj == di->shares)
 263                 return (0);
 264
 265         /*
 266          * Check the from and to snapshots for info on the object. If
 267          * we get ENOENT, then the object just didn't exist in that
 268          * snapshot.  If we get ENOTSUP, then we tried to get
 269          * info on a non-ZPL object, which we don't care about anyway.
 270          */
 271         fobjerr = get_stats_for_obj(di, di->fromsnap, dobj, fobjname,
 272             MAXPATHLEN, &fsb);
 273         if (fobjerr && di->zerr != ENOENT && di->zerr != ENOTSUP)
 274                 return (-1);
 275
 276         tobjerr = get_stats_for_obj(di, di->tosnap, dobj, tobjname,
 277             MAXPATHLEN, &tsb);
 278         if (tobjerr && di->zerr != ENOENT && di->zerr != ENOTSUP)
 279                 return (-1);
 280
 281         /*
 282          * Unallocated object sharing the same meta dnode block
 283          */
 284         if (fobjerr && tobjerr) {
 285                 ASSERT(di->zerr == ENOENT || di->zerr == ENOTSUP);
 286                 di->zerr = 0;
 287                 return (0);
 288         }
 289
 290         di->zerr = 0; /* negate get_stats_for_obj() from side that failed */
 291         fmode = fsb.zs_mode & S_IFMT;
 292         tmode = tsb.zs_mode & S_IFMT;
 293         if (fmode == S_IFDIR || tmode == S_IFDIR || fsb.zs_links == 0 ||
 294             tsb.zs_links == 0)
 295                 change = 0;
 296         else
 297                 change = tsb.zs_links - fsb.zs_links;
 298
 299         if (fobjerr) {
 300                 if (change) {
 301                         print_link_change(fp, di, change, tobjname, &tsb);
 302                         return (0);
 303                 }
 304                 print_file(fp, di, ZDIFF_ADDED, tobjname, &tsb);
 305                 return (0);
 306         } else if (tobjerr) {
 307                 if (change) {
 308                         print_link_change(fp, di, change, fobjname, &fsb);
 309                         return (0);
 310                 }
 311                 print_file(fp, di, ZDIFF_REMOVED, fobjname, &fsb);
 312                 return (0);
 313         }
 314
 315         if (fmode != tmode && fsb.zs_gen == tsb.zs_gen)
 316                 tsb.zs_gen++;   /* Force a generational difference */
 317         same_name = do_name_cmp(fobjname, tobjname);
 318
 319         /* Simple modification or no change */
 320         if (fsb.zs_gen == tsb.zs_gen) {
 321                 /* No apparent changes.  Could we assert !this?  */
 322                 if (fsb.zs_ctime[0] == tsb.zs_ctime[0] &&
 323                     fsb.zs_ctime[1] == tsb.zs_ctime[1])
 324                         return (0);
 325                 if (change) {
 326                         print_link_change(fp, di, change,
 327                             change > 0 ? fobjname : tobjname, &tsb);
 328                 } else if (same_name) {
 329                         print_file(fp, di, ZDIFF_MODIFIED, fobjname, &tsb);
 330                 } else {
 331                         print_rename(fp, di, fobjname, tobjname, &tsb);
 332                 }
 333                 return (0);
 334         } else {
 335                 /* file re-created or object re-used */
 336                 print_file(fp, di, ZDIFF_REMOVED, fobjname, &fsb);
 337                 print_file(fp, di, ZDIFF_ADDED, tobjname, &tsb);
 338                 return (0);
 339         }
 340 }
 341
 342 static int
 343 write_inuse_diffs(FILE *fp, differ_info_t *di, dmu_diff_record_t *dr)
 344 {
 345         uint64_t o;
 346         int err;
 347
 348         for (o = dr->ddr_first; o <= dr->ddr_last; o++) {
 349                 if (err = write_inuse_diffs_one(fp, di, o))
 350                         return (err);
 351         }
 352         return (0);
 353 }
 354
 355 static int
 356 describe_free(FILE *fp, differ_info_t *di, uint64_t object, char *namebuf,
 357     int maxlen)
 358 {
 359         struct zfs_stat sb;
 360
 361         if (get_stats_for_obj(di, di->fromsnap, object, namebuf,
 362             maxlen, &sb) != 0) {
 363                 /* Let it slide, if in the delete queue on from side */
 364                 if (di->zerr == ENOENT && sb.zs_links == 0) {
 365                         di->zerr = 0;
 366                         return (0);
 367                 }
 368                 return (-1);
 369         }
 370
 371         print_file(fp, di, ZDIFF_REMOVED, namebuf, &sb);
 372         return (0);
 373 }
 374
 375 static int
 376 write_free_diffs(FILE *fp, differ_info_t *di, dmu_diff_record_t *dr)
 377 {
 378         zfs_cmd_t zc = { 0 };
 379         libzfs_handle_t *lhdl = di->zhp->zfs_hdl;
 380         char fobjname[MAXPATHLEN];
 381
 382         (void) strlcpy(zc.zc_name, di->fromsnap, sizeof (zc.zc_name));
 383         zc.zc_obj = dr->ddr_first - 1;
 384
 385         ASSERT(di->zerr == 0);
 386
 387         while (zc.zc_obj < dr->ddr_last) {
 388                 int err;
 389
 390                 err = ioctl(lhdl->libzfs_fd, ZFS_IOC_NEXT_OBJ, &zc);
 391                 if (err == 0) {
 392                         if (zc.zc_obj == di->shares) {
 393                                 zc.zc_obj++;
 394                                 continue;
 395                         }
 396                         if (zc.zc_obj > dr->ddr_last) {
 397                                 break;
 398                         }
 399                         err = describe_free(fp, di, zc.zc_obj, fobjname,
 400                             MAXPATHLEN);
 401                         if (err)
 402                                 break;
 403                 } else if (errno == ESRCH) {
 404                         break;
 405                 } else {
 406                         (void) snprintf(di->errbuf, sizeof (di->errbuf),
 407                             dgettext(TEXT_DOMAIN,
 408                             "next allocated object (> %lld) find failure"),
 409                             zc.zc_obj);
 410                         di->zerr = errno;
 411                         break;
 412                 }
 413         }
 414         if (di->zerr)
 415                 return (-1);
 416         return (0);
 417 }
 418
 419 static void *
 420 differ(void *arg)
 421 {
 422         differ_info_t *di = arg;
 423         dmu_diff_record_t dr;
 424         FILE *ofp;
 425         int err = 0;
 426
 427         if ((ofp = fdopen(di->outputfd, "w")) == NULL) {
 428                 di->zerr = errno;
 429                 (void) strerror_r(errno, di->errbuf, sizeof (di->errbuf));
 430                 (void) close(di->datafd);
 431                 return ((void *)-1);
 432         }
 433
 434         for (;;) {
 435                 char *cp = (char *)&dr;
 436                 int len = sizeof (dr);
 437                 int rv;
 438
 439                 do {
 440                         rv = read(di->datafd, cp, len);
 441                         cp += rv;
 442                         len -= rv;
 443                 } while (len > 0 && rv > 0);
 444
 445                 if (rv < 0 || (rv == 0 && len != sizeof (dr))) {
 446                         di->zerr = EPIPE;
 447                         break;
 448                 } else if (rv == 0) {
 449                         /* end of file at a natural breaking point */
 450                         break;
 451                 }
 452
 453                 switch (dr.ddr_type) {
 454                 case DDR_FREE:
 455                         err = write_free_diffs(ofp, di, &dr);
 456                         break;
 457                 case DDR_INUSE:
 458                         err = write_inuse_diffs(ofp, di, &dr);
 459                         break;
 460                 default:
 461                         di->zerr = EPIPE;
 462                         break;
 463                 }
 464
 465                 if (err || di->zerr)
 466                         break;
 467         }
 468
 469         (void) fclose(ofp);
 470         (void) close(di->datafd);
 471         if (err)
 472                 return ((void *)-1);
 473         if (di->zerr) {
 474                 ASSERT(di->zerr == EINVAL);
 475                 (void) snprintf(di->errbuf, sizeof (di->errbuf),
 476                     dgettext(TEXT_DOMAIN,
 477                     "Internal error: bad data from diff IOCTL"));
 478                 return ((void *)-1);
 479         }
 480         return ((void *)0);
 481 }
 482
 483 static int
 484 find_shares_object(differ_info_t *di)
 485 {
 486         char fullpath[MAXPATHLEN];
 487         struct stat64 sb = { 0 };
 488
 489         (void) strlcpy(fullpath, di->dsmnt, MAXPATHLEN);
 490         (void) strlcat(fullpath, ZDIFF_SHARESDIR, MAXPATHLEN);
 491
 492         if (stat64(fullpath, &sb) != 0) {
 493                 (void) snprintf(di->errbuf, sizeof (di->errbuf),
 494                     dgettext(TEXT_DOMAIN, "Cannot stat %s"), fullpath);
 495                 return (zfs_error(di->zhp->zfs_hdl, EZFS_DIFF, di->errbuf));
 496         }
 497
 498         di->shares = (uint64_t)sb.st_ino;
 499         return (0);
 500 }
 501
 502 static int
 503 make_temp_snapshot(differ_info_t *di)
 504 {
 505         libzfs_handle_t *hdl = di->zhp->zfs_hdl;
 506         zfs_cmd_t zc = { 0 };
 507
 508         (void) snprintf(zc.zc_value, sizeof (zc.zc_value),
 509             ZDIFF_PREFIX, getpid());
 510         (void) strlcpy(zc.zc_name, di->ds, sizeof (zc.zc_name));
 511         zc.zc_cleanup_fd = di->cleanupfd;
 512
 513         if (ioctl(hdl->libzfs_fd, ZFS_IOC_TMP_SNAPSHOT, &zc) != 0) {
 514                 int err = errno;
 515                 if (err == EPERM) {
 516                         (void) snprintf(di->errbuf, sizeof (di->errbuf),
 517                             dgettext(TEXT_DOMAIN, "The diff delegated "
 518                             "permission is needed in order\nto create a "
 519                             "just-in-time snapshot for diffing\n"));
 520                         return (zfs_error(hdl, EZFS_DIFF, di->errbuf));
 521                 } else {
 522                         (void) snprintf(di->errbuf, sizeof (di->errbuf),
 523                             dgettext(TEXT_DOMAIN, "Cannot create just-in-time "
 524                             "snapshot of '%s'"), zc.zc_name);
 525                         return (zfs_standard_error(hdl, err, di->errbuf));
 526                 }
 527         }
 528
 529         di->tmpsnap = zfs_strdup(hdl, zc.zc_value);
 530         di->tosnap = zfs_asprintf(hdl, "%s@%s", di->ds, di->tmpsnap);
 531         return (0);
 532 }
 533
 534 static void
 535 teardown_differ_info(differ_info_t *di)
 536 {
 537         free(di->ds);
 538         free(di->dsmnt);
 539         free(di->fromsnap);
 540         free(di->frommnt);
 541         free(di->tosnap);
 542         free(di->tmpsnap);
 543         free(di->tomnt);
 544         (void) close(di->cleanupfd);
 545 }
 546
 547 static int
 548 get_snapshot_names(differ_info_t *di, const char *fromsnap,
 549     const char *tosnap)
 550 {
 551         libzfs_handle_t *hdl = di->zhp->zfs_hdl;
 552         char *atptrf = NULL;
 553         char *atptrt = NULL;
 554         int fdslen, fsnlen;
 555         int tdslen, tsnlen;
 556
 557         /*
 558          * Can accept
 559          *    dataset@snap1
 560          *    dataset@snap1 dataset@snap2
 561          *    dataset@snap1 @snap2
 562          *    dataset@snap1 dataset
 563          *    @snap1 dataset@snap2
 564          */
 565         if (tosnap == NULL) {
 566                 /* only a from snapshot given, must be valid */
 567                 (void) snprintf(di->errbuf, sizeof (di->errbuf),
 568                     dgettext(TEXT_DOMAIN,
 569                     "Badly formed snapshot name %s"), fromsnap);
 570
 571                 if (!zfs_validate_name(hdl, fromsnap, ZFS_TYPE_SNAPSHOT,
 572                     B_FALSE)) {
 573                         return (zfs_error(hdl, EZFS_INVALIDNAME,
 574                             di->errbuf));
 575                 }
 576
 577                 atptrf = strchr(fromsnap, '@');
 578                 ASSERT(atptrf != NULL);
 579                 fdslen = atptrf - fromsnap;
 580
 581                 di->fromsnap = zfs_strdup(hdl, fromsnap);
 582                 di->ds = zfs_strdup(hdl, fromsnap);
 583                 di->ds[fdslen] = '\0';
 584
 585                 /* the to snap will be a just-in-time snap of the head */
 586                 return (make_temp_snapshot(di));
 587         }
 588
 589         (void) snprintf(di->errbuf, sizeof (di->errbuf),
 590             dgettext(TEXT_DOMAIN,
 591             "Unable to determine which snapshots to compare"));
 592
 593         atptrf = strchr(fromsnap, '@');
 594         atptrt = strchr(tosnap, '@');
 595         fdslen = atptrf ? atptrf - fromsnap : strlen(fromsnap);
 596         tdslen = atptrt ? atptrt - tosnap : strlen(tosnap);
 597         fsnlen = strlen(fromsnap) - fdslen;     /* includes @ sign */
 598         tsnlen = strlen(tosnap) - tdslen;       /* includes @ sign */
 599
 600         if (fsnlen <= 1 || tsnlen == 1 || (fdslen == 0 && tdslen == 0) ||
 601             (fsnlen == 0 && tsnlen == 0)) {
 602                 return (zfs_error(hdl, EZFS_INVALIDNAME, di->errbuf));
 603         } else if ((fdslen > 0 && tdslen > 0) &&
 604             ((tdslen != fdslen || strncmp(fromsnap, tosnap, fdslen) != 0))) {
 605                 /*
 606                  * not the same dataset name, might be okay if
 607                  * tosnap is a clone of a fromsnap descendant.
 608                  */
 609                 char origin[ZFS_MAXNAMELEN];
 610                 zprop_source_t src;
 611                 zfs_handle_t *zhp;
 612
 613                 di->ds = zfs_alloc(di->zhp->zfs_hdl, tdslen + 1);
 614                 (void) strncpy(di->ds, tosnap, tdslen);
 615                 di->ds[tdslen] = '\0';
 616
 617                 zhp = zfs_open(hdl, di->ds, ZFS_TYPE_FILESYSTEM);
 618                 while (zhp != NULL) {
 619                         (void) zfs_prop_get(zhp, ZFS_PROP_ORIGIN,
 620                             origin, sizeof (origin), &src, NULL, 0, B_FALSE);
 621
 622                         if (strncmp(origin, fromsnap, fsnlen) == 0)
 623                                 break;
 624
 625                         (void) zfs_close(zhp);
 626                         zhp = zfs_open(hdl, origin, ZFS_TYPE_FILESYSTEM);
 627                 }
 628
 629                 if (zhp == NULL) {
 630                         (void) snprintf(di->errbuf, sizeof (di->errbuf),
 631                             dgettext(TEXT_DOMAIN,
 632                             "Not an earlier snapshot from the same fs"));
 633                         return (zfs_error(hdl, EZFS_INVALIDNAME, di->errbuf));
 634                 } else {
 635                         (void) zfs_close(zhp);
 636                 }
 637
 638                 di->isclone = B_TRUE;
 639                 di->fromsnap = zfs_strdup(hdl, fromsnap);
 640                 if (tsnlen) {
 641                         di->tosnap = zfs_strdup(hdl, tosnap);
 642                 } else {
 643                         return (make_temp_snapshot(di));
 644                 }
 645         } else {
 646                 int dslen = fdslen ? fdslen : tdslen;
 647
 648                 di->ds = zfs_alloc(hdl, dslen + 1);
 649                 (void) strncpy(di->ds, fdslen ? fromsnap : tosnap, dslen);
 650                 di->ds[dslen] = '\0';
 651
 652                 di->fromsnap = zfs_asprintf(hdl, "%s%s", di->ds, atptrf);
 653                 if (tsnlen) {
 654                         di->tosnap = zfs_asprintf(hdl, "%s%s", di->ds, atptrt);
 655                 } else {
 656                         return (make_temp_snapshot(di));
 657                 }
 658         }
 659         return (0);
 660 }
 661
 662 static int
 663 get_mountpoint(differ_info_t *di, char *dsnm, char **mntpt)
 664 {
 665         boolean_t mounted;
 666
 667         mounted = is_mounted(di->zhp->zfs_hdl, dsnm, mntpt);
 668         if (mounted == B_FALSE) {
 669                 (void) snprintf(di->errbuf, sizeof (di->errbuf),
 670                     dgettext(TEXT_DOMAIN,
 671                     "Cannot diff an unmounted snapshot"));
 672                 return (zfs_error(di->zhp->zfs_hdl, EZFS_BADTYPE, di->errbuf));
 673         }
 674
 675         /* Avoid a double slash at the beginning of root-mounted datasets */
 676         if (**mntpt == '/' && *(*mntpt + 1) == '\0')
 677                 **mntpt = '\0';
 678         return (0);
 679 }
 680
 681 static int
 682 get_mountpoints(differ_info_t *di)
 683 {
 684         char *strptr;
 685         char *frommntpt;
 686
 687         /*
 688          * first get the mountpoint for the parent dataset
 689          */
 690         if (get_mountpoint(di, di->ds, &di->dsmnt) != 0)
 691                 return (-1);
 692
 693         strptr = strchr(di->tosnap, '@');
 694         ASSERT3P(strptr, !=, NULL);
 695         di->tomnt = zfs_asprintf(di->zhp->zfs_hdl, "%s%s%s", di->dsmnt,
 696             ZDIFF_SNAPDIR, ++strptr);
 697
 698         strptr = strchr(di->fromsnap, '@');
 699         ASSERT3P(strptr, !=, NULL);
 700
 701         frommntpt = di->dsmnt;
 702         if (di->isclone) {
 703                 char *mntpt;
 704                 int err;
 705
 706                 *strptr = '\0';
 707                 err = get_mountpoint(di, di->fromsnap, &mntpt);
 708                 *strptr = '@';
 709                 if (err != 0)
 710                         return (-1);
 711                 frommntpt = mntpt;
 712         }
 713
 714         di->frommnt = zfs_asprintf(di->zhp->zfs_hdl, "%s%s%s", frommntpt,
 715             ZDIFF_SNAPDIR, ++strptr);
 716
 717         if (di->isclone)
 718                 free(frommntpt);
 719
 720         return (0);
 721 }
 722
 723 static int
 724 setup_differ_info(zfs_handle_t *zhp, const char *fromsnap,
 725     const char *tosnap, differ_info_t *di)
 726 {
 727         di->zhp = zhp;
 728
 729         di->cleanupfd = open(ZFS_DEV, O_RDWR|O_EXCL);
 730         VERIFY(di->cleanupfd >= 0);
 731
 732         if (get_snapshot_names(di, fromsnap, tosnap) != 0)
 733                 return (-1);
 734
 735         if (get_mountpoints(di) != 0)
 736                 return (-1);
 737
 738         if (find_shares_object(di) != 0)
 739                 return (-1);
 740
 741         return (0);
 742 }
 743
 744 int
 745 zfs_show_diffs(zfs_handle_t *zhp, int outfd, const char *fromsnap,
 746     const char *tosnap, int flags)
 747 {
 748         zfs_cmd_t zc = { 0 };
 749         char errbuf[1024];
 750         differ_info_t di = { 0 };
 751         pthread_t tid;
 752         int pipefd[2];
 753         int iocerr;
 754
 755         (void) snprintf(errbuf, sizeof (errbuf),
 756             dgettext(TEXT_DOMAIN, "zfs diff failed"));
 757
 758         if (setup_differ_info(zhp, fromsnap, tosnap, &di)) {
 759                 teardown_differ_info(&di);
 760                 return (-1);
 761         }
 762
 763         if (pipe(pipefd)) {
 764                 zfs_error_aux(zhp->zfs_hdl, strerror(errno));
 765                 teardown_differ_info(&di);
 766                 return (zfs_error(zhp->zfs_hdl, EZFS_PIPEFAILED, errbuf));
 767         }
 768
 769         di.scripted = (flags & ZFS_DIFF_PARSEABLE);
 770         di.classify = (flags & ZFS_DIFF_CLASSIFY);
 771         di.timestamped = (flags & ZFS_DIFF_TIMESTAMP);
 772
 773         di.outputfd = outfd;
 774         di.datafd = pipefd[0];
 775
 776         if (pthread_create(&tid, NULL, differ, &di)) {
 777                 zfs_error_aux(zhp->zfs_hdl, strerror(errno));
 778                 (void) close(pipefd[0]);
 779                 (void) close(pipefd[1]);
 780                 teardown_differ_info(&di);
 781                 return (zfs_error(zhp->zfs_hdl,
 782                     EZFS_THREADCREATEFAILED, errbuf));
 783         }
 784
 785         /* do the ioctl() */
 786         (void) strlcpy(zc.zc_value, di.fromsnap, strlen(di.fromsnap) + 1);
 787         (void) strlcpy(zc.zc_name, di.tosnap, strlen(di.tosnap) + 1);
 788         zc.zc_cookie = pipefd[1];
 789
 790         iocerr = ioctl(zhp->zfs_hdl->libzfs_fd, ZFS_IOC_DIFF, &zc);
 791         if (iocerr != 0) {
 792                 (void) snprintf(errbuf, sizeof (errbuf),
 793                     dgettext(TEXT_DOMAIN, "Unable to obtain diffs"));
 794                 if (errno == EPERM) {
 795                         zfs_error_aux(zhp->zfs_hdl, dgettext(TEXT_DOMAIN,
 796                             "\n   The sys_mount privilege or diff delegated "
 797                             "permission is needed\n   to execute the "
 798                             "diff ioctl"));
 799                 } else if (errno == EXDEV) {
 800                         zfs_error_aux(zhp->zfs_hdl, dgettext(TEXT_DOMAIN,
 801                             "\n   Not an earlier snapshot from the same fs"));
 802                 } else if (errno != EPIPE || di.zerr == 0) {
 803                         zfs_error_aux(zhp->zfs_hdl, strerror(errno));
 804                 }
 805                 (void) close(pipefd[1]);
 806                 (void) pthread_cancel(tid);
 807                 (void) pthread_join(tid, NULL);
 808                 teardown_differ_info(&di);
 809                 if (di.zerr != 0 && di.zerr != EPIPE) {
 810                         zfs_error_aux(zhp->zfs_hdl, strerror(di.zerr));
 811                         return (zfs_error(zhp->zfs_hdl, EZFS_DIFF, di.errbuf));
 812                 } else {
 813                         return (zfs_error(zhp->zfs_hdl, EZFS_DIFFDATA, errbuf));
 814                 }
 815         }
 816
 817         (void) close(pipefd[1]);
 818         (void) pthread_join(tid, NULL);
 819
 820         if (di.zerr != 0) {
 821                 zfs_error_aux(zhp->zfs_hdl, strerror(di.zerr));
 822                 return (zfs_error(zhp->zfs_hdl, EZFS_DIFF, di.errbuf));
 823         }
 824         teardown_differ_info(&di);
 825         return (0);
 826 }