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", 0, 0, 0, 0, 0, 0, 0, "\0", "\0", "\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"), (longlong_t)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", (unsigned char)*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 #ifdef S_IFDOOR
 164         case S_IFDOOR:
 165                 symbol = '>';
 166                 break;
 167 #endif
 168         case S_IFIFO:
 169                 symbol = '|';
 170                 break;
 171         case S_IFLNK:
 172                 symbol = '@';
 173                 break;
 174 #ifdef S_IFPORT
 175         case S_IFPORT:
 176                 symbol = 'P';
 177                 break;
 178 #endif
 179         case S_IFSOCK:
 180                 symbol = '=';
 181                 break;
 182         case S_IFREG:
 183                 symbol = 'F';
 184                 break;
 185         default:
 186                 symbol = '?';
 187                 break;
 188         }
 189         (void) fprintf(fp, "%c", symbol);
 190 }
 191
 192 static void
 193 print_cmn(FILE *fp, differ_info_t *di, const char *file)
 194 {
 195         stream_bytes(fp, di->dsmnt);
 196         stream_bytes(fp, file);
 197 }
 198
 199 static void
 200 print_rename(FILE *fp, differ_info_t *di, const char *old, const char *new,
 201     zfs_stat_t *isb)
 202 {
 203         if (di->timestamped)
 204                 (void) fprintf(fp, "%10lld.%09lld\t",
 205                     (longlong_t)isb->zs_ctime[0],
 206                     (longlong_t)isb->zs_ctime[1]);
 207         (void) fprintf(fp, "%c\t", ZDIFF_RENAMED);
 208         if (di->classify) {
 209                 print_what(fp, isb->zs_mode);
 210                 (void) fprintf(fp, "\t");
 211         }
 212         print_cmn(fp, di, old);
 213         if (di->scripted)
 214                 (void) fprintf(fp, "\t");
 215         else
 216                 (void) fprintf(fp, " -> ");
 217         print_cmn(fp, di, new);
 218         (void) fprintf(fp, "\n");
 219 }
 220
 221 static void
 222 print_link_change(FILE *fp, differ_info_t *di, int delta, const char *file,
 223     zfs_stat_t *isb)
 224 {
 225         if (di->timestamped)
 226                 (void) fprintf(fp, "%10lld.%09lld\t",
 227                     (longlong_t)isb->zs_ctime[0],
 228                     (longlong_t)isb->zs_ctime[1]);
 229         (void) fprintf(fp, "%c\t", ZDIFF_MODIFIED);
 230         if (di->classify) {
 231                 print_what(fp, isb->zs_mode);
 232                 (void) fprintf(fp, "\t");
 233         }
 234         print_cmn(fp, di, file);
 235         (void) fprintf(fp, "\t(%+d)", delta);
 236         (void) fprintf(fp, "\n");
 237 }
 238
 239 static void
 240 print_file(FILE *fp, differ_info_t *di, char type, const char *file,
 241     zfs_stat_t *isb)
 242 {
 243         if (di->timestamped)
 244                 (void) fprintf(fp, "%10lld.%09lld\t",
 245                     (longlong_t)isb->zs_ctime[0],
 246                     (longlong_t)isb->zs_ctime[1]);
 247         (void) fprintf(fp, "%c\t", type);
 248         if (di->classify) {
 249                 print_what(fp, isb->zs_mode);
 250                 (void) fprintf(fp, "\t");
 251         }
 252         print_cmn(fp, di, file);
 253         (void) fprintf(fp, "\n");
 254 }
 255
 256 static int
 257 write_inuse_diffs_one(FILE *fp, differ_info_t *di, uint64_t dobj)
 258 {
 259         struct zfs_stat fsb, tsb;
 260         boolean_t same_name;
 261         mode_t fmode, tmode;
 262         char fobjname[MAXPATHLEN], tobjname[MAXPATHLEN];
 263         int fobjerr, tobjerr;
 264         int change;
 265
 266         if (dobj == di->shares)
 267                 return (0);
 268
 269         /*
 270          * Check the from and to snapshots for info on the object. If
 271          * we get ENOENT, then the object just didn't exist in that
 272          * snapshot.  If we get ENOTSUP, then we tried to get
 273          * info on a non-ZPL object, which we don't care about anyway.
 274          */
 275         fobjerr = get_stats_for_obj(di, di->fromsnap, dobj, fobjname,
 276             MAXPATHLEN, &fsb);
 277         if (fobjerr && di->zerr != ENOENT && di->zerr != ENOTSUP)
 278                 return (-1);
 279
 280         tobjerr = get_stats_for_obj(di, di->tosnap, dobj, tobjname,
 281             MAXPATHLEN, &tsb);
 282         if (tobjerr && di->zerr != ENOENT && di->zerr != ENOTSUP)
 283                 return (-1);
 284
 285         /*
 286          * Unallocated object sharing the same meta dnode block
 287          */
 288         if (fobjerr && tobjerr) {
 289                 ASSERT(di->zerr == ENOENT || di->zerr == ENOTSUP);
 290                 di->zerr = 0;
 291                 return (0);
 292         }
 293
 294         di->zerr = 0; /* negate get_stats_for_obj() from side that failed */
 295         fmode = fsb.zs_mode & S_IFMT;
 296         tmode = tsb.zs_mode & S_IFMT;
 297         if (fmode == S_IFDIR || tmode == S_IFDIR || fsb.zs_links == 0 ||
 298             tsb.zs_links == 0)
 299                 change = 0;
 300         else
 301                 change = tsb.zs_links - fsb.zs_links;
 302
 303         if (fobjerr) {
 304                 if (change) {
 305                         print_link_change(fp, di, change, tobjname, &tsb);
 306                         return (0);
 307                 }
 308                 print_file(fp, di, ZDIFF_ADDED, tobjname, &tsb);
 309                 return (0);
 310         } else if (tobjerr) {
 311                 if (change) {
 312                         print_link_change(fp, di, change, fobjname, &fsb);
 313                         return (0);
 314                 }
 315                 print_file(fp, di, ZDIFF_REMOVED, fobjname, &fsb);
 316                 return (0);
 317         }
 318
 319         if (fmode != tmode && fsb.zs_gen == tsb.zs_gen)
 320                 tsb.zs_gen++;   /* Force a generational difference */
 321         same_name = do_name_cmp(fobjname, tobjname);
 322
 323         /* Simple modification or no change */
 324         if (fsb.zs_gen == tsb.zs_gen) {
 325                 /* No apparent changes.  Could we assert !this?  */
 326                 if (fsb.zs_ctime[0] == tsb.zs_ctime[0] &&
 327                     fsb.zs_ctime[1] == tsb.zs_ctime[1])
 328                         return (0);
 329                 if (change) {
 330                         print_link_change(fp, di, change,
 331                             change > 0 ? fobjname : tobjname, &tsb);
 332                 } else if (same_name) {
 333                         print_file(fp, di, ZDIFF_MODIFIED, fobjname, &tsb);
 334                 } else {
 335                         print_rename(fp, di, fobjname, tobjname, &tsb);
 336                 }
 337                 return (0);
 338         } else {
 339                 /* file re-created or object re-used */
 340                 print_file(fp, di, ZDIFF_REMOVED, fobjname, &fsb);
 341                 print_file(fp, di, ZDIFF_ADDED, tobjname, &tsb);
 342                 return (0);
 343         }
 344 }
 345
 346 static int
 347 write_inuse_diffs(FILE *fp, differ_info_t *di, dmu_diff_record_t *dr)
 348 {
 349         uint64_t o;
 350         int err;
 351
 352         for (o = dr->ddr_first; o <= dr->ddr_last; o++) {
 353                 if ((err = write_inuse_diffs_one(fp, di, o)))
 354                         return (err);
 355         }
 356         return (0);
 357 }
 358
 359 static int
 360 describe_free(FILE *fp, differ_info_t *di, uint64_t object, char *namebuf,
 361     int maxlen)
 362 {
 363         struct zfs_stat sb;
 364
 365         if (get_stats_for_obj(di, di->fromsnap, object, namebuf,
 366             maxlen, &sb) != 0) {
 367                 /* Let it slide, if in the delete queue on from side */
 368                 if (di->zerr == ENOENT && sb.zs_links == 0) {
 369                         di->zerr = 0;
 370                         return (0);
 371                 }
 372                 return (-1);
 373         }
 374
 375         print_file(fp, di, ZDIFF_REMOVED, namebuf, &sb);
 376         return (0);
 377 }
 378
 379 static int
 380 write_free_diffs(FILE *fp, differ_info_t *di, dmu_diff_record_t *dr)
 381 {
 382         zfs_cmd_t zc = {"\0", 0, 0, 0, 0, 0, 0, 0, "\0", "\0", "\0"};
 383         libzfs_handle_t *lhdl = di->zhp->zfs_hdl;
 384         char fobjname[MAXPATHLEN];
 385
 386         (void) strlcpy(zc.zc_name, di->fromsnap, sizeof (zc.zc_name));
 387         zc.zc_obj = dr->ddr_first - 1;
 388
 389         ASSERT(di->zerr == 0);
 390
 391         while (zc.zc_obj < dr->ddr_last) {
 392                 int err;
 393
 394                 err = ioctl(lhdl->libzfs_fd, ZFS_IOC_NEXT_OBJ, &zc);
 395                 if (err == 0) {
 396                         if (zc.zc_obj == di->shares) {
 397                                 zc.zc_obj++;
 398                                 continue;
 399                         }
 400                         if (zc.zc_obj > dr->ddr_last) {
 401                                 break;
 402                         }
 403                         err = describe_free(fp, di, zc.zc_obj, fobjname,
 404                             MAXPATHLEN);
 405                         if (err)
 406                                 break;
 407                 } else if (errno == ESRCH) {
 408                         break;
 409                 } else {
 410                         (void) snprintf(di->errbuf, sizeof (di->errbuf),
 411                             dgettext(TEXT_DOMAIN,
 412                             "next allocated object (> %lld) find failure"),
 413                             (longlong_t)zc.zc_obj);
 414                         di->zerr = errno;
 415                         break;
 416                 }
 417         }
 418         if (di->zerr)
 419                 return (-1);
 420         return (0);
 421 }
 422
 423 static void *
 424 differ(void *arg)
 425 {
 426         differ_info_t *di = arg;
 427         dmu_diff_record_t dr;
 428         FILE *ofp;
 429         int err = 0;
 430
 431         if ((ofp = fdopen(di->outputfd, "w")) == NULL) {
 432                 di->zerr = errno;
 433                 strncpy(di->errbuf, strerror(errno), sizeof (di->errbuf));
 434                 (void) close(di->datafd);
 435                 return ((void *)-1);
 436         }
 437
 438         for (;;) {
 439                 char *cp = (char *)&dr;
 440                 int len = sizeof (dr);
 441                 int rv;
 442
 443                 do {
 444                         rv = read(di->datafd, cp, len);
 445                         cp += rv;
 446                         len -= rv;
 447                 } while (len > 0 && rv > 0);
 448
 449                 if (rv < 0 || (rv == 0 && len != sizeof (dr))) {
 450                         di->zerr = EPIPE;
 451                         break;
 452                 } else if (rv == 0) {
 453                         /* end of file at a natural breaking point */
 454                         break;
 455                 }
 456
 457                 switch (dr.ddr_type) {
 458                 case DDR_FREE:
 459                         err = write_free_diffs(ofp, di, &dr);
 460                         break;
 461                 case DDR_INUSE:
 462                         err = write_inuse_diffs(ofp, di, &dr);
 463                         break;
 464                 default:
 465                         di->zerr = EPIPE;
 466                         break;
 467                 }
 468
 469                 if (err || di->zerr)
 470                         break;
 471         }
 472
 473         (void) fclose(ofp);
 474         (void) close(di->datafd);
 475         if (err)
 476                 return ((void *)-1);
 477         if (di->zerr) {
 478                 ASSERT(di->zerr == EINVAL);
 479                 (void) snprintf(di->errbuf, sizeof (di->errbuf),
 480                     dgettext(TEXT_DOMAIN,
 481                     "Internal error: bad data from diff IOCTL"));
 482                 return ((void *)-1);
 483         }
 484         return ((void *)0);
 485 }
 486
 487 static int
 488 find_shares_object(differ_info_t *di)
 489 {
 490         char fullpath[MAXPATHLEN];
 491         struct stat64 sb = { 0 };
 492
 493         (void) strlcpy(fullpath, di->dsmnt, MAXPATHLEN);
 494         (void) strlcat(fullpath, ZDIFF_SHARESDIR, MAXPATHLEN);
 495
 496         if (stat64(fullpath, &sb) != 0) {
 497                 (void) snprintf(di->errbuf, sizeof (di->errbuf),
 498                     dgettext(TEXT_DOMAIN, "Cannot stat %s"), fullpath);
 499                 return (zfs_error(di->zhp->zfs_hdl, EZFS_DIFF, di->errbuf));
 500         }
 501
 502         di->shares = (uint64_t)sb.st_ino;
 503         return (0);
 504 }
 505
 506 static int
 507 make_temp_snapshot(differ_info_t *di)
 508 {
 509         libzfs_handle_t *hdl = di->zhp->zfs_hdl;
 510         zfs_cmd_t zc = {"\0", 0, 0, 0, 0, 0, 0, 0, "\0", "\0", "\0"};
 511
 512         (void) snprintf(zc.zc_value, sizeof (zc.zc_value),
 513             ZDIFF_PREFIX, getpid());
 514         (void) strlcpy(zc.zc_name, di->ds, sizeof (zc.zc_name));
 515         zc.zc_cleanup_fd = di->cleanupfd;
 516
 517         if (ioctl(hdl->libzfs_fd, ZFS_IOC_TMP_SNAPSHOT, &zc) != 0) {
 518                 int err = errno;
 519                 if (err == EPERM) {
 520                         (void) snprintf(di->errbuf, sizeof (di->errbuf),
 521                             dgettext(TEXT_DOMAIN, "The diff delegated "
 522                             "permission is needed in order\nto create a "
 523                             "just-in-time snapshot for diffing\n"));
 524                         return (zfs_error(hdl, EZFS_DIFF, di->errbuf));
 525                 } else {
 526                         (void) snprintf(di->errbuf, sizeof (di->errbuf),
 527                             dgettext(TEXT_DOMAIN, "Cannot create just-in-time "
 528                             "snapshot of '%s'"), zc.zc_name);
 529                         return (zfs_standard_error(hdl, err, di->errbuf));
 530                 }
 531         }
 532
 533         di->tmpsnap = zfs_strdup(hdl, zc.zc_value);
 534         di->tosnap = zfs_asprintf(hdl, "%s@%s", di->ds, di->tmpsnap);
 535         return (0);
 536 }
 537
 538 static void
 539 teardown_differ_info(differ_info_t *di)
 540 {
 541         free(di->ds);
 542         free(di->dsmnt);
 543         free(di->fromsnap);
 544         free(di->frommnt);
 545         free(di->tosnap);
 546         free(di->tmpsnap);
 547         free(di->tomnt);
 548         (void) close(di->cleanupfd);
 549 }
 550
 551 static int
 552 get_snapshot_names(differ_info_t *di, const char *fromsnap,
 553     const char *tosnap)
 554 {
 555         libzfs_handle_t *hdl = di->zhp->zfs_hdl;
 556         char *atptrf = NULL;
 557         char *atptrt = NULL;
 558         int fdslen, fsnlen;
 559         int tdslen, tsnlen;
 560
 561         /*
 562          * Can accept
 563          *    dataset@snap1
 564          *    dataset@snap1 dataset@snap2
 565          *    dataset@snap1 @snap2
 566          *    dataset@snap1 dataset
 567          *    @snap1 dataset@snap2
 568          */
 569         if (tosnap == NULL) {
 570                 /* only a from snapshot given, must be valid */
 571                 (void) snprintf(di->errbuf, sizeof (di->errbuf),
 572                     dgettext(TEXT_DOMAIN,
 573                     "Badly formed snapshot name %s"), fromsnap);
 574
 575                 if (!zfs_validate_name(hdl, fromsnap, ZFS_TYPE_SNAPSHOT,
 576                     B_FALSE)) {
 577                         return (zfs_error(hdl, EZFS_INVALIDNAME,
 578                             di->errbuf));
 579                 }
 580
 581                 atptrf = strchr(fromsnap, '@');
 582                 ASSERT(atptrf != NULL);
 583                 fdslen = atptrf - fromsnap;
 584
 585                 di->fromsnap = zfs_strdup(hdl, fromsnap);
 586                 di->ds = zfs_strdup(hdl, fromsnap);
 587                 di->ds[fdslen] = '\0';
 588
 589                 /* the to snap will be a just-in-time snap of the head */
 590                 return (make_temp_snapshot(di));
 591         }
 592
 593         (void) snprintf(di->errbuf, sizeof (di->errbuf),
 594             dgettext(TEXT_DOMAIN,
 595             "Unable to determine which snapshots to compare"));
 596
 597         atptrf = strchr(fromsnap, '@');
 598         atptrt = strchr(tosnap, '@');
 599         fdslen = atptrf ? atptrf - fromsnap : strlen(fromsnap);
 600         tdslen = atptrt ? atptrt - tosnap : strlen(tosnap);
 601         fsnlen = strlen(fromsnap) - fdslen;     /* includes @ sign */
 602         tsnlen = strlen(tosnap) - tdslen;       /* includes @ sign */
 603
 604         if (fsnlen <= 1 || tsnlen == 1 || (fdslen == 0 && tdslen == 0) ||
 605             (fsnlen == 0 && tsnlen == 0)) {
 606                 return (zfs_error(hdl, EZFS_INVALIDNAME, di->errbuf));
 607         } else if ((fdslen > 0 && tdslen > 0) &&
 608             ((tdslen != fdslen || strncmp(fromsnap, tosnap, fdslen) != 0))) {
 609                 /*
 610                  * not the same dataset name, might be okay if
 611                  * tosnap is a clone of a fromsnap descendant.
 612                  */
 613                 char origin[ZFS_MAXNAMELEN];
 614                 zprop_source_t src;
 615                 zfs_handle_t *zhp;
 616
 617                 di->ds = zfs_alloc(di->zhp->zfs_hdl, tdslen + 1);
 618                 (void) strncpy(di->ds, tosnap, tdslen);
 619                 di->ds[tdslen] = '\0';
 620
 621                 zhp = zfs_open(hdl, di->ds, ZFS_TYPE_FILESYSTEM);
 622                 while (zhp != NULL) {
 623                         (void) zfs_prop_get(zhp, ZFS_PROP_ORIGIN,
 624                             origin, sizeof (origin), &src, NULL, 0, B_FALSE);
 625
 626                         if (strncmp(origin, fromsnap, fsnlen) == 0)
 627                                 break;
 628
 629                         (void) zfs_close(zhp);
 630                         zhp = zfs_open(hdl, origin, ZFS_TYPE_FILESYSTEM);
 631                 }
 632
 633                 if (zhp == NULL) {
 634                         (void) snprintf(di->errbuf, sizeof (di->errbuf),
 635                             dgettext(TEXT_DOMAIN,
 636                             "Not an earlier snapshot from the same fs"));
 637                         return (zfs_error(hdl, EZFS_INVALIDNAME, di->errbuf));
 638                 } else {
 639                         (void) zfs_close(zhp);
 640                 }
 641
 642                 di->isclone = B_TRUE;
 643                 di->fromsnap = zfs_strdup(hdl, fromsnap);
 644                 if (tsnlen) {
 645                         di->tosnap = zfs_strdup(hdl, tosnap);
 646                 } else {
 647                         return (make_temp_snapshot(di));
 648                 }
 649         } else {
 650                 int dslen = fdslen ? fdslen : tdslen;
 651
 652                 di->ds = zfs_alloc(hdl, dslen + 1);
 653                 (void) strncpy(di->ds, fdslen ? fromsnap : tosnap, dslen);
 654                 di->ds[dslen] = '\0';
 655
 656                 di->fromsnap = zfs_asprintf(hdl, "%s%s", di->ds, atptrf);
 657                 if (tsnlen) {
 658                         di->tosnap = zfs_asprintf(hdl, "%s%s", di->ds, atptrt);
 659                 } else {
 660                         return (make_temp_snapshot(di));
 661                 }
 662         }
 663         return (0);
 664 }
 665
 666 static int
 667 get_mountpoint(differ_info_t *di, char *dsnm, char **mntpt)
 668 {
 669         boolean_t mounted;
 670
 671         mounted = is_mounted(di->zhp->zfs_hdl, dsnm, mntpt);
 672         if (mounted == B_FALSE) {
 673                 (void) snprintf(di->errbuf, sizeof (di->errbuf),
 674                     dgettext(TEXT_DOMAIN,
 675                     "Cannot diff an unmounted snapshot"));
 676                 return (zfs_error(di->zhp->zfs_hdl, EZFS_BADTYPE, di->errbuf));
 677         }
 678
 679         /* Avoid a double slash at the beginning of root-mounted datasets */
 680         if (**mntpt == '/' && *(*mntpt + 1) == '\0')
 681                 **mntpt = '\0';
 682         return (0);
 683 }
 684
 685 static int
 686 get_mountpoints(differ_info_t *di)
 687 {
 688         char *strptr;
 689         char *frommntpt;
 690
 691         /*
 692          * first get the mountpoint for the parent dataset
 693          */
 694         if (get_mountpoint(di, di->ds, &di->dsmnt) != 0)
 695                 return (-1);
 696
 697         strptr = strchr(di->tosnap, '@');
 698         ASSERT3P(strptr, !=, NULL);
 699         di->tomnt = zfs_asprintf(di->zhp->zfs_hdl, "%s%s%s", di->dsmnt,
 700             ZDIFF_SNAPDIR, ++strptr);
 701
 702         strptr = strchr(di->fromsnap, '@');
 703         ASSERT3P(strptr, !=, NULL);
 704
 705         frommntpt = di->dsmnt;
 706         if (di->isclone) {
 707                 char *mntpt;
 708                 int err;
 709
 710                 *strptr = '\0';
 711                 err = get_mountpoint(di, di->fromsnap, &mntpt);
 712                 *strptr = '@';
 713                 if (err != 0)
 714                         return (-1);
 715                 frommntpt = mntpt;
 716         }
 717
 718         di->frommnt = zfs_asprintf(di->zhp->zfs_hdl, "%s%s%s", frommntpt,
 719             ZDIFF_SNAPDIR, ++strptr);
 720
 721         if (di->isclone)
 722                 free(frommntpt);
 723
 724         return (0);
 725 }
 726
 727 static int
 728 setup_differ_info(zfs_handle_t *zhp, const char *fromsnap,
 729     const char *tosnap, differ_info_t *di)
 730 {
 731         di->zhp = zhp;
 732
 733         di->cleanupfd = open(ZFS_DEV, O_RDWR);
 734         VERIFY(di->cleanupfd >= 0);
 735
 736         if (get_snapshot_names(di, fromsnap, tosnap) != 0)
 737                 return (-1);
 738
 739         if (get_mountpoints(di) != 0)
 740                 return (-1);
 741
 742         if (find_shares_object(di) != 0)
 743                 return (-1);
 744
 745         return (0);
 746 }
 747
 748 int
 749 zfs_show_diffs(zfs_handle_t *zhp, int outfd, const char *fromsnap,
 750     const char *tosnap, int flags)
 751 {
 752         zfs_cmd_t zc = {"\0", 0, 0, 0, 0, 0, 0, 0, "\0", "\0", "\0"};
 753         char errbuf[1024];
 754         differ_info_t di = { 0 };
 755         pthread_t tid;
 756         int pipefd[2];
 757         int iocerr;
 758
 759         (void) snprintf(errbuf, sizeof (errbuf),
 760             dgettext(TEXT_DOMAIN, "zfs diff failed"));
 761
 762         if (setup_differ_info(zhp, fromsnap, tosnap, &di)) {
 763                 teardown_differ_info(&di);
 764                 return (-1);
 765         }
 766
 767         if (pipe(pipefd)) {
 768                 zfs_error_aux(zhp->zfs_hdl, strerror(errno));
 769                 teardown_differ_info(&di);
 770                 return (zfs_error(zhp->zfs_hdl, EZFS_PIPEFAILED, errbuf));
 771         }
 772
 773         di.scripted = (flags & ZFS_DIFF_PARSEABLE);
 774         di.classify = (flags & ZFS_DIFF_CLASSIFY);
 775         di.timestamped = (flags & ZFS_DIFF_TIMESTAMP);
 776
 777         di.outputfd = outfd;
 778         di.datafd = pipefd[0];
 779
 780         if (pthread_create(&tid, NULL, differ, &di)) {
 781                 zfs_error_aux(zhp->zfs_hdl, strerror(errno));
 782                 (void) close(pipefd[0]);
 783                 (void) close(pipefd[1]);
 784                 teardown_differ_info(&di);
 785                 return (zfs_error(zhp->zfs_hdl,
 786                     EZFS_THREADCREATEFAILED, errbuf));
 787         }
 788
 789         /* do the ioctl() */
 790         (void) strlcpy(zc.zc_value, di.fromsnap, strlen(di.fromsnap) + 1);
 791         (void) strlcpy(zc.zc_name, di.tosnap, strlen(di.tosnap) + 1);
 792         zc.zc_cookie = pipefd[1];
 793
 794         iocerr = ioctl(zhp->zfs_hdl->libzfs_fd, ZFS_IOC_DIFF, &zc);
 795         if (iocerr != 0) {
 796                 (void) snprintf(errbuf, sizeof (errbuf),
 797                     dgettext(TEXT_DOMAIN, "Unable to obtain diffs"));
 798                 if (errno == EPERM) {
 799                         zfs_error_aux(zhp->zfs_hdl, dgettext(TEXT_DOMAIN,
 800                             "\n   The sys_mount privilege or diff delegated "
 801                             "permission is needed\n   to execute the "
 802                             "diff ioctl"));
 803                 } else if (errno == EXDEV) {
 804                         zfs_error_aux(zhp->zfs_hdl, dgettext(TEXT_DOMAIN,
 805                             "\n   Not an earlier snapshot from the same fs"));
 806                 } else if (errno != EPIPE || di.zerr == 0) {
 807                         zfs_error_aux(zhp->zfs_hdl, strerror(errno));
 808                 }
 809                 (void) close(pipefd[1]);
 810                 (void) pthread_cancel(tid);
 811                 (void) pthread_join(tid, NULL);
 812                 teardown_differ_info(&di);
 813                 if (di.zerr != 0 && di.zerr != EPIPE) {
 814                         zfs_error_aux(zhp->zfs_hdl, strerror(di.zerr));
 815                         return (zfs_error(zhp->zfs_hdl, EZFS_DIFF, di.errbuf));
 816                 } else {
 817                         return (zfs_error(zhp->zfs_hdl, EZFS_DIFFDATA, errbuf));
 818                 }
 819         }
 820
 821         (void) close(pipefd[1]);
 822         (void) pthread_join(tid, NULL);
 823
 824         if (di.zerr != 0) {
 825                 zfs_error_aux(zhp->zfs_hdl, strerror(di.zerr));
 826                 return (zfs_error(zhp->zfs_hdl, EZFS_DIFF, di.errbuf));
 827         }
 828         teardown_differ_info(&di);
 829         return (0);
 830 }