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  * Copyright 2015 Nexenta Systems, Inc. All rights reserved.
  25  */
  26
  27 /*
  28  * zfs diff support
  29  */
  30 #include <ctype.h>
  31 #include <errno.h>
  32 #include <libintl.h>
  33 #include <string.h>
  34 #include <sys/types.h>
  35 #include <sys/stat.h>
  36 #include <fcntl.h>
  37 #include <attr.h>
  38 #include <stddef.h>
  39 #include <unistd.h>
  40 #include <stdio.h>
  41 #include <stdlib.h>
  42 #include <stropts.h>
  43 #include <pthread.h>
  44 #include <sys/zfs_ioctl.h>
  45 #include <libzfs.h>
  46 #include "libzfs_impl.h"
  47
  48 #define ZDIFF_SNAPDIR           "/.zfs/snapshot/"
  49 #define ZDIFF_SHARESDIR         "/.zfs/shares/"
  50 #define ZDIFF_PREFIX            "zfs-diff-%d"
  51
  52 #define ZDIFF_ADDED     '+'
  53 #define ZDIFF_MODIFIED  'M'
  54 #define ZDIFF_REMOVED   '-'
  55 #define ZDIFF_RENAMED   'R'
  56
  57 static boolean_t
  58 do_name_cmp(const char *fpath, const char *tpath)
  59 {
  60         char *fname, *tname;
  61         fname = strrchr(fpath, '/') + 1;
  62         tname = strrchr(tpath, '/') + 1;
  63         return (strcmp(fname, tname) == 0);
  64 }
  65
  66 typedef struct differ_info {
  67         zfs_handle_t *zhp;
  68         char *fromsnap;
  69         char *frommnt;
  70         char *tosnap;
  71         char *tomnt;
  72         char *ds;
  73         char *dsmnt;
  74         char *tmpsnap;
  75         char errbuf[1024];
  76         boolean_t isclone;
  77         boolean_t scripted;
  78         boolean_t classify;
  79         boolean_t timestamped;
  80         uint64_t shares;
  81         int zerr;
  82         int cleanupfd;
  83         int outputfd;
  84         int datafd;
  85 } differ_info_t;
  86
  87 /*
  88  * Given a {dsname, object id}, get the object path
  89  */
  90 static int
  91 get_stats_for_obj(differ_info_t *di, const char *dsname, uint64_t obj,
  92     char *pn, int maxlen, zfs_stat_t *sb)
  93 {
  94         zfs_cmd_t zc = {"\0"};
  95         int error;
  96
  97         (void) strlcpy(zc.zc_name, dsname, sizeof (zc.zc_name));
  98         zc.zc_obj = obj;
  99
 100         errno = 0;
 101         error = ioctl(di->zhp->zfs_hdl->libzfs_fd, ZFS_IOC_OBJ_TO_STATS, &zc);
 102         di->zerr = errno;
 103
 104         /* we can get stats even if we failed to get a path */
 105         (void) memcpy(sb, &zc.zc_stat, sizeof (zfs_stat_t));
 106         if (error == 0) {
 107                 ASSERT(di->zerr == 0);
 108                 (void) strlcpy(pn, zc.zc_value, maxlen);
 109                 return (0);
 110         }
 111
 112         if (di->zerr == EPERM) {
 113                 (void) snprintf(di->errbuf, sizeof (di->errbuf),
 114                     dgettext(TEXT_DOMAIN,
 115                     "The sys_config privilege or diff delegated permission "
 116                     "is needed\nto discover path names"));
 117                 return (-1);
 118         } else {
 119                 (void) snprintf(di->errbuf, sizeof (di->errbuf),
 120                     dgettext(TEXT_DOMAIN,
 121                     "Unable to determine path or stats for "
 122                     "object %lld in %s"), (longlong_t)obj, dsname);
 123                 return (-1);
 124         }
 125 }
 126
 127 /*
 128  * stream_bytes
 129  *
 130  * Prints a file name out a character at a time.  If the character is
 131  * not in the range of what we consider "printable" ASCII, display it
 132  * as an escaped 4-digit octal value.  ASCII values less than a space
 133  * are all control characters and we declare the upper end as the
 134  * DELete character.  This also is the last 7-bit ASCII character.
 135  * We choose to treat all 8-bit ASCII as not printable for this
 136  * application.
 137  */
 138 static void
 139 stream_bytes(FILE *fp, const char *string)
 140 {
 141         while (*string) {
 142                 if (*string > ' ' && *string != '\\' && *string < '\177')
 143                         (void) fprintf(fp, "%c", *string++);
 144                 else
 145                         (void) fprintf(fp, "\\%04o", (unsigned char)*string++);
 146         }
 147 }
 148
 149 static void
 150 print_what(FILE *fp, mode_t what)
 151 {
 152         char symbol;
 153
 154         switch (what & S_IFMT) {
 155         case S_IFBLK:
 156                 symbol = 'B';
 157                 break;
 158         case S_IFCHR:
 159                 symbol = 'C';
 160                 break;
 161         case S_IFDIR:
 162                 symbol = '/';
 163                 break;
 164 #ifdef S_IFDOOR
 165         case S_IFDOOR:
 166                 symbol = '>';
 167                 break;
 168 #endif
 169         case S_IFIFO:
 170                 symbol = '|';
 171                 break;
 172         case S_IFLNK:
 173                 symbol = '@';
 174                 break;
 175 #ifdef S_IFPORT
 176         case S_IFPORT:
 177                 symbol = 'P';
 178                 break;
 179 #endif
 180         case S_IFSOCK:
 181                 symbol = '=';
 182                 break;
 183         case S_IFREG:
 184                 symbol = 'F';
 185                 break;
 186         default:
 187                 symbol = '?';
 188                 break;
 189         }
 190         (void) fprintf(fp, "%c", symbol);
 191 }
 192
 193 static void
 194 print_cmn(FILE *fp, differ_info_t *di, const char *file)
 195 {
 196         stream_bytes(fp, di->dsmnt);
 197         stream_bytes(fp, file);
 198 }
 199
 200 static void
 201 print_rename(FILE *fp, differ_info_t *di, const char *old, const char *new,
 202     zfs_stat_t *isb)
 203 {
 204         if (di->timestamped)
 205                 (void) fprintf(fp, "%10lld.%09lld\t",
 206                     (longlong_t)isb->zs_ctime[0],
 207                     (longlong_t)isb->zs_ctime[1]);
 208         (void) fprintf(fp, "%c\t", ZDIFF_RENAMED);
 209         if (di->classify) {
 210                 print_what(fp, isb->zs_mode);
 211                 (void) fprintf(fp, "\t");
 212         }
 213         print_cmn(fp, di, old);
 214         if (di->scripted)
 215                 (void) fprintf(fp, "\t");
 216         else
 217                 (void) fprintf(fp, " -> ");
 218         print_cmn(fp, di, new);
 219         (void) fprintf(fp, "\n");
 220 }
 221
 222 static void
 223 print_link_change(FILE *fp, differ_info_t *di, int delta, const char *file,
 224     zfs_stat_t *isb)
 225 {
 226         if (di->timestamped)
 227                 (void) fprintf(fp, "%10lld.%09lld\t",
 228                     (longlong_t)isb->zs_ctime[0],
 229                     (longlong_t)isb->zs_ctime[1]);
 230         (void) fprintf(fp, "%c\t", ZDIFF_MODIFIED);
 231         if (di->classify) {
 232                 print_what(fp, isb->zs_mode);
 233                 (void) fprintf(fp, "\t");
 234         }
 235         print_cmn(fp, di, file);
 236         (void) fprintf(fp, "\t(%+d)", delta);
 237         (void) fprintf(fp, "\n");
 238 }
 239
 240 static void
 241 print_file(FILE *fp, differ_info_t *di, char type, const char *file,
 242     zfs_stat_t *isb)
 243 {
 244         if (di->timestamped)
 245                 (void) fprintf(fp, "%10lld.%09lld\t",
 246                     (longlong_t)isb->zs_ctime[0],
 247                     (longlong_t)isb->zs_ctime[1]);
 248         (void) fprintf(fp, "%c\t", type);
 249         if (di->classify) {
 250                 print_what(fp, isb->zs_mode);
 251                 (void) fprintf(fp, "\t");
 252         }
 253         print_cmn(fp, di, file);
 254         (void) fprintf(fp, "\n");
 255 }
 256
 257 static int
 258 write_inuse_diffs_one(FILE *fp, differ_info_t *di, uint64_t dobj)
 259 {
 260         struct zfs_stat fsb, tsb;
 261         boolean_t same_name;
 262         mode_t fmode, tmode;
 263         char fobjname[MAXPATHLEN], tobjname[MAXPATHLEN];
 264         int fobjerr, tobjerr;
 265         int change;
 266
 267         if (dobj == di->shares)
 268                 return (0);
 269
 270         /*
 271          * Check the from and to snapshots for info on the object. If
 272          * we get ENOENT, then the object just didn't exist in that
 273          * snapshot.  If we get ENOTSUP, then we tried to get
 274          * info on a non-ZPL object, which we don't care about anyway.
 275          */
 276         fobjerr = get_stats_for_obj(di, di->fromsnap, dobj, fobjname,
 277             MAXPATHLEN, &fsb);
 278         if (fobjerr && di->zerr != ENOENT && di->zerr != ENOTSUP)
 279                 return (-1);
 280
 281         tobjerr = get_stats_for_obj(di, di->tosnap, dobj, tobjname,
 282             MAXPATHLEN, &tsb);
 283         if (tobjerr && di->zerr != ENOENT && di->zerr != ENOTSUP)
 284                 return (-1);
 285
 286         /*
 287          * Unallocated object sharing the same meta dnode block
 288          */
 289         if (fobjerr && tobjerr) {
 290                 ASSERT(di->zerr == ENOENT || di->zerr == ENOTSUP);
 291                 di->zerr = 0;
 292                 return (0);
 293         }
 294
 295         di->zerr = 0; /* negate get_stats_for_obj() from side that failed */
 296         fmode = fsb.zs_mode & S_IFMT;
 297         tmode = tsb.zs_mode & S_IFMT;
 298         if (fmode == S_IFDIR || tmode == S_IFDIR || fsb.zs_links == 0 ||
 299             tsb.zs_links == 0)
 300                 change = 0;
 301         else
 302                 change = tsb.zs_links - fsb.zs_links;
 303
 304         if (fobjerr) {
 305                 if (change) {
 306                         print_link_change(fp, di, change, tobjname, &tsb);
 307                         return (0);
 308                 }
 309                 print_file(fp, di, ZDIFF_ADDED, tobjname, &tsb);
 310                 return (0);
 311         } else if (tobjerr) {
 312                 if (change) {
 313                         print_link_change(fp, di, change, fobjname, &fsb);
 314                         return (0);
 315                 }
 316                 print_file(fp, di, ZDIFF_REMOVED, fobjname, &fsb);
 317                 return (0);
 318         }
 319
 320         if (fmode != tmode && fsb.zs_gen == tsb.zs_gen)
 321                 tsb.zs_gen++;   /* Force a generational difference */
 322         same_name = do_name_cmp(fobjname, tobjname);
 323
 324         /* Simple modification or no change */
 325         if (fsb.zs_gen == tsb.zs_gen) {
 326                 /* No apparent changes.  Could we assert !this?  */
 327                 if (fsb.zs_ctime[0] == tsb.zs_ctime[0] &&
 328                     fsb.zs_ctime[1] == tsb.zs_ctime[1])
 329                         return (0);
 330                 if (change) {
 331                         print_link_change(fp, di, change,
 332                             change > 0 ? fobjname : tobjname, &tsb);
 333                 } else if (same_name) {
 334                         print_file(fp, di, ZDIFF_MODIFIED, fobjname, &tsb);
 335                 } else {
 336                         print_rename(fp, di, fobjname, tobjname, &tsb);
 337                 }
 338                 return (0);
 339         } else {
 340                 /* file re-created or object re-used */
 341                 print_file(fp, di, ZDIFF_REMOVED, fobjname, &fsb);
 342                 print_file(fp, di, ZDIFF_ADDED, tobjname, &tsb);
 343                 return (0);
 344         }
 345 }
 346
 347 static int
 348 write_inuse_diffs(FILE *fp, differ_info_t *di, dmu_diff_record_t *dr)
 349 {
 350         uint64_t o;
 351         int err;
 352
 353         for (o = dr->ddr_first; o <= dr->ddr_last; o++) {
 354                 if ((err = write_inuse_diffs_one(fp, di, o)))
 355                         return (err);
 356         }
 357         return (0);
 358 }
 359
 360 static int
 361 describe_free(FILE *fp, differ_info_t *di, uint64_t object, char *namebuf,
 362     int maxlen)
 363 {
 364         struct zfs_stat sb;
 365
 366         if (get_stats_for_obj(di, di->fromsnap, object, namebuf,
 367             maxlen, &sb) != 0) {
 368                 /* Let it slide, if in the delete queue on from side */
 369                 if (di->zerr == ENOENT && sb.zs_links == 0) {
 370                         di->zerr = 0;
 371                         return (0);
 372                 }
 373                 return (-1);
 374         }
 375
 376         print_file(fp, di, ZDIFF_REMOVED, namebuf, &sb);
 377         return (0);
 378 }
 379
 380 static int
 381 write_free_diffs(FILE *fp, differ_info_t *di, dmu_diff_record_t *dr)
 382 {
 383         zfs_cmd_t zc = {"\0"};
 384         libzfs_handle_t *lhdl = di->zhp->zfs_hdl;
 385         char fobjname[MAXPATHLEN];
 386
 387         (void) strlcpy(zc.zc_name, di->fromsnap, sizeof (zc.zc_name));
 388         zc.zc_obj = dr->ddr_first - 1;
 389
 390         ASSERT(di->zerr == 0);
 391
 392         while (zc.zc_obj < dr->ddr_last) {
 393                 int err;
 394
 395                 err = ioctl(lhdl->libzfs_fd, ZFS_IOC_NEXT_OBJ, &zc);
 396                 if (err == 0) {
 397                         if (zc.zc_obj == di->shares) {
 398                                 zc.zc_obj++;
 399                                 continue;
 400                         }
 401                         if (zc.zc_obj > dr->ddr_last) {
 402                                 break;
 403                         }
 404                         err = describe_free(fp, di, zc.zc_obj, fobjname,
 405                             MAXPATHLEN);
 406                         if (err)
 407                                 break;
 408                 } else if (errno == ESRCH) {
 409                         break;
 410                 } else {
 411                         (void) snprintf(di->errbuf, sizeof (di->errbuf),
 412                             dgettext(TEXT_DOMAIN,
 413                             "next allocated object (> %lld) find failure"),
 414                             (longlong_t)zc.zc_obj);
 415                         di->zerr = errno;
 416                         break;
 417                 }
 418         }
 419         if (di->zerr)
 420                 return (-1);
 421         return (0);
 422 }
 423
 424 static void *
 425 differ(void *arg)
 426 {
 427         differ_info_t *di = arg;
 428         dmu_diff_record_t dr;
 429         FILE *ofp;
 430         int err = 0;
 431
 432         if ((ofp = fdopen(di->outputfd, "w")) == NULL) {
 433                 di->zerr = errno;
 434                 strncpy(di->errbuf, strerror(errno), sizeof (di->errbuf));
 435                 (void) close(di->datafd);
 436                 return ((void *)-1);
 437         }
 438
 439         for (;;) {
 440                 char *cp = (char *)&dr;
 441                 int len = sizeof (dr);
 442                 int rv;
 443
 444                 do {
 445                         rv = read(di->datafd, cp, len);
 446                         cp += rv;
 447                         len -= rv;
 448                 } while (len > 0 && rv > 0);
 449
 450                 if (rv < 0 || (rv == 0 && len != sizeof (dr))) {
 451                         di->zerr = EPIPE;
 452                         break;
 453                 } else if (rv == 0) {
 454                         /* end of file at a natural breaking point */
 455                         break;
 456                 }
 457
 458                 switch (dr.ddr_type) {
 459                 case DDR_FREE:
 460                         err = write_free_diffs(ofp, di, &dr);
 461                         break;
 462                 case DDR_INUSE:
 463                         err = write_inuse_diffs(ofp, di, &dr);
 464                         break;
 465                 default:
 466                         di->zerr = EPIPE;
 467                         break;
 468                 }
 469
 470                 if (err || di->zerr)
 471                         break;
 472         }
 473
 474         (void) fclose(ofp);
 475         (void) close(di->datafd);
 476         if (err)
 477                 return ((void *)-1);
 478         if (di->zerr) {
 479                 ASSERT(di->zerr == EINVAL);
 480                 (void) snprintf(di->errbuf, sizeof (di->errbuf),
 481                     dgettext(TEXT_DOMAIN,
 482                     "Internal error: bad data from diff IOCTL"));
 483                 return ((void *)-1);
 484         }
 485         return ((void *)0);
 486 }
 487
 488 static int
 489 find_shares_object(differ_info_t *di)
 490 {
 491         char fullpath[MAXPATHLEN];
 492         struct stat64 sb = { 0 };
 493
 494         (void) strlcpy(fullpath, di->dsmnt, MAXPATHLEN);
 495         (void) strlcat(fullpath, ZDIFF_SHARESDIR, MAXPATHLEN);
 496
 497         if (stat64(fullpath, &sb) != 0) {
 498                 (void) snprintf(di->errbuf, sizeof (di->errbuf),
 499                     dgettext(TEXT_DOMAIN, "Cannot stat %s"), fullpath);
 500                 return (zfs_error(di->zhp->zfs_hdl, EZFS_DIFF, di->errbuf));
 501         }
 502
 503         di->shares = (uint64_t)sb.st_ino;
 504         return (0);
 505 }
 506
 507 static int
 508 make_temp_snapshot(differ_info_t *di)
 509 {
 510         libzfs_handle_t *hdl = di->zhp->zfs_hdl;
 511         zfs_cmd_t zc = {"\0"};
 512
 513         (void) snprintf(zc.zc_value, sizeof (zc.zc_value),
 514             ZDIFF_PREFIX, getpid());
 515         (void) strlcpy(zc.zc_name, di->ds, sizeof (zc.zc_name));
 516         zc.zc_cleanup_fd = di->cleanupfd;
 517
 518         if (ioctl(hdl->libzfs_fd, ZFS_IOC_TMP_SNAPSHOT, &zc) != 0) {
 519                 int err = errno;
 520                 if (err == EPERM) {
 521                         (void) snprintf(di->errbuf, sizeof (di->errbuf),
 522                             dgettext(TEXT_DOMAIN, "The diff delegated "
 523                             "permission is needed in order\nto create a "
 524                             "just-in-time snapshot for diffing\n"));
 525                         return (zfs_error(hdl, EZFS_DIFF, di->errbuf));
 526                 } else {
 527                         (void) snprintf(di->errbuf, sizeof (di->errbuf),
 528                             dgettext(TEXT_DOMAIN, "Cannot create just-in-time "
 529                             "snapshot of '%s'"), zc.zc_name);
 530                         return (zfs_standard_error(hdl, err, di->errbuf));
 531                 }
 532         }
 533
 534         di->tmpsnap = zfs_strdup(hdl, zc.zc_value);
 535         di->tosnap = zfs_asprintf(hdl, "%s@%s", di->ds, di->tmpsnap);
 536         return (0);
 537 }
 538
 539 static void
 540 teardown_differ_info(differ_info_t *di)
 541 {
 542         free(di->ds);
 543         free(di->dsmnt);
 544         free(di->fromsnap);
 545         free(di->frommnt);
 546         free(di->tosnap);
 547         free(di->tmpsnap);
 548         free(di->tomnt);
 549         (void) close(di->cleanupfd);
 550 }
 551
 552 static int
 553 get_snapshot_names(differ_info_t *di, const char *fromsnap,
 554     const char *tosnap)
 555 {
 556         libzfs_handle_t *hdl = di->zhp->zfs_hdl;
 557         char *atptrf = NULL;
 558         char *atptrt = NULL;
 559         int fdslen, fsnlen;
 560         int tdslen, tsnlen;
 561
 562         /*
 563          * Can accept
 564          *    dataset@snap1
 565          *    dataset@snap1 dataset@snap2
 566          *    dataset@snap1 @snap2
 567          *    dataset@snap1 dataset
 568          *    @snap1 dataset@snap2
 569          */
 570         if (tosnap == NULL) {
 571                 /* only a from snapshot given, must be valid */
 572                 (void) snprintf(di->errbuf, sizeof (di->errbuf),
 573                     dgettext(TEXT_DOMAIN,
 574                     "Badly formed snapshot name %s"), fromsnap);
 575
 576                 if (!zfs_validate_name(hdl, fromsnap, ZFS_TYPE_SNAPSHOT,
 577                     B_FALSE)) {
 578                         return (zfs_error(hdl, EZFS_INVALIDNAME,
 579                             di->errbuf));
 580                 }
 581
 582                 atptrf = strchr(fromsnap, '@');
 583                 ASSERT(atptrf != NULL);
 584                 fdslen = atptrf - fromsnap;
 585
 586                 di->fromsnap = zfs_strdup(hdl, fromsnap);
 587                 di->ds = zfs_strdup(hdl, fromsnap);
 588                 di->ds[fdslen] = '\0';
 589
 590                 /* the to snap will be a just-in-time snap of the head */
 591                 return (make_temp_snapshot(di));
 592         }
 593
 594         (void) snprintf(di->errbuf, sizeof (di->errbuf),
 595             dgettext(TEXT_DOMAIN,
 596             "Unable to determine which snapshots to compare"));
 597
 598         atptrf = strchr(fromsnap, '@');
 599         atptrt = strchr(tosnap, '@');
 600         fdslen = atptrf ? atptrf - fromsnap : strlen(fromsnap);
 601         tdslen = atptrt ? atptrt - tosnap : strlen(tosnap);
 602         fsnlen = strlen(fromsnap) - fdslen;     /* includes @ sign */
 603         tsnlen = strlen(tosnap) - tdslen;       /* includes @ sign */
 604
 605         if (fsnlen <= 1 || tsnlen == 1 || (fdslen == 0 && tdslen == 0) ||
 606             (fsnlen == 0 && tsnlen == 0)) {
 607                 return (zfs_error(hdl, EZFS_INVALIDNAME, di->errbuf));
 608         } else if ((fdslen > 0 && tdslen > 0) &&
 609             ((tdslen != fdslen || strncmp(fromsnap, tosnap, fdslen) != 0))) {
 610                 /*
 611                  * not the same dataset name, might be okay if
 612                  * tosnap is a clone of a fromsnap descendant.
 613                  */
 614                 char origin[ZFS_MAXNAMELEN];
 615                 zprop_source_t src;
 616                 zfs_handle_t *zhp;
 617
 618                 di->ds = zfs_alloc(di->zhp->zfs_hdl, tdslen + 1);
 619                 (void) strncpy(di->ds, tosnap, tdslen);
 620                 di->ds[tdslen] = '\0';
 621
 622                 zhp = zfs_open(hdl, di->ds, ZFS_TYPE_FILESYSTEM);
 623                 while (zhp != NULL) {
 624                         if (zfs_prop_get(zhp, ZFS_PROP_ORIGIN, origin,
 625                             sizeof (origin), &src, NULL, 0, B_FALSE) != 0) {
 626                                 (void) zfs_close(zhp);
 627                                 zhp = NULL;
 628                                 break;
 629                         }
 630                         if (strncmp(origin, fromsnap, fsnlen) == 0)
 631                                 break;
 632
 633                         (void) zfs_close(zhp);
 634                         zhp = zfs_open(hdl, origin, ZFS_TYPE_FILESYSTEM);
 635                 }
 636
 637                 if (zhp == NULL) {
 638                         (void) snprintf(di->errbuf, sizeof (di->errbuf),
 639                             dgettext(TEXT_DOMAIN,
 640                             "Not an earlier snapshot from the same fs"));
 641                         return (zfs_error(hdl, EZFS_INVALIDNAME, di->errbuf));
 642                 } else {
 643                         (void) zfs_close(zhp);
 644                 }
 645
 646                 di->isclone = B_TRUE;
 647                 di->fromsnap = zfs_strdup(hdl, fromsnap);
 648                 if (tsnlen) {
 649                         di->tosnap = zfs_strdup(hdl, tosnap);
 650                 } else {
 651                         return (make_temp_snapshot(di));
 652                 }
 653         } else {
 654                 int dslen = fdslen ? fdslen : tdslen;
 655
 656                 di->ds = zfs_alloc(hdl, dslen + 1);
 657                 (void) strncpy(di->ds, fdslen ? fromsnap : tosnap, dslen);
 658                 di->ds[dslen] = '\0';
 659
 660                 di->fromsnap = zfs_asprintf(hdl, "%s%s", di->ds, atptrf);
 661                 if (tsnlen) {
 662                         di->tosnap = zfs_asprintf(hdl, "%s%s", di->ds, atptrt);
 663                 } else {
 664                         return (make_temp_snapshot(di));
 665                 }
 666         }
 667         return (0);
 668 }
 669
 670 static int
 671 get_mountpoint(differ_info_t *di, char *dsnm, char **mntpt)
 672 {
 673         boolean_t mounted;
 674
 675         mounted = is_mounted(di->zhp->zfs_hdl, dsnm, mntpt);
 676         if (mounted == B_FALSE) {
 677                 (void) snprintf(di->errbuf, sizeof (di->errbuf),
 678                     dgettext(TEXT_DOMAIN,
 679                     "Cannot diff an unmounted snapshot"));
 680                 return (zfs_error(di->zhp->zfs_hdl, EZFS_BADTYPE, di->errbuf));
 681         }
 682
 683         /* Avoid a double slash at the beginning of root-mounted datasets */
 684         if (**mntpt == '/' && *(*mntpt + 1) == '\0')
 685                 **mntpt = '\0';
 686         return (0);
 687 }
 688
 689 static int
 690 get_mountpoints(differ_info_t *di)
 691 {
 692         char *strptr;
 693         char *frommntpt;
 694
 695         /*
 696          * first get the mountpoint for the parent dataset
 697          */
 698         if (get_mountpoint(di, di->ds, &di->dsmnt) != 0)
 699                 return (-1);
 700
 701         strptr = strchr(di->tosnap, '@');
 702         ASSERT3P(strptr, !=, NULL);
 703         di->tomnt = zfs_asprintf(di->zhp->zfs_hdl, "%s%s%s", di->dsmnt,
 704             ZDIFF_SNAPDIR, ++strptr);
 705
 706         strptr = strchr(di->fromsnap, '@');
 707         ASSERT3P(strptr, !=, NULL);
 708
 709         frommntpt = di->dsmnt;
 710         if (di->isclone) {
 711                 char *mntpt;
 712                 int err;
 713
 714                 *strptr = '\0';
 715                 err = get_mountpoint(di, di->fromsnap, &mntpt);
 716                 *strptr = '@';
 717                 if (err != 0)
 718                         return (-1);
 719                 frommntpt = mntpt;
 720         }
 721
 722         di->frommnt = zfs_asprintf(di->zhp->zfs_hdl, "%s%s%s", frommntpt,
 723             ZDIFF_SNAPDIR, ++strptr);
 724
 725         if (di->isclone)
 726                 free(frommntpt);
 727
 728         return (0);
 729 }
 730
 731 static int
 732 setup_differ_info(zfs_handle_t *zhp, const char *fromsnap,
 733     const char *tosnap, differ_info_t *di)
 734 {
 735         di->zhp = zhp;
 736
 737         di->cleanupfd = open(ZFS_DEV, O_RDWR);
 738         VERIFY(di->cleanupfd >= 0);
 739
 740         if (get_snapshot_names(di, fromsnap, tosnap) != 0)
 741                 return (-1);
 742
 743         if (get_mountpoints(di) != 0)
 744                 return (-1);
 745
 746         if (find_shares_object(di) != 0)
 747                 return (-1);
 748
 749         return (0);
 750 }
 751
 752 int
 753 zfs_show_diffs(zfs_handle_t *zhp, int outfd, const char *fromsnap,
 754     const char *tosnap, int flags)
 755 {
 756         zfs_cmd_t zc = {"\0"};
 757         char errbuf[1024];
 758         differ_info_t di = { 0 };
 759         pthread_t tid;
 760         int pipefd[2];
 761         int iocerr;
 762
 763         (void) snprintf(errbuf, sizeof (errbuf),
 764             dgettext(TEXT_DOMAIN, "zfs diff failed"));
 765
 766         if (setup_differ_info(zhp, fromsnap, tosnap, &di)) {
 767                 teardown_differ_info(&di);
 768                 return (-1);
 769         }
 770
 771         if (pipe(pipefd)) {
 772                 zfs_error_aux(zhp->zfs_hdl, strerror(errno));
 773                 teardown_differ_info(&di);
 774                 return (zfs_error(zhp->zfs_hdl, EZFS_PIPEFAILED, errbuf));
 775         }
 776
 777         di.scripted = (flags & ZFS_DIFF_PARSEABLE);
 778         di.classify = (flags & ZFS_DIFF_CLASSIFY);
 779         di.timestamped = (flags & ZFS_DIFF_TIMESTAMP);
 780
 781         di.outputfd = outfd;
 782         di.datafd = pipefd[0];
 783
 784         if (pthread_create(&tid, NULL, differ, &di)) {
 785                 zfs_error_aux(zhp->zfs_hdl, strerror(errno));
 786                 (void) close(pipefd[0]);
 787                 (void) close(pipefd[1]);
 788                 teardown_differ_info(&di);
 789                 return (zfs_error(zhp->zfs_hdl,
 790                     EZFS_THREADCREATEFAILED, errbuf));
 791         }
 792
 793         /* do the ioctl() */
 794         (void) strlcpy(zc.zc_value, di.fromsnap, strlen(di.fromsnap) + 1);
 795         (void) strlcpy(zc.zc_name, di.tosnap, strlen(di.tosnap) + 1);
 796         zc.zc_cookie = pipefd[1];
 797
 798         iocerr = ioctl(zhp->zfs_hdl->libzfs_fd, ZFS_IOC_DIFF, &zc);
 799         if (iocerr != 0) {
 800                 (void) snprintf(errbuf, sizeof (errbuf),
 801                     dgettext(TEXT_DOMAIN, "Unable to obtain diffs"));
 802                 if (errno == EPERM) {
 803                         zfs_error_aux(zhp->zfs_hdl, dgettext(TEXT_DOMAIN,
 804                             "\n   The sys_mount privilege or diff delegated "
 805                             "permission is needed\n   to execute the "
 806                             "diff ioctl"));
 807                 } else if (errno == EXDEV) {
 808                         zfs_error_aux(zhp->zfs_hdl, dgettext(TEXT_DOMAIN,
 809                             "\n   Not an earlier snapshot from the same fs"));
 810                 } else if (errno != EPIPE || di.zerr == 0) {
 811                         zfs_error_aux(zhp->zfs_hdl, strerror(errno));
 812                 }
 813                 (void) close(pipefd[1]);
 814                 (void) pthread_cancel(tid);
 815                 (void) pthread_join(tid, NULL);
 816                 teardown_differ_info(&di);
 817                 if (di.zerr != 0 && di.zerr != EPIPE) {
 818                         zfs_error_aux(zhp->zfs_hdl, strerror(di.zerr));
 819                         return (zfs_error(zhp->zfs_hdl, EZFS_DIFF, di.errbuf));
 820                 } else {
 821                         return (zfs_error(zhp->zfs_hdl, EZFS_DIFFDATA, errbuf));
 822                 }
 823         }
 824
 825         (void) close(pipefd[1]);
 826         (void) pthread_join(tid, NULL);
 827
 828         if (di.zerr != 0) {
 829                 zfs_error_aux(zhp->zfs_hdl, strerror(di.zerr));
 830                 return (zfs_error(zhp->zfs_hdl, EZFS_DIFF, di.errbuf));
 831         }
 832         teardown_differ_info(&di);
 833         return (0);
 834 }