usr/src/lib/libzfs/common/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  * Copyright (c) 2015, 2017 by Delphix. All rights reserved.
  26  * Copyright 2016 Joyent, Inc.
  27  * Copyright 2016 Igor Kozhukhov <ikozhukhov@gmail.com>
  28  */
  29
  30 /*
  31  * zfs diff support
  32  */
  33 #include <ctype.h>
  34 #include <errno.h>
  35 #include <libintl.h>
  36 #include <string.h>
  37 #include <sys/types.h>
  38 #include <sys/stat.h>
  39 #include <fcntl.h>
  40 #include <attr.h>
  41 #include <stddef.h>
  42 #include <unistd.h>
  43 #include <stdio.h>
  44 #include <stdlib.h>
  45 #include <stropts.h>
  46 #include <pthread.h>
  47 #include <sys/zfs_ioctl.h>
  48 #include <libzfs.h>
  49 #include "libzfs_impl.h"
  50
  51 #define ZDIFF_SNAPDIR           "/.zfs/snapshot/"
  52 #define ZDIFF_SHARESDIR         "/.zfs/shares/"
  53 #define ZDIFF_PREFIX            "zfs-diff-%d"
  54
  55 #define ZDIFF_ADDED     '+'
  56 #define ZDIFF_MODIFIED  'M'
  57 #define ZDIFF_REMOVED   '-'
  58 #define ZDIFF_RENAMED   'R'
  59
  60 typedef struct differ_info {
  61         zfs_handle_t *zhp;
  62         char *fromsnap;
  63         char *frommnt;
  64         char *tosnap;
  65         char *tomnt;
  66         char *ds;
  67         char *dsmnt;
  68         char *tmpsnap;
  69         char errbuf[1024];
  70         boolean_t isclone;
  71         boolean_t scripted;
  72         boolean_t classify;
  73         boolean_t timestamped;
  74         uint64_t shares;
  75         int zerr;
  76         int cleanupfd;
  77         int outputfd;
  78         int datafd;
  79 } differ_info_t;
  80
  81 /*
  82  * Given a {dsname, object id}, get the object path
  83  */
  84 static int
  85 get_stats_for_obj(differ_info_t *di, const char *dsname, uint64_t obj,
  86     char *pn, int maxlen, zfs_stat_t *sb)
  87 {
  88         zfs_cmd_t zc = { 0 };
  89         int error;
  90
  91         (void) strlcpy(zc.zc_name, dsname, sizeof (zc.zc_name));
  92         zc.zc_obj = obj;
  93
  94         errno = 0;
  95         error = ioctl(di->zhp->zfs_hdl->libzfs_fd, ZFS_IOC_OBJ_TO_STATS, &zc);
  96         di->zerr = errno;
  97
  98         /* we can get stats even if we failed to get a path */
  99         (void) memcpy(sb, &zc.zc_stat, sizeof (zfs_stat_t));
 100         if (error == 0) {
 101                 ASSERT(di->zerr == 0);
 102                 (void) strlcpy(pn, zc.zc_value, maxlen);
 103                 return (0);
 104         }
 105
 106         if (di->zerr == ESTALE) {
 107                 (void) snprintf(pn, maxlen, "(on_delete_queue)");
 108                 return (0);
 109         } else if (di->zerr == EPERM) {
 110                 (void) snprintf(di->errbuf, sizeof (di->errbuf),
 111                     dgettext(TEXT_DOMAIN,
 112                     "The sys_config privilege or diff delegated permission "
 113                     "is needed\nto discover path names"));
 114                 return (-1);
 115         } else {
 116                 (void) snprintf(di->errbuf, sizeof (di->errbuf),
 117                     dgettext(TEXT_DOMAIN,
 118                     "Unable to determine path or stats for "
 119                     "object %lld in %s"), obj, dsname);
 120                 return (-1);
 121         }
 122 }
 123
 124 /*
 125  * stream_bytes
 126  *
 127  * Prints a file name out a character at a time.  If the character is
 128  * not in the range of what we consider "printable" ASCII, display it
 129  * as an escaped 3-digit octal value.  ASCII values less than a space
 130  * are all control characters and we declare the upper end as the
 131  * DELete character.  This also is the last 7-bit ASCII character.
 132  * We choose to treat all 8-bit ASCII as not printable for this
 133  * application.
 134  */
 135 static void
 136 stream_bytes(FILE *fp, const char *string)
 137 {
 138         char c;
 139
 140         while ((c = *string++) != '\0') {
 141                 if (c > ' ' && c != '\\' && c < '\177') {
 142                         (void) fprintf(fp, "%c", c);
 143                 } else {
 144                         (void) fprintf(fp, "\\%03o", (uint8_t)c);
 145                 }
 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         case S_IFDOOR:
 165                 symbol = '>';
 166                 break;
 167         case S_IFIFO:
 168                 symbol = '|';
 169                 break;
 170         case S_IFLNK:
 171                 symbol = '@';
 172                 break;
 173         case S_IFPORT:
 174                 symbol = 'P';
 175                 break;
 176         case S_IFSOCK:
 177                 symbol = '=';
 178                 break;
 179         case S_IFREG:
 180                 symbol = 'F';
 181                 break;
 182         default:
 183                 symbol = '?';
 184                 break;
 185         }
 186         (void) fprintf(fp, "%c", symbol);
 187 }
 188
 189 static void
 190 print_cmn(FILE *fp, differ_info_t *di, const char *file)
 191 {
 192         stream_bytes(fp, di->dsmnt);
 193         stream_bytes(fp, file);
 194 }
 195
 196 static void
 197 print_rename(FILE *fp, differ_info_t *di, const char *old, const char *new,
 198     zfs_stat_t *isb)
 199 {
 200         if (di->timestamped)
 201                 (void) fprintf(fp, "%10lld.%09lld\t",
 202                     (longlong_t)isb->zs_ctime[0],
 203                     (longlong_t)isb->zs_ctime[1]);
 204         (void) fprintf(fp, "%c\t", ZDIFF_RENAMED);
 205         if (di->classify) {
 206                 print_what(fp, isb->zs_mode);
 207                 (void) fprintf(fp, "\t");
 208         }
 209         print_cmn(fp, di, old);
 210         if (di->scripted)
 211                 (void) fprintf(fp, "\t");
 212         else
 213                 (void) fprintf(fp, " -> ");
 214         print_cmn(fp, di, new);
 215         (void) fprintf(fp, "\n");
 216 }
 217
 218 static void
 219 print_link_change(FILE *fp, differ_info_t *di, int delta, const char *file,
 220     zfs_stat_t *isb)
 221 {
 222         if (di->timestamped)
 223                 (void) fprintf(fp, "%10lld.%09lld\t",
 224                     (longlong_t)isb->zs_ctime[0],
 225                     (longlong_t)isb->zs_ctime[1]);
 226         (void) fprintf(fp, "%c\t", ZDIFF_MODIFIED);
 227         if (di->classify) {
 228                 print_what(fp, isb->zs_mode);
 229                 (void) fprintf(fp, "\t");
 230         }
 231         print_cmn(fp, di, file);
 232         (void) fprintf(fp, "\t(%+d)", delta);
 233         (void) fprintf(fp, "\n");
 234 }
 235
 236 static void
 237 print_file(FILE *fp, differ_info_t *di, char type, const char *file,
 238     zfs_stat_t *isb)
 239 {
 240         if (di->timestamped)
 241                 (void) fprintf(fp, "%10lld.%09lld\t",
 242                     (longlong_t)isb->zs_ctime[0],
 243                     (longlong_t)isb->zs_ctime[1]);
 244         (void) fprintf(fp, "%c\t", type);
 245         if (di->classify) {
 246                 print_what(fp, isb->zs_mode);
 247                 (void) fprintf(fp, "\t");
 248         }
 249         print_cmn(fp, di, file);
 250         (void) fprintf(fp, "\n");
 251 }
 252
 253 static int
 254 write_inuse_diffs_one(FILE *fp, differ_info_t *di, uint64_t dobj)
 255 {
 256         struct zfs_stat fsb, tsb;
 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
 318         /* Simple modification or no change */
 319         if (fsb.zs_gen == tsb.zs_gen) {
 320                 /* No apparent changes.  Could we assert !this?  */
 321                 if (fsb.zs_ctime[0] == tsb.zs_ctime[0] &&
 322                     fsb.zs_ctime[1] == tsb.zs_ctime[1])
 323                         return (0);
 324                 if (change) {
 325                         print_link_change(fp, di, change,
 326                             change > 0 ? fobjname : tobjname, &tsb);
 327                 } else if (strcmp(fobjname, tobjname) == 0) {
 328                         print_file(fp, di, ZDIFF_MODIFIED, fobjname, &tsb);
 329                 } else {
 330                         print_rename(fp, di, fobjname, tobjname, &tsb);
 331                 }
 332                 return (0);
 333         } else {
 334                 /* file re-created or object re-used */
 335                 print_file(fp, di, ZDIFF_REMOVED, fobjname, &fsb);
 336                 print_file(fp, di, ZDIFF_ADDED, tobjname, &tsb);
 337                 return (0);
 338         }
 339 }
 340
 341 static int
 342 write_inuse_diffs(FILE *fp, differ_info_t *di, dmu_diff_record_t *dr)
 343 {
 344         uint64_t o;
 345         int err;
 346
 347         for (o = dr->ddr_first; o <= dr->ddr_last; o++) {
 348                 if ((err = write_inuse_diffs_one(fp, di, o)) != 0)
 349                         return (err);
 350         }
 351         return (0);
 352 }
 353
 354 static int
 355 describe_free(FILE *fp, differ_info_t *di, uint64_t object, char *namebuf,
 356     int maxlen)
 357 {
 358         struct zfs_stat sb;
 359
 360         if (get_stats_for_obj(di, di->fromsnap, object, namebuf,
 361             maxlen, &sb) != 0) {
 362                 /* Let it slide, if in the delete queue on from side */
 363                 if (di->zerr == ENOENT && sb.zs_links == 0) {
 364                         di->zerr = 0;
 365                         return (0);
 366                 }
 367                 return (-1);
 368         }
 369
 370         print_file(fp, di, ZDIFF_REMOVED, namebuf, &sb);
 371         return (0);
 372 }
 373
 374 static int
 375 write_free_diffs(FILE *fp, differ_info_t *di, dmu_diff_record_t *dr)
 376 {
 377         zfs_cmd_t zc = { 0 };
 378         libzfs_handle_t *lhdl = di->zhp->zfs_hdl;
 379         char fobjname[MAXPATHLEN];
 380
 381         (void) strlcpy(zc.zc_name, di->fromsnap, sizeof (zc.zc_name));
 382         zc.zc_obj = dr->ddr_first - 1;
 383
 384         ASSERT(di->zerr == 0);
 385
 386         while (zc.zc_obj < dr->ddr_last) {
 387                 int err;
 388
 389                 err = ioctl(lhdl->libzfs_fd, ZFS_IOC_NEXT_OBJ, &zc);
 390                 if (err == 0) {
 391                         if (zc.zc_obj == di->shares) {
 392                                 zc.zc_obj++;
 393                                 continue;
 394                         }
 395                         if (zc.zc_obj > dr->ddr_last) {
 396                                 break;
 397                         }
 398                         err = describe_free(fp, di, zc.zc_obj, fobjname,
 399                             MAXPATHLEN);
 400                         if (err)
 401                                 break;
 402                 } else if (errno == ESRCH) {
 403                         break;
 404                 } else {
 405                         (void) snprintf(di->errbuf, sizeof (di->errbuf),
 406                             dgettext(TEXT_DOMAIN,
 407                             "next allocated object (> %lld) find failure"),
 408                             zc.zc_obj);
 409                         di->zerr = errno;
 410                         break;
 411                 }
 412         }
 413         if (di->zerr)
 414                 return (-1);
 415         return (0);
 416 }
 417
 418 static void *
 419 differ(void *arg)
 420 {
 421         differ_info_t *di = arg;
 422         dmu_diff_record_t dr;
 423         FILE *ofp;
 424         int err = 0;
 425
 426         if ((ofp = fdopen(di->outputfd, "w")) == NULL) {
 427                 di->zerr = errno;
 428                 (void) strerror_r(errno, di->errbuf, sizeof (di->errbuf));
 429                 (void) close(di->datafd);
 430                 return ((void *)-1);
 431         }
 432
 433         for (;;) {
 434                 char *cp = (char *)&dr;
 435                 int len = sizeof (dr);
 436                 int rv;
 437
 438                 do {
 439                         rv = read(di->datafd, cp, len);
 440                         cp += rv;
 441                         len -= rv;
 442                 } while (len > 0 && rv > 0);
 443
 444                 if (rv < 0 || (rv == 0 && len != sizeof (dr))) {
 445                         di->zerr = EPIPE;
 446                         break;
 447                 } else if (rv == 0) {
 448                         /* end of file at a natural breaking point */
 449                         break;
 450                 }
 451
 452                 switch (dr.ddr_type) {
 453                 case DDR_FREE:
 454                         err = write_free_diffs(ofp, di, &dr);
 455                         break;
 456                 case DDR_INUSE:
 457                         err = write_inuse_diffs(ofp, di, &dr);
 458                         break;
 459                 default:
 460                         di->zerr = EPIPE;
 461                         break;
 462                 }
 463
 464                 if (err || di->zerr)
 465                         break;
 466         }
 467
 468         (void) fclose(ofp);
 469         (void) close(di->datafd);
 470         if (err)
 471                 return ((void *)-1);
 472         if (di->zerr) {
 473                 ASSERT(di->zerr == EINVAL);
 474                 (void) snprintf(di->errbuf, sizeof (di->errbuf),
 475                     dgettext(TEXT_DOMAIN,
 476                     "Internal error: bad data from diff IOCTL"));
 477                 return ((void *)-1);
 478         }
 479         return ((void *)0);
 480 }
 481
 482 static int
 483 find_shares_object(differ_info_t *di)
 484 {
 485         char fullpath[MAXPATHLEN];
 486         struct stat64 sb = { 0 };
 487
 488         (void) strlcpy(fullpath, di->dsmnt, MAXPATHLEN);
 489         (void) strlcat(fullpath, ZDIFF_SHARESDIR, MAXPATHLEN);
 490
 491         if (stat64(fullpath, &sb) != 0) {
 492                 (void) snprintf(di->errbuf, sizeof (di->errbuf),
 493                     dgettext(TEXT_DOMAIN, "Cannot stat %s"), fullpath);
 494                 return (zfs_error(di->zhp->zfs_hdl, EZFS_DIFF, di->errbuf));
 495         }
 496
 497         di->shares = (uint64_t)sb.st_ino;
 498         return (0);
 499 }
 500
 501 static int
 502 make_temp_snapshot(differ_info_t *di)
 503 {
 504         libzfs_handle_t *hdl = di->zhp->zfs_hdl;
 505         zfs_cmd_t zc = { 0 };
 506
 507         (void) snprintf(zc.zc_value, sizeof (zc.zc_value),
 508             ZDIFF_PREFIX, getpid());
 509         (void) strlcpy(zc.zc_name, di->ds, sizeof (zc.zc_name));
 510         zc.zc_cleanup_fd = di->cleanupfd;
 511
 512         if (ioctl(hdl->libzfs_fd, ZFS_IOC_TMP_SNAPSHOT, &zc) != 0) {
 513                 int err = errno;
 514                 if (err == EPERM) {
 515                         (void) snprintf(di->errbuf, sizeof (di->errbuf),
 516                             dgettext(TEXT_DOMAIN, "The diff delegated "
 517                             "permission is needed in order\nto create a "
 518                             "just-in-time snapshot for diffing\n"));
 519                         return (zfs_error(hdl, EZFS_DIFF, di->errbuf));
 520                 } else {
 521                         (void) snprintf(di->errbuf, sizeof (di->errbuf),
 522                             dgettext(TEXT_DOMAIN, "Cannot create just-in-time "
 523                             "snapshot of '%s'"), zc.zc_name);
 524                         return (zfs_standard_error(hdl, err, di->errbuf));
 525                 }
 526         }
 527
 528         di->tmpsnap = zfs_strdup(hdl, zc.zc_value);
 529         di->tosnap = zfs_asprintf(hdl, "%s@%s", di->ds, di->tmpsnap);
 530         return (0);
 531 }
 532
 533 static void
 534 teardown_differ_info(differ_info_t *di)
 535 {
 536         free(di->ds);
 537         free(di->dsmnt);
 538         free(di->fromsnap);
 539         free(di->frommnt);
 540         free(di->tosnap);
 541         free(di->tmpsnap);
 542         free(di->tomnt);
 543         (void) close(di->cleanupfd);
 544 }
 545
 546 static int
 547 get_snapshot_names(differ_info_t *di, const char *fromsnap,
 548     const char *tosnap)
 549 {
 550         libzfs_handle_t *hdl = di->zhp->zfs_hdl;
 551         char *atptrf = NULL;
 552         char *atptrt = NULL;
 553         int fdslen, fsnlen;
 554         int tdslen, tsnlen;
 555
 556         /*
 557          * Can accept
 558          *    dataset@snap1
 559          *    dataset@snap1 dataset@snap2
 560          *    dataset@snap1 @snap2
 561          *    dataset@snap1 dataset
 562          *    @snap1 dataset@snap2
 563          */
 564         if (tosnap == NULL) {
 565                 /* only a from snapshot given, must be valid */
 566                 (void) snprintf(di->errbuf, sizeof (di->errbuf),
 567                     dgettext(TEXT_DOMAIN,
 568                     "Badly formed snapshot name %s"), fromsnap);
 569
 570                 if (!zfs_validate_name(hdl, fromsnap, ZFS_TYPE_SNAPSHOT,
 571                     B_FALSE)) {
 572                         return (zfs_error(hdl, EZFS_INVALIDNAME,
 573                             di->errbuf));
 574                 }
 575
 576                 atptrf = strchr(fromsnap, '@');
 577                 ASSERT(atptrf != NULL);
 578                 fdslen = atptrf - fromsnap;
 579
 580                 di->fromsnap = zfs_strdup(hdl, fromsnap);
 581                 di->ds = zfs_strdup(hdl, fromsnap);
 582                 di->ds[fdslen] = '\0';
 583
 584                 /* the to snap will be a just-in-time snap of the head */
 585                 return (make_temp_snapshot(di));
 586         }
 587
 588         (void) snprintf(di->errbuf, sizeof (di->errbuf),
 589             dgettext(TEXT_DOMAIN,
 590             "Unable to determine which snapshots to compare"));
 591
 592         atptrf = strchr(fromsnap, '@');
 593         atptrt = strchr(tosnap, '@');
 594         fdslen = atptrf ? atptrf - fromsnap : strlen(fromsnap);
 595         tdslen = atptrt ? atptrt - tosnap : strlen(tosnap);
 596         fsnlen = strlen(fromsnap) - fdslen;     /* includes @ sign */
 597         tsnlen = strlen(tosnap) - tdslen;       /* includes @ sign */
 598
 599         if (fsnlen <= 1 || tsnlen == 1 || (fdslen == 0 && tdslen == 0) ||
 600             (fsnlen == 0 && tsnlen == 0)) {
 601                 return (zfs_error(hdl, EZFS_INVALIDNAME, di->errbuf));
 602         } else if ((fdslen > 0 && tdslen > 0) &&
 603             ((tdslen != fdslen || strncmp(fromsnap, tosnap, fdslen) != 0))) {
 604                 /*
 605                  * not the same dataset name, might be okay if
 606                  * tosnap is a clone of a fromsnap descendant.
 607                  */
 608                 char origin[ZFS_MAX_DATASET_NAME_LEN];
 609                 zprop_source_t src;
 610                 zfs_handle_t *zhp;
 611
 612                 di->ds = zfs_alloc(di->zhp->zfs_hdl, tdslen + 1);
 613                 (void) strncpy(di->ds, tosnap, tdslen);
 614                 di->ds[tdslen] = '\0';
 615
 616                 zhp = zfs_open(hdl, di->ds, ZFS_TYPE_FILESYSTEM);
 617                 while (zhp != NULL) {
 618                         if (zfs_prop_get(zhp, ZFS_PROP_ORIGIN, origin,
 619                             sizeof (origin), &src, NULL, 0, B_FALSE) != 0) {
 620                                 (void) zfs_close(zhp);
 621                                 zhp = NULL;
 622                                 break;
 623                         }
 624                         if (strncmp(origin, fromsnap, fsnlen) == 0)
 625                                 break;
 626
 627                         (void) zfs_close(zhp);
 628                         zhp = zfs_open(hdl, origin, ZFS_TYPE_FILESYSTEM);
 629                 }
 630
 631                 if (zhp == NULL) {
 632                         (void) snprintf(di->errbuf, sizeof (di->errbuf),
 633                             dgettext(TEXT_DOMAIN,
 634                             "Not an earlier snapshot from the same fs"));
 635                         return (zfs_error(hdl, EZFS_INVALIDNAME, di->errbuf));
 636                 } else {
 637                         (void) zfs_close(zhp);
 638                 }
 639
 640                 di->isclone = B_TRUE;
 641                 di->fromsnap = zfs_strdup(hdl, fromsnap);
 642                 if (tsnlen) {
 643                         di->tosnap = zfs_strdup(hdl, tosnap);
 644                 } else {
 645                         return (make_temp_snapshot(di));
 646                 }
 647         } else {
 648                 int dslen = fdslen ? fdslen : tdslen;
 649
 650                 di->ds = zfs_alloc(hdl, dslen + 1);
 651                 (void) strncpy(di->ds, fdslen ? fromsnap : tosnap, dslen);
 652                 di->ds[dslen] = '\0';
 653
 654                 di->fromsnap = zfs_asprintf(hdl, "%s%s", di->ds, atptrf);
 655                 if (tsnlen) {
 656                         di->tosnap = zfs_asprintf(hdl, "%s%s", di->ds, atptrt);
 657                 } else {
 658                         return (make_temp_snapshot(di));
 659                 }
 660         }
 661         return (0);
 662 }
 663
 664 static int
 665 get_mountpoint(differ_info_t *di, char *dsnm, char **mntpt)
 666 {
 667         boolean_t mounted;
 668
 669         mounted = is_mounted(di->zhp->zfs_hdl, dsnm, mntpt);
 670         if (mounted == B_FALSE) {
 671                 (void) snprintf(di->errbuf, sizeof (di->errbuf),
 672                     dgettext(TEXT_DOMAIN,
 673                     "Cannot diff an unmounted snapshot"));
 674                 return (zfs_error(di->zhp->zfs_hdl, EZFS_BADTYPE, di->errbuf));
 675         }
 676
 677         /* Avoid a double slash at the beginning of root-mounted datasets */
 678         if (**mntpt == '/' && *(*mntpt + 1) == '\0')
 679                 **mntpt = '\0';
 680         return (0);
 681 }
 682
 683 static int
 684 get_mountpoints(differ_info_t *di)
 685 {
 686         char *strptr;
 687         char *frommntpt;
 688
 689         /*
 690          * first get the mountpoint for the parent dataset
 691          */
 692         if (get_mountpoint(di, di->ds, &di->dsmnt) != 0)
 693                 return (-1);
 694
 695         strptr = strchr(di->tosnap, '@');
 696         ASSERT3P(strptr, !=, NULL);
 697         di->tomnt = zfs_asprintf(di->zhp->zfs_hdl, "%s%s%s", di->dsmnt,
 698             ZDIFF_SNAPDIR, ++strptr);
 699
 700         strptr = strchr(di->fromsnap, '@');
 701         ASSERT3P(strptr, !=, NULL);
 702
 703         frommntpt = di->dsmnt;
 704         if (di->isclone) {
 705                 char *mntpt;
 706                 int err;
 707
 708                 *strptr = '\0';
 709                 err = get_mountpoint(di, di->fromsnap, &mntpt);
 710                 *strptr = '@';
 711                 if (err != 0)
 712                         return (-1);
 713                 frommntpt = mntpt;
 714         }
 715
 716         di->frommnt = zfs_asprintf(di->zhp->zfs_hdl, "%s%s%s", frommntpt,
 717             ZDIFF_SNAPDIR, ++strptr);
 718
 719         if (di->isclone)
 720                 free(frommntpt);
 721
 722         return (0);
 723 }
 724
 725 static int
 726 setup_differ_info(zfs_handle_t *zhp, const char *fromsnap,
 727     const char *tosnap, differ_info_t *di)
 728 {
 729         di->zhp = zhp;
 730
 731         di->cleanupfd = open(ZFS_DEV, O_RDWR|O_EXCL);
 732         VERIFY(di->cleanupfd >= 0);
 733
 734         if (get_snapshot_names(di, fromsnap, tosnap) != 0)
 735                 return (-1);
 736
 737         if (get_mountpoints(di) != 0)
 738                 return (-1);
 739
 740         if (find_shares_object(di) != 0)
 741                 return (-1);
 742
 743         return (0);
 744 }
 745
 746 int
 747 zfs_show_diffs(zfs_handle_t *zhp, int outfd, const char *fromsnap,
 748     const char *tosnap, int flags)
 749 {
 750         zfs_cmd_t zc = { 0 };
 751         char errbuf[1024];
 752         differ_info_t di = { 0 };
 753         pthread_t tid;
 754         int pipefd[2];
 755         int iocerr;
 756
 757         (void) snprintf(errbuf, sizeof (errbuf),
 758             dgettext(TEXT_DOMAIN, "zfs diff failed"));
 759
 760         if (setup_differ_info(zhp, fromsnap, tosnap, &di)) {
 761                 teardown_differ_info(&di);
 762                 return (-1);
 763         }
 764
 765         if (pipe(pipefd)) {
 766                 zfs_error_aux(zhp->zfs_hdl, strerror(errno));
 767                 teardown_differ_info(&di);
 768                 return (zfs_error(zhp->zfs_hdl, EZFS_PIPEFAILED, errbuf));
 769         }
 770
 771         di.scripted = (flags & ZFS_DIFF_PARSEABLE);
 772         di.classify = (flags & ZFS_DIFF_CLASSIFY);
 773         di.timestamped = (flags & ZFS_DIFF_TIMESTAMP);
 774
 775         di.outputfd = outfd;
 776         di.datafd = pipefd[0];
 777
 778         if (pthread_create(&tid, NULL, differ, &di)) {
 779                 zfs_error_aux(zhp->zfs_hdl, strerror(errno));
 780                 (void) close(pipefd[0]);
 781                 (void) close(pipefd[1]);
 782                 teardown_differ_info(&di);
 783                 return (zfs_error(zhp->zfs_hdl,
 784                     EZFS_THREADCREATEFAILED, errbuf));
 785         }
 786
 787         /* do the ioctl() */
 788         (void) strlcpy(zc.zc_value, di.fromsnap, strlen(di.fromsnap) + 1);
 789         (void) strlcpy(zc.zc_name, di.tosnap, strlen(di.tosnap) + 1);
 790         zc.zc_cookie = pipefd[1];
 791
 792         iocerr = ioctl(zhp->zfs_hdl->libzfs_fd, ZFS_IOC_DIFF, &zc);
 793         if (iocerr != 0) {
 794                 (void) snprintf(errbuf, sizeof (errbuf),
 795                     dgettext(TEXT_DOMAIN, "Unable to obtain diffs"));
 796                 if (errno == EPERM) {
 797                         zfs_error_aux(zhp->zfs_hdl, dgettext(TEXT_DOMAIN,
 798                             "\n   The sys_mount privilege or diff delegated "
 799                             "permission is needed\n   to execute the "
 800                             "diff ioctl"));
 801                 } else if (errno == EXDEV) {
 802                         zfs_error_aux(zhp->zfs_hdl, dgettext(TEXT_DOMAIN,
 803                             "\n   Not an earlier snapshot from the same fs"));
 804                 } else if (errno != EPIPE || di.zerr == 0) {
 805                         zfs_error_aux(zhp->zfs_hdl, strerror(errno));
 806                 }
 807                 (void) close(pipefd[1]);
 808                 (void) pthread_cancel(tid);
 809                 (void) pthread_join(tid, NULL);
 810                 teardown_differ_info(&di);
 811                 if (di.zerr != 0 && di.zerr != EPIPE) {
 812                         zfs_error_aux(zhp->zfs_hdl, strerror(di.zerr));
 813                         return (zfs_error(zhp->zfs_hdl, EZFS_DIFF, di.errbuf));
 814                 } else {
 815                         return (zfs_error(zhp->zfs_hdl, EZFS_DIFFDATA, errbuf));
 816                 }
 817         }
 818
 819         (void) close(pipefd[1]);
 820         (void) pthread_join(tid, NULL);
 821
 822         if (di.zerr != 0) {
 823                 zfs_error_aux(zhp->zfs_hdl, strerror(di.zerr));
 824                 return (zfs_error(zhp->zfs_hdl, EZFS_DIFF, di.errbuf));
 825         }
 826         teardown_differ_info(&di);
 827         return (0);
 828 }