root/source3/modules/onefs_shadow_copy.c

/* [<][>][^][v][top][bottom][index][help] */

DEFINITIONS

This source file includes following definitions.
  1. osc_get_names_directory_fd
  2. osc_time_compare
  3. osc_timespec_compare
  4. osc_timespec_is_zero
  5. osc_snapshot_create
  6. osc_snapshot_destroy
  7. osc_snapshot_destroy_list
  8. osc_snapshot_compare
  9. osc_snapshot_insert
  10. osc_process_snapshot
  11. osc_process_snapshot_directory
  12. osc_snapshot_ctx_init
  13. osc_snapshot_ctx_clean
  14. osc_get_snapshot_ctx
  15. osc_snapshot_ctx_is_valid
  16. osc_directory_ctx_create
  17. osc_directory_ctx_destroy
  18. osc_directory_ctx_expand_version_list
  19. osc_directory_ctx_append_version
  20. osc_make_directory_ctx
  21. osc_version_opendir
  22. osc_version_readdir
  23. osc_version_closedir
  24. osc_canonicalize_path

   1 /*
   2  * Unix SMB/CIFS implementation.
   3  *
   4  * OneFS shadow copy implementation that utilizes the file system's native
   5  * snapshot support. This file does all of the heavy lifting.
   6  *
   7  * Copyright (C) Dave Richards, 2007
   8  * Copyright (C) Tim Prouty, 2009
   9  *
  10  * This program is free software; you can redistribute it and/or modify
  11  * it under the terms of the GNU General Public License as published by
  12  * the Free Software Foundation; either version 3 of the License, or
  13  * (at your option) any later version.
  14  *
  15  * This program is distributed in the hope that it will be useful,
  16  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  17  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  18  * GNU General Public License for more details.
  19  *
  20  * You should have received a copy of the GNU General Public License
  21  * along with this program; if not, see <http://www.gnu.org/licenses/>.
  22  */
  23 
  24 #include <ifs/ifs_syscalls.h>
  25 #include <sys/types.h>
  26 #include <sys/isi_enc.h>
  27 #include <sys/module.h>
  28 #include <sys/stat.h>
  29 #include <sys/syscall.h>
  30 #include <sys/time.h>
  31 #include <dirent.h>
  32 #include <errno.h>
  33 #include <fcntl.h>
  34 #include <limits.h>
  35 #include <search.h>
  36 #include <stdio.h>
  37 #include <stdlib.h>
  38 #include <string.h>
  39 #include <unistd.h>
  40 
  41 #include "onefs_shadow_copy.h"
  42 
  43 /* Copied from ../include/proto.h */
  44 void become_root(void);
  45 void unbecome_root(void);
  46 
  47 #define SNAPSHOT_DIRECTORY      ".snapshot"
  48 
  49 #define MAX_VERSIONS            64
  50 
  51 /**
  52  * A snapshot object.
  53  *
  54  * During snapshot enumeration, snapshots are represented by snapshot objects
  55  * and are stored in a snapshot set.  The snapshot object represents one
  56  * snapshot within the set.  An important thing to note about the set is that
  57  * the key of the snapshot object is the tv_sec component of the is_time
  58  * member.  What this means is that we only store one snapshot for each
  59  * second.  If multiple snapshots were created within the same second, we'll
  60  * keep the earliest one and ignore the rest.  Thus, not all snapshots are
  61  * necessarily retained.
  62  */
  63 struct osc_snapshot {
  64         char *                  is_name;
  65         struct timespec         is_time;
  66         struct osc_snapshot *   is_next;
  67 };
  68 
  69 /**
  70  * A snapshot context object.
  71  *
  72  * Snapshot contexts are used to pass information throughout the snapshot
  73  * enumeration routines.  As a result, snapshot contexts are stored on the
  74  * stack and are both created and destroyed within a single API function.
  75  */
  76 struct osc_snapshot_ctx {
  77         void *          osc_set;
  78         struct timespec osc_mtime;
  79 };
  80 
  81 /**
  82  * A directory context.
  83  *
  84  * Directory contexts are the underlying data structured used to enumerate
  85  * snapshot versions.  An opendir()-, readdir()- and closedir()-like interface
  86  * is provided that utilizes directory contexts.  At the API level, directory
  87  * contexts are passed around as void pointers.  Directory contexts are
  88  * allocated on the heap and their lifetime is dictated by the calling
  89  * routine.
  90  */
  91 struct osc_directory_ctx {
  92         size_t          idc_pos;
  93         size_t          idc_len;
  94         size_t          idc_size;
  95         char **         idc_version;
  96 };
  97 
  98 /**
  99  * Return a file descriptor to the STF names directory.
 100  *
 101  * Opens the STF names directory and returns a file descriptor to it.
 102  * Subsequent calls return the same value (avoiding the need to re-open the
 103  * directory repeatedly).  Caveat caller: don't close the file descriptor or
 104  * you will be shot!
 105  */
 106 static int
 107 osc_get_names_directory_fd(void)
     /* [<][>][^][v][top][bottom][index][help] */
 108 {
 109         static int fd = -1;
 110 
 111         if (fd == -1) {
 112                 become_root();
 113                 fd = pctl2_lin_open(STF_NAMES_LIN, HEAD_SNAPID, O_RDONLY);
 114                 unbecome_root();
 115         }
 116 
 117         return fd;
 118 }
 119 
 120 /**
 121  * Compare two time values.
 122  *
 123  * Accepts two struct timespecs and compares the tv_sec components of these
 124  * values.  It returns -1 if the first value preceeds the second, 0 if they
 125  * are equal and +1 if the first values succeeds the second.
 126  */
 127 static int
 128 osc_time_compare(const struct timespec *tsp1, const struct timespec *tsp2)
     /* [<][>][^][v][top][bottom][index][help] */
 129 {
 130         return (tsp1->tv_sec < tsp2->tv_sec) ? -1 :
 131                (tsp1->tv_sec > tsp2->tv_sec) ? +1 : 0;
 132 }
 133 
 134 /**
 135  * Compare two timespec values.
 136  *
 137  * Compares two timespec values.  It returns -1 if the first value preceeds
 138  * the second, 0 if they are equal and +1 if the first values succeeds the
 139  * second.
 140  */
 141 static int
 142 osc_timespec_compare(const struct timespec *tsp1, const struct timespec *tsp2)
     /* [<][>][^][v][top][bottom][index][help] */
 143 {
 144         return (tsp1->tv_sec  < tsp2->tv_sec)  ? -1 :
 145                (tsp1->tv_sec  > tsp2->tv_sec)  ? +1 :
 146                (tsp1->tv_nsec < tsp2->tv_nsec) ? -1 :
 147                (tsp1->tv_nsec > tsp2->tv_nsec) ? +1 : 0;
 148 }
 149 
 150 /**
 151  * Determine whether a timespec value is zero.
 152  *
 153  * Return 1 if the struct timespec provided is zero and 0 otherwise.
 154  */
 155 static int
 156 osc_timespec_is_zero(const struct timespec *tsp)
     /* [<][>][^][v][top][bottom][index][help] */
 157 {
 158         return (tsp->tv_sec  == 0) &&
 159                (tsp->tv_nsec == 0);
 160 }
 161 
 162 /**
 163  * Create a snapshot object.
 164  *
 165  * Allocates and initializes a new snapshot object.  In addition to allocating
 166  * space for the snapshot object itself, space is allocated for the snapshot
 167  * name.  Both the name and time are then copied to the new object.
 168  */
 169 static struct osc_snapshot *
 170 osc_snapshot_create(const char *name, const struct timespec *tsp)
     /* [<][>][^][v][top][bottom][index][help] */
 171 {
 172         struct osc_snapshot *isp;
 173 
 174         isp = malloc(sizeof *isp);
 175         if (isp == NULL)
 176                 goto out;
 177 
 178         isp->is_name = malloc(strlen(name) + 1);
 179         if (isp->is_name == NULL) {
 180                 free(isp);
 181                 isp = NULL;
 182                 goto out;
 183         }
 184 
 185         strcpy(isp->is_name, name);
 186         isp->is_time = *tsp;
 187         isp->is_next = NULL;
 188 
 189  out:
 190         return isp;
 191 }
 192 
 193 /**
 194  * Destroy a snapshot object.
 195  *
 196  * Frees both the name and the snapshot object itself.  Appropriate NULL
 197  * checking is performed because counting on free to do so is immoral.
 198  */
 199 static void
 200 osc_snapshot_destroy(struct osc_snapshot *isp)
     /* [<][>][^][v][top][bottom][index][help] */
 201 {
 202         if (isp != NULL) {
 203                 if (isp->is_name != NULL)
 204                         free(isp->is_name);
 205                 free(isp);
 206         }
 207 }
 208 
 209 /**
 210  * Destroy all snapshots in the snapshot list.
 211  *
 212  * Calls osc_snapshot_destroy() on each snapshot in the list.
 213  */
 214 static void
 215 osc_snapshot_destroy_list(struct osc_snapshot *isp)
     /* [<][>][^][v][top][bottom][index][help] */
 216 {
 217         struct osc_snapshot *tmp;
 218 
 219         while (isp != NULL) {
 220                 tmp = isp;
 221                 isp = isp->is_next;
 222                 osc_snapshot_destroy(tmp);
 223         }
 224 }
 225 
 226 /**
 227  * Compare two snapshot objects.
 228  *
 229  * Compare two snapshot objects.  It is really just a wrapper for
 230  * osc_time_compare(), which compare the time value of the two snapshots.
 231  * N.B. time value in this context refers only to the tv_sec component.
 232  */
 233 static int
 234 osc_snapshot_compare(const void *vp1, const void *vp2)
     /* [<][>][^][v][top][bottom][index][help] */
 235 {
 236         const struct osc_snapshot *isp1 = vp1;
 237         const struct osc_snapshot *isp2 = vp2;
 238 
 239         return -osc_time_compare(&isp1->is_time, &isp2->is_time);
 240 }
 241 
 242 /**
 243  * Insert a snapshot into the snapshot set.
 244  *
 245  * Inserts a new snapshot into the snapshot set.  The key for snapshots is
 246  * their creation time (it's actually the seconds portion of the creation
 247  * time).  If a duplicate snapshot is found in the set, the new snapshot is
 248  * added to a linked list of snapshots for that second.
 249  */
 250 static void
 251 osc_snapshot_insert(struct osc_snapshot_ctx *oscp, const char *name,
     /* [<][>][^][v][top][bottom][index][help] */
 252     const struct timespec *tsp, int *errorp)
 253 {
 254         struct osc_snapshot *isp1;
 255         struct osc_snapshot **ispp;
 256 
 257         isp1 = osc_snapshot_create(name, tsp);
 258         if (isp1 == NULL) {
 259                 *errorp = 1;
 260                 return;
 261         }
 262 
 263         ispp = tsearch(isp1, &oscp->osc_set, osc_snapshot_compare);
 264         if (ispp != NULL) {
 265                 struct osc_snapshot *isp2 = *ispp;
 266 
 267                 /* If this is the only snapshot for this second, we're done. */
 268                 if (isp2 == isp1)
 269                         return;
 270 
 271                 /* Collision: add the new snapshot to the list. */
 272                 isp1->is_next = isp2->is_next;
 273                 isp2->is_next = isp1;
 274 
 275         } else
 276                 *errorp = 1;
 277 
 278 }
 279 
 280 /**
 281  * Process the next snapshot.
 282  *
 283  * Called for (almost) every entry in a .snapshot directory, ("." and ".." are
 284  * ignored in osc_process_snapshot_directory()).  All other entries are passed
 285  * to osc_process_snapshot(), however.  These entries can fall into one of two
 286  * categories: snapshot names and snapshot aliases.  We only care about
 287  * snapshot names (as aliases are just redundant entries).  Once it verifies
 288  * that name represents a valid snapshot name, it calls fstat() to get the
 289  * creation time of the snapshot and then calls osc_snapshot_insert() to add
 290  * this entry to the snapshot set.
 291  */
 292 static void
 293 osc_process_snapshot(struct osc_snapshot_ctx *oscp, const char *name,
     /* [<][>][^][v][top][bottom][index][help] */
 294     int *errorp)
 295 {
 296         int fd;
 297         struct stf_stat stf_stat;
 298         struct stat stbuf;
 299 
 300         fd = osc_get_names_directory_fd();
 301         if (fd == -1)
 302                 goto out;
 303 
 304         fd = enc_openat(fd, name, ENC_DEFAULT, O_RDONLY);
 305         if (fd == -1)
 306                 goto out;
 307 
 308         memset(&stf_stat, 0, sizeof stf_stat);
 309         if (ifs_snap_stat(fd, &stf_stat) == -1)
 310                 goto out;
 311 
 312         if (stf_stat.sf_type != SF_STF)
 313                 goto out;
 314 
 315         if (fstat(fd, &stbuf) == -1)
 316                 goto out;
 317 
 318         osc_snapshot_insert(oscp, name, &stbuf.st_birthtimespec, errorp);
 319 
 320  out:
 321         if (fd != -1)
 322                 close(fd);
 323 }
 324 
 325 /**
 326  * Process a snapshot directory.
 327  *
 328  * Opens the snapshot directory and calls osc_process_snapshot() for each
 329  * entry.  (Well ok, "." and ".."  are ignored.)  The goal here is to add all
 330  * snapshots in the directory to the snapshot set.
 331  */
 332 static void
 333 osc_process_snapshot_directory(struct osc_snapshot_ctx *oscp, int *errorp)
     /* [<][>][^][v][top][bottom][index][help] */
 334 {
 335         int fd;
 336         struct stat stbuf;
 337         DIR *dirp;
 338         struct dirent *dp;
 339 
 340         fd = osc_get_names_directory_fd();
 341         if (fd == -1)
 342                 goto out;
 343 
 344         if (fstat(fd, &stbuf) == -1)
 345                 goto out;
 346 
 347         dirp = opendir(SNAPSHOT_DIRECTORY);
 348         if (dirp == NULL)
 349                 goto out;
 350 
 351         for (;;) {
 352                 dp = readdir(dirp);
 353                 if (dp == NULL)
 354                         break;
 355 
 356                 if (dp->d_name[0] == '.' && (dp->d_name[1] == '\0' ||
 357                     (dp->d_name[1] == '.' && dp->d_name[2] == '\0')))
 358                         continue;
 359 
 360                 osc_process_snapshot(oscp, dp->d_name, errorp);
 361                 if (*errorp)
 362                         break;
 363         }
 364 
 365         closedir(dirp);
 366 
 367         if (!*errorp)
 368                 oscp->osc_mtime = stbuf.st_mtimespec;
 369 
 370  out:
 371         return;
 372 }
 373 
 374 /**
 375  * Initialize a snapshot context object.
 376  *
 377  * Clears all members of the context object.
 378  */
 379 static void
 380 osc_snapshot_ctx_init(struct osc_snapshot_ctx *oscp)
     /* [<][>][^][v][top][bottom][index][help] */
 381 {
 382         memset(oscp, 0, sizeof *oscp);
 383 }
 384 
 385 /**
 386  * Desoy a snapshot context object.
 387  *
 388  * Frees all snapshots associated with the snapshot context and then calls
 389  * osc_snapshot_ctx_init() to re-initialize the context object.
 390  */
 391 static void
 392 osc_snapshot_ctx_clean(struct osc_snapshot_ctx *oscp)
     /* [<][>][^][v][top][bottom][index][help] */
 393 {
 394         struct osc_snapshot *tmp;
 395 
 396         while (oscp->osc_set != NULL) {
 397                 tmp = *(void **)oscp->osc_set;
 398                 tdelete(tmp, &oscp->osc_set, osc_snapshot_compare);
 399                 osc_snapshot_destroy_list(tmp);
 400         }
 401 
 402         osc_snapshot_ctx_init(oscp);
 403 }
 404 
 405 /**
 406  * Return the "global" snapshot context.
 407  *
 408  * We maintain a single open snapshot context.  Return a pointer to it.
 409  */
 410 static struct osc_snapshot_ctx *
 411 osc_get_snapshot_ctx(void)
     /* [<][>][^][v][top][bottom][index][help] */
 412 {
 413         static struct osc_snapshot_ctx osc = { 0, { 0, 0 } };
 414 
 415         return &osc;
 416 }
 417 
 418 /**
 419  * Determine whether a snapshot context is still valid.
 420  *
 421  * "Valid" in this context means "reusable".  We can re-use a previous
 422  * snapshot context iff we successfully built a previous snapshot context
 423  * and no snapshots have been created or deleted since we did so.
 424  * A "names" directory exists within our snapshot
 425  * implementation in which all snapshot names are entered.  Each time a
 426  * snapshot is created or deleted, an entry must be added or removed.
 427  * When this happens the modification time on the "names" directory
 428  * changes.  Therefore, a snapshot context is valid iff the context
 429  * pointer is non-NULL, the cached modification time is non-zero
 430  * (zero means uninitialized), and the modification time of the "names"
 431  * directory matches the cached value.
 432  */
 433 static int
 434 osc_snapshot_ctx_is_valid(struct osc_snapshot_ctx *oscp)
     /* [<][>][^][v][top][bottom][index][help] */
 435 {
 436         int fd;
 437         struct stat stbuf;
 438 
 439         if (oscp == NULL)
 440                 return 0;
 441 
 442         if (osc_timespec_is_zero(&oscp->osc_mtime))
 443                 return 0;
 444 
 445         fd = osc_get_names_directory_fd();
 446         if (fd == -1)
 447                 return 0;
 448 
 449         if (fstat(fd, &stbuf) == -1)
 450                 return 0;
 451 
 452         if (osc_timespec_compare(&oscp->osc_mtime, &stbuf.st_mtimespec) != 0)
 453                 return 0;
 454 
 455         return 1;
 456 }
 457 
 458 /**
 459  * Create and initialize a directory context.
 460  *
 461  * Allocates a directory context from the heap and initializes it.
 462  */
 463 static struct osc_directory_ctx *
 464 osc_directory_ctx_create(void)
     /* [<][>][^][v][top][bottom][index][help] */
 465 {
 466         struct osc_directory_ctx *idcp;
 467 
 468         idcp = malloc(sizeof *idcp);
 469         if (idcp != NULL)
 470                 memset(idcp, 0, sizeof *idcp);
 471 
 472         return idcp;
 473 }
 474 
 475 /**
 476  * Destroy a directory context.
 477  *
 478  * Frees any versions associated with the directory context and then frees the
 479  * context itself.
 480  */
 481 static void
 482 osc_directory_ctx_destroy(struct osc_directory_ctx *idcp)
     /* [<][>][^][v][top][bottom][index][help] */
 483 {
 484         int i;
 485 
 486         if (idcp == NULL)
 487                 return;
 488 
 489         for (i = 0; i < idcp->idc_len; i++)
 490                 free(idcp->idc_version[i]);
 491 
 492         free(idcp);
 493 }
 494 
 495 /**
 496  * Expand the size of a directory context's version list.
 497  *
 498  * If osc_directory_ctx_append_version() detects that the version list is too
 499  * small to accomodate a new version string, it called
 500  * osc_directory_ctx_expand_version_list() to expand the version list.
 501  */
 502 static void
 503 osc_directory_ctx_expand_version_list(struct osc_snapshot_ctx *oscp,
     /* [<][>][^][v][top][bottom][index][help] */
 504     struct osc_directory_ctx *idcp, int *errorp)
 505 {
 506         size_t size;
 507         char **cpp;
 508 
 509         size = idcp->idc_size * 2 ?: 1;
 510 
 511         cpp = realloc(idcp->idc_version, size * sizeof (char *));
 512         if (cpp == NULL) {
 513                 *errorp = 1;
 514                 return;
 515         }
 516 
 517         idcp->idc_size = size;
 518         idcp->idc_version = cpp;
 519 }
 520 
 521 /**
 522  * Append a new version to a directory context.
 523  *
 524  * Appends a snapshot version to the
 525  * directory context's version list.
 526  */
 527 static void
 528 osc_directory_ctx_append_version(struct osc_snapshot_ctx *oscp,
     /* [<][>][^][v][top][bottom][index][help] */
 529     struct osc_directory_ctx *idcp, const struct timespec *tsp, int *errorp)
 530 {
 531         char *cp;
 532         struct tm *tmp;
 533         char text[64];
 534 
 535         if (idcp->idc_len >= MAX_VERSIONS)
 536                 return;
 537 
 538         if (idcp->idc_len >= idcp->idc_size) {
 539                 osc_directory_ctx_expand_version_list(oscp, idcp, errorp);
 540                 if (*errorp)
 541                         return;
 542         }
 543 
 544         tmp = gmtime(&tsp->tv_sec);
 545         if (tmp == NULL) {
 546                 *errorp = 1;
 547                 return;
 548         }
 549 
 550         snprintf(text, sizeof text,
 551             "@GMT-%04u.%02u.%02u-%02u.%02u.%02u",
 552             tmp->tm_year + 1900,
 553             tmp->tm_mon + 1,
 554             tmp->tm_mday,
 555             tmp->tm_hour,
 556             tmp->tm_min,
 557             tmp->tm_sec);
 558 
 559         cp = malloc(strlen(text) + 1);
 560         if (cp == NULL) {
 561                 *errorp = 1;
 562                 return;
 563         }
 564 
 565         strcpy(cp, text);
 566 
 567         idcp->idc_version[idcp->idc_len++] = cp;
 568 }
 569 
 570 /**
 571  * Make a directory context from a snapshot context.
 572  *
 573  * Once a snapshot context has been completely filled-in,
 574  * osc_make_directory_ctx() is used to build a directory context from it.  The
 575  * idea here is to create version for each snapshot in the snapshot set.
 576  */
 577 static void
 578 osc_make_directory_ctx(struct osc_snapshot_ctx *oscp,
     /* [<][>][^][v][top][bottom][index][help] */
 579     struct osc_directory_ctx *idcp, int *errorp)
 580 {
 581         static void
 582         walk(const void *vp, VISIT v, int level)
 583         {
 584                 const struct osc_snapshot *isp;
 585 
 586                 if ((v != postorder && v != leaf) || *errorp)
 587                         return;
 588 
 589                 isp = *(const struct osc_snapshot **)(u_long)vp;
 590 
 591                 osc_directory_ctx_append_version(oscp, idcp, &isp->is_time,
 592                     errorp);
 593         }
 594 
 595         twalk(oscp->osc_set, walk);
 596 }
 597 
 598 /**
 599  * Open a version directory.
 600  *
 601  * Opens a version directory.  What this really means is that
 602  * osc_version_opendir() returns a handle to a directory context, which can be
 603  * used to retrieve version strings.
 604  */
 605 void *
 606 osc_version_opendir(void)
     /* [<][>][^][v][top][bottom][index][help] */
 607 {
 608         int error = 0;
 609         struct osc_directory_ctx *idcp;
 610         struct osc_snapshot_ctx *oscp;
 611 
 612         idcp = osc_directory_ctx_create();
 613         if (idcp == NULL)
 614                 goto error_out;
 615 
 616         oscp = osc_get_snapshot_ctx();
 617 
 618         if (!osc_snapshot_ctx_is_valid(oscp)) {
 619                 osc_snapshot_ctx_clean(oscp);
 620                 osc_process_snapshot_directory(oscp, &error);
 621                 if (error)
 622                         goto error_out;
 623         }
 624 
 625         osc_make_directory_ctx(oscp, idcp, &error);
 626         if (error)
 627                 goto error_out;
 628 
 629         goto out;
 630 
 631  error_out:
 632         if (idcp != NULL) {
 633                 osc_directory_ctx_destroy(idcp);
 634                 idcp = NULL;
 635         }
 636 
 637  out:
 638         return (void *)idcp;
 639 }
 640 
 641 /**
 642  * Read the next version directory entry.
 643  *
 644  * Returns the name of the next version in the version directory, or NULL if
 645  * we're at the end of the directory.  What this really does is return the
 646  * next version from the version list stored in the directory context.
 647  */
 648 char *
 649 osc_version_readdir(void *vp)
     /* [<][>][^][v][top][bottom][index][help] */
 650 {
 651         struct osc_directory_ctx *idcp = vp;
 652 
 653         if (idcp == NULL)
 654                 return NULL;
 655 
 656         if (idcp->idc_pos >= idcp->idc_len)
 657                 return NULL;
 658 
 659         return idcp->idc_version[idcp->idc_pos++];
 660 }
 661 
 662 /**
 663  * Close the version directory.
 664  *
 665  * Destroys the underlying directory context.
 666  */
 667 void
 668 osc_version_closedir(void *vp)
     /* [<][>][^][v][top][bottom][index][help] */
 669 {
 670         struct osc_directory_ctx *idcp = vp;
 671 
 672         if (idcp != NULL)
 673                 osc_directory_ctx_destroy(idcp);
 674 }
 675 
 676 /**
 677  * Canonicalize a path.
 678  *
 679  * Converts paths of the form @GMT-.. to paths of the form ../.snapshot/..
 680  * It's not the prettiest routine I've ever written, but what the heck?
 681  */
 682 char *
 683 osc_canonicalize_path(const char *path, char *snap_component)
     /* [<][>][^][v][top][bottom][index][help] */
 684 {
 685         int error = 0;
 686         struct osc_snapshot_ctx *oscp;
 687         struct tm tm;
 688         int n;
 689         struct osc_snapshot is;
 690         struct osc_snapshot **ispp;
 691         struct osc_snapshot *isp;
 692         char *cpath = NULL;
 693         char *cpath2 = NULL;
 694         const char *snap_component_orig = snap_component;
 695         struct stat sb;
 696 
 697         oscp = osc_get_snapshot_ctx();
 698 
 699         if (!osc_snapshot_ctx_is_valid(oscp)) {
 700                 osc_snapshot_ctx_clean(oscp);
 701                 osc_process_snapshot_directory(oscp, &error);
 702                 if (error)
 703                         goto out;
 704         }
 705 
 706         memset(&tm, 0, sizeof tm);
 707         n = sscanf(snap_component,
 708             "@GMT-%4u.%2u.%2u-%2u.%2u.%2u",
 709             &tm.tm_year,
 710             &tm.tm_mon,
 711             &tm.tm_mday,
 712             &tm.tm_hour,
 713             &tm.tm_min,
 714             &tm.tm_sec);
 715         if (n != 6)
 716                 goto out;
 717 
 718         tm.tm_year -= 1900;
 719         tm.tm_mon -= 1;
 720 
 721         is.is_name = NULL;
 722         is.is_time.tv_sec = timegm(&tm);
 723         is.is_time.tv_nsec = 0;
 724 
 725         ispp = tfind(&is, &oscp->osc_set, osc_snapshot_compare);
 726         if (ispp == NULL)
 727                 goto out;
 728         isp = *ispp;
 729 
 730         /* Determine the path after "@GMT-..." */
 731         while (*snap_component != '/' && *snap_component != '\0')
 732                 snap_component++;
 733 
 734         while (*snap_component == '/')
 735                 snap_component++;
 736 
 737         cpath = malloc(strlen(SNAPSHOT_DIRECTORY) + strlen(isp->is_name) +
 738             strlen(path) + 3);
 739 
 740         if (cpath == NULL)
 741                 goto out;
 742 
 743         /*
 744          * Use the first snapshot that has a successful stat for the requested
 745          * path.
 746          */
 747         while (true) {
 748 
 749                 sprintf(cpath, "%s/%s", SNAPSHOT_DIRECTORY, isp->is_name);
 750 
 751                 /* Append path before "@GMT-..." */
 752                 if (snap_component_orig != path) {
 753                         strcat(cpath, "/");
 754                         strncat(cpath, path, snap_component_orig - path);
 755                 }
 756 
 757                 /* Append path after "@GMT-..." */
 758                 if (*snap_component != '\0') {
 759                         strcat(cpath, "/");
 760                         strcat(cpath, snap_component);
 761                 }
 762 
 763                 /* If there is a valid snapshot for this file, we're done. */
 764                 if (stat(cpath, &sb) == 0)
 765                         break;
 766 
 767                 /* Try the next snapshot. If this was the last one, give up. */
 768                 isp = isp->is_next;
 769                 if (isp == NULL)
 770                         break;
 771 
 772                 /* If the realloc fails, give up. */
 773                 cpath2 = realloc(cpath, strlen(SNAPSHOT_DIRECTORY) +
 774                     strlen(isp->is_name) + strlen(path) + 3);
 775                 if (cpath2 == NULL)
 776                         break;
 777                 cpath = cpath2;
 778         }
 779 
 780  out:
 781         return cpath;
 782 }

/* [<][>][^][v][top][bottom][index][help] */