contrib/libarchive-1.3.1/tar/tree.c

   1 /*-
   2  * Copyright (c) 2003-2004 Tim Kientzle
   3  * All rights reserved.
   4  *
   5  * Redistribution and use in source and binary forms, with or without
   6  * modification, are permitted provided that the following conditions
   7  * are met:
   8  * 1. Redistributions of source code must retain the above copyright
   9  *    notice, this list of conditions and the following disclaimer
  10  *    in this position and unchanged.
  11  * 2. Redistributions in binary form must reproduce the above copyright
  12  *    notice, this list of conditions and the following disclaimer in the
  13  *    documentation and/or other materials provided with the distribution.
  14  *
  15  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR(S) ``AS IS'' AND ANY EXPRESS OR
  16  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
  17  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
  18  * IN NO EVENT SHALL THE AUTHOR(S) BE LIABLE FOR ANY DIRECT, INDIRECT,
  19  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
  20  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  21  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  22  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  23  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
  24  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  25  */
  26
  27 /*-
  28  * This is a new directory-walking system that addresses a number
  29  * of problems I've had with fts(3).  In particular, it has no
  30  * pathname-length limits (other than the size of 'int'), handles
  31  * deep logical traversals, uses considerably less memory, and has
  32  * an opaque interface (easier to modify in the future).
  33  *
  34  * Internally, it keeps a single list of "tree_entry" items that
  35  * represent filesystem objects that require further attention.
  36  * Non-directories are not kept in memory: they are pulled from
  37  * readdir(), returned to the client, then freed as soon as possible.
  38  * Any directory entry to be traversed gets pushed onto the stack.
  39  *
  40  * There is surprisingly little information that needs to be kept for
  41  * each item on the stack.  Just the name, depth (represented here as the
  42  * string length of the parent directory's pathname), and some markers
  43  * indicating how to get back to the parent (via chdir("..") for a
  44  * regular dir or via fchdir(2) for a symlink).
  45  */
  46 #include "bsdtar_platform.h"
  47 __FBSDID("$FreeBSD: src/usr.bin/tar/tree.c,v 1.4 2006/03/21 17:03:51 kientzle Exp $");
  48
  49 #include <sys/stat.h>
  50 #include <dirent.h>
  51 #include <errno.h>
  52 #include <fcntl.h>
  53 #include <stdlib.h>
  54 #include <string.h>
  55 #include <unistd.h>
  56
  57 #include "tree.h"
  58
  59 /*
  60  * TODO:
  61  *    1) Loop checking.
  62  *    3) Arbitrary logical traversals by closing/reopening intermediate fds.
  63  */
  64
  65 struct tree_entry {
  66         struct tree_entry *next;
  67         struct tree_entry *parent;
  68         char *name;
  69         size_t dirname_length;
  70         dev_t dev;
  71         ino_t ino;
  72         int fd;
  73         int flags;
  74 };
  75
  76 /* Definitions for tree_entry.flags bitmap. */
  77 #define isDir 1 /* This entry is a regular directory. */
  78 #define isDirLink 2 /* This entry is a symbolic link to a directory. */
  79 #define needsPreVisit 4 /* This entry needs to be previsited. */
  80 #define needsPostVisit 8 /* This entry needs to be postvisited. */
  81
  82 /*
  83  * Local data for this package.
  84  */
  85 struct tree {
  86         struct tree_entry       *stack;
  87         struct tree_entry       *current;
  88         DIR     *d;
  89         int      initialDirFd;
  90         int      flags;
  91         int      visit_type;
  92         int      tree_errno; /* Error code from last failed operation. */
  93
  94         char    *buff;
  95         const char      *basename;
  96         size_t   buff_length;
  97         size_t   path_length;
  98         size_t   dirname_length;
  99
 100         int      depth;
 101         int      openCount;
 102         int      maxOpenCount;
 103
 104         struct stat     lst;
 105         struct stat     st;
 106 };
 107
 108 /* Definitions for tree.flags bitmap. */
 109 #define needsReturn 8  /* Marks first entry as not having been returned yet. */
 110 #define hasStat 16  /* The st entry is set. */
 111 #define hasLstat 32 /* The lst entry is set. */
 112
 113
 114 #ifdef HAVE_DIRENT_D_NAMLEN
 115 /* BSD extension; avoids need for a strlen() call. */
 116 #define D_NAMELEN(dp)   (dp)->d_namlen
 117 #else
 118 #define D_NAMELEN(dp)   (strlen((dp)->d_name))
 119 #endif
 120
 121 #if 0
 122 #include <stdio.h>
 123 void
 124 tree_dump(struct tree *t, FILE *out)
 125 {
 126         struct tree_entry *te;
 127
 128         fprintf(out, "\tdepth: %d\n", t->depth);
 129         fprintf(out, "\tbuff: %s\n", t->buff);
 130         fprintf(out, "\tpwd: "); fflush(stdout); system("pwd");
 131         fprintf(out, "\taccess: %s\n", t->basename);
 132         fprintf(out, "\tstack:\n");
 133         for (te = t->stack; te != NULL; te = te->next) {
 134                 fprintf(out, "\t\tte->name: %s%s%s\n", te->name,
 135                     te->flags & needsPreVisit ? "" : " *",
 136                     t->current == te ? " (current)" : "");
 137         }
 138 }
 139 #endif
 140
 141 /*
 142  * Add a directory path to the current stack.
 143  */
 144 static void
 145 tree_push(struct tree *t, const char *path)
 146 {
 147         struct tree_entry *te;
 148
 149         te = malloc(sizeof(*te));
 150         memset(te, 0, sizeof(*te));
 151         te->next = t->stack;
 152         t->stack = te;
 153         te->fd = -1;
 154         te->name = strdup(path);
 155         te->flags = needsPreVisit | needsPostVisit;
 156         te->dirname_length = t->dirname_length;
 157 }
 158
 159 /*
 160  * Append a name to the current path.
 161  */
 162 static void
 163 tree_append(struct tree *t, const char *name, size_t name_length)
 164 {
 165         char *p;
 166
 167         if (t->buff != NULL)
 168                 t->buff[t->dirname_length] = '\0';
 169         /* Strip trailing '/' from name, unless entire name is "/". */
 170         while (name_length > 1 && name[name_length - 1] == '/')
 171                 name_length--;
 172
 173         /* Resize pathname buffer as needed. */
 174         while (name_length + 1 + t->dirname_length >= t->buff_length) {
 175                 t->buff_length *= 2;
 176                 if (t->buff_length < 1024)
 177                         t->buff_length = 1024;
 178                 t->buff = realloc(t->buff, t->buff_length);
 179         }
 180         p = t->buff + t->dirname_length;
 181         t->path_length = t->dirname_length + name_length;
 182         /* Add a separating '/' if it's needed. */
 183         if (t->dirname_length > 0 && p[-1] != '/') {
 184                 *p++ = '/';
 185                 t->path_length ++;
 186         }
 187         strncpy(p, name, name_length);
 188         p[name_length] = '\0';
 189         t->basename = p;
 190 }
 191
 192 /*
 193  * Open a directory tree for traversal.
 194  */
 195 struct tree *
 196 tree_open(const char *path)
 197 {
 198         struct tree *t;
 199
 200         t = malloc(sizeof(*t));
 201         memset(t, 0, sizeof(*t));
 202         tree_append(t, path, strlen(path));
 203         t->initialDirFd = open(".", O_RDONLY);
 204         /*
 205          * During most of the traversal, items are set up and then
 206          * returned immediately from tree_next().  That doesn't work
 207          * for the very first entry, so we set a flag for this special
 208          * case.
 209          */
 210         t->flags = needsReturn;
 211         return (t);
 212 }
 213
 214 /*
 215  * We've finished a directory; ascend back to the parent.
 216  */
 217 static void
 218 tree_ascend(struct tree *t)
 219 {
 220         struct tree_entry *te;
 221
 222         te = t->stack;
 223         t->depth--;
 224         if (te->flags & isDirLink) {
 225                 fchdir(te->fd);
 226                 close(te->fd);
 227                 t->openCount--;
 228         } else {
 229                 chdir("..");
 230         }
 231 }
 232
 233 /*
 234  * Pop the working stack.
 235  */
 236 static void
 237 tree_pop(struct tree *t)
 238 {
 239         struct tree_entry *te;
 240
 241         t->buff[t->dirname_length] = '\0';
 242         if (t->stack == t->current && t->current != NULL)
 243                 t->current = t->current->parent;
 244         te = t->stack;
 245         t->stack = te->next;
 246         t->dirname_length = te->dirname_length;
 247         t->basename = t->buff + t->dirname_length;
 248         /* Special case: starting dir doesn't skip leading '/'. */
 249         if (t->dirname_length > 0)
 250                 t->basename++;
 251         free(te->name);
 252         free(te);
 253 }
 254
 255 /*
 256  * Get the next item in the tree traversal.
 257  */
 258 int
 259 tree_next(struct tree *t)
 260 {
 261         struct dirent *de = NULL;
 262
 263         /* Handle the startup case by returning the initial entry. */
 264         if (t->flags & needsReturn) {
 265                 t->flags &= ~needsReturn;
 266                 return (t->visit_type = TREE_REGULAR);
 267         }
 268
 269         while (t->stack != NULL) {
 270                 /* If there's an open dir, get the next entry from there. */
 271                 while (t->d != NULL) {
 272                         de = readdir(t->d);
 273                         if (de == NULL) {
 274                                 closedir(t->d);
 275                                 t->d = NULL;
 276                         } else if (de->d_name[0] == '.'
 277                             && de->d_name[1] == '\0') {
 278                                 /* Skip '.' */
 279                         } else if (de->d_name[0] == '.'
 280                             && de->d_name[1] == '.'
 281                             && de->d_name[2] == '\0') {
 282                                 /* Skip '..' */
 283                         } else {
 284                                 /*
 285                                  * Append the path to the current path
 286                                  * and return it.
 287                                  */
 288                                 tree_append(t, de->d_name, D_NAMELEN(de));
 289                                 t->flags &= ~hasLstat;
 290                                 t->flags &= ~hasStat;
 291                                 return (t->visit_type = TREE_REGULAR);
 292                         }
 293                 }
 294
 295                 /* If the current dir needs to be visited, set it up. */
 296                 if (t->stack->flags & needsPreVisit) {
 297                         t->current = t->stack;
 298                         tree_append(t, t->stack->name, strlen(t->stack->name));
 299                         t->stack->flags &= ~needsPreVisit;
 300                         /* If it is a link, set up fd for the ascent. */
 301                         if (t->stack->flags & isDirLink) {
 302                                 t->stack->fd = open(".", O_RDONLY);
 303                                 t->openCount++;
 304                                 if (t->openCount > t->maxOpenCount)
 305                                         t->maxOpenCount = t->openCount;
 306                         }
 307                         t->dirname_length = t->path_length;
 308                         if (chdir(t->stack->name) != 0) {
 309                                 /* chdir() failed; return error */
 310                                 tree_pop(t);
 311                                 t->tree_errno = errno;
 312                                 return (t->visit_type = TREE_ERROR_DIR);
 313                         }
 314                         t->depth++;
 315                         t->d = opendir(".");
 316                         if (t->d == NULL) {
 317                                 tree_ascend(t); /* Undo "chdir" */
 318                                 tree_pop(t);
 319                                 t->tree_errno = errno;
 320                                 return (t->visit_type = TREE_ERROR_DIR);
 321                         }
 322                         t->flags &= ~hasLstat;
 323                         t->flags &= ~hasStat;
 324                         t->basename = ".";
 325                         return (t->visit_type = TREE_POSTDESCENT);
 326                 }
 327
 328                 /* We've done everything necessary for the top stack entry. */
 329                 if (t->stack->flags & needsPostVisit) {
 330                         tree_ascend(t);
 331                         tree_pop(t);
 332                         t->flags &= ~hasLstat;
 333                         t->flags &= ~hasStat;
 334                         return (t->visit_type = TREE_POSTASCENT);
 335                 }
 336         }
 337         return (t->visit_type = 0);
 338 }
 339
 340 /*
 341  * Return error code.
 342  */
 343 int
 344 tree_errno(struct tree *t)
 345 {
 346         return (t->tree_errno);
 347 }
 348
 349 /*
 350  * Called by the client to mark the directory just returned from
 351  * tree_next() as needing to be visited.
 352  */
 353 void
 354 tree_descend(struct tree *t)
 355 {
 356         if (t->visit_type != TREE_REGULAR)
 357                 return;
 358
 359         if (tree_current_is_physical_dir(t)) {
 360                 tree_push(t, t->basename);
 361                 t->stack->flags |= isDir;
 362         } else if (tree_current_is_dir(t)) {
 363                 tree_push(t, t->basename);
 364                 t->stack->flags |= isDirLink;
 365         }
 366 }
 367
 368 /*
 369  * Get the stat() data for the entry just returned from tree_next().
 370  */
 371 const struct stat *
 372 tree_current_stat(struct tree *t)
 373 {
 374         if (!(t->flags & hasStat)) {
 375                 if (stat(t->basename, &t->st) != 0)
 376                         return NULL;
 377                 t->flags |= hasStat;
 378         }
 379         return (&t->st);
 380 }
 381
 382 /*
 383  * Get the lstat() data for the entry just returned from tree_next().
 384  */
 385 const struct stat *
 386 tree_current_lstat(struct tree *t)
 387 {
 388         if (!(t->flags & hasLstat)) {
 389                 if (lstat(t->basename, &t->lst) != 0)
 390                         return NULL;
 391                 t->flags |= hasLstat;
 392         }
 393         return (&t->lst);
 394 }
 395
 396 /*
 397  * Test whether current entry is a dir or dir link.
 398  */
 399 int
 400 tree_current_is_dir(struct tree *t)
 401 {
 402         /* If we've already pulled stat(), just use that. */
 403         if (t->flags & hasStat)
 404                 return (S_ISDIR(tree_current_stat(t)->st_mode));
 405
 406         /* If we've already pulled lstat(), we may be able to use that. */
 407         if (t->flags & hasLstat) {
 408                 /* If lstat() says it's a dir, it must be a dir. */
 409                 if (S_ISDIR(tree_current_lstat(t)->st_mode))
 410                         return 1;
 411                 /* If it's not a dir and not a link, we're done. */
 412                 if (!S_ISLNK(tree_current_lstat(t)->st_mode))
 413                         return 0;
 414                 /*
 415                  * If the above two tests fail, then it's a link, but
 416                  * we don't know whether it's a link to a dir or a
 417                  * non-dir.
 418                  */
 419         }
 420
 421         /* TODO: Use a more efficient mechanism when available. */
 422         return (S_ISDIR(tree_current_stat(t)->st_mode));
 423 }
 424
 425 /*
 426  * Test whether current entry is a physical directory.
 427  */
 428 int
 429 tree_current_is_physical_dir(struct tree *t)
 430 {
 431         /* If we've already pulled lstat(), just use that. */
 432         if (t->flags & hasLstat)
 433                 return (S_ISDIR(tree_current_lstat(t)->st_mode));
 434
 435         /* TODO: Use a more efficient mechanism when available. */
 436         return (S_ISDIR(tree_current_lstat(t)->st_mode));
 437 }
 438
 439 /*
 440  * Test whether current entry is a symbolic link.
 441  */
 442 int
 443 tree_current_is_physical_link(struct tree *t)
 444 {
 445         /* If we've already pulled lstat(), just use that. */
 446         if (t->flags & hasLstat)
 447                 return (S_ISLNK(tree_current_lstat(t)->st_mode));
 448
 449         /* TODO: Use a more efficient mechanism when available. */
 450         return (S_ISLNK(tree_current_lstat(t)->st_mode));
 451 }
 452
 453 /*
 454  * Return the access path for the entry just returned from tree_next().
 455  */
 456 const char *
 457 tree_current_access_path(struct tree *t)
 458 {
 459         return (t->basename);
 460 }
 461
 462 /*
 463  * Return the full path for the entry just returned from tree_next().
 464  */
 465 const char *
 466 tree_current_path(struct tree *t)
 467 {
 468         return (t->buff);
 469 }
 470
 471 /*
 472  * Return the length of the path for the entry just returned from tree_next().
 473  */
 474 size_t
 475 tree_current_pathlen(struct tree *t)
 476 {
 477         return (t->path_length);
 478 }
 479
 480 /*
 481  * Return the nesting depth of the entry just returned from tree_next().
 482  */
 483 int
 484 tree_current_depth(struct tree *t)
 485 {
 486         return (t->depth);
 487 }
 488
 489 /*
 490  * Terminate the traversal and release any resources.
 491  */
 492 void
 493 tree_close(struct tree *t)
 494 {
 495         /* Release anything remaining in the stack. */
 496         while (t->stack != NULL)
 497                 tree_pop(t);
 498         if (t->buff)
 499                 free(t->buff);
 500         /* chdir() back to where we started. */
 501         if (t->initialDirFd >= 0) {
 502                 fchdir(t->initialDirFd);
 503                 close(t->initialDirFd);
 504                 t->initialDirFd = -1;
 505         }
 506         free(t);
 507 }