misc-utils/namei.c

   1 /*
   2  * Copyright (C) 2008 Karel Zak <kzak@redhat.com>
   3  *
   4  * This file is part of util-linux.
   5  *
   6  * This file is free software; you can redistribute it and/or modify
   7  * it under the terms of the GNU General Public License as published by
   8  * the Free Software Foundation; either version 2 of the License, or
   9  * (at your option) any later version.
  10  *
  11  * This file is distributed in the hope that it will be useful,
  12  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14  * GNU General Public License for more details.
  15  *
  16  * The original namei(1) was written by:
  17  *      Roger S. Southwick (May 2, 1990)
  18  *      Steve Tell (March 28, 1991)
  19  *      Arkadiusz Miśkiewicz (1999-02-22)
  20  *      Li Zefan (2007-09-10).
  21  */
  22 #include <stdio.h>
  23 #include <unistd.h>
  24 #include <getopt.h>
  25 #include <string.h>
  26 #include <stdlib.h>
  27 #include <errno.h>
  28 #include <sys/types.h>
  29 #include <sys/stat.h>
  30 #include <sys/param.h>
  31 #include <pwd.h>
  32 #include <grp.h>
  33
  34 #ifdef HAVE_LIBSELINUX
  35 # include <selinux/selinux.h>
  36 #endif
  37
  38 #include "c.h"
  39 #include "xalloc.h"
  40 #include "nls.h"
  41 #include "widechar.h"
  42 #include "strutils.h"
  43 #include "closestream.h"
  44 #include "idcache.h"
  45
  46 #ifndef MAXSYMLINKS
  47 #define MAXSYMLINKS 256
  48 #endif
  49
  50 #define NAMEI_NOLINKS   (1 << 1)
  51 #define NAMEI_MODES     (1 << 2)
  52 #define NAMEI_MNTS      (1 << 3)
  53 #define NAMEI_OWNERS    (1 << 4)
  54 #define NAMEI_VERTICAL  (1 << 5)
  55 #define NAMEI_CONTEXT   (1 << 6)
  56
  57
  58 struct namei {
  59         struct stat     st;             /* item lstat() */
  60         char            *name;          /* item name */
  61         char            *abslink;       /* absolute symlink path */
  62         int             relstart;       /* offset of relative path in 'abslink' */
  63         struct namei    *next;          /* next item */
  64         int             level;
  65         int             mountpoint;     /* is mount point */
  66         int             noent;          /* this item not existing (stores errno from stat()) */
  67 #ifdef HAVE_LIBSELINUX
  68         int             context_len;    /* length of selinux contexts, as returned by lgetfilecon(3) */
  69         char            *context;       /* selinux contexts, as set by lgetfilecon(3) */
  70 #endif
  71 };
  72
  73 static int flags;
  74 static struct idcache *gcache;  /* groupnames */
  75 static struct idcache *ucache;  /* usernames */
  76
  77 static void
  78 free_namei(struct namei *nm)
  79 {
  80         while (nm) {
  81                 struct namei *next = nm->next;
  82 #ifdef HAVE_LIBSELINUX
  83                 free(nm->context);
  84 #endif
  85                 free(nm->name);
  86                 free(nm->abslink);
  87                 free(nm);
  88                 nm = next;
  89         }
  90 }
  91
  92 static void
  93 readlink_to_namei(struct namei *nm, const char *path)
  94 {
  95         char sym[PATH_MAX];
  96         ssize_t sz;
  97         int isrel = 0;
  98
  99         sz = readlink(path, sym, sizeof(sym));
 100         if (sz < 1)
 101                 err(EXIT_FAILURE, _("failed to read symlink: %s"), path);
 102         if (*sym != '/') {
 103                 char *p = strrchr(path, '/');
 104
 105                 if (p) {
 106                         isrel = 1;
 107                         nm->relstart = p - path;
 108                         sz += nm->relstart + 1;
 109                 }
 110         }
 111         nm->abslink = xmalloc(sz + 1);
 112
 113         if (isrel) {
 114                 /* create the absolute path from the relative symlink */
 115                 memcpy(nm->abslink, path, nm->relstart);
 116                 *(nm->abslink + nm->relstart) = '/';
 117                 nm->relstart++;
 118                 memcpy(nm->abslink + nm->relstart, sym, sz - nm->relstart);
 119         } else
 120                 /* - absolute link (foo -> /path/bar)
 121                  * - or link without any subdir (foo -> bar)
 122                  */
 123                 memcpy(nm->abslink, sym, sz);
 124
 125         nm->abslink[sz] = '\0';
 126 }
 127
 128 static struct stat *
 129 dotdot_stat(const char *dirname, struct stat *st)
 130 {
 131         char *path;
 132         size_t len;
 133
 134 #define DOTDOTDIR       "/.."
 135
 136         if (!dirname)
 137                 return NULL;
 138
 139         len = strlen(dirname);
 140         path = xmalloc(len + sizeof(DOTDOTDIR));
 141
 142         memcpy(path, dirname, len);
 143         memcpy(path + len, DOTDOTDIR, sizeof(DOTDOTDIR));
 144
 145         if (stat(path, st))
 146                 err(EXIT_FAILURE, _("stat of %s failed"), path);
 147         free(path);
 148         return st;
 149 }
 150
 151 static struct namei *
 152 new_namei(struct namei *parent, const char *path, const char *fname, int lev)
 153 {
 154         struct namei *nm;
 155
 156         if (!fname)
 157                 return NULL;
 158         nm = xcalloc(1, sizeof(*nm));
 159         if (parent)
 160                 parent->next = nm;
 161
 162         nm->level = lev;
 163         nm->name = xstrdup(fname);
 164
 165 #ifdef HAVE_LIBSELINUX
 166         /* Don't use is_selinux_enabled() here. We need info about a context
 167          * also on systems where SELinux is (temporary) disabled */
 168         nm->context_len = lgetfilecon(path, &nm->context);
 169 #endif
 170         if (lstat(path, &nm->st) != 0) {
 171                 nm->noent = errno;
 172                 return nm;
 173         }
 174
 175         if (S_ISLNK(nm->st.st_mode))
 176                 readlink_to_namei(nm, path);
 177         if (flags & NAMEI_OWNERS) {
 178                 add_uid(ucache, nm->st.st_uid);
 179                 add_gid(gcache, nm->st.st_gid);
 180         }
 181
 182         if ((flags & NAMEI_MNTS) && S_ISDIR(nm->st.st_mode)) {
 183                 struct stat stbuf, *sb = NULL;
 184
 185                 if (parent && S_ISDIR(parent->st.st_mode))
 186                         sb = &parent->st;
 187                 else if (!parent || S_ISLNK(parent->st.st_mode))
 188                         sb = dotdot_stat(path, &stbuf);
 189
 190                 if (sb && (sb->st_dev != nm->st.st_dev ||   /* different device */
 191                            sb->st_ino == nm->st.st_ino))    /* root directory */
 192                         nm->mountpoint = 1;
 193         }
 194
 195         return nm;
 196 }
 197
 198 static struct namei *
 199 add_namei(struct namei *parent, const char *orgpath, int start, struct namei **last)
 200 {
 201         struct namei *nm = NULL, *first = NULL;
 202         char *fname, *end, *path;
 203         int level = 0;
 204
 205         if (!orgpath)
 206                 return NULL;
 207         if (parent) {
 208                 nm = parent;
 209                 level = parent->level + 1;
 210         }
 211         path = xstrdup(orgpath);
 212         fname = path + start;
 213
 214         /* root directory */
 215         if (*fname == '/') {
 216                 while (*fname == '/')
 217                         fname++; /* eat extra '/' */
 218                 first = nm = new_namei(nm, "/", "/", level);
 219         }
 220
 221         for (end = fname; fname && end; ) {
 222                 /* set end of filename */
 223                 if (*fname) {
 224                         end = strchr(fname, '/');
 225                         if (end)
 226                                 *end = '\0';
 227
 228                         /* create a new entry */
 229                         nm = new_namei(nm, path, fname, level);
 230                 } else
 231                         end = NULL;
 232                 if (!first)
 233                         first = nm;
 234                 /* set begin of the next filename */
 235                 if (end) {
 236                         *end++ = '/';
 237                         while (*end == '/')
 238                                 end++; /* eat extra '/' */
 239                 }
 240                 fname = end;
 241         }
 242
 243         if (last)
 244                 *last = nm;
 245
 246         free(path);
 247
 248         return first;
 249 }
 250
 251 static int
 252 follow_symlinks(struct namei *nm)
 253 {
 254         int symcount = 0;
 255
 256         for (; nm; nm = nm->next) {
 257                 struct namei *next, *last;
 258
 259                 if (nm->noent)
 260                         continue;
 261                 if (!S_ISLNK(nm->st.st_mode))
 262                         continue;
 263                 if (++symcount > MAXSYMLINKS) {
 264                         /* drop the rest of the list */
 265                         free_namei(nm->next);
 266                         nm->next = NULL;
 267                         return -1;
 268                 }
 269                 next = nm->next;
 270                 nm->next = add_namei(nm, nm->abslink, nm->relstart, &last);
 271                 if (last)
 272                         last->next = next;
 273                 else
 274                         nm->next = next;
 275         }
 276         return 0;
 277 }
 278
 279 static int
 280 print_namei(struct namei *nm, char *path)
 281 {
 282         int i;
 283
 284         if (path)
 285                 printf("f: %s\n", path);
 286
 287         for (; nm; nm = nm->next) {
 288                 char md[11];
 289
 290                 if (nm->noent) {
 291                         int blanks = 1;
 292                         if (flags & NAMEI_MODES)
 293                                 blanks += 9;
 294                         if (flags & NAMEI_OWNERS)
 295                                 blanks += ucache->width + gcache->width + 2;
 296                         if (!(flags & NAMEI_VERTICAL))
 297                                 blanks += 1;
 298                         if (!(flags & NAMEI_CONTEXT))
 299                                 blanks += 1;
 300                         blanks += nm->level * 2;
 301                         printf("%*s ", blanks, "");
 302                         printf("%s - %s\n", nm->name, strerror(nm->noent));
 303                         return -1;
 304                 }
 305
 306                 xstrmode(nm->st.st_mode, md);
 307
 308                 if (nm->mountpoint)
 309                         md[0] = 'D';
 310
 311                 if (!(flags & NAMEI_VERTICAL)) {
 312                         for (i = 0; i < nm->level; i++)
 313                                 fputs("  ", stdout);
 314                         fputc(' ', stdout);
 315                 }
 316
 317                 if (flags & NAMEI_MODES)
 318                         printf("%s", md);
 319                 else
 320                         printf("%c", md[0]);
 321
 322                 if (flags & NAMEI_OWNERS) {
 323                         printf(" %-*s", ucache->width,
 324                                 get_id(ucache, nm->st.st_uid)->name);
 325                         printf(" %-*s", gcache->width,
 326                                 get_id(gcache, nm->st.st_gid)->name);
 327                 }
 328 #ifdef HAVE_LIBSELINUX
 329                 if (flags & NAMEI_CONTEXT) {
 330                         if (nm->context)
 331                                 printf(" %-*s", nm->context_len, nm->context);
 332                         else
 333                                 printf(" ?");
 334                 }
 335 #endif
 336                 if (flags & NAMEI_VERTICAL)
 337                         for (i = 0; i < nm->level; i++)
 338                                 fputs("  ", stdout);
 339
 340                 if (S_ISLNK(nm->st.st_mode))
 341                         printf(" %s -> %s\n", nm->name,
 342                                         nm->abslink + nm->relstart);
 343                 else
 344                         printf(" %s\n", nm->name);
 345         }
 346         return 0;
 347 }
 348
 349 static void __attribute__((__noreturn__)) usage(void)
 350 {
 351         const char *p = program_invocation_short_name;
 352         FILE *out = stdout;
 353
 354         if (!*p)
 355                 p = "namei";
 356
 357         fputs(USAGE_HEADER, out);
 358         fprintf(out,
 359               _(" %s [options] <pathname>...\n"), p);
 360
 361         fputs(USAGE_SEPARATOR, out);
 362         fputs(_("Follow a pathname until a terminal point is found.\n"), out);
 363
 364         fputs(USAGE_OPTIONS, out);
 365         fputs(_(
 366                 " -x, --mountpoints   show mount point directories with a 'D'\n"
 367                 " -m, --modes         show the mode bits of each file\n"
 368                 " -o, --owners        show owner and group name of each file\n"
 369                 " -l, --long          use a long listing format (-m -o -v) \n"
 370                 " -n, --nosymlinks    don't follow symlinks\n"
 371                 " -v, --vertical      vertical align of modes and owners\n"), out);
 372 #ifdef HAVE_LIBSELINUX
 373         fputs(_( " -Z, --context       print any security context of each file \n"), out);
 374 #endif
 375
 376         fprintf(out, USAGE_HELP_OPTIONS(21));
 377
 378         fprintf(out, USAGE_MAN_TAIL("namei(1)"));
 379         exit(EXIT_SUCCESS);
 380 }
 381
 382 static const struct option longopts[] =
 383 {
 384         { "help",        no_argument, NULL, 'h' },
 385         { "version",     no_argument, NULL, 'V' },
 386         { "mountpoints", no_argument, NULL, 'x' },
 387         { "modes",       no_argument, NULL, 'm' },
 388         { "owners",      no_argument, NULL, 'o' },
 389         { "long",        no_argument, NULL, 'l' },
 390         { "nolinks",     no_argument, NULL, 'n' },
 391         { "vertical",    no_argument, NULL, 'v' },
 392 #ifdef HAVE_LIBSELINUX
 393         { "context",     no_argument, NULL, 'Z' },
 394 #endif
 395         { NULL, 0, NULL, 0 },
 396 };
 397
 398 int
 399 main(int argc, char **argv)
 400 {
 401         int c;
 402         int rc = EXIT_SUCCESS;
 403         static const char *shortopts =
 404 #ifdef HAVE_LIBSELINUX
 405                 "Z"
 406 #endif
 407                 "hVlmnovx";
 408
 409         setlocale(LC_ALL, "");
 410         bindtextdomain(PACKAGE, LOCALEDIR);
 411         textdomain(PACKAGE);
 412         close_stdout_atexit();
 413
 414         while ((c = getopt_long(argc, argv, shortopts, longopts, NULL)) != -1) {
 415                 switch(c) {
 416                 case 'l':
 417                         flags |= (NAMEI_OWNERS | NAMEI_MODES | NAMEI_VERTICAL);
 418                         break;
 419                 case 'm':
 420                         flags |= NAMEI_MODES;
 421                         break;
 422                 case 'n':
 423                         flags |= NAMEI_NOLINKS;
 424                         break;
 425                 case 'o':
 426                         flags |= NAMEI_OWNERS;
 427                         break;
 428                 case 'x':
 429                         flags |= NAMEI_MNTS;
 430                         break;
 431                 case 'v':
 432                         flags |= NAMEI_VERTICAL;
 433                         break;
 434 #ifdef HAVE_LIBSELINUX
 435                 case 'Z':
 436                         flags |= NAMEI_CONTEXT;
 437                         break;
 438 #endif
 439                 case 'h':
 440                         usage();
 441                 case 'V':
 442                         print_version(EXIT_SUCCESS);
 443                 default:
 444                         errtryhelp(EXIT_FAILURE);
 445                 }
 446         }
 447
 448         if (optind == argc) {
 449                 warnx(_("pathname argument is missing"));
 450                 errtryhelp(EXIT_FAILURE);
 451         }
 452
 453         ucache = new_idcache();
 454         if (!ucache)
 455                 err(EXIT_FAILURE, _("failed to allocate UID cache"));
 456         gcache = new_idcache();
 457         if (!gcache)
 458                 err(EXIT_FAILURE, _("failed to allocate GID cache"));
 459
 460         for(; optind < argc; optind++) {
 461                 char *path = argv[optind];
 462                 struct namei *nm = NULL;
 463                 struct stat st;
 464
 465                 if (stat(path, &st) != 0)
 466                         rc = EXIT_FAILURE;
 467
 468                 nm = add_namei(NULL, path, 0, NULL);
 469                 if (nm) {
 470                         int sml = 0;
 471                         if (!(flags & NAMEI_NOLINKS))
 472                                 sml = follow_symlinks(nm);
 473                         if (print_namei(nm, path)) {
 474                                 rc = EXIT_FAILURE;
 475                                 continue;
 476                         }
 477                         free_namei(nm);
 478                         if (sml == -1) {
 479                                 rc = EXIT_FAILURE;
 480                                 warnx(_("%s: exceeded limit of symlinks"), path);
 481                                 continue;
 482                         }
 483                 }
 484         }
 485
 486         free_idcache(ucache);
 487         free_idcache(gcache);
 488
 489         return rc;
 490 }