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