util/symlinks.c

   1 #define _FILE_OFFSET_BITS 64
   2 #define _LARGEFILE_SOURCE
   3 #define _LARGEFILE64_SOURCE
   4
   5 #include <unistd.h>
   6 #ifndef _POSIX_SOURCE
   7 #define _POSIX_SOURCE
   8 #endif
   9 #include <stdio.h>
  10 #include <stdlib.h>
  11 #ifdef HAVE_MALLOC_H
  12 #include <malloc.h>
  13 #endif
  14 #include <string.h>
  15 #include <fcntl.h>
  16 #include <sys/param.h>
  17 #include <sys/types.h>
  18 #include <sys/stat.h>
  19 #include <dirent.h>
  20 #include <time.h>
  21 #include <stddef.h>
  22 #include <errno.h>
  23
  24 #ifndef S_ISLNK
  25 #define S_ISLNK(mode) (((mode) & (_S_IFMT)) == (_S_IFLNK))
  26 #endif
  27
  28 #ifndef PATH_MAX
  29 #define PATH_MAX 1024
  30 #endif
  31
  32 #define progver "%s: scan/change symbolic links - v1.3 - by Mark Lord\n\n"
  33 static char *progname;
  34 static int verbose = 0, fix_links = 0, recurse = 0, delete = 0, shorten = 0,
  35                 testing = 0, single_fs = 1;
  36
  37 /*
  38  * tidypath removes excess slashes and "." references from a path string
  39  */
  40
  41 static int substr (char *s, char *old, char *new)
  42 {
  43         char *tmp = NULL;
  44         int oldlen = strlen(old), newlen = 0;
  45
  46         if (NULL == strstr(s, old))
  47                 return 0;
  48
  49         if (new)
  50                 newlen = strlen(new);
  51
  52         if (newlen > oldlen) {
  53                 if ((tmp = malloc(strlen(s))) == NULL) {
  54                         fprintf(stderr, "no memory\n");
  55                         exit (1);
  56                 }
  57         }
  58
  59         while (NULL != (s = strstr(s, old))) {
  60                 char *p, *old_s = s;
  61
  62                 if (new) {
  63                         if (newlen > oldlen)
  64                                 old_s = strcpy(tmp, s);
  65                         p = new;
  66                         while (*p)
  67                                 *s++ = *p++;
  68                 }
  69                 p = old_s + oldlen;
  70                 while ((*s++ = *p++));
  71         }
  72         if (tmp)
  73                 free(tmp);
  74         return 1;
  75 }
  76
  77
  78 static int tidy_path (char *path)
  79 {
  80         int tidied = 0;
  81         char *s, *p;
  82
  83         s = path + strlen(path) - 1;
  84         if (s[0] != '/') {      /* tmp trailing slash simplifies things */
  85                 s[1] = '/';
  86                 s[2] = '\0';
  87         }
  88         while (substr(path, "/./", "/"))
  89                 tidied = 1;
  90         while (substr(path, "//", "/"))
  91                 tidied = 1;
  92
  93         while ((p = strstr(path,"/../")) != NULL) {
  94                 s = p+3;
  95                 for (p--; p != path; p--) if (*p == '/') break;
  96                 if (*p != '/')
  97                         break;
  98                 while ((*p++ = *s++));
  99                 tidied = 1;
 100         }
 101         if (*path == '\0')
 102                 strcpy(path,"/");
 103         p = path + strlen(path) - 1;
 104         if (p != path && *p == '/')
 105                 *p-- = '\0';    /* remove tmp trailing slash */
 106         while (p != path && *p == '/') {        /* remove any others */
 107                 *p-- = '\0';
 108                 tidied = 1;
 109         }
 110         while (!strncmp(path,"./",2)) {
 111                 for (p = path, s = path+2; (*p++ = *s++););
 112                 tidied = 1;
 113         }
 114         return tidied;
 115 }
 116
 117 static int shorten_path (char *path, char *abspath)
 118 {
 119         static char dir[PATH_MAX];
 120         int shortened = 0;
 121         char *p;
 122
 123         /* get rid of unnecessary "../dir" sequences */
 124         while (abspath && strlen(abspath) > 1 && (p = strstr(path,"../"))) {
 125                 /* find innermost occurance of "../dir", and save "dir" */
 126                 int slashes = 2;
 127                 char *a, *s, *d = dir;
 128                 while ((s = strstr(p+3, "../"))) {
 129                         ++slashes;
 130                         p = s;
 131                 }
 132                 s = p+3;
 133                 *d++ = '/';
 134                 while (*s && *s != '/')
 135                         *d++ = *s++;
 136                 *d++ = '/';
 137                 *d = '\0';
 138                 if (!strcmp(dir,"//"))
 139                         break;
 140                 /* note: p still points at ../dir */
 141                 if (*s != '/' || !*++s)
 142                         break;
 143                 a = abspath + strlen(abspath) - 1;
 144                 while (slashes-- > 0) {
 145                         if (a <= abspath)
 146                                 goto ughh;
 147                         while (*--a != '/') {
 148                                 if (a <= abspath)
 149                                         goto ughh;
 150                         }
 151                 }
 152                 if (strncmp(dir, a, strlen(dir)))
 153                         break;
 154                 while ((*p++ = *s++)); /* delete the ../dir */
 155                 shortened = 1;
 156         }
 157 ughh:
 158         return shortened;
 159 }
 160
 161
 162 static void fix_symlink (char *path, dev_t my_dev)
 163 {
 164         static char lpath[PATH_MAX], new[PATH_MAX], abspath[PATH_MAX];
 165         char *p, *np, *lp, *tail, *msg;
 166         struct stat stbuf, lstbuf;
 167         int c, fix_abs = 0, fix_messy = 0, fix_long = 0;
 168
 169         if ((c = readlink(path, lpath, sizeof(lpath))) == -1) {
 170                 perror(path);
 171                 return;
 172         }
 173         lpath[c] = '\0';        /* readlink does not null terminate it */
 174
 175         /* construct the absolute address of the link */
 176         abspath[0] = '\0';
 177         if (lpath[0] != '/') {
 178                 strcat(abspath,path);
 179                 c = strlen(abspath);
 180                 if ((c > 0) && (abspath[c-1] == '/'))
 181                         abspath[c-1] = '\0'; /* cut trailing / */
 182                 if ((p = strrchr(abspath,'/')) != NULL)
 183                         *p = '\0'; /* cut last component */
 184                 strcat(abspath,"/");
 185         }
 186         strcat(abspath,lpath);
 187         (void) tidy_path(abspath);
 188
 189         /* check for various things */
 190         if (stat(abspath, &stbuf) == -1) {
 191                 printf("dangling: %s -> %s\n", path, lpath);
 192                 if (delete) {
 193                         if (unlink (path)) {
 194                                 perror(path);
 195                         } else
 196                                 printf("deleted:  %s -> %s\n", path, lpath);
 197                 }
 198                 return;
 199         }
 200
 201         if (single_fs)
 202                 lstat(abspath, &lstbuf); /* if the above didn't fail, then this shouldn't */
 203
 204         if (single_fs && lstbuf.st_dev != my_dev) {
 205                 msg = "other_fs:";
 206         } else if (lpath[0] == '/') {
 207                 msg = "absolute:";
 208                 fix_abs = 1;
 209         } else if (verbose) {
 210                 msg = "relative:";
 211         } else
 212                 msg = NULL;
 213         fix_messy = tidy_path(strcpy(new,lpath));
 214         if (shorten)
 215                 fix_long = shorten_path(new, path);
 216         if (!fix_abs) {
 217                 if (fix_messy)
 218                         msg = "messy:   ";
 219                 else if (fix_long)
 220                         msg = "lengthy: ";
 221         }
 222         if (msg != NULL)
 223                 printf("%s %s -> %s\n", msg, path, lpath);
 224         if (!(fix_links || testing) || !(fix_messy || fix_abs || fix_long))
 225                 return;
 226
 227         if (fix_abs) {
 228                 /* convert an absolute link to relative: */
 229                 /* point tail at first part of lpath that differs from path */
 230                 /* point p    at first part of path  that differs from lpath */
 231                 (void) tidy_path(lpath);
 232                 tail = lp = lpath;
 233                 p = path;
 234                 while (*p && (*p == *lp)) {
 235                         if (*lp++ == '/') {
 236                                 tail = lp;
 237                                 while (*++p == '/');
 238                         }
 239                 }
 240
 241                 /* now create new, with "../"s followed by tail */
 242                 np = new;
 243                 while (*p) {
 244                         if (*p++ == '/') {
 245                                 *np++ = '.';
 246                                 *np++ = '.';
 247                                 *np++ = '/';
 248                                 while (*p == '/') ++p;
 249                         }
 250                 }
 251                 strcpy (np, tail);
 252                 (void) tidy_path(new);
 253                 if (shorten) (void) shorten_path(new, path);
 254         }
 255         shorten_path(new,path);
 256         if (!testing) {
 257                 if (unlink (path)) {
 258                         perror(path);
 259                         return;
 260                 }
 261                 if (symlink(new, path)) {
 262                         perror(path);
 263                         return;
 264                 }
 265         }
 266         printf("changed:  %s -> %s\n", path, new);
 267 }
 268
 269 static void dirwalk (char *path, int pathlen, dev_t dev)
 270 {
 271         char *name;
 272         DIR *dfd;
 273         static struct stat st;
 274         static struct dirent *dp;
 275
 276         if ((dfd = opendir(path)) == NULL) {
 277                 perror(path);
 278                 return;
 279         }
 280
 281         name = path + pathlen;
 282         if (*(name-1) != '/')
 283                 *name++ = '/';
 284
 285         while ((dp = readdir(dfd)) != NULL ) {
 286                 strcpy(name, dp->d_name);
 287                 if (strcmp(name, ".") && strcmp(name,"..")) {
 288                         if (lstat(path, &st) == -1) {
 289                                 perror(path);
 290                         } else if (st.st_dev == dev) {
 291                                 if (S_ISLNK(st.st_mode)) {
 292                                         fix_symlink (path, dev);
 293                                 } else if (recurse && S_ISDIR(st.st_mode)) {
 294                                         dirwalk(path, strlen(path), dev);
 295                                 }
 296                         }
 297                 }
 298         }
 299         closedir(dfd);
 300         path[pathlen] = '\0';
 301 }
 302
 303 static void usage_error (void)
 304 {
 305         fprintf(stderr, progver, progname);
 306         fprintf(stderr, "Usage:\t%s [-cdorstv] LINK|DIR ...\n\n", progname);
 307         fprintf(stderr, "Flags:"
 308                 "\t-c == change absolute/messy links to relative\n"
 309                 "\t-d == delete dangling links\n"
 310                 "\t-o == warn about links across file systems\n"
 311                 "\t-r == recurse into subdirs\n"
 312                 "\t-s == shorten lengthy links (displayed in output only when -c not specified)\n"
 313                 "\t-t == show what would be done by -c\n"
 314                 "\t-v == verbose (show all symlinks)\n\n");
 315         exit(1);
 316 }
 317
 318 int main(int argc, char **argv)
 319 {
 320 #if defined (_GNU_SOURCE) && defined (__GLIBC__)
 321         static char path[PATH_MAX+2];
 322         char* cwd = get_current_dir_name();
 323 #else
 324         static char path[PATH_MAX+2], cwd[PATH_MAX+2];
 325 #endif
 326         int dircount = 0;
 327         char c, *p;
 328
 329         if  ((progname = (char *) strrchr(*argv, '/')) == NULL)
 330                 progname = *argv;
 331         else
 332                 progname++;
 333
 334 #if defined (_GNU_SOURCE) && defined (__GLIBC__)
 335         if (NULL == cwd) {
 336                 fprintf(stderr,"get_current_dir_name() failed\n");
 337 #else
 338         if (NULL == getcwd(cwd,PATH_MAX)) {
 339                 fprintf(stderr,"getcwd() failed\n");
 340 #endif
 341                 exit (1);
 342         }
 343 #if defined (_GNU_SOURCE) && defined (__GLIBC__)
 344         cwd = realloc(cwd, strlen(cwd)+2);
 345         if (cwd == NULL) {
 346                 fprintf(stderr, "realloc() failed\n");
 347                 exit (1);
 348         }
 349 #endif
 350         if (!*cwd || cwd[strlen(cwd)-1] != '/')
 351                 strcat(cwd,"/");
 352
 353         while (--argc) {
 354                 p = *++argv;
 355                 if (*p == '-') {
 356                         if (*++p == '\0')
 357                                 usage_error();
 358                         while ((c = *p++)) {
 359                                      if (c == 'c')      fix_links = 1;
 360                                 else if (c == 'd')      delete    = 1;
 361                                 else if (c == 'o')      single_fs = 0;
 362                                 else if (c == 'r')      recurse   = 1;
 363                                 else if (c == 's')      shorten   = 1;
 364                                 else if (c == 't')      testing   = 1;
 365                                 else if (c == 'v')      verbose   = 1;
 366                                 else                    usage_error();
 367                         }
 368                 } else {
 369                         struct stat st;
 370                         if (*p == '/')
 371                                 *path = '\0';
 372                         else
 373                                 strcpy(path,cwd);
 374                         tidy_path(strcat(path, p));
 375                         if (lstat(path, &st) == -1)
 376                                 perror(path);
 377                         else if (S_ISLNK(st.st_mode))
 378                                 fix_symlink(path, st.st_dev);
 379                         else
 380                                 dirwalk(path, strlen(path), st.st_dev);
 381                         ++dircount;
 382                 }
 383         }
 384         if (dircount == 0)
 385                 usage_error();
 386         exit (0);
 387 }