util/symlinks.c

   1 #define _FILE_OFFSET_BITS 64
   2 #ifndef _LARGEFILE_SOURCE
   3 #define _LARGEFILE_SOURCE
   4 #endif
   5 #ifndef _LARGEFILE64_SOURCE
   6 #define _LARGEFILE64_SOURCE
   7 #endif
   8
   9 #include <unistd.h>
  10 #ifndef _POSIX_SOURCE
  11 #define _POSIX_SOURCE
  12 #endif
  13 #include <stdio.h>
  14 #include <stdlib.h>
  15 #ifdef HAVE_MALLOC_H
  16 #include <malloc.h>
  17 #endif
  18 #include <string.h>
  19 #include <fcntl.h>
  20 #include <sys/param.h>
  21 #include <sys/types.h>
  22 #include <sys/stat.h>
  23 #include <dirent.h>
  24 #include <time.h>
  25 #include <stddef.h>
  26 #include <errno.h>
  27
  28 #ifndef S_ISLNK
  29 #define S_ISLNK(mode) (((mode) & (_S_IFMT)) == (_S_IFLNK))
  30 #endif
  31
  32 #ifndef PATH_MAX
  33 #define PATH_MAX 1024
  34 #endif
  35
  36 #define progver "%s: scan/change symbolic links - v1.3 - by Mark Lord\n\n"
  37 static char *progname;
  38 static int verbose = 0, fix_links = 0, recurse = 0, delete = 0, shorten = 0,
  39                 testing = 0, single_fs = 1;
  40
  41 /*
  42  * tidypath removes excess slashes and "." references from a path string
  43  */
  44
  45 static int substr (char *s, char *old, char *new)
  46 {
  47         char *tmp = NULL;
  48         int oldlen = strlen(old), newlen = 0;
  49
  50         if (NULL == strstr(s, old))
  51                 return 0;
  52
  53         if (new)
  54                 newlen = strlen(new);
  55
  56         if (newlen > oldlen) {
  57                 if ((tmp = malloc(strlen(s))) == NULL) {
  58                         fprintf(stderr, "no memory\n");
  59                         exit (1);
  60                 }
  61         }
  62
  63         while (NULL != (s = strstr(s, old))) {
  64                 char *p, *old_s = s;
  65
  66                 if (new) {
  67                         if (newlen > oldlen)
  68                                 old_s = strcpy(tmp, s);
  69                         p = new;
  70                         while (*p)
  71                                 *s++ = *p++;
  72                 }
  73                 p = old_s + oldlen;
  74                 while ((*s++ = *p++));
  75         }
  76         if (tmp)
  77                 free(tmp);
  78         return 1;
  79 }
  80
  81
  82 static int tidy_path (char *path)
  83 {
  84         int tidied = 0;
  85         char *s, *p;
  86
  87         s = path + strlen(path) - 1;
  88         if (s[0] != '/') {      /* tmp trailing slash simplifies things */
  89                 s[1] = '/';
  90                 s[2] = '\0';
  91         }
  92         while (substr(path, "/./", "/"))
  93                 tidied = 1;
  94         while (substr(path, "//", "/"))
  95                 tidied = 1;
  96
  97         while ((p = strstr(path,"/../")) != NULL) {
  98                 s = p+3;
  99                 for (p--; p != path; p--) if (*p == '/') break;
 100                 if (*p != '/')
 101                         break;
 102                 while ((*p++ = *s++));
 103                 tidied = 1;
 104         }
 105         if (*path == '\0')
 106                 strcpy(path,"/");
 107         p = path + strlen(path) - 1;
 108         if (p != path && *p == '/')
 109                 *p-- = '\0';    /* remove tmp trailing slash */
 110         while (p != path && *p == '/') {        /* remove any others */
 111                 *p-- = '\0';
 112                 tidied = 1;
 113         }
 114         while (!strncmp(path,"./",2)) {
 115                 for (p = path, s = path+2; (*p++ = *s++););
 116                 tidied = 1;
 117         }
 118         return tidied;
 119 }
 120
 121 static int shorten_path (char *path, char *abspath)
 122 {
 123         static char dir[PATH_MAX];
 124         int shortened = 0;
 125         char *p;
 126
 127         /* get rid of unnecessary "../dir" sequences */
 128         while (abspath && strlen(abspath) > 1 && (p = strstr(path,"../"))) {
 129                 /* find innermost occurrence of "../dir", and save "dir" */
 130                 int slashes = 2;
 131                 char *a, *s, *d = dir;
 132                 while ((s = strstr(p+3, "../"))) {
 133                         ++slashes;
 134                         p = s;
 135                 }
 136                 s = p+3;
 137                 *d++ = '/';
 138                 while (*s && *s != '/')
 139                         *d++ = *s++;
 140                 *d++ = '/';
 141                 *d = '\0';
 142                 if (!strcmp(dir,"//"))
 143                         break;
 144                 /* note: p still points at ../dir */
 145                 if (*s != '/' || !*++s)
 146                         break;
 147                 a = abspath + strlen(abspath) - 1;
 148                 while (slashes-- > 0) {
 149                         if (a <= abspath)
 150                                 goto ughh;
 151                         while (*--a != '/') {
 152                                 if (a <= abspath)
 153                                         goto ughh;
 154                         }
 155                 }
 156                 if (strncmp(dir, a, strlen(dir)))
 157                         break;
 158                 while ((*p++ = *s++)); /* delete the ../dir */
 159                 shortened = 1;
 160         }
 161 ughh:
 162         return shortened;
 163 }
 164
 165
 166 static void fix_symlink (char *path, dev_t my_dev)
 167 {
 168         static char lpath[PATH_MAX], new[PATH_MAX], abspath[PATH_MAX];
 169         char *p, *np, *lp, *tail, *msg;
 170         struct stat stbuf, lstbuf;
 171         int c, fix_abs = 0, fix_messy = 0, fix_long = 0;
 172
 173         if ((c = readlink(path, lpath, sizeof(lpath) - 1)) == -1) {
 174                 perror(path);
 175                 return;
 176         }
 177         lpath[c] = '\0';        /* readlink does not null terminate it */
 178
 179         /* construct the absolute address of the link */
 180         abspath[0] = '\0';
 181         if (lpath[0] != '/') {
 182                 strcat(abspath,path);
 183                 c = strlen(abspath);
 184                 if ((c > 0) && (abspath[c-1] == '/'))
 185                         abspath[c-1] = '\0'; /* cut trailing / */
 186                 if ((p = strrchr(abspath,'/')) != NULL)
 187                         *p = '\0'; /* cut last component */
 188                 strcat(abspath,"/");
 189         }
 190         strcat(abspath,lpath);
 191         (void) tidy_path(abspath);
 192
 193         /* check for various things */
 194         if (stat(abspath, &stbuf) == -1) {
 195                 printf("dangling: %s -> %s\n", path, lpath);
 196                 if (delete) {
 197                         if (unlink (path)) {
 198                                 perror(path);
 199                         } else
 200                                 printf("deleted:  %s -> %s\n", path, lpath);
 201                 }
 202                 return;
 203         }
 204
 205         if (single_fs)
 206                 lstat(abspath, &lstbuf); /* if the above didn't fail, then this shouldn't */
 207
 208         if (single_fs && lstbuf.st_dev != my_dev) {
 209                 msg = "other_fs:";
 210         } else if (lpath[0] == '/') {
 211                 msg = "absolute:";
 212                 fix_abs = 1;
 213         } else if (verbose) {
 214                 msg = "relative:";
 215         } else
 216                 msg = NULL;
 217         fix_messy = tidy_path(strcpy(new,lpath));
 218         if (shorten)
 219                 fix_long = shorten_path(new, path);
 220         if (!fix_abs) {
 221                 if (fix_messy)
 222                         msg = "messy:   ";
 223                 else if (fix_long)
 224                         msg = "lengthy: ";
 225         }
 226         if (msg != NULL)
 227                 printf("%s %s -> %s\n", msg, path, lpath);
 228         if (!(fix_links || testing) || !(fix_messy || fix_abs || fix_long))
 229                 return;
 230
 231         if (fix_abs) {
 232                 /* convert an absolute link to relative: */
 233                 /* point tail at first part of lpath that differs from path */
 234                 /* point p    at first part of path  that differs from lpath */
 235                 (void) tidy_path(lpath);
 236                 tail = lp = lpath;
 237                 p = path;
 238                 while (*p && (*p == *lp)) {
 239                         if (*lp++ == '/') {
 240                                 tail = lp;
 241                                 while (*++p == '/');
 242                         }
 243                 }
 244
 245                 /* now create new, with "../"s followed by tail */
 246                 np = new;
 247                 while (*p) {
 248                         if (*p++ == '/') {
 249                                 *np++ = '.';
 250                                 *np++ = '.';
 251                                 *np++ = '/';
 252                                 while (*p == '/') ++p;
 253                         }
 254                 }
 255                 strcpy (np, tail);
 256                 (void) tidy_path(new);
 257                 if (shorten) (void) shorten_path(new, path);
 258         }
 259         shorten_path(new,path);
 260         if (!testing) {
 261                 if (unlink (path)) {
 262                         perror(path);
 263                         return;
 264                 }
 265                 if (symlink(new, path)) {
 266                         perror(path);
 267                         return;
 268                 }
 269         }
 270         printf("changed:  %s -> %s\n", path, new);
 271 }
 272
 273 static void dirwalk (char *path, int pathlen, dev_t dev)
 274 {
 275         char *name;
 276         DIR *dfd;
 277         static struct stat st;
 278         static struct dirent *dp;
 279
 280         if ((dfd = opendir(path)) == NULL) {
 281                 perror(path);
 282                 return;
 283         }
 284
 285         name = path + pathlen;
 286         if (*(name-1) != '/')
 287                 *name++ = '/';
 288
 289         while ((dp = readdir(dfd)) != NULL ) {
 290                 strcpy(name, dp->d_name);
 291                 if (strcmp(name, ".") && strcmp(name,"..")) {
 292                         if (lstat(path, &st) == -1) {
 293                                 perror(path);
 294                         } else if (st.st_dev == dev) {
 295                                 if (S_ISLNK(st.st_mode)) {
 296                                         fix_symlink (path, dev);
 297                                 } else if (recurse && S_ISDIR(st.st_mode)) {
 298                                         dirwalk(path, strlen(path), dev);
 299                                 }
 300                         }
 301                 }
 302         }
 303         closedir(dfd);
 304         path[pathlen] = '\0';
 305 }
 306
 307 static void usage_error (void)
 308 {
 309         fprintf(stderr, progver, progname);
 310         fprintf(stderr, "Usage:\t%s [-cdorstv] LINK|DIR ...\n\n", progname);
 311         fprintf(stderr, "Flags:"
 312                 "\t-c == change absolute/messy links to relative\n"
 313                 "\t-d == delete dangling links\n"
 314                 "\t-o == warn about links across file systems\n"
 315                 "\t-r == recurse into subdirs\n"
 316                 "\t-s == shorten lengthy links (displayed in output only when -c not specified)\n"
 317                 "\t-t == show what would be done by -c\n"
 318                 "\t-v == verbose (show all symlinks)\n\n");
 319         exit(1);
 320 }
 321
 322 int main(int argc, char **argv)
 323 {
 324 #if defined (_GNU_SOURCE) && defined (__GLIBC__)
 325         static char path[PATH_MAX+2];
 326         char* cwd = get_current_dir_name();
 327 #else
 328         static char path[PATH_MAX+2], cwd[PATH_MAX+2];
 329 #endif
 330         int dircount = 0;
 331         char c, *p;
 332
 333         if  ((progname = (char *) strrchr(*argv, '/')) == NULL)
 334                 progname = *argv;
 335         else
 336                 progname++;
 337
 338 #if defined (_GNU_SOURCE) && defined (__GLIBC__)
 339         if (NULL == cwd) {
 340                 fprintf(stderr,"get_current_dir_name() failed\n");
 341 #else
 342         if (NULL == getcwd(cwd,PATH_MAX)) {
 343                 fprintf(stderr,"getcwd() failed\n");
 344 #endif
 345                 exit (1);
 346         }
 347 #if defined (_GNU_SOURCE) && defined (__GLIBC__)
 348         cwd = realloc(cwd, strlen(cwd)+2);
 349         if (cwd == NULL) {
 350                 fprintf(stderr, "realloc() failed\n");
 351                 exit (1);
 352         }
 353 #endif
 354         if (!*cwd || cwd[strlen(cwd)-1] != '/')
 355                 strcat(cwd,"/");
 356
 357         while (--argc) {
 358                 p = *++argv;
 359                 if (*p == '-') {
 360                         if (*++p == '\0')
 361                                 usage_error();
 362                         while ((c = *p++)) {
 363                                      if (c == 'c')      fix_links = 1;
 364                                 else if (c == 'd')      delete    = 1;
 365                                 else if (c == 'o')      single_fs = 0;
 366                                 else if (c == 'r')      recurse   = 1;
 367                                 else if (c == 's')      shorten   = 1;
 368                                 else if (c == 't')      testing   = 1;
 369                                 else if (c == 'v')      verbose   = 1;
 370                                 else                    usage_error();
 371                         }
 372                 } else {
 373                         struct stat st;
 374                         if (*p == '/')
 375                                 *path = '\0';
 376                         else
 377                                 strcpy(path,cwd);
 378                         tidy_path(strcat(path, p));
 379                         if (lstat(path, &st) == -1)
 380                                 perror(path);
 381                         else if (S_ISLNK(st.st_mode))
 382                                 fix_symlink(path, st.st_dev);
 383                         else
 384                                 dirwalk(path, strlen(path), st.st_dev);
 385                         ++dircount;
 386                 }
 387         }
 388         if (dircount == 0)
 389                 usage_error();
 390         exit (0);
 391 }