symlinks.c

   1 #include "cache.h"
   2
   3 struct pathname {
   4         int len;
   5         char path[PATH_MAX];
   6 };
   7
   8 /* Return matching pathname prefix length, or zero if not matching */
   9 static inline int match_pathname(int len, const char *name, struct pathname *match)
  10 {
  11         int match_len = match->len;
  12         return (len > match_len &&
  13                 name[match_len] == '/' &&
  14                 !memcmp(name, match->path, match_len)) ? match_len : 0;
  15 }
  16
  17 static inline void set_pathname(int len, const char *name, struct pathname *match)
  18 {
  19         if (len < PATH_MAX) {
  20                 match->len = len;
  21                 memcpy(match->path, name, len);
  22                 match->path[len] = 0;
  23         }
  24 }
  25
  26 int has_symlink_leading_path(int len, const char *name)
  27 {
  28         static struct pathname link, nonlink;
  29         char path[PATH_MAX];
  30         struct stat st;
  31         char *sp;
  32         int known_dir;
  33
  34         /*
  35          * See if the last known symlink cache matches.
  36          */
  37         if (match_pathname(len, name, &link))
  38                 return 1;
  39
  40         /*
  41          * Get rid of the last known directory part
  42          */
  43         known_dir = match_pathname(len, name, &nonlink);
  44
  45         while ((sp = strchr(name + known_dir + 1, '/')) != NULL) {
  46                 int thislen = sp - name ;
  47                 memcpy(path, name, thislen);
  48                 path[thislen] = 0;
  49
  50                 if (lstat(path, &st))
  51                         return 0;
  52                 if (S_ISDIR(st.st_mode)) {
  53                         set_pathname(thislen, path, &nonlink);
  54                         known_dir = thislen;
  55                         continue;
  56                 }
  57                 if (S_ISLNK(st.st_mode)) {
  58                         set_pathname(thislen, path, &link);
  59                         return 1;
  60                 }
  61                 break;
  62         }
  63         return 0;
  64 }