abspath.c

   1 #include "cache.h"
   2
   3 /*
   4  * Do not use this for inspecting *tracked* content.  When path is a
   5  * symlink to a directory, we do not want to say it is a directory when
   6  * dealing with tracked content in the working tree.
   7  */
   8 int is_directory(const char *path)
   9 {
  10         struct stat st;
  11         return (!stat(path, &st) && S_ISDIR(st.st_mode));
  12 }
  13
  14 /* We allow "recursive" symbolic links. Only within reason, though. */
  15 #define MAXDEPTH 5
  16
  17 /*
  18  * Use this to get the real path, i.e. resolve links. If you want an
  19  * absolute path but don't mind links, use absolute_path.
  20  *
  21  * If path is our buffer, then return path, as it's already what the
  22  * user wants.
  23  */
  24 const char *real_path(const char *path)
  25 {
  26         static char bufs[2][PATH_MAX + 1], *buf = bufs[0], *next_buf = bufs[1];
  27         char cwd[1024] = "";
  28         int buf_index = 1;
  29
  30         int depth = MAXDEPTH;
  31         char *last_elem = NULL;
  32         struct stat st;
  33
  34         /* We've already done it */
  35         if (path == buf || path == next_buf)
  36                 return path;
  37
  38         if (strlcpy(buf, path, PATH_MAX) >= PATH_MAX)
  39                 die ("Too long path: %.*s", 60, path);
  40
  41         while (depth--) {
  42                 if (!is_directory(buf)) {
  43                         char *last_slash = strrchr(buf, '/');
  44                         if (last_slash) {
  45                                 *last_slash = '\0';
  46                                 last_elem = xstrdup(last_slash + 1);
  47                         } else {
  48                                 last_elem = xstrdup(buf);
  49                                 *buf = '\0';
  50                         }
  51                 }
  52
  53                 if (*buf) {
  54                         if (!*cwd && !getcwd(cwd, sizeof(cwd)))
  55                                 die_errno ("Could not get current working directory");
  56
  57                         if (chdir(buf))
  58                                 die_errno ("Could not switch to '%s'", buf);
  59                 }
  60                 if (!getcwd(buf, PATH_MAX))
  61                         die_errno ("Could not get current working directory");
  62
  63                 if (last_elem) {
  64                         size_t len = strlen(buf);
  65                         if (len + strlen(last_elem) + 2 > PATH_MAX)
  66                                 die ("Too long path name: '%s/%s'",
  67                                                 buf, last_elem);
  68                         if (len && buf[len-1] != '/')
  69                                 buf[len++] = '/';
  70                         strcpy(buf + len, last_elem);
  71                         free(last_elem);
  72                         last_elem = NULL;
  73                 }
  74
  75                 if (!lstat(buf, &st) && S_ISLNK(st.st_mode)) {
  76                         ssize_t len = readlink(buf, next_buf, PATH_MAX);
  77                         if (len < 0)
  78                                 die_errno ("Invalid symlink '%s'", buf);
  79                         if (PATH_MAX <= len)
  80                                 die("symbolic link too long: %s", buf);
  81                         next_buf[len] = '\0';
  82                         buf = next_buf;
  83                         buf_index = 1 - buf_index;
  84                         next_buf = bufs[buf_index];
  85                 } else
  86                         break;
  87         }
  88
  89         if (*cwd && chdir(cwd))
  90                 die_errno ("Could not change back to '%s'", cwd);
  91
  92         return buf;
  93 }
  94
  95 static const char *get_pwd_cwd(void)
  96 {
  97         static char cwd[PATH_MAX + 1];
  98         char *pwd;
  99         struct stat cwd_stat, pwd_stat;
 100         if (getcwd(cwd, PATH_MAX) == NULL)
 101                 return NULL;
 102         pwd = getenv("PWD");
 103         if (pwd && strcmp(pwd, cwd)) {
 104                 stat(cwd, &cwd_stat);
 105                 if (!stat(pwd, &pwd_stat) &&
 106                     pwd_stat.st_dev == cwd_stat.st_dev &&
 107                     pwd_stat.st_ino == cwd_stat.st_ino) {
 108                         strlcpy(cwd, pwd, PATH_MAX);
 109                 }
 110         }
 111         return cwd;
 112 }
 113
 114 /*
 115  * Use this to get an absolute path from a relative one. If you want
 116  * to resolve links, you should use real_path.
 117  *
 118  * If the path is already absolute, then return path. As the user is
 119  * never meant to free the return value, we're safe.
 120  */
 121 const char *absolute_path(const char *path)
 122 {
 123         static char buf[PATH_MAX + 1];
 124
 125         if (is_absolute_path(path)) {
 126                 if (strlcpy(buf, path, PATH_MAX) >= PATH_MAX)
 127                         die("Too long path: %.*s", 60, path);
 128         } else {
 129                 size_t len;
 130                 const char *fmt;
 131                 const char *cwd = get_pwd_cwd();
 132                 if (!cwd)
 133                         die_errno("Cannot determine the current working directory");
 134                 len = strlen(cwd);
 135                 fmt = (len > 0 && is_dir_sep(cwd[len-1])) ? "%s%s" : "%s/%s";
 136                 if (snprintf(buf, PATH_MAX, fmt, cwd, path) >= PATH_MAX)
 137                         die("Too long path: %.*s", 60, path);
 138         }
 139         return buf;
 140 }