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 (!*path)
  39                 die("The empty string is not a valid path");
  40
  41         if (strlcpy(buf, path, PATH_MAX) >= PATH_MAX)
  42                 die ("Too long path: %.*s", 60, path);
  43
  44         while (depth--) {
  45                 if (!is_directory(buf)) {
  46                         char *last_slash = find_last_dir_sep(buf);
  47                         if (last_slash) {
  48                                 last_elem = xstrdup(last_slash + 1);
  49                                 last_slash[1] = '\0';
  50                         } else {
  51                                 last_elem = xstrdup(buf);
  52                                 *buf = '\0';
  53                         }
  54                 }
  55
  56                 if (*buf) {
  57                         if (!*cwd && !getcwd(cwd, sizeof(cwd)))
  58                                 die_errno ("Could not get current working directory");
  59
  60                         if (chdir(buf))
  61                                 die_errno ("Could not switch to '%s'", buf);
  62                 }
  63                 if (!getcwd(buf, PATH_MAX))
  64                         die_errno ("Could not get current working directory");
  65
  66                 if (last_elem) {
  67                         size_t len = strlen(buf);
  68                         if (len + strlen(last_elem) + 2 > PATH_MAX)
  69                                 die ("Too long path name: '%s/%s'",
  70                                                 buf, last_elem);
  71                         if (len && !is_dir_sep(buf[len-1]))
  72                                 buf[len++] = '/';
  73                         strcpy(buf + len, last_elem);
  74                         free(last_elem);
  75                         last_elem = NULL;
  76                 }
  77
  78                 if (!lstat(buf, &st) && S_ISLNK(st.st_mode)) {
  79                         ssize_t len = readlink(buf, next_buf, PATH_MAX);
  80                         if (len < 0)
  81                                 die_errno ("Invalid symlink '%s'", buf);
  82                         if (PATH_MAX <= len)
  83                                 die("symbolic link too long: %s", buf);
  84                         next_buf[len] = '\0';
  85                         buf = next_buf;
  86                         buf_index = 1 - buf_index;
  87                         next_buf = bufs[buf_index];
  88                 } else
  89                         break;
  90         }
  91
  92         if (*cwd && chdir(cwd))
  93                 die_errno ("Could not change back to '%s'", cwd);
  94
  95         return buf;
  96 }
  97
  98 static const char *get_pwd_cwd(void)
  99 {
 100         static char cwd[PATH_MAX + 1];
 101         char *pwd;
 102         struct stat cwd_stat, pwd_stat;
 103         if (getcwd(cwd, PATH_MAX) == NULL)
 104                 return NULL;
 105         pwd = getenv("PWD");
 106         if (pwd && strcmp(pwd, cwd)) {
 107                 stat(cwd, &cwd_stat);
 108                 if ((cwd_stat.st_dev || cwd_stat.st_ino) &&
 109                     !stat(pwd, &pwd_stat) &&
 110                     pwd_stat.st_dev == cwd_stat.st_dev &&
 111                     pwd_stat.st_ino == cwd_stat.st_ino) {
 112                         strlcpy(cwd, pwd, PATH_MAX);
 113                 }
 114         }
 115         return cwd;
 116 }
 117
 118 /*
 119  * Use this to get an absolute path from a relative one. If you want
 120  * to resolve links, you should use real_path.
 121  *
 122  * If the path is already absolute, then return path. As the user is
 123  * never meant to free the return value, we're safe.
 124  */
 125 const char *absolute_path(const char *path)
 126 {
 127         static char buf[PATH_MAX + 1];
 128
 129         if (!*path) {
 130                 die("The empty string is not a valid path");
 131         } else if (is_absolute_path(path)) {
 132                 if (strlcpy(buf, path, PATH_MAX) >= PATH_MAX)
 133                         die("Too long path: %.*s", 60, path);
 134         } else {
 135                 size_t len;
 136                 const char *fmt;
 137                 const char *cwd = get_pwd_cwd();
 138                 if (!cwd)
 139                         die_errno("Cannot determine the current working directory");
 140                 len = strlen(cwd);
 141                 fmt = (len > 0 && is_dir_sep(cwd[len-1])) ? "%s%s" : "%s/%s";
 142                 if (snprintf(buf, PATH_MAX, fmt, cwd, path) >= PATH_MAX)
 143                         die("Too long path: %.*s", 60, path);
 144         }
 145         return buf;
 146 }
 147
 148 /*
 149  * Unlike prefix_path, this should be used if the named file does
 150  * not have to interact with index entry; i.e. name of a random file
 151  * on the filesystem.
 152  */
 153 const char *prefix_filename(const char *pfx, int pfx_len, const char *arg)
 154 {
 155         static char path[PATH_MAX];
 156 #ifndef WIN32
 157         if (!pfx_len || is_absolute_path(arg))
 158                 return arg;
 159         memcpy(path, pfx, pfx_len);
 160         strcpy(path + pfx_len, arg);
 161 #else
 162         char *p;
 163         /* don't add prefix to absolute paths, but still replace '\' by '/' */
 164         if (is_absolute_path(arg))
 165                 pfx_len = 0;
 166         else if (pfx_len)
 167                 memcpy(path, pfx, pfx_len);
 168         strcpy(path + pfx_len, arg);
 169         for (p = path + pfx_len; *p; p++)
 170                 if (*p == '\\')
 171                         *p = '/';
 172 #endif
 173         return path;
 174 }