Correct the behavior of the utils_expand_path function
authorRaphaël Beamonte <raphael.beamonte@gmail.com>
Wed, 13 Nov 2013 05:34:37 +0000 (00:34 -0500)
committerDavid Goulet <dgoulet@ev0ke.net>
Wed, 13 Nov 2013 21:18:06 +0000 (16:18 -0500)
Even if the utils_expand_path function was intended to allow to
use unexistent directory paths, it was in fact only working for
some kind of arguments. Paths like "foo", "bar/" or "bar/foo"
when the "bar" directory does not exist wasn't working. This
patch introduce a new way to expand paths in this function that
also works properly for these kind of arguments.

Signed-off-by: Raphaël Beamonte <raphael.beamonte@gmail.com>
src/common/utils.c

index 4ccf36a6c781bc09bbcb6a1108af8354d275e9b6..6938a5ae52f6cac2e12465b37e3caafe8ae61d23 100644 (file)
@@ -112,7 +112,7 @@ error:
 LTTNG_HIDDEN
 char *utils_expand_path(const char *path)
 {
-       const char *end_path = path;
+       const char *end_path = NULL;
        char *next, *cut_path = NULL, *expanded_path = NULL;
 
        /* Safety net */
@@ -120,38 +120,80 @@ char *utils_expand_path(const char *path)
                goto error;
        }
 
-       /* Find last token delimited by '/' */
-       while ((next = strpbrk(end_path + 1, "/"))) {
-               end_path = next;
-       }
-
-       /* Cut last token from original path */
-       cut_path = strndup(path, end_path - path);
-
+       /* Allocate memory for the expanded path */
        expanded_path = zmalloc(PATH_MAX);
        if (expanded_path == NULL) {
                PERROR("zmalloc expand path");
                goto error;
        }
 
-       expanded_path = realpath((char *)cut_path, expanded_path);
-       if (expanded_path == NULL) {
-               switch (errno) {
-               case ENOENT:
-                       ERR("%s: No such file or directory", cut_path);
-                       break;
-               default:
-                       PERROR("realpath utils expand path");
-                       break;
+       /* If given path is already absolute */
+       if (*path == '/') {
+               strncpy(expanded_path, path, PATH_MAX);
+       /* Else, we have some work to do */
+       } else {
+               /* Pointer to the last char of the path */
+               const char *last_char = path + strlen(path) - 1;
+
+               end_path = path;
+
+               /* Split part that will be resolved by realpath (relative path from
+                * current directory using ./ or ../ only) and part that could not
+                * (directory names)
+                */
+               while ((next = strpbrk(end_path, "/")) && (next != last_char)) {
+                       end_path = next + 1;
+                       if (strncmp(end_path, "./", 2) != 0 &&
+                                       strncmp(end_path, "../", 3) != 0) {
+                               break;
+                       }
+               }
+
+               /* If this is the end of the string, and we still can resolve it */
+               if (strncmp(end_path, "..\0", 3) == 0 ||
+                               strncmp(end_path, ".\0", 2) == 0) {
+                       end_path += strlen(end_path);
+               }
+
+               /* If the end part is the whole path, we are in the current dir */
+               if (end_path == path) {
+                       cut_path = strdup(".");
+               /* Else, cut the resolvable part from original path */
+               } else {
+                       cut_path = strndup(path, end_path - path);
+               }
+
+               /* Resolve the canonical path of the first part of the path */
+               expanded_path = realpath((char *)cut_path, expanded_path);
+               if (expanded_path == NULL) {
+                       switch (errno) {
+                       case ENOENT:
+                               ERR("%s: No such file or directory", cut_path);
+                               break;
+                       default:
+                               PERROR("realpath utils expand path");
+                               break;
+                       }
+                       goto error;
+               }
+
+               /* Add end part to expanded path if not empty */
+               if (*end_path != 0) {
+                       strncat(expanded_path, "/", PATH_MAX - strlen(expanded_path) - 1);
+                       strncat(expanded_path, end_path,
+                                       PATH_MAX - strlen(expanded_path) - 1);
                }
-               goto error;
        }
 
-       /* Add end part to expanded path */
-       strncat(expanded_path, end_path, PATH_MAX - strlen(expanded_path) - 1);
+       /* Resolve the internal './' and '../' strings */
+       next = utils_resolve_relative(expanded_path);
+       if (next == NULL) {
+               goto error;
+       }
 
+       free(expanded_path);
        free(cut_path);
-       return expanded_path;
+       return next;
 
 error:
        free(expanded_path);
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