Fifth batch for 2.6
[gitweb.git] / tree-walk.c
index 5dd9a718047bc14e9ae840a46d1f71cb435fd6d7..6dccd2d5dd78e0ee71c1ebc771a99010a56db157 100644 (file)
@@ -415,6 +415,12 @@ int traverse_trees(int n, struct tree_desc *t, struct traverse_info *info)
        return error;
 }
 
+struct dir_state {
+       void *tree;
+       unsigned long size;
+       unsigned char sha1[20];
+};
+
 static int find_tree_entry(struct tree_desc *t, const char *name, unsigned char *result, unsigned *mode)
 {
        int namelen = strlen(name);
@@ -478,6 +484,206 @@ int get_tree_entry(const unsigned char *tree_sha1, const char *name, unsigned ch
        return retval;
 }
 
+/*
+ * This is Linux's built-in max for the number of symlinks to follow.
+ * That limit, of course, does not affect git, but it's a reasonable
+ * choice.
+ */
+#define GET_TREE_ENTRY_FOLLOW_SYMLINKS_MAX_LINKS 40
+
+/**
+ * Find a tree entry by following symlinks in tree_sha (which is
+ * assumed to be the root of the repository).  In the event that a
+ * symlink points outside the repository (e.g. a link to /foo or a
+ * root-level link to ../foo), the portion of the link which is
+ * outside the repository will be returned in result_path, and *mode
+ * will be set to 0.  It is assumed that result_path is uninitialized.
+ * If there are no symlinks, or the end result of the symlink chain
+ * points to an object inside the repository, result will be filled in
+ * with the sha1 of the found object, and *mode will hold the mode of
+ * the object.
+ *
+ * See the code for enum follow_symlink_result for a description of
+ * the return values.
+ */
+enum follow_symlinks_result get_tree_entry_follow_symlinks(unsigned char *tree_sha1, const char *name, unsigned char *result, struct strbuf *result_path, unsigned *mode)
+{
+       int retval = MISSING_OBJECT;
+       struct dir_state *parents = NULL;
+       size_t parents_alloc = 0;
+       ssize_t parents_nr = 0;
+       unsigned char current_tree_sha1[20];
+       struct strbuf namebuf = STRBUF_INIT;
+       struct tree_desc t;
+       int follows_remaining = GET_TREE_ENTRY_FOLLOW_SYMLINKS_MAX_LINKS;
+       int i;
+
+       init_tree_desc(&t, NULL, 0UL);
+       strbuf_init(result_path, 0);
+       strbuf_addstr(&namebuf, name);
+       hashcpy(current_tree_sha1, tree_sha1);
+
+       while (1) {
+               int find_result;
+               char *first_slash;
+               char *remainder = NULL;
+
+               if (!t.buffer) {
+                       void *tree;
+                       unsigned char root[20];
+                       unsigned long size;
+                       tree = read_object_with_reference(current_tree_sha1,
+                                                         tree_type, &size,
+                                                         root);
+                       if (!tree)
+                               goto done;
+
+                       ALLOC_GROW(parents, parents_nr + 1, parents_alloc);
+                       parents[parents_nr].tree = tree;
+                       parents[parents_nr].size = size;
+                       hashcpy(parents[parents_nr].sha1, root);
+                       parents_nr++;
+
+                       if (namebuf.buf[0] == '\0') {
+                               hashcpy(result, root);
+                               retval = FOUND;
+                               goto done;
+                       }
+
+                       if (!size)
+                               goto done;
+
+                       /* descend */
+                       init_tree_desc(&t, tree, size);
+               }
+
+               /* Handle symlinks to e.g. a//b by removing leading slashes */
+               while (namebuf.buf[0] == '/') {
+                       strbuf_remove(&namebuf, 0, 1);
+               }
+
+               /* Split namebuf into a first component and a remainder */
+               if ((first_slash = strchr(namebuf.buf, '/'))) {
+                       *first_slash = 0;
+                       remainder = first_slash + 1;
+               }
+
+               if (!strcmp(namebuf.buf, "..")) {
+                       struct dir_state *parent;
+                       /*
+                        * We could end up with .. in the namebuf if it
+                        * appears in a symlink.
+                        */
+
+                       if (parents_nr == 1) {
+                               if (remainder)
+                                       *first_slash = '/';
+                               strbuf_add(result_path, namebuf.buf,
+                                          namebuf.len);
+                               *mode = 0;
+                               retval = FOUND;
+                               goto done;
+                       }
+                       parent = &parents[parents_nr - 1];
+                       free(parent->tree);
+                       parents_nr--;
+                       parent = &parents[parents_nr - 1];
+                       init_tree_desc(&t, parent->tree, parent->size);
+                       strbuf_remove(&namebuf, 0, remainder ? 3 : 2);
+                       continue;
+               }
+
+               /* We could end up here via a symlink to dir/.. */
+               if (namebuf.buf[0] == '\0') {
+                       hashcpy(result, parents[parents_nr - 1].sha1);
+                       retval = FOUND;
+                       goto done;
+               }
+
+               /* Look up the first (or only) path component in the tree. */
+               find_result = find_tree_entry(&t, namebuf.buf,
+                                             current_tree_sha1, mode);
+               if (find_result) {
+                       goto done;
+               }
+
+               if (S_ISDIR(*mode)) {
+                       if (!remainder) {
+                               hashcpy(result, current_tree_sha1);
+                               retval = FOUND;
+                               goto done;
+                       }
+                       /* Descend the tree */
+                       t.buffer = NULL;
+                       strbuf_remove(&namebuf, 0,
+                                     1 + first_slash - namebuf.buf);
+               } else if (S_ISREG(*mode)) {
+                       if (!remainder) {
+                               hashcpy(result, current_tree_sha1);
+                               retval = FOUND;
+                       } else {
+                               retval = NOT_DIR;
+                       }
+                       goto done;
+               } else if (S_ISLNK(*mode)) {
+                       /* Follow a symlink */
+                       unsigned long link_len;
+                       size_t len;
+                       char *contents, *contents_start;
+                       struct dir_state *parent;
+                       enum object_type type;
+
+                       if (follows_remaining-- == 0) {
+                               /* Too many symlinks followed */
+                               retval = SYMLINK_LOOP;
+                               goto done;
+                       }
+
+                       /*
+                        * At this point, we have followed at a least
+                        * one symlink, so on error we need to report this.
+                        */
+                       retval = DANGLING_SYMLINK;
+
+                       contents = read_sha1_file(current_tree_sha1, &type,
+                                                 &link_len);
+
+                       if (!contents)
+                               goto done;
+
+                       if (contents[0] == '/') {
+                               strbuf_addstr(result_path, contents);
+                               free(contents);
+                               *mode = 0;
+                               retval = FOUND;
+                               goto done;
+                       }
+
+                       if (remainder)
+                               len = first_slash - namebuf.buf;
+                       else
+                               len = namebuf.len;
+
+                       contents_start = contents;
+
+                       parent = &parents[parents_nr - 1];
+                       init_tree_desc(&t, parent->tree, parent->size);
+                       strbuf_splice(&namebuf, 0, len,
+                                     contents_start, link_len);
+                       if (remainder)
+                               namebuf.buf[link_len] = '/';
+                       free(contents);
+               }
+       }
+done:
+       for (i = 0; i < parents_nr; i++)
+               free(parents[i].tree);
+       free(parents);
+
+       strbuf_release(&namebuf);
+       return retval;
+}
+
 static int match_entry(const struct pathspec_item *item,
                       const struct name_entry *entry, int pathlen,
                       const char *match, int matchlen,