diff options
Diffstat (limited to 'tree-walk.c')
| -rw-r--r-- | tree-walk.c | 206 |
1 files changed, 206 insertions, 0 deletions
diff --git a/tree-walk.c b/tree-walk.c index 5dd9a71804..6dccd2d5dd 100644 --- a/tree-walk.c +++ b/tree-walk.c @@ -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, |