From e8805af1c33d79750a979014c021cd63d780c720 Mon Sep 17 00:00:00 2001 From: Martin Ågren Date: Thu, 28 Feb 2019 21:36:28 +0100 Subject: setup: fix memory leaks with `struct repository_format` MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit After we set up a `struct repository_format`, it owns various pieces of allocated memory. We then either use those members, because we decide we want to use the "candidate" repository format, or we discard the candidate / scratch space. In the first case, we transfer ownership of the memory to a few global variables. In the latter case, we just silently drop the struct and end up leaking memory. Introduce an initialization macro `REPOSITORY_FORMAT_INIT` and a function `clear_repository_format()`, to be used on each side of `read_repository_format()`. To have a clear and simple memory ownership, let all users of `struct repository_format` duplicate the strings that they take from it, rather than stealing the pointers. Call `clear_...()` at the start of `read_...()` instead of just zeroing the struct, since we sometimes enter the function multiple times. Thus, it is important to initialize the struct before calling `read_...()`, so document that. It's also important because we might not even call `read_...()` before we call `clear_...()`, see, e.g., builtin/init-db.c. Teach `read_...()` to clear the struct on error, so that it is reset to a safe state, and document this. (In `setup_git_directory_gently()`, we look at `repo_fmt.hash_algo` even if `repo_fmt.version` is -1, which we weren't actually supposed to do per the API. After this commit, that's ok.) We inherit the existing code's combining "error" and "no version found". Both are signalled through `version == -1` and now both cause us to clear any partial configuration we have picked up. For "extensions.*", that's fine, since they require a positive version number. For "core.bare" and "core.worktree", we're already verifying that we have a non-negative version number before using them. Signed-off-by: Martin Ågren Signed-off-by: Junio C Hamano --- cache.h | 31 ++++++++++++++++++++++++++++--- 1 file changed, 28 insertions(+), 3 deletions(-) (limited to 'cache.h') diff --git a/cache.h b/cache.h index ca36b44ee0..8c32c904c3 100644 --- a/cache.h +++ b/cache.h @@ -961,6 +961,10 @@ extern char *repository_format_partial_clone; extern const char *core_partial_clone_filter_default; extern int repository_format_worktree_config; +/* + * You _have_ to initialize a `struct repository_format` using + * `= REPOSITORY_FORMAT_INIT` before calling `read_repository_format()`. + */ struct repository_format { int version; int precious_objects; @@ -972,14 +976,35 @@ struct repository_format { struct string_list unknown_extensions; }; +/* + * Always use this to initialize a `struct repository_format` + * to a well-defined, default state before calling + * `read_repository()`. + */ +#define REPOSITORY_FORMAT_INIT \ +{ \ + .version = -1, \ + .is_bare = -1, \ + .hash_algo = GIT_HASH_SHA1, \ + .unknown_extensions = STRING_LIST_INIT_DUP, \ +} + /* * Read the repository format characteristics from the config file "path" into - * "format" struct. Returns the numeric version. On error, -1 is returned, - * format->version is set to -1, and all other fields in the struct are - * undefined. + * "format" struct. Returns the numeric version. On error, or if no version is + * found in the configuration, -1 is returned, format->version is set to -1, + * and all other fields in the struct are set to the default configuration + * (REPOSITORY_FORMAT_INIT). Always initialize the struct using + * REPOSITORY_FORMAT_INIT before calling this function. */ int read_repository_format(struct repository_format *format, const char *path); +/* + * Free the memory held onto by `format`, but not the struct itself. + * (No need to use this after `read_repository_format()` fails.) + */ +void clear_repository_format(struct repository_format *format); + /* * Verify that the repository described by repository_format is something we * can read. If it is, return 0. Otherwise, return -1, and "err" will describe -- cgit v1.3