kernel/git - git - PowerEL Git System

Author	SHA1	Message	Date
Ævar Arnfjörð Bjarmason	a8cc594333	hooks: fix an obscure TOCTOU "did we just run a hook?" race Fix a Time-of-check to time-of-use (TOCTOU) race in code added in `680ee550d7` (commit: skip discarding the index if there is no pre-commit hook, 2017-08-14). This obscure race condition can occur if we e.g. ran the "pre-commit" hook and it modified the index, but hook_exists() returns false later on (e.g., because the hook itself went away, the directory became unreadable, etc.). Then we won't call discard_cache() when we should have. The race condition itself probably doesn't matter, and users would have been unlikely to run into it in practice. This problem has been noted on-list when `680ee550d7` was discussed[1], but had not been fixed. This change is mainly intended to improve the readability of the code involved, and to make reasoning about it more straightforward. It wasn't as obvious what we were trying to do here, but by having an "invoked_hook" it's clearer that e.g. our discard_cache() is happening because of the earlier hook execution. Let's also change this for the push-to-checkout hook. Now instead of checking if the hook exists and either doing a push to checkout or a push to deploy we'll always attempt a push to checkout. If the hook doesn't exist we'll fall back on push to deploy. The same behavior as before, without the TOCTOU race. See `0855331941` (receive-pack: support push-to-checkout hook, 2014-12-01) for the introduction of the previous behavior. This leaves uses of hook_exists() in two places that matter. The "reference-transaction" check in refs.c, see `6754159767` (refs: implement reference transaction hook, 2020-06-19), and the "prepare-commit-msg" hook, see `66618a50f9` (sequencer: run 'prepare-commit-msg' hook, 2018-01-24). In both of those cases we're saving ourselves CPU time by not preparing data for the hook that we'll then do nothing with if we don't have the hook. So using this "invoked_hook" pattern doesn't make sense in those cases. The "reference-transaction" and "prepare-commit-msg" hook also aren't racy. In those cases we'll skip the hook runs if we race with a new hook being added, whereas in the TOCTOU races being fixed here we were incorrectly skipping the required post-hook logic. 1. https://lore.kernel.org/git/20170810191613.kpmhzg4seyxy3cpq@sigill.intra.peff.net/ Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>	3 years ago
Emily Shaffer	1a3017d908	hooks: convert worktree 'post-checkout' hook to hook library Move the running of the 'post-checkout' hook away from run-command.h to the new hook.h library in builtin/worktree.c. For this special case we need a change to the hook API to teach it to run the hook from a given directory. We cannot skip the "absolute_path" flag and just check if "dir" is specified as we'd then fail to find our hook in the new dir we'd chdir() to. We currently don't have a use-case for running a hook not in our "base" repository at a given absolute path, so let's have "dir" imply absolute_path(find_hook(hook_name)). Signed-off-by: Emily Shaffer <emilyshaffer@google.com> Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com> Acked-by: Emily Shaffer <emilyshaffer@google.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>	3 years ago
Ævar Arnfjörð Bjarmason	ab81cf242c	hook API: add a run_hooks_l() wrapper Add a run_hooks_l() wrapper, we'll use it in subsequent commits for the simple cases of wanting to run a single hook under a given name along with a list of arguments. Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com> Reviewed-by: Emily Shaffer <emilyshaffer@google.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>	3 years ago
Ævar Arnfjörð Bjarmason	474c119fda	hook API: add a run_hooks() wrapper Add a run_hooks() wrapper, we'll use it in subsequent commits for the simple cases of wanting to run a single hook under a given name, without providing options such as "env" or "args". Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com> Reviewed-by: Emily Shaffer <emilyshaffer@google.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>	3 years ago
Emily Shaffer	96e7225b31	hook: add 'run' subcommand In order to enable hooks to be run as an external process, by a standalone Git command, or by tools which wrap Git, provide an external means to run all configured hook commands for a given hook event. Most of our hooks require more complex functionality than this, but let's start with the bare minimum required to support our simplest hooks. In terms of implementation the usage_with_options() and "goto usage" pattern here mirrors that of builtin/{commit-graph,multi-pack-index}.c. Some of the implementation here, such as a function being named run_hooks_opt() when it's tasked with running one hook, to using the run_processes_parallel_tr2() API to run with jobs=1 is somewhere between a bit odd and and an overkill for the current features of this "hook run" command and the hook.[ch] API. This code will eventually be able to run multiple hooks declared in config in parallel, by starting out with these names and APIs we reduce the later churn of renaming functions, switching from the run_command() to run_processes_parallel_tr2() API etc. Signed-off-by: Emily Shaffer <emilyshaffer@google.com> Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com> Acked-by: Emily Shaffer <emilyshaffer@google.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>	3 years ago
Emily Shaffer	330155ed8a	hook.c: add a hook_exists() wrapper and use it in bugreport.c Add a boolean version of the find_hook() function for those callers who are only interested in checking whether the hook exists, not what the path to it is. Signed-off-by: Emily Shaffer <emilyshaffer@google.com> Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>	3 years ago
Ævar Arnfjörð Bjarmason	5e3aba33da	hook.[ch]: move find_hook() from run-command.c to hook.c Move the find_hook() function from run-command.c to a new hook.c library. This change establishes a stub library that's pretty pointless right now, but will see much wider use with Emily Shaffer's upcoming "configuration-based hooks" series. Eventually all the hook related code will live in hook.[ch]. Let's start that process by moving the simple find_hook() function over as-is. Signed-off-by: Emily Shaffer <emilyshaffer@google.com> Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>	3 years ago