Revision 9cf85473209ea8ae2b56c13145c4704d12ee1374 authored by Filip Hejsek on 28 January 2024, 04:09:17 UTC, committed by Johannes Schindelin on 17 April 2024, 20:30:01 UTC
While it is expected to have several git dirs within the `.git/modules/` tree, it is important that they do not interfere with each other. For example, if one submodule was called "captain" and another submodule "captain/hooks", their respective git dirs would clash, as they would be located in `.git/modules/captain/` and `.git/modules/captain/hooks/`, respectively, i.e. the latter's files could clash with the actual Git hooks of the former. To prevent these clashes, and in particular to prevent hooks from being written and then executed as part of a recursive clone, we introduced checks as part of the fix for CVE-2019-1387 in a8dee3ca61 (Disallow dubiously-nested submodule git directories, 2019-10-01). It is currently possible to bypass the check for clashing submodule git dirs in two ways: 1. parallel cloning 2. checkout --recurse-submodules Let's check not only before, but also after parallel cloning (and before checking out the submodule), that the git dir is not clashing with another one, otherwise fail. This addresses the parallel cloning issue. As to the parallel checkout issue: It requires quite a few manual steps to create clashing git dirs because Git itself would refuse to initialize the inner one, as demonstrated by the test case. Nevertheless, let's teach the recursive checkout (namely, the `submodule_move_head()` function that is used by the recursive checkout) to be careful to verify that it does not use a clashing git dir, and if it does, disable it (by deleting the `HEAD` file so that subsequent Git calls won't recognize it as a git dir anymore). Note: The parallel cloning test case contains a `cat err` that proved to be highly useful when analyzing the racy nature of the operation (the operation can fail with three different error messages, depending on timing), and was left on purpose to ease future debugging should the need arise. Signed-off-by: Filip Hejsek <filip.hejsek@gmail.com> Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
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fsmonitor--daemon.h
#ifndef FSMONITOR_DAEMON_H
#define FSMONITOR_DAEMON_H
#ifdef HAVE_FSMONITOR_DAEMON_BACKEND
#include "cache.h"
#include "dir.h"
#include "run-command.h"
#include "simple-ipc.h"
#include "thread-utils.h"
#include "fsmonitor-path-utils.h"
struct fsmonitor_batch;
struct fsmonitor_token_data;
/*
* Create a new batch of path(s). The returned batch is considered
* private and not linked into the fsmonitor daemon state. The caller
* should fill this batch with one or more paths and then publish it.
*/
struct fsmonitor_batch *fsmonitor_batch__new(void);
/*
* Free the list of batches starting with this one.
*/
void fsmonitor_batch__free_list(struct fsmonitor_batch *batch);
/*
* Add this path to this batch of modified files.
*
* The batch should be private and NOT (yet) linked into the fsmonitor
* daemon state and therefore not yet visible to worker threads and so
* no locking is required.
*/
void fsmonitor_batch__add_path(struct fsmonitor_batch *batch, const char *path);
struct fsm_listen_data; /* opaque platform-specific data for listener thread */
struct fsm_health_data; /* opaque platform-specific data for health thread */
struct fsmonitor_daemon_state {
pthread_t listener_thread;
pthread_t health_thread;
pthread_mutex_t main_lock;
struct strbuf path_worktree_watch;
struct strbuf path_gitdir_watch;
struct alias_info alias;
int nr_paths_watching;
struct fsmonitor_token_data *current_token_data;
struct strbuf path_cookie_prefix;
pthread_cond_t cookies_cond;
int cookie_seq;
struct hashmap cookies;
int listen_error_code;
int health_error_code;
struct fsm_listen_data *listen_data;
struct fsm_health_data *health_data;
struct ipc_server_data *ipc_server_data;
struct strbuf path_ipc;
};
/*
* Pathname classifications.
*
* The daemon classifies the pathnames that it receives from file
* system notification events into the following categories and uses
* that to decide whether clients are told about them. (And to watch
* for file system synchronization events.)
*
* The daemon only collects and reports on the set of modified paths
* within the working directory (proper).
*
* The client should only care about paths within the working
* directory proper (inside the working directory and not ".git" nor
* inside of ".git/"). That is, the client has read the index and is
* asking for a list of any paths in the working directory that have
* been modified since the last token. The client does not care about
* file system changes within the ".git/" directory (such as new loose
* objects or packfiles). So the client will only receive paths that
* are classified as IS_WORKDIR_PATH.
*
* Note that ".git" is usually a directory and is therefore inside
* the cone of the FS watch that we have on the working directory root,
* so we will also get FS events for disk activity on and within ".git/"
* that we need to respond to or filter from the client.
*
* But Git also allows ".git" to be a *file* that points to a GITDIR
* outside of the working directory. When this happens, we need to
* create FS watches on both the working directory root *and* on the
* (external) GITDIR root. (The latter is required because we put
* cookie files inside it and use them to sync with the FS event
* stream.)
*
* Note that in the context of this discussion, I'm using "GITDIR"
* to only mean an external GITDIR referenced by a ".git" file.
*
* The platform FS event backends will receive watch-specific
* relative paths (except for those OS's that always emit absolute
* paths). We use the following enum and routines to classify each
* path so that we know how to handle it. There is a slight asymmetry
* here because ".git/" is inside the working directory and the
* (external) GITDIR is not, and therefore how we handle events may
* vary slightly, so I have different enums for "IS...DOT_GIT..." and
* "IS...GITDIR...".
*
* The daemon uses the IS_DOT_GIT and IS_GITDIR internally to mean the
* exact ".git" file/directory or GITDIR directory. If the daemon
* receives a delete event for either of these paths, it will
* automatically shutdown, for example.
*
* Note that the daemon DOES NOT explicitly watch nor special case the
* index. The daemon does not read the index nor have any internal
* index-relative state, so there are no "IS...INDEX..." enum values.
*/
enum fsmonitor_path_type {
IS_WORKDIR_PATH = 0,
IS_DOT_GIT,
IS_INSIDE_DOT_GIT,
IS_INSIDE_DOT_GIT_WITH_COOKIE_PREFIX,
IS_GITDIR,
IS_INSIDE_GITDIR,
IS_INSIDE_GITDIR_WITH_COOKIE_PREFIX,
IS_OUTSIDE_CONE,
};
/*
* Classify a pathname relative to the root of the working directory.
*/
enum fsmonitor_path_type fsmonitor_classify_path_workdir_relative(
const char *relative_path);
/*
* Classify a pathname relative to a <gitdir> that is external to the
* worktree directory.
*/
enum fsmonitor_path_type fsmonitor_classify_path_gitdir_relative(
const char *relative_path);
/*
* Classify an absolute pathname received from a filesystem event.
*/
enum fsmonitor_path_type fsmonitor_classify_path_absolute(
struct fsmonitor_daemon_state *state,
const char *path);
/*
* Prepend the this batch of path(s) onto the list of batches associated
* with the current token. This makes the batch visible to worker threads.
*
* The caller no longer owns the batch and must not free it.
*
* Wake up the client threads waiting on these cookies.
*/
void fsmonitor_publish(struct fsmonitor_daemon_state *state,
struct fsmonitor_batch *batch,
const struct string_list *cookie_names);
/*
* If the platform-specific layer loses sync with the filesystem,
* it should call this to invalidate cached data and abort waiting
* threads.
*/
void fsmonitor_force_resync(struct fsmonitor_daemon_state *state);
#endif /* HAVE_FSMONITOR_DAEMON_BACKEND */
#endif /* FSMONITOR_DAEMON_H */
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