git/shallow.c, branch v2.0.2

shallow: verify shallow file after taking lock

2014-03-17T22:03:32Z

Before writing the shallow file, we stat() the existing file to make sure it has not been updated since our operation began. However, we do not do so under a lock, so there is a possible race: 1. Process A takes the lock. 2. Process B calls check_shallow_file_for_update and finds no update. 3. Process A commits the lockfile. 4. Process B takes the lock, then overwrite's process A's changes. We can fix this by doing our check while we hold the lock. Signed-off-by: Jeff King Signed-off-by: Junio C Hamano

shallow: automatically clean up shallow tempfiles

2014-02-27T20:07:13Z

We sometimes write tempfiles of the form "shallow_XXXXXX" during fetch/push operations with shallow repositories. Under normal circumstances, we clean up the result when we are done. However, we do no take steps to clean up after ourselves when we exit due to die() or signal death. This patch teaches the tempfile creation code to register handlers to clean up after ourselves. To handle this, we change the ownership semantics of the filename returned by setup_temporary_shallow. It now keeps a copy of the filename itself, and returns only a const pointer to it. We can also do away with explicit tempfile removal in the callers. They all exit not long after finishing with the file, so they can rely on the auto-cleanup, simplifying the code. Note that we keep things simple and maintain only a single filename to be cleaned. This is sufficient for the current caller, but we future-proof it with a die("BUG"). Signed-off-by: Jeff King Signed-off-by: Junio C Hamano

shallow: use stat_validity to check for up-to-date file

2014-02-27T20:04:23Z

When we are about to write the shallow file, we check that it has not changed since we last read it. Instead of hand-rolling this, we can use stat_validity. This is built around the index stat-check, so it is more robust than just checking the mtime, as we do now (it uses the same check as we do for index files). The new code also handles the case of a shallow file appearing unexpectedly. With the current code, two simultaneous processes making us shallow (e.g., two "git fetch --depth=1" running at the same time in a non-shallow repository) can race to overwrite each other. As a bonus, we also remove a race in determining the stat information of what we read (we stat and then open, leaving a race window; instead we should open and then fstat the descriptor). Signed-off-by: Jeff King Signed-off-by: Junio C Hamano

Merge branch 'nd/shallow-clone'

2014-01-17T20:21:20Z

Fetching from a shallow-cloned repository used to be forbidden, primarily because the codepaths involved were not carefully vetted and we did not bother supporting such usage. This attempts to allow object transfer out of a shallow-cloned repository in a controlled way (i.e. the receiver become a shallow repository with truncated history). * nd/shallow-clone: (31 commits) t5537: fix incorrect expectation in test case 10 shallow: remove unused code send-pack.c: mark a file-local function static git-clone.txt: remove shallow clone limitations prune: clean .git/shallow after pruning objects clone: use git protocol for cloning shallow repo locally send-pack: support pushing from a shallow clone via http receive-pack: support pushing to a shallow clone via http smart-http: support shallow fetch/clone remote-curl: pass ref SHA-1 to fetch-pack as well send-pack: support pushing to a shallow clone receive-pack: allow pushes that update .git/shallow connected.c: add new variant that runs with --shallow-file add GIT_SHALLOW_FILE to propagate --shallow-file to subprocesses receive/send-pack: support pushing from a shallow clone receive-pack: reorder some code in unpack() fetch: add --update-shallow to accept refs that update .git/shallow upload-pack: make sure deepening preserves shallow roots fetch: support fetching from a shallow repository clone: support remote shallow repository ...

shallow: remove unused code

2014-01-06T17:05:40Z

Commit 58babfff ("shallow.c: the 8 steps to select new commits for .git/shallow", 05-12-2013) added a function to implement step 5 of the quoted eight steps, namely 'remove_nonexistent_ours_in_pack()'. This function implements an optional optimization step in the new shallow commit selection algorithm. However, this function has no callers. (The commented out call sites would need to change, in order to provide information required by the function.) Signed-off-by: Ramsay Jones Acked-by: Nguyễn Thái Ngọc Duy Signed-off-by: Junio C Hamano

prune: clean .git/shallow after pruning objects

2013-12-11T00:14:19Z

This patch teaches "prune" to remove shallow roots that are no longer reachable from any refs (e.g. when the relevant refs are removed). Signed-off-by: Nguyễn Thái Ngọc Duy Signed-off-by: Junio C Hamano

receive-pack: allow pushes that update .git/shallow

2013-12-11T00:14:18Z

The basic 8 steps to update .git/shallow does not fully apply here because the user may choose to accept just a few refs (while fetch always accepts all refs). The steps are modified a bit. 1-6. same as before. After calling assign_shallow_commits_to_refs at step 6, each shallow commit has a bitmap that marks all refs that require it. 7. mark all "ours" shallow commits that are reachable from any refs. We will need to do the original step 7 on them later. 8. go over all shallow commit bitmaps, mark refs that require new shallow commits. 9. setup a strict temporary shallow file to plug all the holes, even if it may cut some of our history short. This file is used by all hooks. The hooks could use --shallow-file=$GIT_DIR/shallow to overcome this and reach everything in current repo. 10. go over the new refs one by one. For each ref, do the reachability test if it needs a shallow commit on the list from step 7. Remove it if it's reachable from our refs. Gather all required shallow commits, run check_everything_connected() with the new ref, then install them to .git/shallow. This mode is disabled by default and can be turned on with receive.shallowupdate Signed-off-by: Nguyễn Thái Ngọc Duy Signed-off-by: Junio C Hamano

add GIT_SHALLOW_FILE to propagate --shallow-file to subprocesses

2013-12-11T00:14:17Z

This may be needed when a hook is run after a new shallow pack is received, but .git/shallow is not settled yet. A temporary shallow file to plug all loose ends should be used instead. GIT_SHALLOW_FILE is overriden by --shallow-file. --shallow-file does not work in this case because the hook may spawn many git subprocesses and the launch commands do not have --shallow-file as it's a recent addition. Signed-off-by: Nguyễn Thái Ngọc Duy Signed-off-by: Junio C Hamano

upload-pack: make sure deepening preserves shallow roots

2013-12-11T00:14:17Z

When "fetch --depth=N" where N exceeds the longest chain of history in the source repo, usually we just send an "unshallow" line to the client so full history is obtained. When the source repo is shallow we need to make sure to "unshallow" the current shallow point _and_ "shallow" again when the commit reaches its shallow bottom in the source repo. This should fix both cases: large and --unshallow. Signed-off-by: Nguyễn Thái Ngọc Duy Signed-off-by: Junio C Hamano

shallow.c: steps 6 and 7 to select new commits for .git/shallow

2013-12-11T00:14:16Z

Signed-off-by: Nguyễn Thái Ngọc Duy Signed-off-by: Junio C Hamano