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2017-10-07read-cache: leave lock in right state in `write_locked_index()`Libravatar Martin Ågren1-3/+1
If the original version of `write_locked_index()` returned with an error, it didn't roll back the lockfile unless the error occured at the very end, during closing/committing. See commit 03b866477 (read-cache: new API write_locked_index instead of write_index/write_cache, 2014-06-13). In commit 9f41c7a6b (read-cache: close index.lock in do_write_index, 2017-04-26), we learned to close the lock slightly earlier in the callstack. That was mostly a side-effect of lockfiles being implemented using temporary files, but didn't cause any real harm. Recently, commit 076aa2cbd (tempfile: auto-allocate tempfiles on heap, 2017-09-05) introduced a subtle bug. If the temporary file is deleted (i.e., the lockfile is rolled back), the tempfile-pointer in the `struct lock_file` will be left dangling. Thus, an attempt to reuse the lockfile, or even just to roll it back, will induce undefined behavior -- most likely a crash. Besides not crashing, we clearly want to make things consistent. The guarantees which the lockfile-machinery itself provides is A) if we ask to commit and it fails, roll back, and B) if we ask to close and it fails, do _not_ roll back. Let's do the same for consistency. Do not delete the temporary file in `do_write_index()`. One of its callers, `write_locked_index()` will thereby avoid rolling back the lock. The other caller, `write_shared_index()`, will delete its temporary file anyway. Both of these callers will avoid undefined behavior (crashing). Teach `write_locked_index(..., COMMIT_LOCK)` to roll back the lock before returning. If we have already succeeded and committed, it will be a noop. Simplify the existing callers where we now have a superfluous call to `rollback_lockfile()`. That should keep future readers from wondering why the callers are inconsistent. Signed-off-by: Martin Ågren <martin.agren@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2017-10-06treewide: prefer lockfiles on the stackLibravatar Martin Ågren1-4/+4
There is no longer any need to allocate and leak a `struct lock_file`. The previous patch addressed an instance where we needed a minor tweak alongside the trivial changes. Deal with the remaining instances where we allocate and leak a struct within a single function. Change them to have the `struct lock_file` on the stack instead. These instances were identified by running `git grep "^\s*struct lock_file\s*\*"`. Signed-off-by: Martin Ågren <martin.agren@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2017-05-08tree: convert parse_tree_indirect to struct object_idLibravatar brian m. carlson1-2/+2
Convert parse_tree_indirect to take a pointer to struct object_id. Update all the callers. This transformation was achieved using the following semantic patch and manual updates to the declaration and definition. Update builtin/checkout.c manually as well, since it uses a ternary expression not handled by the semantic patch. @@ expression E1; @@ - parse_tree_indirect(E1.hash) + parse_tree_indirect(&E1) @@ expression E1; @@ - parse_tree_indirect(E1->hash) + parse_tree_indirect(E1) Signed-off-by: brian m. carlson <sandals@crustytoothpaste.net> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2017-05-08merge: convert checkout_fast_forward to struct object_idLibravatar brian m. carlson1-4/+4
Converting checkout_fast_forward is required to convert parse_tree_indirect. Signed-off-by: brian m. carlson <sandals@crustytoothpaste.net> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2016-12-07lockfile: LOCK_REPORT_ON_ERRORLibravatar Junio C Hamano1-1/+1
The "libify sequencer" topic stopped passing the die_on_error option to hold_locked_index(), and this lost an error message from "git merge --ff-only $commit" when there are competing updates in progress. The command still exits with a non-zero status, but that is not of much help for an interactive user. The last thing the command says is "Updating $from..$to". We used to follow it with a big error message that makes it clear that "merge --ff-only" did not succeed. What is sad is that we should have noticed this regression while reviewing the change. It was clear that the update to the checkout_fast_forward() function made a failing hold_locked_index() silent, but the only caller of the checkout_fast_forward() function had this comment: if (checkout_fast_forward(from, to, 1)) - exit(128); /* the callee should have complained already */ + return -1; /* the callee should have complained already */ which clearly contradicted the assumption X-<. Add a new option LOCK_REPORT_ON_ERROR that can be passed instead of LOCK_DIE_ON_ERROR to the hold_lock*() family of functions and teach checkout_fast_forward() to use it to fix this regression. After going thourgh all calls to hold_lock*() family of functions that used to pass LOCK_DIE_ON_ERROR but were modified to pass 0 in the "libify sequencer" topic "git show --first-parent 2a4062a4a8", it appears that this is the only one that has become silent. Many others used to give detailed report that talked about "there may be competing Git process running" but with the series merged they now only give a single liner "Unable to lock ...", some of which may have to be tweaked further, but at least they say something, unlike the one this patch fixes. Reported-by: Robbie Iannucci <iannucci@google.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2016-09-09sequencer: lib'ify checkout_fast_forward()Libravatar Johannes Schindelin1-3/+6
Instead of dying there, let the caller high up in the callchain notice the error and handle it (by dying, still). The only callers of checkout_fast_forward(), cmd_merge(), pull_into_void(), cmd_pull() and sequencer's fast_forward_to(), already check the return value and handle it appropriately. With this step, we make it notice an error return from this function. So this is a safe conversion to make checkout_fast_forward() callable from new callers that want it not to die, without changing the external behaviour of anything existing. Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2015-11-20Convert struct object to object_idLibravatar brian m. carlson1-1/+1
struct object is one of the major data structures dealing with object IDs. Convert it to use struct object_id instead of an unsigned char array. Convert get_object_hash to refer to the new member as well. Signed-off-by: brian m. carlson <sandals@crustytoothpaste.net> Signed-off-by: Jeff King <peff@peff.net>
2014-10-01lockfile.h: extract new header file for the functions in lockfile.cLibravatar Michael Haggerty1-0/+1
Move the interface declaration for the functions in lockfile.c from cache.h to a new file, lockfile.h. Add #includes where necessary (and remove some redundant includes of cache.h by files that already include builtin.h). Move the documentation of the lock_file state diagram from lockfile.c to the new header file. Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2014-07-16Merge branch 'nd/split-index'Libravatar Junio C Hamano1-4/+3
An experiment to use two files (the base file and incremental changes relative to it) to represent the index to reduce I/O cost of rewriting a large index when only small part of the working tree changes. * nd/split-index: (32 commits) t1700: new tests for split-index mode t2104: make sure split index mode is off for the version test read-cache: force split index mode with GIT_TEST_SPLIT_INDEX read-tree: note about dropping split-index mode or index version read-tree: force split-index mode off on --index-output rev-parse: add --shared-index-path to get shared index path update-index --split-index: do not split if $GIT_DIR is read only update-index: new options to enable/disable split index mode split-index: strip pathname of on-disk replaced entries split-index: do not invalidate cache-tree at read time split-index: the reading part split-index: the writing part read-cache: mark updated entries for split index read-cache: save deleted entries in split index read-cache: mark new entries for split index read-cache: split-index mode read-cache: save index SHA-1 after reading entry.c: update cache_changed if refresh_cache is set in checkout_entry() cache-tree: mark istate->cache_changed on prime_cache_tree() cache-tree: mark istate->cache_changed on cache tree update ...
2014-06-19merge: use argv_array when spawning merge strategyLibravatar Jeff King1-29/+13
This is shorter, and avoids a rather complicated set of allocation and free steps. Signed-off-by: Jeff King <peff@peff.net> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2014-06-13read-cache: new API write_locked_index instead of write_index/write_cacheLibravatar Nguyễn Thái Ngọc Duy1-4/+3
Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2012-10-29Move try_merge_command and checkout_fast_forward to libgit.aLibravatar Nguyễn Thái Ngọc Duy1-0/+112
These functions are called in sequencer.c, which is part of libgit.a. This makes libgit.a potentially require builtin/merge.c for external git commands. Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com> Signed-off-by: Jeff King <peff@peff.net>