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authorJeff King <peff@peff.net>2009-01-22 05:59:56 (GMT)
committerJunio C Hamano <gitster@pobox.com>2009-01-22 06:46:52 (GMT)
commit479b0ae81c9291a8bb8d7b2347cc58eeaa701304 (patch)
treed58e5dc1bdaa252ae7b2910c5195d45e0fa3d536 /lockfile.c
parentd28250654f4150f391b0fab6713ecb5748ccfd98 (diff)
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diff: refactor tempfile cleanup handling
There are two pieces of code that create tempfiles for diff: run_external_diff and run_textconv. The former cleans up its tempfiles in the face of premature death (i.e., by die() or by signal), but the latter does not. After this patch, they will both use the same cleanup routines. To make clear what the change is, let me first explain what happens now: - run_external_diff uses a static global array of 2 diff_tempfile structs (since it knows it will always need exactly 2 tempfiles). It calls prepare_temp_file (which doesn't know anything about the global array) on each of the structs, creating the tempfiles that need to be cleaned up. It then registers atexit and signal handlers to look through the global array and remove the tempfiles. If it succeeds, it calls the handler manually (which marks the tempfile structs as unused). - textconv has its own tempfile struct, which it allocates using prepare_temp_file and cleans up manually. No signal or atexit handlers. The new code moves the installation of cleanup handlers into the prepare_temp_file function. Which means that that function now has to understand that there is static tempfile storage. So what happens now is: - run_external_diff calls prepare_temp_file - prepare_temp_file calls claim_diff_tempfile, which allocates an unused slot from our global array - prepare_temp_file installs (if they have not already been installed) atexit and signal handlers for cleanup - prepare_temp_file sets up the tempfile as usual - prepare_temp_file returns a pointer to the allocated tempfile The advantage being that run_external_diff no longer has to care about setting up cleanup handlers. Now by virtue of calling prepare_temp_file, run_textconv gets the same benefit, as will any future users of prepare_temp_file. There are also a few side benefits to the specific implementation: - we now install cleanup handlers _before_ allocating the tempfile, closing a race which could leave temp cruft - when allocating a slot in the global array, we will now detect a situation where the old slots were not properly vacated (i.e., somebody forgot to call remove upon leaving the function). In the old code, such a situation would silently overwrite the tempfile names, meaning we would forget to clean them up. The new code dies with a bug warning. - we make sure only to install the signal handler once. This isn't a big deal, since we are just overwriting the old handler, but will become an issue when a later patch converts the code to use sigchain Signed-off-by: Jeff King <peff@peff.net> Signed-off-by: Junio C Hamano <gitster@pobox.com>
Diffstat (limited to 'lockfile.c')
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