[PATCH v2 1/1] diff: munmap() file contents before running external diff

From: Johannes Schindelin via GitGitGadget <gitgitgadget@gmail.com>
Date: Jul 11, 2019, 08:23 UTC
Message-ID: <8a0213291b2afc8db9243808319dc86b736122c8.1562833419.git.gitgitgadget@gmail.com>
In-Reply-To: <pull.213.v2.git.gitgitgadget@gmail.com>

From: Johannes Schindelin <johannes.schindelin@gmx.de>

When running an external diff from, say, a diff tool, it is safe to assume that we want to write the files in question. On Windows, that means that there cannot be any other process holding an open handle to said files, or even just a mapped region.

So let's make sure that `git diff` itself is not holding any open handle to the files in question.

In fact, we will just release the file pair right away, as the external diff uses the files we just wrote, so we do not need to hold the file contents in memory anymore.

This fixes https://github.com/git-for-windows/git/issues/1315

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
---
 diff.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/diff.c b/diff.c
index 4d3cf83a27..42affb6dcf 100644
--- a/diff.c
+++ b/diff.c
@@ -4206,6 +4206,8 @@ static void run_external_diff(const char *pgm,
 	argv_array_pushf(&env, "GIT_DIFF_PATH_COUNTER=%d", ++o->diff_path_counter);
 	argv_array_pushf(&env, "GIT_DIFF_PATH_TOTAL=%d", q->nr);
 
+	diff_free_filespec_data(one);
+	diff_free_filespec_data(two);
 	if (run_command_v_opt_cd_env(argv.argv, RUN_USING_SHELL, NULL, env.argv))
 		die(_("external diff died, stopping at %s"), name);

-- 
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