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From: Varun Naik <vcnaik94@gmail.com>
To: git@vger.kernel.org
Cc: Varun Naik <vcnaik94@gmail.com>
Subject: [PATCH] read-cache.c: do not die if mmap fails
Date: Sat, 13 Jul 2019 20:01:53 -0700
Message-ID: <20190714030153.22022-1-vcnaik94@gmail.com> (raw)

do_read_index() mmaps the index, or tries to die with an error message
on failure. It should call xmmap_gently(), which returns MAP_FAILED,
rather than xmmap(), which dies with its own error message.

An easy way to cause this mmap to fail is by setting $GIT_INDEX_FILE to
a path to a directory and then invoking any command that reads from the
index.

Signed-off-by: Varun Naik <vcnaik94@gmail.com>
---
I believe this is the only place that calls xmmap() when it should be
calling xmmap_gently(). There is a related recent commit 3203566a71
("Use xmmap_gently instead of xmmap in use_pack", 2019-05-16).

 read-cache.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/read-cache.c b/read-cache.c
index 22e7b9944e..4e30dafa9d 100644
--- a/read-cache.c
+++ b/read-cache.c
@@ -2140,7 +2140,7 @@ int do_read_index(struct index_state *istate, const char *path, int must_exist)
 	if (mmap_size < sizeof(struct cache_header) + the_hash_algo->rawsz)
 		die(_("%s: index file smaller than expected"), path);
 
-	mmap = xmmap(NULL, mmap_size, PROT_READ, MAP_PRIVATE, fd, 0);
+	mmap = xmmap_gently(NULL, mmap_size, PROT_READ, MAP_PRIVATE, fd, 0);
 	if (mmap == MAP_FAILED)
 		die_errno(_("%s: unable to map index file"), path);
 	close(fd);
-- 
2.22.0


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Thread overview: 2+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-07-14  3:01 Varun Naik [this message]
2019-07-14 18:59 ` Junio C Hamano

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