Re: [PATCH] read-cache.c: do not die if mmap fails
From: Junio C Hamano <hidden>
Date: 2019-07-14 18:59:57
Varun Naik [off-list ref] writes:
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 <redacted>
---
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).Nice find and thanks for checking other callsites of xmmap().
quoted hunk
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);