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authorJeff King <peff@peff.net>2015-05-28 03:54:00 -0400
committerJunio C Hamano <gitster@pobox.com>2015-05-28 11:32:04 -0700
commita1293ef7c3690829a6ac47fc45f3f26b96b5c9f5 (patch)
treea683cb52e5e6f965b1d8e4142d4af765e310ad3c /read-cache.c
parentfdf96a20acf96a6ac538df8113b2aafd6ed71d50 (diff)
downloadgit-a1293ef7c3690829a6ac47fc45f3f26b96b5c9f5.tar.gz
read-cache.c: drop PROT_WRITE from mmap of index
Once upon a time, git's in-memory representation of a cache entry actually pointed to the mmap'd on-disk data. So in 520fc24 (Allow writing to the private index file mapping., 2005-04-26), we specified PROT_WRITE so that we could tweak the entries while we run (in our own MAP_PRIVATE copy-on-write version, of course). Later, 7a51ed6 (Make on-disk index representation separate from in-core one, 2008-01-14) stopped doing this; we copy the data into our in-core representation, and then drop the mmap immediately. We can therefore drop the PROT_WRITE flag. It's probably not hurting anything as it is, but it's potentially confusing. Note that we could also mark the mapping as "const" to verify that we never write to it. However, we don't typically do that for our other maps, as it then requires casting to munmap() it. Signed-off-by: Jeff King <peff@peff.net> Signed-off-by: Junio C Hamano <gitster@pobox.com>
Diffstat (limited to 'read-cache.c')
-rw-r--r--read-cache.c2
1 files changed, 1 insertions, 1 deletions
diff --git a/read-cache.c b/read-cache.c
index 9cff715d6b..cc67dd1d5d 100644
--- a/read-cache.c
+++ b/read-cache.c
@@ -1525,7 +1525,7 @@ int do_read_index(struct index_state *istate, const char *path, int must_exist)
if (mmap_size < sizeof(struct cache_header) + 20)
die("index file smaller than expected");
- mmap = xmmap(NULL, mmap_size, PROT_READ | PROT_WRITE, MAP_PRIVATE, fd, 0);
+ mmap = xmmap(NULL, mmap_size, PROT_READ, MAP_PRIVATE, fd, 0);
if (mmap == MAP_FAILED)
die_errno("unable to map index file");
close(fd);