From: Carlo Marcelo Arenas Belón <carenas@gmail.com>
Date: Tue, 23 Oct 2018 12:35:19 +0000 (-0700)
Subject: compat: make sure git_mmap is not expected to write
X-Git-Tag: v2.20.0-rc0~99^2
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=bf1e6da79157ff765fc92b45ac96442b9f56ff8b;p=thirdparty%2Fgit.git

compat: make sure git_mmap is not expected to write

in f48000fc ("Yank writing-back support from gitfakemmap.", 2005-10-08)
support for writting back changes was removed but the specific prot
flag that would be used was not checked for

Signed-off-by: Carlo Marcelo Arenas Belón <carenas@gmail.com>
Acked-by: Johannes Schindelin <Johannes.Schindelin@gmx.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
---

diff --git a/compat/mmap.c b/compat/mmap.c
index 7f662fef7b..14d31010df 100644
--- a/compat/mmap.c
+++ b/compat/mmap.c
@@ -4,7 +4,7 @@ void *git_mmap(void *start, size_t length, int prot, int flags, int fd, off_t of
 {
 	size_t n = 0;
 
-	if (start != NULL || !(flags & MAP_PRIVATE))
+	if (start != NULL || flags != MAP_PRIVATE || prot != PROT_READ)
 		die("Invalid usage of mmap when built with NO_MMAP");
 
 	start = xmalloc(length);