[PATCH v2] compat: make sure git_mmap is not expected to write

["Carlo Marcelo Arenas Belón" <carenas@gmail.com>]

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

Acked-by: Johannes Schindelin <Johannes.Schindelin@gmx.de>
Signed-off-by: Carlo Marcelo Arenas Belón <carenas@gmail.com>
---
Changes in v2:
    
* reset-author to match signature
* cleanup commit message and add ACK

 compat/mmap.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

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);
-- 
2.19.1