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authorJohannes Schindelin <johannes.schindelin@gmx.de>2016-04-22 16:31:26 +0200
committerJunio C Hamano <gitster@pobox.com>2016-04-22 15:01:15 -0700
commit7ce7ee2d8228a97f023c7e34488ed83a557d83fb (patch)
treecd0abdb9d35986108bcf8fe442bc394b53bfe8d2 /compat
parent6a730e10a76d1e03a9554292419201534c1521f1 (diff)
downloadgit-7ce7ee2d8228a97f023c7e34488ed83a557d83fb.tar.gz
git-7ce7ee2d8228a97f023c7e34488ed83a557d83fb.tar.xz
mmap(win32): avoid copy-on-write when it is unnecessary
Often we are mmap()ing read-only. In those cases, it is wasteful to map in copy-on-write mode. Even worse: it can cause errors where we run out of space in the page file. So let's be extra careful to map files in read-only mode whenever possible. Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de> Signed-off-by: Junio C Hamano <gitster@pobox.com>
Diffstat (limited to 'compat')
-rw-r--r--compat/win32mmap.c5
1 files changed, 3 insertions, 2 deletions
diff --git a/compat/win32mmap.c b/compat/win32mmap.c
index 3a39f0fad..b836169b3 100644
--- a/compat/win32mmap.c
+++ b/compat/win32mmap.c
@@ -22,14 +22,15 @@ void *git_mmap(void *start, size_t length, int prot, int flags, int fd, off_t of
die("Invalid usage of mmap when built with USE_WIN32_MMAP");
hmap = CreateFileMapping((HANDLE)_get_osfhandle(fd), NULL,
- PAGE_WRITECOPY, 0, 0, NULL);
+ prot == PROT_READ ? PAGE_READONLY : PAGE_WRITECOPY, 0, 0, NULL);
if (!hmap) {
errno = EINVAL;
return MAP_FAILED;
}
- temp = MapViewOfFileEx(hmap, FILE_MAP_COPY, h, l, length, start);
+ temp = MapViewOfFileEx(hmap, prot == PROT_READ ?
+ FILE_MAP_READ : FILE_MAP_COPY, h, l, length, start);
if (!CloseHandle(hmap))
warning("unable to close file mapping handle");