[PATCH] Seek back to current filepos when mmap()ing with NO_MMAP

From: Johannes Schindelin <johannes.schindelin@gmx.de>
Date: Nov 15, 2006, 16:27 UTC
Message-ID: <Pine.LNX.4.63.0611151727000.13772@wbgn013.biozentrum.uni-wuerzburg.de>

"git-index-pack --fix-thin" relies on mmap() not changing the current file position (otherwise the pack will be corrupted when writing the final SHA1). Meet that expectation.

Signed-off-by: Johannes Schindelin <Johannes.Schindelin@gmx.de>
---

	Sorry for not catching that earlier. It only affects platforms
	where you have to set NO_MMAP=YesPlease, anyway.

 compat/mmap.c |    6 ++++++
 1 files changed, 6 insertions(+), 0 deletions(-)

diff --git a/compat/mmap.c b/compat/mmap.c
index 55cb120..a4d2e50 100644
--- a/compat/mmap.c
+++ b/compat/mmap.c
@@ -7,6 +7,7 @@
 void *gitfakemmap(void *start, size_t length, int prot , int flags, int fd, off_t offset)
 {
 	int n = 0;
+	off_t current_offset = lseek(fd, 0, SEEK_CUR);
 
 	if (start != NULL || !(flags & MAP_PRIVATE))
 		die("Invalid usage of gitfakemmap.");
@@ -39,6 +40,11 @@ void *gitfakemmap(void *start, size_t le
 		n += count;
 	}
 
+	if (current_offset != lseek(fd, current_offset, SEEK_SET)) {
+		errno = EINVAL;
+		return MAP_FAILED;
+	}
+
 	return start;
 }

-- 
dummy-dirty