path: root/csum-file.h
diff options
authorJunio C Hamano <>2011-11-18 00:26:54 (GMT)
committerJunio C Hamano <>2011-11-30 22:27:59 (GMT)
commit6c526148644475acbc047faaeb57d42fde1f667d (patch)
tree1bf8400d2f5dff6ea15775b8b8af47af2e740617 /csum-file.h
parent0e990530ae6d6c6805d31c666953541f762dd402 (diff)
csum-file: introduce sha1file_checkpoint
It is useful to be able to rewind a check-summed file to a certain previous state after writing data into it using sha1write() API. The fast-import command does this after streaming a blob data to the packfile being generated and then noticing that the same blob has already been written, and it does this with a private code truncate_pack() that is commented as "Yes, this is a layering violation". Introduce two API functions, sha1file_checkpoint(), that allows the caller to save a state of a sha1file, and then later revert it to the saved state. Use it to reimplement truncate_pack(). Signed-off-by: Junio C Hamano <>
Diffstat (limited to 'csum-file.h')
1 files changed, 9 insertions, 0 deletions
diff --git a/csum-file.h b/csum-file.h
index 6a7967c..3b540bd 100644
--- a/csum-file.h
+++ b/csum-file.h
@@ -17,6 +17,15 @@ struct sha1file {
unsigned char buffer[8192];
+/* Checkpoint */
+struct sha1file_checkpoint {
+ off_t offset;
+ git_SHA_CTX ctx;
+extern void sha1file_checkpoint(struct sha1file *, struct sha1file_checkpoint *);
+extern int sha1file_truncate(struct sha1file *, struct sha1file_checkpoint *);
/* sha1close flags */
#define CSUM_CLOSE 1
#define CSUM_FSYNC 2