From 6c526148644475acbc047faaeb57d42fde1f667d Mon Sep 17 00:00:00 2001 From: Junio C Hamano Date: Thu, 17 Nov 2011 16:26:54 -0800 Subject: 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 --- csum-file.h | 9 +++++++++ 1 file changed, 9 insertions(+) (limited to 'csum-file.h') diff --git a/csum-file.h b/csum-file.h index 6a7967c6bf..3b540bdc21 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 -- cgit v1.2.3