Add git-write-blob.

A new command, git-write-blob, is introduced.  This registers
the contents of any file on the filesystem as a blob in the
object database and reports its SHA1 to the standard output.
To implement it, the patch promotes index_fd() from a static
function in update-cache.c to extern and moves it to a library
source, sha1_file.c.

This command is used to update git-merge-one-file-script so that
it does not smudge the work tree.

Signed-off-by: Junio C Hamano <junkio@cox.net>

1 files changed, 51 insertions, 0 deletions

diff --git a/sha1_file.c b/sha1_file.c
index ced0791847..cb556cae5c 100644
--- a/sha1_file.c
+++ b/sha1_file.c
@@ -460,3 +460,54 @@ int has_sha1_file(const unsigned char *sha1)
 		return 1;
 	return 0;
 }
+
+int index_fd(unsigned char *sha1, int fd, struct stat *st)
+{
+	z_stream stream;
+	unsigned long size = st->st_size;
+	int max_out_bytes = size + 200;
+	void *out = xmalloc(max_out_bytes);
+	void *metadata = xmalloc(200);
+	int metadata_size;
+	void *in;
+	SHA_CTX c;
+
+	in = "";
+	if (size)
+		in = mmap(NULL, size, PROT_READ, MAP_PRIVATE, fd, 0);
+	close(fd);
+	if (!out || (int)(long)in == -1)
+		return -1;
+
+	metadata_size = 1+sprintf(metadata, "blob %lu", size);
+
+	SHA1_Init(&c);
+	SHA1_Update(&c, metadata, metadata_size);
+	SHA1_Update(&c, in, size);
+	SHA1_Final(sha1, &c);
+
+	memset(&stream, 0, sizeof(stream));
+	deflateInit(&stream, Z_BEST_COMPRESSION);
+
+	/*
+	 * ASCII size + nul byte
+	 */	
+	stream.next_in = metadata;
+	stream.avail_in = metadata_size;
+	stream.next_out = out;
+	stream.avail_out = max_out_bytes;
+	while (deflate(&stream, 0) == Z_OK)
+		/* nothing */;
+
+	/*
+	 * File content
+	 */
+	stream.next_in = in;
+	stream.avail_in = size;
+	while (deflate(&stream, Z_FINISH) == Z_OK)
+		/*nothing */;
+
+	deflateEnd(&stream);
+	
+	return write_sha1_buffer(sha1, out, stream.total_out);
+}