Created fast-import, a tool to quickly generating a pack from blobs.

Signed-off-by: Shawn O. Pearce <spearce@spearce.org>

.gitignore

@@ -32,6 +32,7 @@ git-diff-index
 git-diff-stages
 git-diff-tree
 git-describe
+git-fast-import
 git-fetch
 git-fetch-pack
 git-findtags

Makefile

@@ -186,6 +186,7 @@ SIMPLE_PROGRAMS = \
 PROGRAMS = \
 	git-convert-objects$X git-fetch-pack$X git-fsck-objects$X \
 	git-hash-object$X git-index-pack$X git-local-fetch$X \
+	git-fast-import$X \
 	git-merge-base$X \
 	git-merge-index$X git-mktag$X git-mktree$X git-patch-id$X \
 	git-peek-remote$X git-receive-pack$X \

fast-import.c

@@ -0,0 +1,214 @@
+#include "builtin.h"
+#include "cache.h"
+#include "object.h"
+#include "blob.h"
+#include "delta.h"
+#include "pack.h"
+#include "csum-file.h"
+
+static int max_depth = 10;
+static unsigned long object_count;
+static int packfd;
+static int current_depth;
+static void *lastdat;
+static unsigned long lastdatlen;
+static unsigned char lastsha1[20];
+
+static ssize_t yread(int fd, void *buffer, size_t length)
+{
+	ssize_t ret = 0;
+	while (ret < length) {
+		ssize_t size = xread(fd, (char *) buffer + ret, length - ret);
+		if (size < 0) {
+			return size;
+		}
+		if (size == 0) {
+			return ret;
+		}
+		ret += size;
+	}
+	return ret;
+}
+
+static ssize_t ywrite(int fd, void *buffer, size_t length)
+{
+	ssize_t ret = 0;
+	while (ret < length) {
+		ssize_t size = xwrite(fd, (char *) buffer + ret, length - ret);
+		if (size < 0) {
+			return size;
+		}
+		if (size == 0) {
+			return ret;
+		}
+		ret += size;
+	}
+	return ret;
+}
+
+static unsigned long encode_header(enum object_type type, unsigned long size, unsigned char *hdr)
+{
+	int n = 1;
+	unsigned char c;
+
+	if (type < OBJ_COMMIT || type > OBJ_DELTA)
+		die("bad type %d", type);
+
+	c = (type << 4) | (size & 15);
+	size >>= 4;
+	while (size) {
+		*hdr++ = c | 0x80;
+		c = size & 0x7f;
+		size >>= 7;
+		n++;
+	}
+	*hdr = c;
+	return n;
+}
+
+static void write_blob (void *dat, unsigned long datlen)
+{
+	z_stream s;
+	void *out, *delta;
+	unsigned char hdr[64];
+	unsigned long hdrlen, deltalen;
+
+	if (lastdat && current_depth < max_depth) {
+		delta = diff_delta(lastdat, lastdatlen,
+			dat, datlen,
+			&deltalen, 0);
+	} else
+		delta = 0;
+
+	memset(&s, 0, sizeof(s));
+	deflateInit(&s, zlib_compression_level);
+
+	if (delta) {
+		current_depth++;
+		s.next_in = delta;
+		s.avail_in = deltalen;
+		hdrlen = encode_header(OBJ_DELTA, deltalen, hdr);
+		if (ywrite(packfd, hdr, hdrlen) != hdrlen)
+			die("Can't write object header: %s", strerror(errno));
+		if (ywrite(packfd, lastsha1, sizeof(lastsha1)) != sizeof(lastsha1))
+			die("Can't write object base: %s", strerror(errno));
+	} else {
+		current_depth = 0;
+		s.next_in = dat;
+		s.avail_in = datlen;
+		hdrlen = encode_header(OBJ_BLOB, datlen, hdr);
+		if (ywrite(packfd, hdr, hdrlen) != hdrlen)
+			die("Can't write object header: %s", strerror(errno));
+	}
+
+	s.avail_out = deflateBound(&s, s.avail_in);
+	s.next_out = out = xmalloc(s.avail_out);
+	while (deflate(&s, Z_FINISH) == Z_OK)
+		/* nothing */;
+	deflateEnd(&s);
+
+	if (ywrite(packfd, out, s.total_out) != s.total_out)
+		die("Failed writing compressed data %s", strerror(errno));
+
+	free(out);
+	if (delta)
+		free(delta);
+}
+
+static void init_pack_header ()
+{
+	const char* magic = "PACK";
+	unsigned long version = 2;
+	unsigned long zero = 0;
+
+	version = htonl(version);
+
+	if (ywrite(packfd, (char*)magic, 4) != 4)
+		die("Can't write pack magic: %s", strerror(errno));
+	if (ywrite(packfd, &version, 4) != 4)
+		die("Can't write pack version: %s", strerror(errno));
+	if (ywrite(packfd, &zero, 4) != 4)
+		die("Can't write 0 object count: %s", strerror(errno));
+}
+
+static void fixup_header_footer ()
+{
+	SHA_CTX c;
+	char hdr[8];
+	unsigned char sha1[20];
+	unsigned long cnt;
+	char *buf;
+	size_t n;
+
+	if (lseek(packfd, 0, SEEK_SET) != 0)
+		die("Failed seeking to start: %s", strerror(errno));
+
+	SHA1_Init(&c);
+	if (yread(packfd, hdr, 8) != 8)
+		die("Failed reading header: %s", strerror(errno));
+	SHA1_Update(&c, hdr, 8);
+
+fprintf(stderr, "%lu objects\n", object_count);
+	cnt = htonl(object_count);
+	SHA1_Update(&c, &cnt, 4);
+	if (ywrite(packfd, &cnt, 4) != 4)
+		die("Failed writing object count: %s", strerror(errno));
+
+	buf = xmalloc(128 * 1024);
+	for (;;) {
+		n = xread(packfd, buf, 128 * 1024);
+		if (n <= 0)
+			break;
+		SHA1_Update(&c, buf, n);
+	}
+	free(buf);
+
+	SHA1_Final(sha1, &c);
+	if (ywrite(packfd, sha1, sizeof(sha1)) != sizeof(sha1))
+		die("Failed writing pack checksum: %s", strerror(errno));
+}
+
+int main (int argc, const char **argv)
+{
+	packfd = open(argv[1], O_RDWR|O_CREAT|O_TRUNC, 0666);
+	if (packfd < 0)
+		die("Can't create pack file %s: %s", argv[1], strerror(errno));
+
+	init_pack_header();
+	for (;;) {
+		unsigned long datlen;
+		int hdrlen;
+		void *dat;
+		char hdr[128];
+		unsigned char sha1[20];
+		SHA_CTX c;
+
+		if (yread(0, &datlen, 4) != 4)
+			break;
+
+		dat = xmalloc(datlen);
+		if (yread(0, dat, datlen) != datlen)
+			break;
+
+		hdrlen = sprintf(hdr, "blob %lu", datlen) + 1;
+		SHA1_Init(&c);
+		SHA1_Update(&c, hdr, hdrlen);
+		SHA1_Update(&c, dat, datlen);
+		SHA1_Final(sha1, &c);
+
+		write_blob(dat, datlen);
+		object_count++;
+		printf("%s\n", sha1_to_hex(sha1));
+		fflush(stdout);
+
+		if (lastdat)
+			free(lastdat);
+		lastdat = dat;
+		lastdatlen = datlen;
+		memcpy(lastsha1, sha1, sizeof(sha1));
+	}
+	fixup_header_footer();
+	close(packfd);
+
+	return 0;
+}