[RFC/PATCH v4 36/49] odb-helper: add read_packetized_git_object_to_fd()

[Christian Couder <christian.couder@gmail.com>]

Signed-off-by: Christian Couder <chriscool@tuxfamily.org>
---
 odb-helper.c | 84 +++++++++++++++++++++++++++++++++++++++++++++++++++++++-----
 1 file changed, 78 insertions(+), 6 deletions(-)

diff --git a/odb-helper.c b/odb-helper.c
index 0017faa36e..a27208463c 100644
--- a/odb-helper.c
+++ b/odb-helper.c
@@ -142,6 +142,82 @@ static int check_object_process_error(int err,
 	return err;
 }
 
+static ssize_t read_packetized_git_object_to_fd(struct odb_helper *o,
+						const unsigned char *sha1,
+						int fd_in, int fd_out)
+{
+	ssize_t total_read = 0;
+	unsigned long total_got = 0;
+	int packet_len;
+	git_zstream stream;
+	int zret = Z_STREAM_END;
+	git_SHA_CTX hash;
+	unsigned char real_sha1[20];
+
+	memset(&stream, 0, sizeof(stream));
+	git_inflate_init(&stream);
+	git_SHA1_Init(&hash);
+
+	for (;;) {
+		/* packet_read() writes a '\0' extra byte at the end */
+		char buf[LARGE_PACKET_DATA_MAX + 1];
+
+		packet_len = packet_read(fd_in, NULL, NULL,
+			buf, LARGE_PACKET_DATA_MAX + 1,
+			PACKET_READ_GENTLE_ON_EOF);
+
+		if (packet_len <= 0)
+			break;
+
+		write_or_die(fd_out, buf, packet_len);
+
+		stream.next_in = (unsigned char *)buf;
+		stream.avail_in = packet_len;
+		do {
+			unsigned char inflated[4096];
+			unsigned long got;
+
+			stream.next_out = inflated;
+			stream.avail_out = sizeof(inflated);
+			zret = git_inflate(&stream, Z_SYNC_FLUSH);
+			got = sizeof(inflated) - stream.avail_out;
+
+			git_SHA1_Update(&hash, inflated, got);
+			/* skip header when counting size */
+			if (!total_got) {
+				const unsigned char *p = memchr(inflated, '\0', got);
+				if (p)
+					got -= p - inflated + 1;
+				else
+					got = 0;
+			}
+			total_got += got;
+		} while (stream.avail_in && zret == Z_OK);
+
+		total_read += packet_len;
+	}
+
+	git_inflate_end(&stream);
+
+	if (packet_len < 0)
+		return packet_len;
+
+	git_SHA1_Final(real_sha1, &hash);
+
+	if (zret != Z_STREAM_END) {
+		warning("bad zlib data from odb helper '%s' for %s",
+			o->name, sha1_to_hex(sha1));
+		return -1;
+	}
+	if (hashcmp(real_sha1, sha1)) {
+		warning("sha1 mismatch from odb helper '%s' for %s (got %s)",
+			o->name, sha1_to_hex(sha1), sha1_to_hex(real_sha1));
+		return -1;
+	}
+
+	return total_read;
+}
+
 static int read_object_process(struct odb_helper *o, const unsigned char *sha1, int fd)
 {
 	int err;
@@ -174,12 +250,8 @@ static int read_object_process(struct odb_helper *o, const unsigned char *sha1,
 	if (err)
 		goto done;
 
-	if (o->fetch_kind != ODB_FETCH_KIND_FAULT_IN) {
-		struct strbuf buf;
-		read_packetized_to_strbuf(process->out, &buf);
-		if (err)
-			goto done;
-	}
+	if (o->fetch_kind != ODB_FETCH_KIND_FAULT_IN)
+		err = read_packetized_git_object_to_fd(o, sha1, process->out, fd) < 0;
 
 	subprocess_read_status(process->out, &status);
 	err = strcmp(status.buf, "success");
-- 
2.13.1.565.gbfcd7a9048