pack: move find_pack_entry_one(), is_pack_valid()

Signed-off-by: Jonathan Tan <jonathantanmy@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

1 files changed, 75 insertions, 1 deletions

diff --git a/packfile.c b/packfile.c
index f251e38783..20562304b7 100644
--- a/packfile.c
+++ b/packfile.c
@@ -7,6 +7,7 @@
 #include "delta.h"
 #include "list.h"
 #include "streaming.h"
+#include "sha1-lookup.h"
 
 char *odb_pack_name(struct strbuf *buf,
 		    const unsigned char *sha1,
@@ -509,7 +510,7 @@ static int open_packed_git_1(struct packed_git *p)
 	return 0;
 }
 
-int open_packed_git(struct packed_git *p)
+static int open_packed_git(struct packed_git *p)
 {
 	if (!open_packed_git_1(p))
 		return 0;
@@ -1700,3 +1701,76 @@ off_t nth_packed_object_offset(const struct packed_git *p, uint32_t n)
 				   ntohl(*((uint32_t *)(index + 4)));
 	}
 }
+
+off_t find_pack_entry_one(const unsigned char *sha1,
+				  struct packed_git *p)
+{
+	const uint32_t *level1_ofs = p->index_data;
+	const unsigned char *index = p->index_data;
+	unsigned hi, lo, stride;
+	static int debug_lookup = -1;
+
+	if (debug_lookup < 0)
+		debug_lookup = !!getenv("GIT_DEBUG_LOOKUP");
+
+	if (!index) {
+		if (open_pack_index(p))
+			return 0;
+		level1_ofs = p->index_data;
+		index = p->index_data;
+	}
+	if (p->index_version > 1) {
+		level1_ofs += 2;
+		index += 8;
+	}
+	index += 4 * 256;
+	hi = ntohl(level1_ofs[*sha1]);
+	lo = ((*sha1 == 0x0) ? 0 : ntohl(level1_ofs[*sha1 - 1]));
+	if (p->index_version > 1) {
+		stride = 20;
+	} else {
+		stride = 24;
+		index += 4;
+	}
+
+	if (debug_lookup)
+		printf("%02x%02x%02x... lo %u hi %u nr %"PRIu32"\n",
+		       sha1[0], sha1[1], sha1[2], lo, hi, p->num_objects);
+
+	while (lo < hi) {
+		unsigned mi = (lo + hi) / 2;
+		int cmp = hashcmp(index + mi * stride, sha1);
+
+		if (debug_lookup)
+			printf("lo %u hi %u rg %u mi %u\n",
+			       lo, hi, hi - lo, mi);
+		if (!cmp)
+			return nth_packed_object_offset(p, mi);
+		if (cmp > 0)
+			hi = mi;
+		else
+			lo = mi+1;
+	}
+	return 0;
+}
+
+int is_pack_valid(struct packed_git *p)
+{
+	/* An already open pack is known to be valid. */
+	if (p->pack_fd != -1)
+		return 1;
+
+	/* If the pack has one window completely covering the
+	 * file size, the pack is known to be valid even if
+	 * the descriptor is not currently open.
+	 */
+	if (p->windows) {
+		struct pack_window *w = p->windows;
+
+		if (!w->offset && w->len == p->pack_size)
+			return 1;
+	}
+
+	/* Force the pack to open to prove its valid. */
+	return !open_packed_git(p);
+}