1 files changed, 86 insertions, 0 deletions
diff --git a/builtin/show-index.c b/builtin/show-index.c
new file mode 100644
index 000000000000..a6e678809efe
--- /dev/null
+++ b/builtin/show-index.c
@@ -0,0 +1,86 @@
+#include "builtin.h"
+#include "cache.h"
+#include "pack.h"
+
+static const char show_index_usage[] =
+"git show-index";
+
+int cmd_show_index(int argc, const char **argv, const char *prefix)
+{
+	int i;
+	unsigned nr;
+	unsigned int version;
+	static unsigned int top_index[256];
+
+	if (argc != 1)
+		usage(show_index_usage);
+	if (fread(top_index, 2 * 4, 1, stdin) != 1)
+		die("unable to read header");
+	if (top_index[0] == htonl(PACK_IDX_SIGNATURE)) {
+		version = ntohl(top_index[1]);
+		if (version < 2 || version > 2)
+			die("unknown index version");
+		if (fread(top_index, 256 * 4, 1, stdin) != 1)
+			die("unable to read index");
+	} else {
+		version = 1;
+		if (fread(&top_index[2], 254 * 4, 1, stdin) != 1)
+			die("unable to read index");
+	}
+	nr = 0;
+	for (i = 0; i < 256; i++) {
+		unsigned n = ntohl(top_index[i]);
+		if (n < nr)
+			die("corrupt index file");
+		nr = n;
+	}
+	if (version == 1) {
+		for (i = 0; i < nr; i++) {
+			unsigned int offset, entry[6];
+
+			if (fread(entry, 4 + 20, 1, stdin) != 1)
+				die("unable to read entry %u/%u", i, nr);
+			offset = ntohl(entry[0]);
+			printf("%u %s\n", offset, sha1_to_hex((void *)(entry+1)));
+		}
+	} else {
+		unsigned off64_nr = 0;
+		struct {
+			unsigned char sha1[20];
+			uint32_t crc;
+			uint32_t off;
+		} *entries;
+		ALLOC_ARRAY(entries, nr);
+		for (i = 0; i < nr; i++)
+			if (fread(entries[i].sha1, 20, 1, stdin) != 1)
+				die("unable to read sha1 %u/%u", i, nr);
+		for (i = 0; i < nr; i++)
+			if (fread(&entries[i].crc, 4, 1, stdin) != 1)
+				die("unable to read crc %u/%u", i, nr);
+		for (i = 0; i < nr; i++)
+			if (fread(&entries[i].off, 4, 1, stdin) != 1)
+				die("unable to read 32b offset %u/%u", i, nr);
+		for (i = 0; i < nr; i++) {
+			uint64_t offset;
+			uint32_t off = ntohl(entries[i].off);
+			if (!(off & 0x80000000)) {
+				offset = off;
+			} else {
+				uint32_t off64[2];
+				if ((off & 0x7fffffff) != off64_nr)
+					die("inconsistent 64b offset index");
+				if (fread(off64, 8, 1, stdin) != 1)
+					die("unable to read 64b offset %u", off64_nr);
+				offset = (((uint64_t)ntohl(off64[0])) << 32) |
+						     ntohl(off64[1]);
+				off64_nr++;
+			}
+			printf("%" PRIuMAX " %s (%08"PRIx32")\n",
+			       (uintmax_t) offset,
+			       sha1_to_hex(entries[i].sha1),
+			       ntohl(entries[i].crc));
+		}
+		free(entries);
+	}
+	return 0;
+}