cat-file: add "--literally" option

index 4d02efc..949ef4c 100644
@@ -830,6 +830,7 @@ extern int is_ntfs_dotgit(const char *name);
 
 /* object replacement */
 #define LOOKUP_REPLACE_OBJECT 1
+#define LOOKUP_LITERALLY 2
 extern void *read_sha1_file_extended(const unsigned char *sha1, enum object_type *type, unsigned long *size, unsigned flag);
 static inline void *read_sha1_file(const unsigned char *sha1, enum object_type *type, unsigned long *size)
 {

@@ -1296,6 +1297,7 @@ struct object_info {
 	unsigned long *sizep;
 	unsigned long *disk_sizep;
 	unsigned char *delta_base_sha1;
+	struct strbuf *typename;
 
 	/* Response */
 	enum {

index 69a60ec..1068ca0 100644
@@ -1564,6 +1564,36 @@ int unpack_sha1_header(git_zstream *stream, unsigned char *map, unsigned long ma
 	return git_inflate(stream, 0);
 }
 
+static int unpack_sha1_header_literally(git_zstream *stream, unsigned char *map,
+					unsigned long mapsize,
+					struct strbuf *header)
+{
+	unsigned char buffer[32], *cp;
+	unsigned long bufsiz = sizeof(buffer);
+	int status;
+
+	/* Get the data stream */
+	memset(stream, 0, sizeof(*stream));
+	stream->next_in = map;
+	stream->avail_in = mapsize;
+	stream->next_out = buffer;
+	stream->avail_out = bufsiz;
+
+	git_inflate_init(stream);
+
+	do {
+		status = git_inflate(stream, 0);
+		strbuf_add(header, buffer, stream->next_out - buffer);
+		for (cp = buffer; cp < stream->next_out; cp++)
+			if (!*cp)
+				/* Found the NUL at the end of the header */
+				return 0;
+		stream->next_out = buffer;
+		stream->avail_out = bufsiz;
+	} while (status == Z_OK);
+	return -1;
+}
+
 static void *unpack_sha1_rest(git_zstream *stream, void *buffer, unsigned long size, const unsigned char *sha1)
 {
 	int bytes = strlen(buffer) + 1;

@@ -2524,13 +2554,16 @@ struct packed_git *find_sha1_pack(const unsigned char *sha1,
 }
 
 static int sha1_loose_object_info(const unsigned char *sha1,
-				  struct object_info *oi)
+				  struct object_info *oi,
+				  int flags)
 {
-	int status;
+	int status = 0;
 	unsigned long mapsize, size;
 	void *map;
 	git_zstream stream;
 	char hdr[32];
+	struct strbuf hdrbuf = STRBUF_INIT;
+	char *hdrp;
 
 	if (oi->delta_base_sha1)
 		hashclr(oi->delta_base_sha1);

@@ -2557,10 +2590,25 @@ static int sha1_loose_object_info(const unsigned char *sha1,
 		return -1;
 	if (oi->disk_sizep)
 		*oi->disk_sizep = mapsize;
-	if (unpack_sha1_header(&stream, map, mapsize, hdr, sizeof(hdr)) < 0)
-		status = error("unable to unpack %s header",
-			       sha1_to_hex(sha1));
-	else if ((status = parse_sha1_header(hdr, &size)) < 0)
+	if ((flags & LOOKUP_LITERALLY)) {
+		if (unpack_sha1_header_literally(&stream, map, mapsize, &hdrbuf) < 0)
+			status = error("unable to unpack %s header with --literally",
+				       sha1_to_hex(sha1));
+		hdrp = hdrbuf.buf;
+	} else {
+		if (unpack_sha1_header(&stream, map, mapsize, hdr, sizeof(hdr)) < 0) {
+			status = error("unable to unpack %s header",
+				       sha1_to_hex(sha1));
+		}
+		hdrp = hdr;
+	}
+	if (status)
+		; /* We're already checking for errors */
+	else if ((flags & LOOKUP_LITERALLY)) {
+		size_t typelen = strcspn(hdrbuf.buf, " ");
+		strbuf_add(oi->typename, hdrbuf.buf, typelen);
+	}
+	else if ((status = parse_sha1_header(hdrp, &size)) < 0)
 		status = error("unable to parse %s header", sha1_to_hex(sha1));
 	else if (oi->sizep)
 		*oi->sizep = size;

@@ -2568,6 +2616,10 @@ static int sha1_loose_object_info(const unsigned char *sha1,
 	munmap(map, mapsize);
 	if (oi->typep)
 		*oi->typep = status;
+	if (oi->typename && 0 <= status && typename(status))
+		strbuf_addstr(oi->typename, typename(status));
+	if (hdrp == hdrbuf.buf)
+		strbuf_release(&hdrbuf);
 	return 0;
 }
 

@@ -2594,7 +2646,7 @@ int sha1_object_info_extended(const unsigned char *sha1, struct object_info *oi,
 
 	if (!find_pack_entry(real, &e)) {
 		/* Most likely it's a loose object. */
-		if (!sha1_loose_object_info(real, oi)) {
+		if (!sha1_loose_object_info(real, oi, flags)) {
 			oi->whence = OI_LOOSE;
 			return 0;
 		}

@@ -2635,6 +2687,24 @@ int sha1_object_info(const unsigned char *sha1, unsigned long *sizep)
 	return type;
 }
 
+int sha1_object_info_literally(const unsigned char *sha1)
+{
+	enum object_type type;
+	struct strbuf sb = STRBUF_INIT;
+	struct object_info oi = {NULL};
+
+	oi.typename = &sb;
+	oi.typep = &type;
+	if (sha1_object_info_extended(sha1, &oi, LOOKUP_LITERALLY) < 0)
+		return -1;
+	if (*oi.typep > 0)
+		printf("%s\n", typename(*oi.typep));
+	else
+		printf("%s\n", oi.typename->buf);
+	strbuf_release(oi.typename);
+	return 0;
+}
+
 static void *read_packed_sha1(const unsigned char *sha1,
 			      enum object_type *type, unsigned long *size)
 {

index df99df4..2af9f40 100644
@@ -9,7 +9,8 @@
 #include "userdiff.h"
 #include "streaming.h"
 
-static int cat_one_file(int opt, const char *exp_type, const char *obj_name)
+static int cat_one_file(int opt, const char *exp_type, const char *obj_name,
+			int literally)
 {
 	unsigned char sha1[20];
 	enum object_type type;

@@ -23,6 +24,8 @@ static int cat_one_file(int opt, const char *exp_type, const char *obj_name)
 	buf = NULL;
 	switch (opt) {
 	case 't':
+		if (literally)
+			return sha1_object_info_literally(sha1);
 		type = sha1_object_info(sha1, NULL);
 		if (type > 0) {
 			printf("%s\n", typename(type));

@@ -323,7 +326,7 @@ static int batch_objects(struct batch_options *opt)
 }
 
 static const char * const cat_file_usage[] = {
-	N_("git cat-file (-t | -s | -e | -p | <type> | --textconv) <object>"),
+	N_("git cat-file (-t|-s|-e|-p|<type>|--textconv|-t --literally) <object>"),
 	N_("git cat-file (--batch | --batch-check) < <list-of-objects>"),
 	NULL
 };

@@ -359,6 +362,7 @@ int cmd_cat_file(int argc, const char **argv, const char *prefix)
 	int opt = 0;
 	const char *exp_type = NULL, *obj_name = NULL;
 	struct batch_options batch = {0};
+	int literally = 0;
 
 	const struct option options[] = {
 		OPT_GROUP(N_("<type> can be one of: blob, tree, commit, tag")),

@@ -369,6 +373,8 @@ int cmd_cat_file(int argc, const char **argv, const char *prefix)
 		OPT_SET_INT('p', NULL, &opt, N_("pretty-print object's content"), 'p'),
 		OPT_SET_INT(0, "textconv", &opt,
 			    N_("for blob objects, run textconv on object's content"), 'c'),
+		OPT_BOOL( 0, "literally", &literally,
+			  N_("show the type of the given loose object, use for debugging")),
 		{ OPTION_CALLBACK, 0, "batch", &batch, "format",
 			N_("show info and content of objects fed from the standard input"),
 			PARSE_OPT_OPTARG, batch_option_callback },

@@ -380,7 +386,7 @@ int cmd_cat_file(int argc, const char **argv, const char *prefix)
 
 	git_config(git_cat_file_config, NULL);
 
-	if (argc != 3 && argc != 2)
+	if (argc != 3 && argc != 2 && argc != 4)
 		usage_with_options(cat_file_usage, options);
 
 	argc = parse_options(argc, argv, prefix, options, cat_file_usage, 0);

@@ -405,5 +411,10 @@ int cmd_cat_file(int argc, const char **argv, const char *prefix)
 	if (batch.enabled)
 		return batch_objects(&batch);
 
-	return cat_one_file(opt, exp_type, obj_name);
+	if (literally && opt == 't')
+		return cat_one_file(opt, exp_type, obj_name, literally);
+	else if (literally)
+		usage_with_options(cat_file_usage, options);
+
+	return cat_one_file(opt, exp_type, obj_name, literally);
 }