[PATCH 24/31] archive-tar: make hash size independent

["brian m. carlson" <sandals@crustytoothpaste.net>]

Make the tar generation code hash size independent by using
the_hash_algo.  Make the tar parsing code compute the header value based
on the hash algorithm in use. Update a variable name and switch to
hash_to_hex.

Signed-off-by: brian m. carlson <sandals@crustytoothpaste.net>
---
 archive-tar.c               |  7 ++++---
 builtin/get-tar-commit-id.c | 11 +++++++++--
 2 files changed, 13 insertions(+), 5 deletions(-)

diff --git a/archive-tar.c b/archive-tar.c
index 4aabd566fb..a5ba55c11e 100644
--- a/archive-tar.c
+++ b/archive-tar.c
@@ -326,14 +326,15 @@ static int write_tar_entry(struct archiver_args *args,
 
 static void write_global_extended_header(struct archiver_args *args)
 {
-	const unsigned char *sha1 = args->commit_sha1;
+	const unsigned char *hash = args->commit_sha1;
 	struct strbuf ext_header = STRBUF_INIT;
 	struct ustar_header header;
 	unsigned int mode;
 
-	if (sha1)
+	if (hash)
 		strbuf_append_ext_header(&ext_header, "comment",
-					 sha1_to_hex(sha1), 40);
+					 hash_to_hex(hash),
+					 the_hash_algo->hexsz);
 	if (args->time > USTAR_MAX_MTIME) {
 		strbuf_append_ext_header_uint(&ext_header, "mtime",
 					      args->time);
diff --git a/builtin/get-tar-commit-id.c b/builtin/get-tar-commit-id.c
index 2706fcfaf2..2760549e91 100644
--- a/builtin/get-tar-commit-id.c
+++ b/builtin/get-tar-commit-id.c
@@ -5,6 +5,7 @@
 #include "commit.h"
 #include "tar.h"
 #include "builtin.h"
+#include "strbuf.h"
 #include "quote.h"
 
 static const char builtin_get_tar_commit_id_usage[] =
@@ -21,6 +22,8 @@ int cmd_get_tar_commit_id(int argc, const char **argv, const char *prefix)
 	char *content = buffer + RECORDSIZE;
 	const char *comment;
 	ssize_t n;
+	char *hdrprefix;
+	int ret;
 
 	if (argc != 1)
 		usage(builtin_get_tar_commit_id_usage);
@@ -32,10 +35,14 @@ int cmd_get_tar_commit_id(int argc, const char **argv, const char *prefix)
 		die_errno("git get-tar-commit-id: EOF before reading tar header");
 	if (header->typeflag[0] != 'g')
 		return 1;
-	if (!skip_prefix(content, "52 comment=", &comment))
+
+	hdrprefix = xstrfmt("%zu comment=", the_hash_algo->hexsz + strlen(" comment=") + 2 + 1);
+	ret = skip_prefix(content, hdrprefix, &comment);
+	free(hdrprefix);
+	if (!ret)
 		return 1;
 
-	if (write_in_full(1, comment, 41) < 0)
+	if (write_in_full(1, comment, the_hash_algo->hexsz + 1) < 0)
 		die_errno("git get-tar-commit-id: write error");
 
 	return 0;