Hello,

This adds an alternative set of functions to deal with sha256 hash
digest that behaves like the sha1 ones we already have.  On top of
these there's a generic got_parse_hash_digest() that uses the hash
algorithm specified as argument.  Finally, to prevent future breakage,
this adds got_parse_object_id() that fills the struct got_object_id.
The memset() is important: in the future I'd like to grow it with a
field, and the explicit zeroing will prevent breakages due to
un-initialized fields (we have many object ids lying on the stack.)

Finally, I'm also replacing almost all got_parse_sha1_digest() calls,
only a few in gotd and one in got-read-patch remains.  The various
enum got_hash_algorithm introduced in various places will be soon
bubbled up and disappear soon-ish.

ok?

diff /home/op/w/got
commit - 53bf0b541977b66862040d4b633fb6b5d3a3c6c8
path + /home/op/w/got
blob - 6a161bc20df5aaa7789395593ab2ffc6fbe4b1fb
file + include/got_object.h
--- include/got_object.h
+++ include/got_object.h
@@ -16,6 +16,11 @@ struct got_object_id {
 
 #define GOT_OBJECT_ID_HEX_MAXLEN SHA1_DIGEST_STRING_LENGTH
 
+enum got_hash_algorithm {
+	GOT_HASH_SHA1,
+	GOT_HASH_SHA256,
+};
+
 struct got_object_id {
 	u_int8_t sha1[SHA1_DIGEST_LENGTH];
 };
blob - 141cb2590fa14834c63381929a0a7438ae3e4556
file + lib/got_lib_hash.h
--- lib/got_lib_hash.h
+++ lib/got_lib_hash.h
@@ -15,7 +15,16 @@
  */
 
 #define GOT_SHA1_STRING_ZERO "0000000000000000000000000000000000000000"
+#define GOT_SHA256_STRING_ZERO "0000000000000000000000000000000000000000000000000000000000000000"
 
 int got_parse_xdigit(uint8_t *, const char *);
+
 int got_parse_sha1_digest(uint8_t *, const char *);
 char *got_sha1_digest_to_str(const uint8_t *, char *, size_t);
+
+int got_parse_sha256_digest(uint8_t *, const char *);
+char *got_sha256_digest_to_str(const uint8_t *, char *, size_t);
+
+int got_parse_hash_digest(uint8_t *, const char *, enum got_hash_algorithm);
+int got_parse_object_id(struct got_object_id *, const char *,
+    enum got_hash_algorithm);
blob - fb4d3a30adf9281507aea3424f4c2711b1d3a28c
file + lib/hash.c
--- lib/hash.c
+++ lib/hash.c
@@ -15,13 +15,18 @@
  */
 
 #include <sys/types.h>
+#include <sys/queue.h>
+
 #include <sha1.h>
 #include <sha2.h>
 #include <errno.h>
 #include <stdio.h>
 #include <stdlib.h>
+#include <string.h>
 #include <limits.h>
 
+#include "got_object.h"
+
 #include "got_lib_hash.h"
 
 int
@@ -83,3 +88,73 @@ got_sha1_digest_to_str(const uint8_t *digest, char *bu
 
 	return buf;
 }
+
+int
+got_parse_sha256_digest(uint8_t *digest, const char *line)
+{
+	uint8_t b = 0;
+	char hex[3] = {'\0', '\0', '\0'};
+	int i, j;
+
+	for (i = 0; i < SHA256_DIGEST_LENGTH; i++) {
+		if (line[0] == '\0' || line[1] == '\0')
+			return 0;
+		for (j = 0; j < 2; j++) {
+			hex[j] = *line;
+			line++;
+		}
+		if (!got_parse_xdigit(&b, hex))
+			return 0;
+		digest[i] = b;
+	}
+
+	return 1;
+}
+
+char *
+got_sha256_digest_to_str(const uint8_t *digest, char *buf, size_t size)
+{
+	char *p = buf;
+	char hex[3];
+	int i;
+
+	if (size < SHA256_DIGEST_STRING_LENGTH)
+		return NULL;
+
+	for (i = 0; i < SHA256_DIGEST_LENGTH; i++) {
+		snprintf(hex, sizeof(hex), "%.2x", digest[i]);
+		p[0] = hex[0];
+		p[1] = hex[1];
+		p += 2;
+	}
+	p[0] = '\0';
+
+	return buf;
+}
+
+int
+got_parse_hash_digest(uint8_t *digest, const char *line,
+    enum got_hash_algorithm algo)
+{
+	switch (algo) {
+	case GOT_HASH_SHA1:
+		return got_parse_sha1_digest(digest, line);
+	case GOT_HASH_SHA256:
+		return got_parse_sha256_digest(digest, line);
+	default:
+		return 0;
+	}
+}
+
+int
+got_parse_object_id(struct got_object_id *id, const char *line,
+    enum got_hash_algorithm algo)
+{
+	memset(id, 0, sizeof(*id));
+
+	/* XXX: temporary until we grow got_object_id */
+	if (algo != GOT_HASH_SHA1)
+		return 0;
+
+	return got_parse_hash_digest(id->sha1, line, algo);
+}
blob - f8b902a4c27338568c455eb639ecba5cbb38b8c2
file + lib/object.c
--- lib/object.c
+++ lib/object.c
@@ -151,7 +151,7 @@ got_object_open_by_id_str(struct got_object **obj, str
 {
 	struct got_object_id id;
 
-	if (!got_parse_sha1_digest(id.sha1, id_str))
+	if (!got_parse_object_id(&id, id_str, GOT_HASH_SHA1))
 		return got_error_path(id_str, GOT_ERR_BAD_OBJ_ID_STR);
 
 	return got_object_open(obj, repo, &id);
blob - 67c3bc37ea78571d6f3c25478ae3e612ee235f22
file + lib/object_parse.c
--- lib/object_parse.c
+++ lib/object_parse.c
@@ -387,7 +387,7 @@ got_object_commit_add_parent(struct got_commit_object 
 	if (err)
 		return err;
 
-	if (!got_parse_sha1_digest(qid->id.sha1, id_str)) {
+	if (!got_parse_object_id(&qid->id, id_str, GOT_HASH_SHA1)) {
 		err = got_error(GOT_ERR_BAD_OBJ_DATA);
 		got_object_qid_free(qid);
 		return err;
@@ -620,6 +620,7 @@ got_object_parse_commit(struct got_commit_object **com
     size_t len)
 {
 	const struct got_error *err = NULL;
+	enum got_hash_algorithm algo = GOT_HASH_SHA1;
 	char *s = buf;
 	size_t label_len;
 	ssize_t remain = (ssize_t)len;
@@ -639,7 +640,7 @@ got_object_parse_commit(struct got_commit_object **com
 			goto done;
 		}
 		s += label_len;
-		if (!got_parse_sha1_digest((*commit)->tree_id->sha1, s)) {
+		if (!got_parse_object_id((*commit)->tree_id, s, algo)) {
 			err = got_error(GOT_ERR_BAD_OBJ_DATA);
 			goto done;
 		}
@@ -974,6 +975,7 @@ got_object_parse_tag(struct got_tag_object **tag, uint
 got_object_parse_tag(struct got_tag_object **tag, uint8_t *buf, size_t len)
 {
 	const struct got_error *err = NULL;
+	enum got_hash_algorithm algo = GOT_HASH_SHA1;
 	size_t remain = len;
 	char *s = buf;
 	size_t label_len;
@@ -993,7 +995,7 @@ got_object_parse_tag(struct got_tag_object **tag, uint
 			goto done;
 		}
 		s += label_len;
-		if (!got_parse_sha1_digest((*tag)->id.sha1, s)) {
+		if (!got_parse_object_id(&(*tag)->id, s, algo)) {
 			err = got_error(GOT_ERR_BAD_OBJ_DATA);
 			goto done;
 		}
blob - 92514335bde2a392e0211cb8f5903c931aac55d2
file + lib/patch.c
--- lib/patch.c
+++ lib/patch.c
@@ -706,7 +706,7 @@ open_blob(char **path, FILE **fp, const char *blobid,
 			return err;
 		idptr = matched_id;
 	} else {
-		if (!got_parse_sha1_digest(id.sha1, blobid))
+		if (!got_parse_object_id(&id, blobid, GOT_HASH_SHA1))
 			return got_error(GOT_ERR_BAD_OBJ_ID_STR);
 		idptr = &id;
 	}
blob - b7e19bcfc7a34cea70cf48a5c32ab66ee4acb857
file + lib/reference.c
--- lib/reference.c
+++ lib/reference.c
@@ -155,6 +155,7 @@ parse_ref_line(struct got_reference **ref, const char 
 parse_ref_line(struct got_reference **ref, const char *name, const char *line,
     time_t mtime)
 {
+	enum got_hash_algorithm algo = GOT_HASH_SHA1;
 	struct got_object_id id;
 
 	if (strncmp(line, "ref: ", 5) == 0) {
@@ -162,7 +163,7 @@ parse_ref_line(struct got_reference **ref, const char 
 		return parse_symref(ref, name, line);
 	}
 
-	if (!got_parse_sha1_digest(id.sha1, line))
+	if (!got_parse_object_id(&id, line, algo))
 		return got_error(GOT_ERR_BAD_REF_DATA);
 
 	return alloc_ref(ref, name, &id, 0, mtime);
@@ -292,6 +293,7 @@ parse_packed_ref_line(struct got_reference **ref, cons
 parse_packed_ref_line(struct got_reference **ref, const char *abs_refname,
     const char *line, time_t mtime)
 {
+	enum got_hash_algorithm algo = GOT_HASH_SHA1;
 	struct got_object_id id;
 	const char *name;
 
@@ -300,7 +302,7 @@ parse_packed_ref_line(struct got_reference **ref, cons
 	if (line[0] == '#' || line[0] == '^')
 		return NULL;
 
-	if (!got_parse_sha1_digest(id.sha1, line))
+	if (!got_parse_object_id(&id, line, algo))
 		return got_error(GOT_ERR_BAD_REF_DATA);
 
 	if (abs_refname) {
blob - abff91e2c234cdd1c87f05d07d2a9d02a0cc98e4
file + lib/repository.c
--- lib/repository.c
+++ lib/repository.c
@@ -1738,6 +1738,7 @@ match_loose_object(struct got_object_id **unique_id, c
 	}
 	while ((dent = readdir(dir)) != NULL) {
 		int cmp;
+		enum got_hash_algorithm algo = GOT_HASH_SHA1;
 
 		free(id_str);
 		id_str = NULL;
@@ -1751,7 +1752,7 @@ match_loose_object(struct got_object_id **unique_id, c
 			goto done;
 		}
 
-		if (!got_parse_sha1_digest(id.sha1, id_str))
+		if (!got_parse_object_id(&id, id_str, algo))
 			continue;
 
 		/*
@@ -2291,6 +2292,7 @@ got_repo_get_loose_object_info(int *nobjects, off_t *o
 			char *id_str;
 			int fd;
 			struct stat sb;
+			enum got_hash_algorithm algo = GOT_HASH_SHA1;
 
 			if (strcmp(dent->d_name, ".") == 0 ||
 			    strcmp(dent->d_name, "..") == 0)
@@ -2301,7 +2303,7 @@ got_repo_get_loose_object_info(int *nobjects, off_t *o
 				goto done;
 			}
 
-			if (!got_parse_sha1_digest(id.sha1, id_str)) {
+			if (!got_parse_object_id(&id, id_str, algo)) {
 				free(id_str);
 				continue;
 			}
blob - d552b4a35a689baa8cf628c010eb5adfc9d57ce4
file + lib/repository_admin.c
--- lib/repository_admin.c
+++ lib/repository_admin.c
@@ -486,7 +486,7 @@ got_repo_find_pack(FILE **packfile, struct got_object_
 		goto done;
 	}
 	*dot = '\0';
-	if (!got_parse_sha1_digest(id.sha1, p)) {
+	if (!got_parse_object_id(&id, p, GOT_HASH_SHA1)) {
 		err = got_error_fmt(GOT_ERR_BAD_PATH,
 		    "'%s' is not a valid pack file name",
 		    packfile_name);
@@ -685,8 +685,8 @@ get_loose_object_ids(struct got_object_idset **loose_i
 				goto done;
 			}
 
-			memset(&id, 0, sizeof(id));
-			if (!got_parse_sha1_digest(id.sha1, id_str)) {
+			if (!got_parse_object_id(&id, id_str,
+			    GOT_HASH_SHA1)) {
 				free(id_str);
 				continue;
 			}
blob - ecd71cee9f0fb1d68f5a2341e98bfa386fb743c0
file + lib/serve.c
--- lib/serve.c
+++ lib/serve.c
@@ -36,6 +36,7 @@
 #include "got_path.h"
 #include "got_version.h"
 #include "got_reference.h"
+#include "got_object.h"
 
 #include "got_lib_pkt.h"
 #include "got_lib_dial.h"
blob - 9182db0e5c9f34de75291565e8162a16cda84db4
file + libexec/got-fetch-pack/got-fetch-pack.c
--- libexec/got-fetch-pack/got-fetch-pack.c
+++ libexec/got-fetch-pack/got-fetch-pack.c
@@ -300,7 +300,7 @@ fetch_ref(struct imsgbuf *ibuf, struct got_pathlist_he
 	const struct got_error *err;
 	char *theirs = NULL, *mine = NULL;
 
-	if (!got_parse_sha1_digest(want->sha1, id_str)) {
+	if (!got_parse_object_id(want, id_str, GOT_HASH_SHA1)) {
 		err = got_error(GOT_ERR_BAD_OBJ_ID_STR);
 		goto done;
 	}
@@ -619,7 +619,8 @@ fetch_pack(int fd, int packfd, uint8_t *pack_sha1,
 			    "unexpected message from server");
 			goto done;
 		}
-		if (!got_parse_sha1_digest(common_id.sha1, buf + 4)) {
+		if (!got_parse_object_id(&common_id, buf + 4,
+		    GOT_HASH_SHA1)) {
 			err = got_error_msg(GOT_ERR_BAD_PACKET,
 			    "bad object ID in ACK packet from server");
 			goto done;
blob - d1ffc719f8ca4925cb7bf8c3d4e5c8180824fb64
file + libexec/got-send-pack/got-send-pack.c
--- libexec/got-send-pack/got-send-pack.c
+++ libexec/got-send-pack/got-send-pack.c
@@ -414,7 +414,7 @@ send_pack(int fd, struct got_pathlist_head *refs,
 			err = got_error_from_errno("malloc");
 			goto done;
 		}
-		if (!got_parse_sha1_digest(id->sha1, id_str)) {
+		if (!got_parse_object_id(id, id_str, GOT_HASH_SHA1)) {
 			err = got_error(GOT_ERR_BAD_OBJ_ID_STR);
 			goto done;
 		}
blob - 511fd016b578a9308aede2f46618c2b7b6a353c2
file + regress/idset/idset_test.c
--- regress/idset/idset_test.c
+++ regress/idset/idset_test.c
@@ -70,15 +70,15 @@ idset_add_remove_iter(void)
 		goto done;
 	}
 
-	if (!got_parse_sha1_digest(id1.sha1, id_str1)) {
+	if (!got_parse_object_id(&id1, id_str1, GOT_HASH_SHA1)) {
 		err = got_error(GOT_ERR_BAD_OBJ_ID_STR);
 		goto done;
 	}
-	if (!got_parse_sha1_digest(id2.sha1, id_str2)) {
+	if (!got_parse_object_id(&id2, id_str2, GOT_HASH_SHA1)) {
 		err = got_error(GOT_ERR_BAD_OBJ_ID_STR);
 		goto done;
 	}
-	if (!got_parse_sha1_digest(id3.sha1, id_str3)) {
+	if (!got_parse_object_id(&id3, id_str3, GOT_HASH_SHA1)) {
 		err = got_error(GOT_ERR_BAD_OBJ_ID_STR);
 		goto done;
 	}