sha256: further API simplifications for OID parsing

Introduce `git_oid_from_string`, `git_oid_from_prefix`, and
`git_oid_from_raw`, all of which take a `git_oid_t` that indicates what
type of OID should be parsed (SHA1 or SHA256).

This allows users to continue to use `git_oid_fromstr` without any code
changes, while remaining in a SHA1 world.

Note that these are not perfect analogs to the `fromstr` APIs.

* `git_oid_from_string` now takes a NUL terminated string, instead of
  allowing for non-NUL terminated strings. Adding a NUL check feels like
  an important safety consideration for C strings.
* `git_oid_from_prefix` should be used for an OID substring and length.

Previous usages of `git_oid_fromstr` with non-NUL terminated strings
should move to `git_oid_from_prefix` with the hexsize for the given OID
type.

Author: ethomson

examples/general.c

@@ -143,7 +143,7 @@ static void oid_parsing(git_oid *oid)
 	 * key we're working with.
 	 */
 #ifdef GIT_EXPERIMENTAL_SHA256
-	git_oid_fromstr(oid, hex, GIT_OID_SHA1);
+	git_oid_from_string(oid, hex, GIT_OID_SHA1);
 #else
 	git_oid_fromstr(oid, hex);
 #endif
@@ -292,8 +292,8 @@ static void commit_writing(git_repository *repo)
 	 * but you can also use
 	 */
 #ifdef GIT_EXPERIMENTAL_SHA256
-	git_oid_fromstr(&tree_id, "f60079018b664e4e79329a7ef9559c8d9e0378d1", GIT_OID_SHA1);
-	git_oid_fromstr(&parent_id, "5b5b025afb0b4c913b4c338a42934a3863bf3644", GIT_OID_SHA1);
+	git_oid_from_string(&tree_id, "f60079018b664e4e79329a7ef9559c8d9e0378d1", GIT_OID_SHA1);
+	git_oid_from_string(&parent_id, "5b5b025afb0b4c913b4c338a42934a3863bf3644", GIT_OID_SHA1);
 #else
 	git_oid_fromstr(&tree_id, "f60079018b664e4e79329a7ef9559c8d9e0378d1");
 	git_oid_fromstr(&parent_id, "5b5b025afb0b4c913b4c338a42934a3863bf3644");
@@ -363,7 +363,7 @@ static void commit_parsing(git_repository *repo)
 	printf("\n*Commit Parsing*\n");
 
 #ifdef GIT_EXPERIMENTAL_SHA256
-	git_oid_fromstr(&oid, "8496071c1b46c854b31185ea97743be6a8774479", GIT_OID_SHA1);
+	git_oid_from_string(&oid, "8496071c1b46c854b31185ea97743be6a8774479", GIT_OID_SHA1);
 #else
 	git_oid_fromstr(&oid, "8496071c1b46c854b31185ea97743be6a8774479");
 #endif
@@ -436,7 +436,7 @@ static void tag_parsing(git_repository *repo)
 	 * the same way that we would a commit (or any other object).
 	 */
 #ifdef GIT_EXPERIMENTAL_SHA256
-	git_oid_fromstr(&oid, "b25fa35b38051e4ae45d4222e795f9df2e43f1d1", GIT_OID_SHA1);
+	git_oid_from_string(&oid, "b25fa35b38051e4ae45d4222e795f9df2e43f1d1", GIT_OID_SHA1);
 #else
 	git_oid_fromstr(&oid, "b25fa35b38051e4ae45d4222e795f9df2e43f1d1");
 #endif
@@ -488,7 +488,7 @@ static void tree_parsing(git_repository *repo)
 	 * Create the oid and lookup the tree object just like the other objects.
 	 */
 #ifdef GIT_EXPERIMENTAL_SHA256
-	git_oid_fromstr(&oid, "f60079018b664e4e79329a7ef9559c8d9e0378d1", GIT_OID_SHA1);
+	git_oid_from_string(&oid, "f60079018b664e4e79329a7ef9559c8d9e0378d1", GIT_OID_SHA1);
 #else
 	git_oid_fromstr(&oid, "f60079018b664e4e79329a7ef9559c8d9e0378d1");
 #endif
@@ -546,7 +546,7 @@ static void blob_parsing(git_repository *repo)
 	printf("\n*Blob Parsing*\n");
 
 #ifdef GIT_EXPERIMENTAL_SHA256
-	git_oid_fromstr(&oid, "1385f264afb75a56a5bec74243be9b367ba4ca08", GIT_OID_SHA1);
+	git_oid_from_string(&oid, "1385f264afb75a56a5bec74243be9b367ba4ca08", GIT_OID_SHA1);
 #else
 	git_oid_fromstr(&oid, "1385f264afb75a56a5bec74243be9b367ba4ca08");
 #endif
@@ -592,7 +592,7 @@ static void revwalking(git_repository *repo)
 	printf("\n*Revwalking*\n");
 
 #ifdef GIT_EXPERIMENTAL_SHA256
-	git_oid_fromstr(&oid, "5b5b025afb0b4c913b4c338a42934a3863bf3644", GIT_OID_SHA1);
+	git_oid_from_string(&oid, "5b5b025afb0b4c913b4c338a42934a3863bf3644", GIT_OID_SHA1);
 #else
 	git_oid_fromstr(&oid, "5b5b025afb0b4c913b4c338a42934a3863bf3644");
 #endif

examples/rev-list.c

@@ -141,7 +141,7 @@ static int revwalk_parse_revs(git_repository *repo, git_revwalk *walk, struct ar
 				continue;
 
 #ifdef GIT_EXPERIMENTAL_SHA256
-			if ((error = git_oid_fromstr(&oid, curr, GIT_OID_SHA1)))
+			if ((error = git_oid_from_string(&oid, curr, GIT_OID_SHA1)))
 				return error;
 #else
 			if ((error = git_oid_fromstr(&oid, curr)))

include/git2/oid.h

@@ -114,12 +114,62 @@ typedef struct git_oid {
 
 #ifdef GIT_EXPERIMENTAL_SHA256
 
-GIT_EXTERN(int) git_oid_fromstr(git_oid *out, const char *str, git_oid_t type);
-GIT_EXTERN(int) git_oid_fromstrp(git_oid *out, const char *str, git_oid_t type);
-GIT_EXTERN(int) git_oid_fromstrn(git_oid *out, const char *str, size_t length, git_oid_t type);
-GIT_EXTERN(int) git_oid_fromraw(git_oid *out, const unsigned char *raw, git_oid_t type);
+/**
+ * Parse a NUL terminated hex formatted object id string into a `git_oid`.
+ *
+ * The given string must be NUL terminated, and must be the hex size of
+ * the given object ID type - 40 characters for SHA1, 64 characters for
+ * SHA256.
+ *
+ * To parse an incomplete object ID (an object ID prefix), or a sequence
+ * of characters that is not NUL terminated, use `git_oid_from_prefix`.
+ *
+ * @param out oid structure the result is written into.
+ * @param str input hex string
+ * @param type object id type
+ * @return 0 or an error code
+ */
+GIT_EXTERN(int) git_oid_from_string(
+	git_oid *out,
+	const char *str,
+	git_oid_t type);
 
-#else
+/**
+ * Parse the given number of characters out of a hex formatted object id
+ * string into a `git_oid`.
+ *
+ * The given length can be between 0 and the hex size for the given object ID
+ * type - 40 characters for SHA1, 64 characters for SHA256. The remainder of
+ * the `git_oid` will be set to zeros.
+ *
+ * @param out oid structure the result is written into.
+ * @param str input hex prefix
+ * @param type object id type
+ * @return 0 or an error code
+ */
+GIT_EXTERN(int) git_oid_from_prefix(
+	git_oid *out,
+	const char *str,
+	size_t len,
+	git_oid_t type);
+
+/**
+ * Parse a raw object id into a `git_oid`.
+ *
+ * The appropriate number of bytes for the given object ID type will
+ * be read from the byte array - 20 bytes for SHA1, 32 bytes for SHA256.
+ *
+ * @param out oid structure the result is written into.
+ * @param raw raw object ID bytes
+ * @param type object id type
+ * @return 0 or an error code
+ */
+GIT_EXTERN(int) git_oid_from_raw(
+	git_oid *out,
+	const unsigned char *raw,
+	git_oid_t type);
+
+#endif
 
 /**
  * Parse a hex formatted object id into a git_oid.
@@ -168,8 +218,6 @@ GIT_EXTERN(int) git_oid_fromstrn(git_oid *out, const char *str, size_t length);
  */
 GIT_EXTERN(int) git_oid_fromraw(git_oid *out, const unsigned char *raw);
 
-#endif
-
 /**
  * Format a git_oid into a hex string.
  *

src/libgit2/commit_graph.c

@@ -502,7 +502,7 @@ static int git_commit_graph_entry_get_byindex(
 	}
 
 	commit_data = file->commit_data + pos * (oid_size + 4 * sizeof(uint32_t));
-	git_oid__fromraw(&e->tree_oid, commit_data, file->oid_type);
+	git_oid_from_raw(&e->tree_oid, commit_data, file->oid_type);
 	e->parent_indices[0] = ntohl(*((uint32_t *)(commit_data + oid_size)));
 	e->parent_indices[1] = ntohl(
 			*((uint32_t *)(commit_data + oid_size + sizeof(uint32_t))));
@@ -536,7 +536,7 @@ static int git_commit_graph_entry_get_byindex(
 		}
 	}
 
-	git_oid__fromraw(&e->sha1, &file->oid_lookup[pos * oid_size], file->oid_type);
+	git_oid_from_raw(&e->sha1, &file->oid_lookup[pos * oid_size], file->oid_type);
 	return 0;
 }
 

src/libgit2/fetch.c

@@ -80,7 +80,7 @@ static int maybe_want_oid(git_remote *remote, git_refspec *spec)
 	oid_head = git__calloc(1, sizeof(git_remote_head));
 	GIT_ERROR_CHECK_ALLOC(oid_head);
 
-	git_oid__fromstr(&oid_head->oid, spec->src, remote->repo->oid_type);
+	git_oid_from_string(&oid_head->oid, spec->src, remote->repo->oid_type);
 
 	if (spec->dst) {
 		oid_head->name = git__strdup(spec->dst);

src/libgit2/fetchhead.c

@@ -202,7 +202,7 @@ static int fetchhead_ref_parse(
 		return -1;
 	}
 
-	if (git_oid__fromstr(oid, oid_str, oid_type) < 0) {
+	if (git_oid_from_string(oid, oid_str, oid_type) < 0) {
 		const git_error *oid_err = git_error_last();
 		const char *err_msg = oid_err ? oid_err->message : "invalid object ID";
 

src/libgit2/index.c

@@ -2364,7 +2364,7 @@ static int read_reuc(git_index *index, const char *buffer, size_t size)
 				return index_error_invalid("reading reuc entry oid");
 			}
 
-			if (git_oid__fromraw(&lost->oid[i], (const unsigned char *) buffer, index->oid_type) < 0)
+			if (git_oid_from_raw(&lost->oid[i], (const unsigned char *) buffer, index->oid_type) < 0)
 				return -1;
 
 			size -= oid_size;
@@ -2553,14 +2553,14 @@ static int read_entry(
 
 	switch (index->oid_type) {
 	case GIT_OID_SHA1:
-		if (git_oid__fromraw(&entry.id, source_sha1.oid,
+		if (git_oid_from_raw(&entry.id, source_sha1.oid,
 		                     GIT_OID_SHA1) < 0)
 			return -1;
 		entry.flags = ntohs(source_sha1.flags);
 		break;
 #ifdef GIT_EXPERIMENTAL_SHA256
 	case GIT_OID_SHA256:
-		if (git_oid__fromraw(&entry.id, source_sha256.oid,
+		if (git_oid_from_raw(&entry.id, source_sha256.oid,
 		                     GIT_OID_SHA256) < 0)
 			return -1;
 		entry.flags = ntohs(source_sha256.flags);

src/libgit2/indexer.c

@@ -1112,7 +1112,7 @@ static int fix_thin_pack(git_indexer *idx, git_indexer_progress *stats)
 		return -1;
 	}
 
-	git_oid__fromraw(&base, base_info, idx->oid_type);
+	git_oid_from_raw(&base, base_info, idx->oid_type);
 	git_mwindow_close(&w);
 
 	if (has_entry(idx, &base))

src/libgit2/merge.c

@@ -616,7 +616,7 @@ int git_repository_mergehead_foreach(
 			goto cleanup;
 		}
 
-		if ((error = git_oid__fromstr(&oid, line, repo->oid_type)) < 0)
+		if ((error = git_oid_from_string(&oid, line, repo->oid_type)) < 0)
 			goto cleanup;
 
 		if ((error = cb(&oid, payload)) != 0) {

src/libgit2/midx.c

@@ -449,7 +449,7 @@ int git_midx_entry_find(
 		return midx_error("invalid index into the packfile names table");
 	e->pack_index = pack_index;
 	e->offset = offset;
-	git_oid__fromraw(&e->sha1, current, idx->oid_type);
+	git_oid_from_raw(&e->sha1, current, idx->oid_type);
 	return 0;
 }
 
@@ -467,7 +467,7 @@ int git_midx_foreach_entry(
 	oid_size = git_oid_size(idx->oid_type);
 
 	for (i = 0; i < idx->num_objects; ++i) {
-		if ((error = git_oid__fromraw(&oid, &idx->oid_lookup[i * oid_size], idx->oid_type)) < 0)
+		if ((error = git_oid_from_raw(&oid, &idx->oid_lookup[i * oid_size], idx->oid_type)) < 0)
 			return error;
 
 		if ((error = cb(&oid, data)) != 0)

src/libgit2/notes.c

@@ -704,7 +704,7 @@ static int process_entry_path(
 		goto cleanup;
 	}
 
-	error = git_oid__fromstr(annotated_object_id, buf.ptr, it->repo->oid_type);
+	error = git_oid_from_string(annotated_object_id, buf.ptr, it->repo->oid_type);
 
 cleanup:
 	git_str_dispose(&buf);

src/libgit2/object.c

@@ -662,7 +662,7 @@ int git_object__parse_oid_header(
 	if (buffer[header_len + sha_len] != '\n')
 		return -1;
 
-	if (git_oid__fromstr(oid, buffer + header_len, oid_type) < 0)
+	if (git_oid_from_prefix(oid, buffer + header_len, sha_len, oid_type) < 0)
 		return -1;
 
 	*buffer_out = buffer + (header_len + sha_len + 1);

src/libgit2/odb_loose.c

@@ -552,7 +552,10 @@ static int locate_object_short_oid(
 		return git_odb__error_ambiguous("multiple matches in loose objects");
 
 	/* Convert obtained hex formatted oid to raw */
-	error = git_oid__fromstr(res_oid, (char *)state.res_oid, backend->options.oid_type);
+	error = git_oid_from_prefix(res_oid, (char *)state.res_oid,
+		git_oid_hexsize(backend->options.oid_type),
+		backend->options.oid_type);
+
 	if (error)
 		return error;