commit: generic parse mechanism

This allows us to pick which data from a commit we're interested in.
This will be used by the revwalk code, which is only interested in
parents' and committer data.

src/commit.c

@@ -20,6 +20,7 @@
 #include "message.h"
 #include "refs.h"
 #include "object.h"
+#include "array.h"
 #include "oidarray.h"
 
 void git_commit__free(void *_commit)
@@ -383,15 +384,16 @@ int git_commit_amend(
 	return error;
 }
 
-int git_commit__parse_raw(void *_commit, const char *data, size_t size)
+static int commit_parse(git_commit *commit, const char *data, size_t size, unsigned int flags)
 {
-	git_commit *commit = _commit;
 	const char *buffer_start = data, *buffer;
 	const char *buffer_end = buffer_start + size;
 	git_oid parent_id;
 	size_t header_len;
 	git_signature dummy_sig;
 
+	assert(commit && data);
+
 	buffer = buffer_start;
 
 	/* Allocate for one, which will allow not to realloc 90% of the time  */
@@ -399,8 +401,15 @@ int git_commit__parse_raw(void *_commit, const char *data, size_t size)
 	GIT_ERROR_CHECK_ARRAY(commit->parent_ids);
 
 	/* The tree is always the first field */
-	if (git_oid__parse(&commit->tree_id, &buffer, buffer_end, "tree ") < 0)
-		goto bad_buffer;
+	if (!(flags & GIT_COMMIT_PARSE_QUICK)) {
+	    if (git_oid__parse(&commit->tree_id, &buffer, buffer_end, "tree ") < 0)
+			goto bad_buffer;
+	} else {
+		size_t tree_len = strlen("tree ") + GIT_OID_HEXSZ + 1;
+		if (buffer + tree_len > buffer_end)
+			goto bad_buffer;
+		buffer += tree_len;
+	}
 
 	/*
 	 * TODO: commit grafts!
@@ -413,11 +422,13 @@ int git_commit__parse_raw(void *_commit, const char *data, size_t size)
 		git_oid_cpy(new_id, &parent_id);
 	}
 
-	commit->author = git__malloc(sizeof(git_signature));
-	GIT_ERROR_CHECK_ALLOC(commit->author);
+	if (!(flags & GIT_COMMIT_PARSE_QUICK)) {
+		commit->author = git__malloc(sizeof(git_signature));
+		GIT_ERROR_CHECK_ALLOC(commit->author);
 
-	if (git_signature__parse(commit->author, &buffer, buffer_end, "author ", '\n') < 0)
-		return -1;
+		if (git_signature__parse(commit->author, &buffer, buffer_end, "author ", '\n') < 0)
+			return -1;
+	}
 
 	/* Some tools create multiple author fields, ignore the extra ones */
 	while (!git__prefixncmp(buffer, buffer_end - buffer, "author ")) {
@@ -435,6 +446,9 @@ int git_commit__parse_raw(void *_commit, const char *data, size_t size)
 	if (git_signature__parse(commit->committer, &buffer, buffer_end, "committer ", '\n') < 0)
 		return -1;
 
+	if (flags & GIT_COMMIT_PARSE_QUICK)
+		return 0;
+
 	/* Parse add'l header entries */
 	while (buffer < buffer_end) {
 		const char *eoln = buffer;
@@ -477,11 +491,19 @@ bad_buffer:
 	return -1;
 }
 
+int git_commit__parse_raw(void *commit, const char *data, size_t size)
+{
+	return commit_parse(commit, data, size, 0);
+}
+
+int git_commit__parse_ext(git_commit *commit, git_odb_object *odb_obj, unsigned int flags)
+{
+	return commit_parse(commit, git_odb_object_data(odb_obj), git_odb_object_size(odb_obj), flags);
+}
+
 int git_commit__parse(void *_commit, git_odb_object *odb_obj)
 {
-	return git_commit__parse_raw(_commit,
-		git_odb_object_data(odb_obj),
-		git_odb_object_size(odb_obj));
+	return git_commit__parse_ext(_commit, odb_obj, 0);
 }
 
 #define GIT_COMMIT_GETTER(_rvalue, _name, _return) \

src/commit.h

@@ -37,4 +37,10 @@ void git_commit__free(void *commit);
 int git_commit__parse(void *commit, git_odb_object *obj);
 int git_commit__parse_raw(void *commit, const char *data, size_t size);
 
+typedef enum {
+	GIT_COMMIT_PARSE_QUICK = (1 << 0), /**< Only parse parents and committer info */
+} git_commit__parse_flags;
+
+int git_commit__parse_ext(git_commit *commit, git_odb_object *odb_obj, unsigned int flags);
+
 #endif