thodg/libgit2

diff --git a/src/commit.c b/src/commit.c
index ad89088..7cb8f24 100644
--- a/src/commit.c
+++ b/src/commit.c
@@ -29,6 +29,9 @@
 #include "git/odb.h"
 #include "git/repository.h"
 
+#define COMMIT_BASIC_PARSE 0x0
+#define COMMIT_FULL_PARSE 0x1
+
 #define COMMIT_PRINT(commit) {\
 	char oid[41]; oid[40] = 0;\
 	git_oid_fmt(oid, &commit->object.id);\
@@ -65,15 +68,16 @@ const git_oid *git_commit_id(git_commit *c)
 	return &c->object.id;
 }
 
-int git_commit__parse(git_commit *commit, unsigned int parse_flags, int close_db_object)
+int git_commit__parse(git_commit *commit)
 {
+	const int close_db_object = 1;
 	int error = 0;
 
 	if ((error = git_object__source_open((git_object *)commit)) < 0)
 		return error;
 
 	error = git_commit__parse_buffer(commit,
-			commit->object.source.raw.data, commit->object.source.raw.len, parse_flags);
+			commit->object.source.raw.data, commit->object.source.raw.len, COMMIT_BASIC_PARSE);
 
 	if (close_db_object)
 		git_object__source_close((git_object *)commit);
@@ -81,21 +85,23 @@ int git_commit__parse(git_commit *commit, unsigned int parse_flags, int close_db
 	return error;
 }
 
-int git_commit__parse_basic(git_commit *commit)
+int git_commit__parse_full(git_commit *commit)
 {
 	int error;
 
-	if (commit->basic_parse)
+	if (commit->full_parse)
 		return 0;
 
-	error = git_commit__parse(commit,
-			(GIT_COMMIT_TREE | GIT_COMMIT_PARENTS | GIT_COMMIT_TIME), 1);
+	if (git_object__source_open((git_object *)commit) < 0)
+		return GIT_ERROR;
 
-	if (error < 0)
-		return error;
+	error = git_commit__parse_buffer(commit,
+			commit->object.source.raw.data, commit->object.source.raw.len, COMMIT_FULL_PARSE);
 
-	commit->basic_parse = 1;
-	return 0;
+	git_object__source_close((git_object *)commit);
+
+	commit->full_parse = 1;
+	return error;
 }
 
 git_commit *git_commit_lookup(git_repository *repo, const git_oid *id)
@@ -162,6 +168,11 @@ int git__parse_person(git_person *person, char **buffer_out,
 	return 0;
 }
 
+int git__write_person(git_odb_source *src, const char *header, const git_person *person)
+{
+	return git__source_printf(src, "%s %s <%s> %u\n", header, person->name, person->email, person->time);
+}
+
 int git__parse_oid(git_oid *oid, char **buffer_out,
 		const char *buffer_end, const char *header)
 {
@@ -187,6 +198,48 @@ int git__parse_oid(git_oid *oid, char **buffer_out,
 	return 0;
 }
 
+int git__write_oid(git_odb_source *src, const char *header, const git_oid *oid)
+{
+	char hex_oid[41];
+
+	git_oid_fmt(hex_oid, oid);
+	hex_oid[40] = 0;
+
+	return git__source_printf(src, "%s %s\n", header, hex_oid);
+}
+
+int git_commit__writeback(git_commit *commit, git_odb_source *src)
+{
+	git_commit_parents *parent;
+
+	if (commit->tree == NULL)
+		return GIT_ERROR;
+
+	git__write_oid(src, "tree", git_tree_id(commit->tree));
+
+	parent = commit->parents;
+
+	while (parent != NULL) {
+		git__write_oid(src, "parent", git_commit_id(parent->commit));
+		parent = parent->next;
+	}
+
+	if (commit->author == NULL)
+		return GIT_ERROR;
+
+	git__write_person(src, "author", commit->author);
+
+	if (commit->committer == NULL)
+		return GIT_ERROR;
+
+	git__write_person(src, "committer", commit->committer);
+
+	if (commit->message != NULL)
+		git__source_printf(src, "\n%s", commit->message);
+
+	return GIT_SUCCESS;
+}
+
 int git_commit__parse_buffer(git_commit *commit, void *data, size_t len, unsigned int parse_flags)
 {
 	char *buffer = (char *)data;
@@ -198,23 +251,18 @@ int git_commit__parse_buffer(git_commit *commit, void *data, size_t len, unsigne
 	if (git__parse_oid(&oid, &buffer, buffer_end, "tree ") < 0)
 		return GIT_EOBJCORRUPTED;
 
-	if (parse_flags & GIT_COMMIT_TREE)
-		commit->tree = git_tree_lookup(commit->object.repo, &oid);
+	commit->tree = git_tree_lookup(commit->object.repo, &oid);
 
 	/*
 	 * TODO: commit grafts!
 	 */
 
-	if (parse_flags & GIT_COMMIT_PARENTS)
-		clear_parents(commit);
+	clear_parents(commit);
 
 	while (git__parse_oid(&oid, &buffer, buffer_end, "parent ") == 0) {
 		git_commit *parent;
 		git_commit_parents *node;
 
-		if ((parse_flags & GIT_COMMIT_PARENTS) == 0)
-			continue;
-
 		if ((parent = git_commit_lookup(commit->object.repo, &oid)) == NULL)
 			return GIT_ENOTFOUND;
 
@@ -229,7 +277,7 @@ int git_commit__parse_buffer(git_commit *commit, void *data, size_t len, unsigne
 	if (git__parse_person(&person, &buffer, buffer_end, "author ") < 0)
 		return GIT_EOBJCORRUPTED;
 
-	if (parse_flags & GIT_COMMIT_AUTHOR) {
+	if (parse_flags & COMMIT_FULL_PARSE) {
 		if (commit->author)
 			free(commit->author);
 
@@ -240,10 +288,9 @@ int git_commit__parse_buffer(git_commit *commit, void *data, size_t len, unsigne
 	if (git__parse_person(&person, &buffer, buffer_end, "committer ") < 0)
 		return GIT_EOBJCORRUPTED;
 
-	if (parse_flags & GIT_COMMIT_TIME)
-		commit->commit_time = person.time;
+	commit->commit_time = person.time;
 
-	if (parse_flags & GIT_COMMIT_COMMITTER) {
+	if (parse_flags & COMMIT_FULL_PARSE) {
 		if (commit->committer)
 			free(commit->committer);
 
@@ -255,82 +302,105 @@ int git_commit__parse_buffer(git_commit *commit, void *data, size_t len, unsigne
 	while (buffer <= buffer_end && *buffer == '\n')
 		buffer++;
 
-	if (buffer < buffer_end)
-	{
-		if (parse_flags & GIT_COMMIT_MESSAGE) {
-			size_t message_len = buffer_end - buffer;
-
-			commit->message = git__malloc(message_len + 1);
-			memcpy(commit->message, buffer, message_len);
-			commit->message[message_len] = 0;
-		}
+	if (parse_flags & COMMIT_FULL_PARSE && buffer < buffer_end) {
+		char *line_end;
+		size_t message_len = buffer_end - buffer;
 
-		if (parse_flags & GIT_COMMIT_MESSAGE_SHORT) {
-			char *line_end;
-			size_t message_len;
+		/* Short message */
+		message_len = buffer_end - buffer;
+		commit->message = git__malloc(message_len + 1);
+		memcpy(commit->message, buffer, message_len);
+		commit->message[message_len] = 0;
 
-			line_end = memchr(buffer, '\n', buffer_end - buffer);
-			message_len = line_end - buffer;
+		/* Long message */
+		line_end = memchr(buffer, '\n', buffer_end - buffer);
+		message_len = line_end - buffer;
 
-			commit->message_short = git__malloc(message_len + 1);
-			memcpy(commit->message_short, buffer, message_len);
-			commit->message_short[message_len] = 0;
-		}
+		commit->message_short = git__malloc(message_len + 1);
+		memcpy(commit->message_short, buffer, message_len);
+		commit->message_short[message_len] = 0;
 	}
 
 	return 0;
 }
 
-const git_tree *git_commit_tree(git_commit *commit)
+#define GIT_COMMIT_GETTER(_rvalue, _name) \
+	const _rvalue git_commit_##_name(git_commit *commit) \
+	{\
+		if (commit->_name) \
+			return commit->_name; \
+		git_commit__parse_full(commit); \
+		return commit->_name; \
+	}
+
+GIT_COMMIT_GETTER(git_tree *, tree)
+GIT_COMMIT_GETTER(git_person *, author)
+GIT_COMMIT_GETTER(git_person *, committer)
+GIT_COMMIT_GETTER(char *, message)
+GIT_COMMIT_GETTER(char *, message_short)
+
+time_t git_commit_time(git_commit *commit)
 {
-	if (commit->tree)
-		return commit->tree;
+	if (commit->commit_time)
+		return commit->commit_time;
 
-	git_commit__parse(commit, GIT_COMMIT_TREE, 0);
-	return commit->tree;
+	git_commit__parse_full(commit);
+	return commit->commit_time;
 }
 
-const git_person *git_commit_author(git_commit *commit)
+void git_commit_set_tree(git_commit *commit, git_tree *tree)
 {
-	if (commit->author)
-		return commit->author;
-
-	git_commit__parse(commit, GIT_COMMIT_AUTHOR, 0);
-	return commit->author;
+	commit->object.modified = 1;
+	commit->tree = tree;
 }
 
-const git_person *git_commit_committer(git_commit *commit)
+void git_commit_set_author(git_commit *commit, const git_person *author)
 {
-	if (commit->committer)
-		return commit->committer;
+	commit->object.modified = 1;
+	if (commit->author == NULL)
+		commit->author = git__malloc(sizeof(git_person));
 
-	git_commit__parse(commit, GIT_COMMIT_COMMITTER, 0);
-	return commit->committer;
+	memcpy(commit->author, author, sizeof(git_person));
 }
 
-time_t git_commit_time(git_commit *commit)
+void git_commit_set_committer(git_commit *commit, const git_person *committer)
 {
-	if (commit->commit_time)
-		return commit->commit_time;
+	commit->object.modified = 1;
+	if (commit->committer == NULL)
+		commit->committer = git__malloc(sizeof(git_person));
 
-	git_commit__parse(commit, GIT_COMMIT_TIME, 0);
-	return commit->commit_time;
+	memcpy(commit->committer, committer, sizeof(git_person));
 }
 
-const char *git_commit_message(git_commit *commit)
+void git_commit_set_message(git_commit *commit, const char *message)
 {
+	const char *short_message;
+
+	commit->object.modified = 1;
+
 	if (commit->message)
-		return commit->message;
+		free(commit->message);
 
-	git_commit__parse(commit, GIT_COMMIT_MESSAGE, 0);
-	return commit->message;
+	if (commit->message_short)
+		free(commit->message_short);
+
+	commit->message = git__strdup(message);
+	commit->message_short = NULL;
+
+	/* TODO: extract short message */
 }
 
-const char *git_commit_message_short(git_commit *commit)
+void git_commit_add_parent(git_commit *commit, git_commit *new_parent)
 {
-	if (commit->message_short)
-		return commit->message_short;
+	git_commit_parents *node;
 
-	git_commit__parse(commit, GIT_COMMIT_MESSAGE_SHORT, 0);
-	return commit->message_short;
+	commit->object.modified = 1;
+
+	if ((node = git__malloc(sizeof(git_commit_parents))) == NULL)
+		return;
+
+	node->commit = new_parent;
+	node->next = commit->parents;
+	commit->parents = node;
 }
+
diff --git a/src/commit.h b/src/commit.h
index 4e883c0..8039930 100644
--- a/src/commit.h
+++ b/src/commit.h
@@ -7,15 +7,6 @@
 
 #include <time.h>
 
-#define GIT_COMMIT_TREE		(1 << 1)
-#define GIT_COMMIT_PARENTS	(1 << 2)
-#define GIT_COMMIT_AUTHOR	(1 << 3)
-#define GIT_COMMIT_COMMITTER (1 << 4)
-#define GIT_COMMIT_TIME		(1 << 5)
-#define GIT_COMMIT_MESSAGE	(1 << 6)
-#define GIT_COMMIT_MESSAGE_SHORT (1 << 7)
-#define GIT_COMMIT_FOOTERS	(1 << 8)
-
 typedef struct git_commit_parents {
 	git_commit *commit;
 	struct git_commit_parents *next;
@@ -34,16 +25,17 @@ struct git_commit {
 	char *message;
 	char *message_short;
 
-	unsigned basic_parse:1,
-			 odb_open:1;
+	unsigned full_parse:1;
 };
 
 void git_commit__free(git_commit *c);
-int git_commit__parse(git_commit *commit, unsigned int flags, int close_odb);
-int git_commit__parse_basic(git_commit *commit);
+int git_commit__parse(git_commit *commit);
+int git_commit__parse_full(git_commit *commit);
 int git_commit__parse_buffer(git_commit *commit, void *data, size_t len, unsigned int parse_flags);
 void git_commit__mark_uninteresting(git_commit *commit);
 
+int git_commit__writeback(git_commit *commit, git_odb_source *src);
+
 int git__parse_oid(git_oid *oid, char **buffer_out, const char *buffer_end, const char *header);
 int git__parse_person(git_person *person, char **buffer_out, const char *buffer_end, const char *header);
 
diff --git a/src/git/commit.h b/src/git/commit.h
index 56243c5..4387925 100644
--- a/src/git/commit.h
+++ b/src/git/commit.h
@@ -79,6 +79,41 @@ GIT_EXTERN(const git_person *) git_commit_author(git_commit *commit);
  */
 GIT_EXTERN(const git_tree *) git_commit_tree(git_commit *commit);
 
+/*
+ * Add a new parent commit to an existing commit
+ * @param commit the commit object
+ * @param new_parent the new commit which will be a parent
+ */
+GIT_EXTERN(void) git_commit_add_parent(git_commit *commit, git_commit *new_parent);
+
+/*
+ * Set the message of a commit
+ * @param commit the commit object
+ * @param message the new message
+ */
+GIT_EXTERN(void) git_commit_set_message(git_commit *commit, const char *message);
+
+/*
+ * Set the committer of a commit
+ * @param commit the commit object
+ * @param committer the new committer
+ */
+GIT_EXTERN(void) git_commit_set_committer(git_commit *commit, const git_person *committer);
+
+/*
+ * Set the author of a commit
+ * @param commit the commit object
+ * @param author the new author
+ */
+GIT_EXTERN(void) git_commit_set_author(git_commit *commit, const git_person *author);
+
+/*
+ * Set the tree which is pointed to by a commit
+ * @param commit the commit object
+ * @param tree the new tree
+ */
+GIT_EXTERN(void) git_commit_set_tree(git_commit *commit, git_tree *tree);
+
 /** @} */
 GIT_END_DECL
 #endif
diff --git a/src/odb.c b/src/odb.c
index 5c59a4f..8fbcebd 100644
--- a/src/odb.c
+++ b/src/odb.c
@@ -1446,6 +1446,9 @@ int git_odb_read(
 	const git_oid *id)
 {
 attempt:
+
+	assert(out && db);
+
 	if (!git_odb__read_packed(out, db, id))
 		return GIT_SUCCESS;
 	if (!git_odb__read_loose(out, db, id))
diff --git a/src/repository.c b/src/repository.c
index 14c8f45..f353ce0 100644
--- a/src/repository.c
+++ b/src/repository.c
@@ -205,6 +205,8 @@ int git_object__source_writeback(git_object *object)
 	object->source.write_ptr = NULL;
 	object->source.written_bytes = 0;
 
+	object->modified = 0;
+
 	git_object__source_close(object);
 	return GIT_SUCCESS;
 }
@@ -241,6 +243,38 @@ void git_object__source_close(git_object *object)
 	}
 }
 
+int git_object_write(git_object *object)
+{
+	int error;
+	git_odb_source *source;
+
+	assert(object);
+
+	if (object->modified == 0)
+		return GIT_SUCCESS;
+
+	git_object__source_prepare_write(object);
+	source = &object->source;
+
+	switch (source->raw.type) {
+	case GIT_OBJ_COMMIT:
+		error = git_commit__writeback((git_commit *)object, source);
+		break;
+
+	case GIT_OBJ_TREE:
+	case GIT_OBJ_TAG:
+	default:
+		error = GIT_ERROR;
+	}
+
+	if (error < 0) {
+		git_object__source_close(object);
+		return error;
+	}
+	
+	return git_object__source_writeback(object);
+}
+
 void git_object_free(git_object *object)
 {
 	assert(object);
@@ -328,7 +362,7 @@ git_object *git_repository_lookup(git_repository *repo, const git_oid *id, git_o
 	switch (type) {
 
 	case GIT_OBJ_COMMIT:
-		if (git_commit__parse_basic((git_commit *)object) < 0) {
+		if (git_commit__parse((git_commit *)object) < 0) {
 			free(object);
 			return NULL;
 		}
diff --git a/src/repository.h b/src/repository.h
index 8a37687..5074c61 100644
--- a/src/repository.h
+++ b/src/repository.h
@@ -19,6 +19,7 @@ struct git_object {
 	git_oid id;
 	git_repository *repo;
 	git_odb_source source;
+	int in_memory:1, modified:1;
 };
 
 struct git_repository {
diff --git a/src/revwalk.c b/src/revwalk.c
index ca00884..e8d686f 100644
--- a/src/revwalk.c
+++ b/src/revwalk.c
@@ -98,11 +98,6 @@ static git_revwalk_commit *commit_to_walkcommit(git_revwalk *walk, git_commit *c
 	if (commit != NULL)
 		return commit;
 
-	if (!commit_object->basic_parse) {
-		if (git_commit__parse_basic(commit_object) < 0)
-			return NULL;
-	}
-
 	commit = git__malloc(sizeof(git_revwalk_commit));
 	if (commit == NULL)
 		return NULL;
@@ -135,8 +130,6 @@ static git_revwalk_commit *insert_commit(git_revwalk *walk, git_commit *commit_o
 
 	commit->seen = 1;
 
-	assert(commit->commit_object->basic_parse);
-
 	for (parents = commit->commit_object->parents; parents != NULL; parents = parents->next) {
 		git_revwalk_commit *parent;
 
diff --git a/tests/t0401-parse.c b/tests/t0401-parse.c
index d9b3a2a..d97aee1 100644
--- a/tests/t0401-parse.c
+++ b/tests/t0401-parse.c
@@ -5,6 +5,8 @@
 #include <git/commit.h>
 #include <git/revwalk.h>
 
+static const char *odb_dir = "../resources/pack-odb";
+
 static char *test_commits_broken[] = {
 
 /* empty commit */
@@ -58,21 +60,20 @@ par",
 
 static char *test_commits_working[] = {
 /* simple commit with no message */
-"tree f6c0dad3c7b3481caa9d73db21f91964894a945b\n\
+"tree 1810dff58d8a660512d4832e740f692884338ccd\n\
 author Vicent Marti <tanoku@gmail.com> 1273848544 +0200\n\
 committer Vicent Marti <tanoku@gmail.com> 1273848544 +0200\n\
 \n",
 
 /* simple commit, no parent */
-"tree f6c0dad3c7b3481caa9d73db21f91964894a945b\n\
+"tree 1810dff58d8a660512d4832e740f692884338ccd\n\
 author Vicent Marti <tanoku@gmail.com> 1273848544 +0200\n\
 committer Vicent Marti <tanoku@gmail.com> 1273848544 +0200\n\
 \n\
 a simple commit which works\n",
 
 /* simple commit, 1 parents */
-"tree f6c0dad3c7b3481caa9d73db21f91964894a945b\n\
-parent a4a7dce85cf63874e984719f4fdd239f5145052f\n\
+"tree 1810dff58d8a660512d4832e740f692884338ccd\n\
 author Vicent Marti <tanoku@gmail.com> 1273848544 +0200\n\
 committer Vicent Marti <tanoku@gmail.com> 1273848544 +0200\n\
 \n\
@@ -216,16 +217,13 @@ BEGIN_TEST(parse_buffer_test)
 	const int broken_commit_count = sizeof(test_commits_broken) / sizeof(*test_commits_broken);
 	const int working_commit_count = sizeof(test_commits_working) / sizeof(*test_commits_working);
 
-	const unsigned int default_flags = 
-		GIT_COMMIT_AUTHOR | 
-		GIT_COMMIT_COMMITTER | 
-		GIT_COMMIT_TIME |
-		GIT_COMMIT_MESSAGE |
-		GIT_COMMIT_MESSAGE_SHORT; /* parse everything */
-
 	int i;
-	git_repository *repo = git_repository_alloc(NULL);
+	git_repository *repo;
+	git_odb *db;
+
+	must_pass(git_odb_open(&db, odb_dir));
 
+	repo = git_repository_alloc(db);
 	must_be_true(repo != NULL);
 
 	for (i = 0; i < broken_commit_count; ++i) {
@@ -238,7 +236,7 @@ BEGIN_TEST(parse_buffer_test)
 					commit,
 					test_commits_broken[i],
 					strlen(test_commits_broken[i]),
-					default_flags)
+					0x1)
 				);
 
 		git_commit__free(commit);
@@ -254,7 +252,7 @@ BEGIN_TEST(parse_buffer_test)
 					commit,
 					test_commits_working[i],
 					strlen(test_commits_working[i]),
-					default_flags)
+					0x1)
 				);
 
 		git_commit__free(commit);