thodg/libgit2

diff --git a/src/revwalk.c b/src/revwalk.c
index ac0414b..c2c098c 100644
--- a/src/revwalk.c
+++ b/src/revwalk.c
@@ -214,38 +214,43 @@ static int commit_quick_parse(git_revwalk *walk, commit_object *commit, git_rawo
 	}
 
 	commit->parents = alloc_parents(commit, parents);
-	if (commit->parents == NULL)
-		return GIT_ENOMEM;
+	GITERR_CHECK_ALLOC(commit->parents);
 
 	buffer = parents_start;
 	for (i = 0; i < parents; ++i) {
 		git_oid oid;
 
-		if (git_oid_fromstr(&oid, (char *)buffer + strlen("parent ")) < GIT_SUCCESS)
-			return git__throw(GIT_EOBJCORRUPTED, "Failed to parse commit. Parent object is corrupted");
+		if (git_oid_fromstr(&oid, (char *)buffer + strlen("parent ")) < 0)
+			return -1;
 
 		commit->parents[i] = commit_lookup(walk, &oid);
 		if (commit->parents[i] == NULL)
-			return GIT_ENOMEM;
+			return -1;
 
 		buffer += parent_len;
 	}
 
 	commit->out_degree = (unsigned short)parents;
 
-	if ((buffer = memchr(buffer, '\n', buffer_end - buffer)) == NULL)
-		return git__throw(GIT_EOBJCORRUPTED, "Failed to parse commit. Object is corrupted");
+	if ((buffer = memchr(buffer, '\n', buffer_end - buffer)) == NULL) {
+		giterr_set(GITERR_ODB, "Failed to parse commit. Object is corrupted");
+		return -1;
+	}
 
 	buffer = memchr(buffer, '>', buffer_end - buffer);
-	if (buffer == NULL)
-		return git__throw(GIT_EOBJCORRUPTED, "Failed to parse commit. Can't find author");
+	if (buffer == NULL) {
+		giterr_set(GITERR_ODB, "Failed to parse commit. Can't find author");
+		return -1;
+	}
 
-	if (git__strtol32(&commit_time, (char *)buffer + 2, NULL, 10) < GIT_SUCCESS)
-		return git__throw(GIT_EOBJCORRUPTED, "Failed to parse commit. Can't parse commit time");
+	if (git__strtol32(&commit_time, (char *)buffer + 2, NULL, 10) < 0) {
+		giterr_set(GITERR_ODB, "Failed to parse commit. Can't parse commit time");
+		return -1;
+	}
 
 	commit->time = (time_t)commit_time;
 	commit->parsed = 1;
-	return GIT_SUCCESS;
+	return 0;
 }
 
 static int commit_parse(git_revwalk *walk, commit_object *commit)
@@ -254,19 +259,20 @@ static int commit_parse(git_revwalk *walk, commit_object *commit)
 	int error;
 
 	if (commit->parsed)
-		return GIT_SUCCESS;
+		return 0;
 
-	if ((error = git_odb_read(&obj, walk->odb, &commit->oid)) < GIT_SUCCESS)
-		return git__rethrow(error, "Failed to parse commit. Can't read object");
+	if ((error = git_odb_read(&obj, walk->odb, &commit->oid)) < 0)
+		return -1;
 
 	if (obj->raw.type != GIT_OBJ_COMMIT) {
 		git_odb_object_free(obj);
-		return git__throw(GIT_EOBJTYPE, "Failed to parse commit. Object is no commit object");
+		giterr_set(GITERR_INVALID, "Failed to parse commit. Object is no commit object");
+		return -1;
 	}
 
 	error = commit_quick_parse(walk, commit, &obj->raw);
 	git_odb_object_free(obj);
-	return error == GIT_SUCCESS ? GIT_SUCCESS : git__rethrow(error, "Failed to parse commit");
+	return error;
 }
 
 static int interesting(git_pqueue *list)
@@ -368,18 +374,16 @@ int git_merge_base(git_oid *out, git_repository *repo, git_oid *one, git_oid *tw
 {
 	git_revwalk *walk;
 	git_vector list;
-	commit_list *result;
+	commit_list *result = NULL;
 	commit_object *commit;
 	void *contents[1];
-	int error;
 
-	error = git_revwalk_new(&walk, repo);
-	if (error < GIT_SUCCESS)
-		return error;
+	if (git_revwalk_new(&walk, repo) < 0)
+		return -1;
 
 	commit = commit_lookup(walk, two);
 	if (commit == NULL)
-		goto cleanup;
+		goto on_error;
 
 	/* This is just one value, so we can do it on the stack */
 	memset(&list, 0x0, sizeof(git_vector));
@@ -389,22 +393,25 @@ int git_merge_base(git_oid *out, git_repository *repo, git_oid *one, git_oid *tw
 
 	commit = commit_lookup(walk, one);
 	if (commit == NULL)
-		goto cleanup;
+		goto on_error;
 
-	error = merge_bases_many(&result, walk, commit, &list);
-	if (error < GIT_SUCCESS)
-		return error;
+	if (merge_bases_many(&result, walk, commit, &list) < 0)
+		goto on_error;
 
-	if (result == NULL)
+	if (!result) {
+		git_revwalk_free(walk);
 		return GIT_ENOTFOUND;
+	}
 
 	git_oid_cpy(out, &result->item->oid);
 	commit_list_free(&result);
-
-cleanup:
 	git_revwalk_free(walk);
 
-	return GIT_SUCCESS;
+	return 0;
+
+on_error:
+	git_revwalk_free(walk);
+	return -1;
 }
 
 static void mark_uninteresting(commit_object *commit)
@@ -425,18 +432,16 @@ static void mark_uninteresting(commit_object *commit)
 
 static int process_commit(git_revwalk *walk, commit_object *commit, int hide)
 {
-	int error;
-
 	if (hide)
 		mark_uninteresting(commit);
 
 	if (commit->seen)
-		return GIT_SUCCESS;
+		return 0;
 
 	commit->seen = 1;
 
-	if ((error = commit_parse(walk, commit)) < GIT_SUCCESS)
-			return git__rethrow(error, "Failed to process commit");
+	if (commit_parse(walk, commit) < 0)
+		return -1;
 
 	return walk->enqueue(walk, commit);
 }
@@ -444,13 +449,13 @@ static int process_commit(git_revwalk *walk, commit_object *commit, int hide)
 static int process_commit_parents(git_revwalk *walk, commit_object *commit)
 {
 	unsigned short i;
-	int error = GIT_SUCCESS;
 
-	for (i = 0; i < commit->out_degree && error == GIT_SUCCESS; ++i) {
-		error = process_commit(walk, commit->parents[i], commit->uninteresting);
+	for (i = 0; i < commit->out_degree; ++i) {
+		if (process_commit(walk, commit->parents[i], commit->uninteresting) < 0)
+			return -1;
 	}
 
-	return error == GIT_SUCCESS ? GIT_SUCCESS : git__rethrow(error, "Failed to process commit parents");
+	return 0;
 }
 
 static int push_commit(git_revwalk *walk, const git_oid *oid, int uninteresting)
@@ -459,17 +464,17 @@ static int push_commit(git_revwalk *walk, const git_oid *oid, int uninteresting)
 
 	commit = commit_lookup(walk, oid);
 	if (commit == NULL)
-		return git__throw(GIT_ENOTFOUND, "Failed to push commit. Object not found");
+		return -1;
 
 	commit->uninteresting = uninteresting;
 	if (walk->one == NULL && !uninteresting) {
 		walk->one = commit;
 	} else {
-		if (git_vector_insert(&walk->twos, commit) < GIT_SUCCESS)
-			return GIT_ENOMEM;
+		if (git_vector_insert(&walk->twos, commit) < 0)
+			return -1;
 	}
 
-	return GIT_SUCCESS;
+	return 0;
 }
 
 int git_revwalk_push(git_revwalk *walk, const git_oid *oid)
@@ -490,15 +495,17 @@ static int push_ref(git_revwalk *walk, const char *refname, int hide)
 	git_reference *ref, *resolved;
 	int error;
 
-	error = git_reference_lookup(&ref, walk->repo, refname);
-	if (error < GIT_SUCCESS)
-		return error;
+	if (git_reference_lookup(&ref, walk->repo, refname) < 0)
+		return -1;
+
 	error = git_reference_resolve(&resolved, ref);
 	git_reference_free(ref);
-	if (error < GIT_SUCCESS)
-		return error;
+	if (error < 0)
+		return -1;
+
 	error = push_commit(walk, git_reference_oid(resolved), hide);
 	git_reference_free(resolved);
+
 	return error;
 }
 
@@ -515,14 +522,13 @@ static int push_glob_cb(const char *refname, void *data_)
 	if (!git__fnmatch(data->glob, refname, 0))
 		return push_ref(data->walk, refname, data->hide);
 
-	return GIT_SUCCESS;
+	return 0;
 }
 
 static int push_glob(git_revwalk *walk, const char *glob, int hide)
 {
 	git_buf buf = GIT_BUF_INIT;
 	struct push_cb_data data;
-	int error;
 	regex_t preg;
 
 	assert(walk && glob);
@@ -537,28 +543,32 @@ static int push_glob(git_revwalk *walk, const char *glob, int hide)
 	/* If no '?', '*' or '[' exist, we append '/ *' to the glob */
 	memset(&preg, 0x0, sizeof(regex_t));
 	if (regcomp(&preg, "[?*[]", REG_EXTENDED)) {
-		error = git__throw(GIT_EOSERR, "Regex failed to compile");
-		goto cleanup;
+		giterr_set(GITERR_OS, "Regex failed to compile");
+		git_buf_free(&buf);
+		return -1;
 	}
 
 	if (regexec(&preg, glob, 0, NULL, 0))
 		git_buf_puts(&buf, "/*");
 
-	if (git_buf_oom(&buf)) {
-		error = GIT_ENOMEM;
-		goto cleanup;
-	}
+	if (git_buf_oom(&buf))
+		goto on_error;
 
 	data.walk = walk;
 	data.glob = git_buf_cstr(&buf);
 	data.hide = hide;
 
-	error = git_reference_foreach(walk->repo, GIT_REF_LISTALL, push_glob_cb, &data);
+	if (git_reference_foreach(walk->repo, GIT_REF_LISTALL, push_glob_cb, &data) < 0)
+		goto on_error;
 
-cleanup:
 	regfree(&preg);
 	git_buf_free(&buf);
-	return error;
+	return 0;
+
+on_error:
+	regfree(&preg);
+	git_buf_free(&buf);
+	return -1;
 }
 
 int git_revwalk_push_glob(git_revwalk *walk, const char *glob)
@@ -613,16 +623,16 @@ static int revwalk_next_timesort(commit_object **object_out, git_revwalk *walk)
 	commit_object *next;
 
 	while ((next = git_pqueue_pop(&walk->iterator_time)) != NULL) {
-		if ((error = process_commit_parents(walk, next)) < GIT_SUCCESS)
-			return git__rethrow(error, "Failed to load next revision");
+		if ((error = process_commit_parents(walk, next)) < 0)
+			return -1;
 
 		if (!next->uninteresting) {
 			*object_out = next;
-			return GIT_SUCCESS;
+			return 0;
 		}
 	}
 
-	return git__throw(GIT_EREVWALKOVER, "Failed to load next revision");
+	return GIT_EREVWALKOVER;
 }
 
 static int revwalk_next_unsorted(commit_object **object_out, git_revwalk *walk)
@@ -631,16 +641,16 @@ static int revwalk_next_unsorted(commit_object **object_out, git_revwalk *walk)
 	commit_object *next;
 
 	while ((next = commit_list_pop(&walk->iterator_rand)) != NULL) {
-		if ((error = process_commit_parents(walk, next)) < GIT_SUCCESS)
-			return git__rethrow(error, "Failed to load next revision");
+		if ((error = process_commit_parents(walk, next)) < 0)
+			return -1;
 
 		if (!next->uninteresting) {
 			*object_out = next;
-			return GIT_SUCCESS;
+			return 0;
 		}
 	}
 
-	return git__throw(GIT_EREVWALKOVER, "Failed to load next revision");
+	return GIT_EREVWALKOVER;
 }
 
 static int revwalk_next_toposort(commit_object **object_out, git_revwalk *walk)
@@ -651,7 +661,7 @@ static int revwalk_next_toposort(commit_object **object_out, git_revwalk *walk)
 	for (;;) {
 		next = commit_list_pop(&walk->iterator_topo);
 		if (next == NULL)
-			return git__throw(GIT_EREVWALKOVER, "Failed to load next revision");
+			return GIT_EREVWALKOVER;
 
 		if (next->in_degree > 0) {
 			next->topo_delay = 1;
@@ -664,19 +674,19 @@ static int revwalk_next_toposort(commit_object **object_out, git_revwalk *walk)
 			if (--parent->in_degree == 0 && parent->topo_delay) {
 				parent->topo_delay = 0;
 				if (commit_list_insert(parent, &walk->iterator_topo) == NULL)
-					return GIT_ENOMEM;
+					return -1;
 			}
 		}
 
 		*object_out = next;
-		return GIT_SUCCESS;
+		return 0;
 	}
 }
 
 static int revwalk_next_reverse(commit_object **object_out, git_revwalk *walk)
 {
 	*object_out = commit_list_pop(&walk->iterator_reverse);
-	return *object_out ? GIT_SUCCESS : GIT_EREVWALKOVER;
+	return *object_out ? 0 : GIT_EREVWALKOVER;
 }
 
 
@@ -688,36 +698,33 @@ static int prepare_walk(git_revwalk *walk)
 	commit_list *bases = NULL;
 
 	/* first figure out what the merge bases are */
-	error = merge_bases_many(&bases, walk, walk->one, &walk->twos);
-	if (error < GIT_SUCCESS)
-		return error;
+	if (merge_bases_many(&bases, walk, walk->one, &walk->twos) < 0)
+		return -1;
 
 	commit_list_free(&bases);
-	error = process_commit(walk, walk->one, walk->one->uninteresting);
-	if (error < GIT_SUCCESS)
-		return error;
+	if (process_commit(walk, walk->one, walk->one->uninteresting) < 0)
+		return -1;
 
 	git_vector_foreach(&walk->twos, i, two) {
-		error = process_commit(walk, two, two->uninteresting);
-		if (error < GIT_SUCCESS)
-			return error;
+		if (process_commit(walk, two, two->uninteresting) < 0)
+			return -1;
 	}
 
 	if (walk->sorting & GIT_SORT_TOPOLOGICAL) {
 		unsigned short i;
 
-		while ((error = walk->get_next(&next, walk)) == GIT_SUCCESS) {
+		while ((error = walk->get_next(&next, walk)) == 0) {
 			for (i = 0; i < next->out_degree; ++i) {
 				commit_object *parent = next->parents[i];
 				parent->in_degree++;
 			}
 
 			if (commit_list_insert(next, &walk->iterator_topo) == NULL)
-				return GIT_ENOMEM;
+				return -1;
 		}
 
 		if (error != GIT_EREVWALKOVER)
-			return git__rethrow(error, "Failed to prepare revision walk");
+			return -1;
 
 		walk->get_next = &revwalk_next_toposort;
 	}
@@ -726,16 +733,16 @@ static int prepare_walk(git_revwalk *walk)
 
 		while ((error = walk->get_next(&next, walk)) == GIT_SUCCESS)
 			if (commit_list_insert(next, &walk->iterator_reverse) == NULL)
-				return GIT_ENOMEM;
+				return -1;
 
 		if (error != GIT_EREVWALKOVER)
-			return git__rethrow(error, "Failed to prepare revision walk");
+			return -1;
 
 		walk->get_next = &revwalk_next_reverse;
 	}
 
 	walk->walking = 1;
-	return GIT_SUCCESS;
+	return 0;
 }
 
 
@@ -744,12 +751,10 @@ static int prepare_walk(git_revwalk *walk)
 
 int git_revwalk_new(git_revwalk **revwalk_out, git_repository *repo)
 {
-	int error;
 	git_revwalk *walk;
 
 	walk = git__malloc(sizeof(git_revwalk));
-	if (walk == NULL)
-		return GIT_ENOMEM;
+	GITERR_CHECK_ALLOC(walk);
 
 	memset(walk, 0x0, sizeof(git_revwalk));
 
@@ -759,7 +764,7 @@ int git_revwalk_new(git_revwalk **revwalk_out, git_repository *repo)
 
 	if (walk->commits == NULL) {
 		git__free(walk);
-		return GIT_ENOMEM;
+		return -1;
 	}
 
 	git_pqueue_init(&walk->iterator_time, 8, commit_time_cmp);
@@ -772,14 +777,13 @@ int git_revwalk_new(git_revwalk **revwalk_out, git_repository *repo)
 
 	walk->repo = repo;
 
-	error = git_repository_odb(&walk->odb, repo);
-	if (error < GIT_SUCCESS) {
+	if (git_repository_odb(&walk->odb, repo) < 0) {
 		git_revwalk_free(walk);
-		return error;
+		return -1;
 	}
 
 	*revwalk_out = walk;
-	return GIT_SUCCESS;
+	return 0;
 }
 
 void git_revwalk_free(git_revwalk *walk)
@@ -844,8 +848,8 @@ int git_revwalk_next(git_oid *oid, git_revwalk *walk)
 	assert(walk && oid);
 
 	if (!walk->walking) {
-		if ((error = prepare_walk(walk)) < GIT_SUCCESS)
-			return git__rethrow(error, "Failed to load next revision");
+		if ((error = prepare_walk(walk)) < 0)
+			return -1;
 	}
 
 	error = walk->get_next(&next, walk);
@@ -855,11 +859,11 @@ int git_revwalk_next(git_oid *oid, git_revwalk *walk)
 		return GIT_EREVWALKOVER;
 	}
 
-	if (error < GIT_SUCCESS)
-		return git__rethrow(error, "Failed to load next revision");
+	if (error < 0)
+		return -1;
 
 	git_oid_cpy(oid, &next->oid);
-	return GIT_SUCCESS;
+	return 0;
 }
 
 void git_revwalk_reset(git_revwalk *walk)