Update iterators for consistency across library

This updates all the `foreach()` type functions across the library
that take callbacks from the user to have a consistent behavior.
The rules are:

* A callback terminates the loop by returning any non-zero value
* Once the callback returns non-zero, it will not be called again
  (i.e. the loop stops all iteration regardless of state)
* If the callback returns non-zero, the parent fn returns GIT_EUSER
* Although the parent returns GIT_EUSER, no error will be set in
  the library and `giterr_last()` will return NULL if called.

This commit makes those changes across the library and adds tests
for most of the iteration APIs to make sure that they follow the
above rules.

1 files changed, 16 insertions, 6 deletions

diff --git a/src/status.c b/src/status.c
index d78237689..618f60fd0 100644
--- a/src/status.c
+++ b/src/status.c
@@ -114,7 +114,8 @@ int git_status_foreach_ext(
 	if (show == GIT_STATUS_SHOW_INDEX_THEN_WORKDIR) {
 		for (i = 0; !err && i < idx2head->deltas.length; i++) {
 			i2h = GIT_VECTOR_GET(&idx2head->deltas, i);
-			err = cb(i2h->old_file.path, index_delta2status(i2h->status), cbdata);
+			if (cb(i2h->old_file.path, index_delta2status(i2h->status), cbdata))
+				err = GIT_EUSER;
 		}
 		git_diff_list_free(idx2head);
 		idx2head = NULL;
@@ -130,14 +131,17 @@ int git_status_foreach_ext(
 		cmp = !w2i ? -1 : !i2h ? 1 : strcmp(i2h->old_file.path, w2i->old_file.path);
 
 		if (cmp < 0) {
-			err = cb(i2h->old_file.path, index_delta2status(i2h->status), cbdata);
+			if (cb(i2h->old_file.path, index_delta2status(i2h->status), cbdata))
+				err = GIT_EUSER;
 			i++;
 		} else if (cmp > 0) {
-			err = cb(w2i->old_file.path, workdir_delta2status(w2i->status), cbdata);
+			if (cb(w2i->old_file.path, workdir_delta2status(w2i->status), cbdata))
+				err = GIT_EUSER;
 			j++;
 		} else {
-			err = cb(i2h->old_file.path, index_delta2status(i2h->status) |
-					 workdir_delta2status(w2i->status), cbdata);
+			if (cb(i2h->old_file.path, index_delta2status(i2h->status) |
+				   workdir_delta2status(w2i->status), cbdata))
+				err = GIT_EUSER;
 			i++; j++;
 		}
 	}
@@ -146,6 +150,7 @@ cleanup:
 	git_tree_free(head);
 	git_diff_list_free(idx2head);
 	git_diff_list_free(wd2idx);
+
 	return err;
 }
 
@@ -166,9 +171,10 @@ int git_status_foreach(
 }
 
 struct status_file_info {
+	char *expected;
 	unsigned int count;
 	unsigned int status;
-	char *expected;
+	int ambiguous;
 };
 
 static int get_one_status(const char *path, unsigned int status, void *data)
@@ -183,6 +189,7 @@ static int get_one_status(const char *path, unsigned int status, void *data)
 		p_fnmatch(sfi->expected, path, 0) != 0)) {
 		giterr_set(GITERR_INVALID,
 			"Ambiguous path '%s' given to git_status_file", sfi->expected);
+		sfi->ambiguous = true;
 		return GIT_EAMBIGUOUS;
 	}
 
@@ -215,6 +222,9 @@ int git_status_file(
 
 	error = git_status_foreach_ext(repo, &opts, get_one_status, &sfi);
 
+	if (error < 0 && sfi.ambiguous)
+		error = GIT_EAMBIGUOUS;
+
 	if (!error && !sfi.count) {
 		giterr_set(GITERR_INVALID,
 			"Attempt to get status of nonexistent file '%s'", path);