Fix problems in diff iterator record chaining

There is a bug in building the linked list of line records in the
diff iterator and also an off by one element error in the hunk
counts.  This fixes both of these, adds some test data with more
complex sets of hunk and line diffs to exercise this code better.

1 files changed, 31 insertions, 13 deletions

diff --git a/src/diff_output.c b/src/diff_output.c
index ea40c3355..50e3cc1de 100644
--- a/src/diff_output.c
+++ b/src/diff_output.c
@@ -1204,13 +1204,17 @@ static int diffiter_hunk_cb(
 	if (info->last_hunk)
 		info->last_hunk->next = hunk;
 	info->last_hunk = hunk;
+	info->last_line = NULL;
 
 	memcpy(&hunk->range, range, sizeof(hunk->range));
 
 	iter->hunk_count++;
 
-	if (iter->hunk_head == NULL)
-		iter->hunk_curr = iter->hunk_head = hunk;
+	/* adding first hunk to list */
+	if (iter->hunk_head == NULL) {
+		iter->hunk_head = hunk;
+		iter->hunk_curr = NULL;
+	}
 
 	return 0;
 }
@@ -1345,9 +1349,14 @@ int git_diff_iterator_num_hunks_in_file(git_diff_iterator *iter)
 int git_diff_iterator_num_lines_in_hunk(git_diff_iterator *iter)
 {
 	int error = diffiter_do_diff_file(iter);
-	if (!error && iter->hunk_curr)
-		error = iter->hunk_curr->line_count;
-	return error;
+	if (error)
+		return error;
+
+	if (iter->hunk_curr)
+		return iter->hunk_curr->line_count;
+	if (iter->hunk_head)
+		return iter->hunk_head->line_count;
+	return 0;
 }
 
 int git_diff_iterator_next_file(
@@ -1386,7 +1395,7 @@ int git_diff_iterator_next_file(
 	}
 
 	if (iter->ctxt.delta == NULL) {
-		iter->hunk_curr = NULL;
+		iter->hunk_curr = iter->hunk_head = NULL;
 		iter->line_curr = NULL;
 	}
 
@@ -1409,11 +1418,13 @@ int git_diff_iterator_next_hunk(
 		return error;
 
 	if (iter->hunk_curr == NULL) {
-		if (range_ptr) *range_ptr = NULL;
-		if (header) *header = NULL;
-		if (header_len) *header_len = 0;
-		iter->line_curr = NULL;
-		return GIT_ITEROVER;
+		if (iter->hunk_head == NULL)
+			goto no_more_hunks;
+		iter->hunk_curr = iter->hunk_head;
+	} else {
+		if (iter->hunk_curr->next == NULL)
+			goto no_more_hunks;
+		iter->hunk_curr = iter->hunk_curr->next;
 	}
 
 	range = &iter->hunk_curr->range;
@@ -1436,9 +1447,16 @@ int git_diff_iterator_next_hunk(
 	}
 
 	iter->line_curr = iter->hunk_curr->line_head;
-	iter->hunk_curr = iter->hunk_curr->next;
 
 	return error;
+
+no_more_hunks:
+	if (range_ptr) *range_ptr = NULL;
+	if (header) *header = NULL;
+	if (header_len) *header_len = 0;
+	iter->line_curr = NULL;
+
+	return GIT_ITEROVER;
 }
 
 int git_diff_iterator_next_line(
@@ -1453,7 +1471,7 @@ int git_diff_iterator_next_line(
 		return error;
 
 	/* if the user has not called next_hunk yet, call it implicitly (OK?) */
-	if (iter->hunk_curr == iter->hunk_head) {
+	if (iter->hunk_curr == NULL) {
 		error = git_diff_iterator_next_hunk(NULL, NULL, NULL, iter);
 		if (error)
 			return error;