Handle git_buf's from users more liberally

3 files changed, 19 insertions, 0 deletions

diff --git a/src/blob.c b/src/blob.c
index ab344ae98..2e924f37f 100644
--- a/src/blob.c
+++ b/src/blob.c
@@ -347,6 +347,8 @@ int git_blob_filtered_content(
 
 	assert(blob && path && out);
 
+	git_buf_sanitize(out);
+
 	if (check_for_binary_data && git_blob_is_binary(blob))
 		return 0;
 
diff --git a/src/buffer.c b/src/buffer.c
index 20682322e..3283c2d4f 100644
--- a/src/buffer.c
+++ b/src/buffer.c
@@ -100,6 +100,14 @@ void git_buf_free(git_buf *buf)
 	git_buf_init(buf, 0);
 }
 
+void git_buf_sanitize(git_buf *buf)
+{
+	if (buf->ptr == NULL) {
+		assert (buf->size == 0 && buf->asize == 0);
+		buf->ptr = git_buf__initbuf;
+	}
+}
+
 void git_buf_clear(git_buf *buf)
 {
 	buf->size = 0;
diff --git a/src/buffer.h b/src/buffer.h
index c88af6fef..564a4f561 100644
--- a/src/buffer.h
+++ b/src/buffer.h
@@ -51,6 +51,15 @@ extern void git_buf_init(git_buf *buf, size_t initial_size);
 extern int git_buf_try_grow(
 	git_buf *buf, size_t target_size, bool mark_oom, bool preserve_external);
 
+/**
+ * Sanitizes git_buf structures provided from user input.  Users of the
+ * library, when providing git_buf's, may wish to provide a NULL ptr for
+ * ease of handling.  The buffer routines, however, expect a non-NULL ptr
+ * always.  This helper method simply handles NULL input, converting to a
+ * git_buf__initbuf.
+ */
+extern void git_buf_sanitize(git_buf *buf);
+
 extern void git_buf_swap(git_buf *buf_a, git_buf *buf_b);
 extern char *git_buf_detach(git_buf *buf);
 extern void git_buf_attach(git_buf *buf, char *ptr, size_t asize);