Handle git_buf's from users more liberally

include/git2/blob.h

@@ -84,7 +84,7 @@ GIT_EXTERN(git_repository *) git_blob_owner(const git_blob *blob);
  * time.
  *
  * @param blob pointer to the blob
- * @return the pointer; NULL if the blob has no contents
+ * @return the pointer
  */
 GIT_EXTERN(const void *) git_blob_rawcontent(const git_blob *blob);
 

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;
 

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;

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);

tests/filter/blob.c

@@ -47,6 +47,38 @@ void test_filter_blob__all_crlf(void)
 	git_blob_free(blob);
 }
 
+void test_filter_blob__sanitizes(void)
+{
+	git_blob *blob;
+	git_buf buf;
+
+	cl_git_pass(git_revparse_single(
+		(git_object **)&blob, g_repo, "e69de29")); /* zero-byte */
+
+	cl_assert_equal_i(0, git_blob_rawsize(blob));
+	cl_assert_equal_s("", git_blob_rawcontent(blob));
+
+	memset(&buf, 0, sizeof(git_buf));
+	cl_git_pass(git_blob_filtered_content(&buf, blob, "file.bin", 1));
+	cl_assert_equal_sz(0, buf.size);
+	cl_assert_equal_s("", buf.ptr);
+	git_buf_free(&buf);
+
+	memset(&buf, 0, sizeof(git_buf));
+	cl_git_pass(git_blob_filtered_content(&buf, blob, "file.crlf", 1));
+	cl_assert_equal_sz(0, buf.size);
+	cl_assert_equal_s("", buf.ptr);
+	git_buf_free(&buf);
+
+	memset(&buf, 0, sizeof(git_buf));
+	cl_git_pass(git_blob_filtered_content(&buf, blob, "file.lf", 1));
+	cl_assert_equal_sz(0, buf.size);
+	cl_assert_equal_s("", buf.ptr);
+	git_buf_free(&buf);
+
+	git_blob_free(blob);
+}
+
 void test_filter_blob__ident(void)
 {
 	git_oid id;

tests/resources/crlf/.gitted/refs/heads/master

-12faf3c1ea55f572473cec9052fca468c3584ccb
+2c9a868cfdf8e270d0ec68164433376c68fb1789