Add buffer to buffer diff and patch APIs

This adds `git_diff_buffers` and `git_patch_from_buffers`.  This
also includes a bunch of internal refactoring to increase the
shared code between these functions and the blob-to-blob and
blob-to-buffer APIs, as well as some higher level assert helpers
in the tests to also remove redundancy.

1 files changed, 28 insertions, 0 deletions

diff --git a/include/git2/patch.h b/include/git2/patch.h
index 1eca29d4a..f5ec682c6 100644
--- a/include/git2/patch.h
+++ b/include/git2/patch.h
@@ -106,6 +106,34 @@ GIT_EXTERN(int) git_patch_from_blob_and_buffer(
 	const git_diff_options *opts);
 
 /**
+ * Directly generate a patch from the difference between two buffers.
+ *
+ * This is just like `git_diff_buffers()` except it generates a patch
+ * object for the difference instead of directly making callbacks.  You can
+ * use the standard `git_patch` accessor functions to read the patch
+ * data, and you must call `git_patch_free()` on the patch when done.
+ *
+ * @param out The generated patch; NULL on error
+ * @param old_buffer Raw data for old side of diff, or NULL for empty
+ * @param old_len Length of the raw data for old side of the diff
+ * @param old_as_path Treat old buffer as if it had this filename; can be NULL
+ * @param new_buffer Raw data for new side of diff, or NULL for empty
+ * @param new_len Length of raw data for new side of diff
+ * @param new_as_path Treat buffer as if it had this filename; can be NULL
+ * @param opts Options for diff, or NULL for default options
+ * @return 0 on success or error code < 0
+ */
+GIT_EXTERN(int) git_patch_from_buffers(
+	git_patch **out,
+	const void *old_buffer,
+	size_t old_len,
+	const char *old_as_path,
+	const char *new_buffer,
+	size_t new_len,
+	const char *new_as_path,
+	const git_diff_options *opts);
+
+/**
  * Free a git_patch object.
  */
 GIT_EXTERN(void) git_patch_free(git_patch *patch);