introduce `git_diff_from_buffer` to parse diffs

Parse diff files into a `git_diff` structure.

1 files changed, 105 insertions, 0 deletions

diff --git a/src/diff_parse.c b/src/diff_parse.c
new file mode 100644
index 000000000..ffdc8df88
--- /dev/null
+++ b/src/diff_parse.c
@@ -0,0 +1,105 @@
+/*
+ * Copyright (C) the libgit2 contributors. All rights reserved.
+ *
+ * This file is part of libgit2, distributed under the GNU GPL v2 with
+ * a Linking Exception. For full terms see the included COPYING file.
+ */
+#include "common.h"
+#include "diff.h"
+#include "patch.h"
+#include "patch_parse.h"
+
+typedef struct {
+	struct git_diff base;
+
+	git_vector patches;
+} git_diff_parsed;
+
+static void diff_parsed_free(git_diff *d)
+{
+	git_diff_parsed *diff = (git_diff_parsed *)d;
+	git_patch *patch;
+	size_t i;
+
+	git_vector_foreach(&diff->patches, i, patch)
+		git_patch_free(patch);
+
+	git_vector_free(&diff->patches);
+
+	git_vector_free(&diff->base.deltas);
+	git_pool_clear(&diff->base.pool);
+
+	git__memzero(diff, sizeof(*diff));
+	git__free(diff);
+}
+
+static git_diff_parsed *diff_parsed_alloc(void)
+{
+	git_diff_parsed *diff;
+
+	if ((diff = git__calloc(1, sizeof(git_diff_parsed))) == NULL)
+		return NULL;
+
+	GIT_REFCOUNT_INC(diff);
+	diff->base.type = GIT_DIFF_TYPE_PARSED;
+	diff->base.opts.flags &= ~GIT_DIFF_IGNORE_CASE;
+	diff->base.strcomp = git__strcmp;
+	diff->base.strncomp = git__strncmp;
+	diff->base.pfxcomp = git__prefixcmp;
+	diff->base.entrycomp = git_diff__entry_cmp;
+	diff->base.free_fn = diff_parsed_free;
+
+	git_pool_init(&diff->base.pool, 1);
+
+	if (git_vector_init(&diff->patches, 0, NULL) < 0 ||
+		git_vector_init(&diff->base.deltas, 0, git_diff_delta__cmp) < 0) {
+		git_diff_free(&diff->base);
+		return NULL;
+	}
+
+	git_vector_set_cmp(&diff->base.deltas, git_diff_delta__cmp);
+
+	return diff;
+}
+
+int git_diff_from_buffer(
+	git_diff **out,
+	const char *content,
+	size_t content_len)
+{
+	git_diff_parsed *diff;
+	git_patch *patch;
+	git_patch_parse_ctx *ctx = NULL;
+	int error = 0;
+
+	*out = NULL;
+
+	diff = diff_parsed_alloc();
+	GITERR_CHECK_ALLOC(diff);
+
+	ctx = git_patch_parse_ctx_init(content, content_len, NULL);
+	GITERR_CHECK_ALLOC(ctx);
+
+	while (ctx->remain_len) {
+		if ((error = git_patch_parse(&patch, ctx)) < 0)
+			break;
+
+		git_vector_insert(&diff->patches, patch);
+		git_vector_insert(&diff->base.deltas, patch->delta);
+	}
+
+	if (error == GIT_ENOTFOUND && git_vector_length(&diff->patches) > 0) {
+		giterr_clear();
+		error = 0;
+	}
+
+	git_patch_parse_ctx_free(ctx);
+
+	if (error < 0)
+		git_diff_free(&diff->base);
+	else
+		*out = &diff->base;
+
+	return error;
+}
+