1 files changed, 160 insertions, 0 deletions
diff --git a/src/diff_driver.c b/src/diff_driver.c
new file mode 100644
index 000000000..5438afc67
--- /dev/null
+++ b/src/diff_driver.c
@@ -0,0 +1,160 @@
+/*
+ * 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 "git2/attr.h"
+
+#include "diff.h"
+#include "diff_patch.h"
+#include "diff_driver.h"
+#include "strmap.h"
+#include "pool.h"
+#include "map.h"
+#include "buf_text.h"
+
+typedef enum {
+	DIFF_DRIVER_AUTO = 0,
+	DIFF_DRIVER_FALSE = 1,
+	DIFF_DRIVER_TRUE = 2,
+	DIFF_DRIVER_NAMED = 3,
+} git_diff_driver_t;
+
+enum {
+	DIFF_CONTEXT_FIND_NORMAL = 0,
+	DIFF_CONTEXT_FIND_ICASE = (1 << 0),
+	DIFF_CONTEXT_FIND_EXT = (1 << 1),
+};
+
+/* data for finding function context for a given file type */
+struct git_diff_driver {
+	git_diff_driver_t type;
+	git_strarray fn_patterns;
+	int binary;
+};
+
+struct git_diff_driver_registry {
+	git_strmap *drivers;
+	git_pool strings;
+};
+
+static git_diff_driver global_drivers[3] = {
+	{ DIFF_DRIVER_AUTO, { NULL, 0 }, -1 },
+	{ DIFF_DRIVER_FALSE, { NULL, 0 }, 1 },
+	{ DIFF_DRIVER_TRUE, { NULL, 0 }, 0 },
+};
+
+git_diff_driver_registry *git_diff_driver_registry_new()
+{
+	return git__calloc(1, sizeof(git_diff_driver_registry));
+}
+
+void git_diff_driver_registry_free(git_diff_driver_registry *reg)
+{
+	git__free(reg);
+}
+
+int git_diff_driver_lookup(
+	git_diff_driver **out, git_repository *repo, const char *path)
+{
+	const char *value;
+
+	assert(out);
+
+	if (!repo || !path || !strlen(path))
+		goto use_auto;
+
+	if (git_attr_get(&value, repo, 0, path, "diff") < 0)
+		return -1;
+
+	if (GIT_ATTR_FALSE(value)) {
+		*out = &global_drivers[DIFF_DRIVER_FALSE];
+		return 0;
+	}
+
+	else if (GIT_ATTR_TRUE(value)) {
+		*out = &global_drivers[DIFF_DRIVER_TRUE];
+		return 0;
+	}
+
+	/* otherwise look for driver information in config and build driver */
+
+use_auto:
+	*out = &global_drivers[DIFF_DRIVER_AUTO];
+	return 0;
+}
+
+void git_diff_driver_free(git_diff_driver *driver)
+{
+	GIT_UNUSED(driver);
+	/* do nothing for now */
+}
+
+int git_diff_driver_is_binary(git_diff_driver *driver)
+{
+	return driver ? driver->binary : -1;
+}
+
+int git_diff_driver_content_is_binary(
+	git_diff_driver *driver, const char *content, size_t content_len)
+{
+	const git_buf search = { (char *)content, 0, min(content_len, 4000) };
+
+	GIT_UNUSED(driver);
+
+	/* TODO: provide encoding / binary detection callbacks that can
+	 * be UTF-8 aware, etc.  For now, instead of trying to be smart,
+	 * let's just use the simple NUL-byte detection that core git uses.
+	 */
+
+	/* previously was: if (git_buf_text_is_binary(&search)) */
+	if (git_buf_text_contains_nul(&search))
+		return 1;
+
+	return 0;
+}
+
+static long diff_context_find(
+	const char *line,
+	long line_len,
+	char *out,
+	long out_size,
+	void *payload)
+{
+	git_diff_driver *driver = payload;
+	const char *scan;
+
+	GIT_UNUSED(driver);
+
+	if (line_len > 0 && line[line_len - 1] == '\n')
+		line_len--;
+	if (line_len > 0 && line[line_len - 1] == '\r')
+		line_len--;
+	if (!line_len)
+		return -1;
+
+	if (!git__isalpha(*line) && *line != '_' && *line != '$')
+		return -1;
+
+	for (scan = &line[line_len-1]; scan > line && git__isspace(*scan); --scan)
+		/* search backward for non-space */;
+	line_len = scan - line;
+
+	if (line_len >= out_size)
+		line_len = out_size - 1;
+
+	memcpy(out, line, line_len);
+	out[line_len] = '\0';
+
+	return line_len;
+}
+
+git_diff_find_context_fn git_diff_driver_find_content_fn(git_diff_driver *driver)
+{
+	GIT_UNUSED(driver);
+	return diff_context_find;
+}
+