1 files changed, 143 insertions, 0 deletions
diff --git a/diff-helper.c b/diff-helper.c
new file mode 100644
index 0000000000..51bb658be4
--- /dev/null
+++ b/diff-helper.c
@@ -0,0 +1,143 @@
+/*
+ * Copyright (C) 2005 Junio C Hamano
+ */
+#include <limits.h>
+#include "cache.h"
+#include "strbuf.h"
+#include "diff.h"
+
+static int matches_pathspec(const char *name, const char **spec, int cnt)
+{
+	int i;
+	int namelen = strlen(name);
+	for (i = 0; i < cnt; i++) {
+		int speclen = strlen(spec[i]);
+		if (! strncmp(spec[i], name, speclen) &&
+		    speclen <= namelen &&
+		    (name[speclen] == 0 ||
+		     name[speclen] == '/'))
+			return 1;
+	}
+	return 0;
+}
+
+static int parse_oneside_change(const char *cp, struct diff_spec *one,
+				char *path)
+{
+	int ch;
+
+	one->file_valid = one->sha1_valid = 1;
+	one->mode = 0;
+	while ((ch = *cp) && '0' <= ch && ch <= '7') {
+		one->mode = (one->mode << 3) | (ch - '0');
+		cp++;
+	}
+
+	if (strncmp(cp, "\tblob\t", 6))
+		return -1;
+	cp += 6;
+	if (get_sha1_hex(cp, one->blob_sha1))
+		return -1;
+	cp += 40;
+	if (*cp++ != '\t')
+		return -1;
+	strcpy(path, cp);
+	return 0;
+}
+
+static int parse_diff_tree_output(const char *buf,
+				  const char **spec, int cnt, int reverse)
+{
+	struct diff_spec old, new;
+	char path[PATH_MAX];
+	const char *cp = buf;
+	int ch;
+
+	switch (*cp++) {
+	case 'U':
+		if (!cnt || matches_pathspec(cp + 1, spec, cnt))
+			diff_unmerge(cp + 1);
+		return 0;
+	case '+':
+		old.file_valid = 0;
+		parse_oneside_change(cp, &new, path);
+		break;
+	case '-':
+		new.file_valid = 0;
+		parse_oneside_change(cp, &old, path);
+		break;
+	case '*':
+		old.file_valid = old.sha1_valid =
+			new.file_valid = new.sha1_valid = 1;
+		old.mode = new.mode = 0;
+		while ((ch = *cp) && ('0' <= ch && ch <= '7')) {
+			old.mode = (old.mode << 3) | (ch - '0');
+			cp++;
+		}
+		if (strncmp(cp, "->", 2))
+			return -1;
+		cp += 2;
+		while ((ch = *cp) && ('0' <= ch && ch <= '7')) {
+			new.mode = (new.mode << 3) | (ch - '0');
+			cp++;
+		}
+		if (strncmp(cp, "\tblob\t", 6))
+			return -1;
+		cp += 6;
+		if (get_sha1_hex(cp, old.blob_sha1))
+			return -1;
+		cp += 40;
+		if (strncmp(cp, "->", 2))
+			return -1;
+		cp += 2;
+		if (get_sha1_hex(cp, new.blob_sha1))
+			return -1;
+		cp += 40;
+		if (*cp++ != '\t')
+			return -1;
+		strcpy(path, cp);
+		break;
+	default:
+		return -1;
+	}
+	if (!cnt || matches_pathspec(path, spec, cnt)) {
+		if (reverse)
+			run_external_diff(path, &new, &old);
+		else
+			run_external_diff(path, &old, &new);
+	}
+	return 0;
+}
+
+static const char *diff_tree_helper_usage =
+"diff-tree-helper [-R] [-z] paths...";
+
+int main(int ac, const char **av) {
+	struct strbuf sb;
+	int reverse = 0;
+	int line_termination = '\n';
+
+	strbuf_init(&sb);
+
+	while (1 < ac && av[1][0] == '-') {
+		if (av[1][1] == 'R')
+			reverse = 1;
+		else if (av[1][1] == 'z')
+			line_termination = 0;
+		else
+			usage(diff_tree_helper_usage);
+		ac--; av++;
+	}
+	/* the remaining parameters are paths patterns */
+
+	while (1) {
+		int status;
+		read_line(&sb, stdin, line_termination);
+		if (sb.eof)
+			break;
+		status = parse_diff_tree_output(sb.buf, av+1, ac-1, reverse);
+		if (status)
+			fprintf(stderr, "cannot parse %s\n", sb.buf);
+	}
+	return 0;
+}