1 files changed, 85 insertions, 0 deletions
diff --git a/builtin/patch-id.c b/builtin/patch-id.c
new file mode 100644
index 0000000000..af0911e4bd
--- /dev/null
+++ b/builtin/patch-id.c
@@ -0,0 +1,85 @@
+#include "cache.h"
+#include "exec_cmd.h"
+
+static void flush_current_id(int patchlen, unsigned char *id, git_SHA_CTX *c)
+{
+	unsigned char result[20];
+	char name[50];
+
+	if (!patchlen)
+		return;
+
+	git_SHA1_Final(result, c);
+	memcpy(name, sha1_to_hex(id), 41);
+	printf("%s %s\n", sha1_to_hex(result), name);
+	git_SHA1_Init(c);
+}
+
+static int remove_space(char *line)
+{
+	char *src = line;
+	char *dst = line;
+	unsigned char c;
+
+	while ((c = *src++) != '\0') {
+		if (!isspace(c))
+			*dst++ = c;
+	}
+	return dst - line;
+}
+
+static void generate_id_list(void)
+{
+	static unsigned char sha1[20];
+	static char line[1000];
+	git_SHA_CTX ctx;
+	int patchlen = 0;
+
+	git_SHA1_Init(&ctx);
+	while (fgets(line, sizeof(line), stdin) != NULL) {
+		unsigned char n[20];
+		char *p = line;
+		int len;
+
+		if (!memcmp(line, "diff-tree ", 10))
+			p += 10;
+		else if (!memcmp(line, "commit ", 7))
+			p += 7;
+
+		if (!get_sha1_hex(p, n)) {
+			flush_current_id(patchlen, sha1, &ctx);
+			hashcpy(sha1, n);
+			patchlen = 0;
+			continue;
+		}
+
+		/* Ignore commit comments */
+		if (!patchlen && memcmp(line, "diff ", 5))
+			continue;
+
+		/* Ignore git-diff index header */
+		if (!memcmp(line, "index ", 6))
+			continue;
+
+		/* Ignore line numbers when computing the SHA1 of the patch */
+		if (!memcmp(line, "@@ -", 4))
+			continue;
+
+		/* Compute the sha without whitespace */
+		len = remove_space(line);
+		patchlen += len;
+		git_SHA1_Update(&ctx, line, len);
+	}
+	flush_current_id(patchlen, sha1, &ctx);
+}
+
+static const char patch_id_usage[] = "git patch-id < patch";
+
+int cmd_patch_id(int argc, const char **argv, const char *prefix)
+{
+	if (argc != 1)
+		usage(patch_id_usage);
+
+	generate_id_list();
+	return 0;
+}