1 files changed, 155 insertions, 0 deletions
diff --git a/builtin/patch-id.c b/builtin/patch-id.c
new file mode 100644
index 0000000000..f821eb3f0b
--- /dev/null
+++ b/builtin/patch-id.c
@@ -0,0 +1,155 @@
+#include "builtin.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 int scan_hunk_header(const char *p, int *p_before, int *p_after)
+{
+	static const char digits[] = "0123456789";
+	const char *q, *r;
+	int n;
+
+	q = p + 4;
+	n = strspn(q, digits);
+	if (q[n] == ',') {
+		q += n + 1;
+		n = strspn(q, digits);
+	}
+	if (n == 0 || q[n] != ' ' || q[n+1] != '+')
+		return 0;
+
+	r = q + n + 2;
+	n = strspn(r, digits);
+	if (r[n] == ',') {
+		r += n + 1;
+		n = strspn(r, digits);
+	}
+	if (n == 0)
+		return 0;
+
+	*p_before = atoi(q);
+	*p_after = atoi(r);
+	return 1;
+}
+
+static int get_one_patchid(unsigned char *next_sha1, git_SHA_CTX *ctx)
+{
+	static char line[1000];
+	int patchlen = 0, found_next = 0;
+	int before = -1, after = -1;
+
+	while (fgets(line, sizeof(line), stdin) != NULL) {
+		char *p = line;
+		int len;
+
+		if (!memcmp(line, "diff-tree ", 10))
+			p += 10;
+		else if (!memcmp(line, "commit ", 7))
+			p += 7;
+		else if (!memcmp(line, "From ", 5))
+			p += 5;
+		else if (!memcmp(line, "\\ ", 2) && 12 < strlen(line))
+			continue;
+
+		if (!get_sha1_hex(p, next_sha1)) {
+			found_next = 1;
+			break;
+		}
+
+		/* Ignore commit comments */
+		if (!patchlen && memcmp(line, "diff ", 5))
+			continue;
+
+		/* Parsing diff header?  */
+		if (before == -1) {
+			if (!memcmp(line, "index ", 6))
+				continue;
+			else if (!memcmp(line, "--- ", 4))
+				before = after = 1;
+			else if (!isalpha(line[0]))
+				break;
+		}
+
+		/* Looking for a valid hunk header?  */
+		if (before == 0 && after == 0) {
+			if (!memcmp(line, "@@ -", 4)) {
+				/* Parse next hunk, but ignore line numbers.  */
+				scan_hunk_header(line, &before, &after);
+				continue;
+			}
+
+			/* Split at the end of the patch.  */
+			if (memcmp(line, "diff ", 5))
+				break;
+
+			/* Else we're parsing another header.  */
+			before = after = -1;
+		}
+
+		/* If we get here, we're inside a hunk.  */
+		if (line[0] == '-' || line[0] == ' ')
+			before--;
+		if (line[0] == '+' || line[0] == ' ')
+			after--;
+
+		/* Compute the sha without whitespace */
+		len = remove_space(line);
+		patchlen += len;
+		git_SHA1_Update(ctx, line, len);
+	}
+
+	if (!found_next)
+		hashclr(next_sha1);
+
+	return patchlen;
+}
+
+static void generate_id_list(void)
+{
+	unsigned char sha1[20], n[20];
+	git_SHA_CTX ctx;
+	int patchlen;
+
+	git_SHA1_Init(&ctx);
+	hashclr(sha1);
+	while (!feof(stdin)) {
+		patchlen = get_one_patchid(n, &ctx);
+		flush_current_id(patchlen, sha1, &ctx);
+		hashcpy(sha1, n);
+	}
+}
+
+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;
+}