Merge branch 'jc/patch-id' into maint-2.46

The patch parser in "git patch-id" has been tightened to avoid
getting confused by lines that look like a patch header in the log
message.
cf. <Zqh2T_2RLt0SeKF7@tanuki>

* jc/patch-id:
  patch-id: tighten code to detect the patch header
  patch-id: rewrite code that detects the beginning of a patch
  patch-id: make get_one_patchid() more extensible
  patch-id: call flush_current_id() only when needed
  t4204: patch-id supports various input format

Author: gitster

builtin/patch-id.c

@@ -7,10 +7,9 @@
 #include "parse-options.h"
 #include "setup.h"
 
-static void flush_current_id(int patchlen, struct object_id *id, struct object_id *result)
+static void flush_current_id(struct object_id *id, struct object_id *result)
 {
-	if (patchlen)
-		printf("%s %s\n", oid_to_hex(result), oid_to_hex(id));
+	printf("%s %s\n", oid_to_hex(result), oid_to_hex(id));
 }
 
 static int remove_space(char *line)
@@ -60,9 +59,27 @@ static int scan_hunk_header(const char *p, int *p_before, int *p_after)
 	return 1;
 }
 
+/*
+ * flag bits to control get_one_patchid()'s behaviour.
+ *
+ * STABLE/VERBATIM are given from the command line option as
+ * --stable/--verbatim.  FIND_HEADER conveys the internal state
+ * maintained by the caller to allow the function to avoid mistaking
+ * lines of log message before seeing the "diff" part as the beginning
+ * of the next patch.
+ */
+enum {
+	GOPID_STABLE = (1<<0),		/* --stable */
+	GOPID_VERBATIM = (1<<1),	/* --verbatim */
+	GOPID_FIND_HEADER = (1<<2),	/* stop at the beginning of patch message */
+};
+
 static int get_one_patchid(struct object_id *next_oid, struct object_id *result,
-			   struct strbuf *line_buf, int stable, int verbatim)
+			   struct strbuf *line_buf, unsigned flags)
 {
+	int stable = flags & GOPID_STABLE;
+	int verbatim = flags & GOPID_VERBATIM;
+	int find_header = flags & GOPID_FIND_HEADER;
 	int patchlen = 0, found_next = 0;
 	int before = -1, after = -1;
 	int diff_is_binary = 0;
@@ -77,24 +94,40 @@ static int get_one_patchid(struct object_id *next_oid, struct object_id *result,
 		const char *p = line;
 		int len;
 
-		/* Possibly skip over the prefix added by "log" or "format-patch" */
-		if (!skip_prefix(line, "commit ", &p) &&
-		    !skip_prefix(line, "From ", &p) &&
-		    starts_with(line, "\\ ") && 12 < strlen(line)) {
-			if (verbatim)
-				the_hash_algo->update_fn(&ctx, line, strlen(line));
-			continue;
-		}
-
-		if (!get_oid_hex(p, next_oid)) {
-			found_next = 1;
-			break;
+		/*
+		 * The caller hasn't seen us find a patch header and
+		 * return to it, or we have started processing patch
+		 * and may encounter the beginning of the next patch.
+		 */
+		if (find_header) {
+			/*
+			 * If we see a line that begins with "<object name>",
+			 * "commit <object name>" or "From <object name>", it is
+			 * the beginning of a patch.  Return to the caller, as
+			 * we are done with the one we have been processing.
+			 */
+			if (skip_prefix(line, "commit ", &p))
+				;
+			else if (skip_prefix(line, "From ", &p))
+				;
+			if (!get_oid_hex(p, next_oid)) {
+				if (verbatim)
+					the_hash_algo->update_fn(&ctx, line, strlen(line));
+				found_next = 1;
+				break;
+			}
 		}
 
 		/* Ignore commit comments */
 		if (!patchlen && !starts_with(line, "diff "))
 			continue;
 
+		/*
+		 * We are past the commit log message.  Prepare to
+		 * stop at the beginning of the next patch header.
+		 */
+		find_header = 1;
+
 		/* Parsing diff header?  */
 		if (before == -1) {
 			if (starts_with(line, "GIT binary patch") ||
@@ -127,6 +160,16 @@ static int get_one_patchid(struct object_id *next_oid, struct object_id *result,
 				break;
 		}
 
+		/*
+		 * A hunk about an incomplete line may have this
+		 * marker at the end, which should just be ignored.
+		 */
+		if (starts_with(line, "\\ ") && 12 < strlen(line)) {
+			if (verbatim)
+				the_hash_algo->update_fn(&ctx, line, strlen(line));
+			continue;
+		}
+
 		if (diff_is_binary) {
 			if (starts_with(line, "diff ")) {
 				diff_is_binary = 0;
@@ -173,17 +216,20 @@ static int get_one_patchid(struct object_id *next_oid, struct object_id *result,
 	return patchlen;
 }
 
-static void generate_id_list(int stable, int verbatim)
+static void generate_id_list(unsigned flags)
 {
 	struct object_id oid, n, result;
 	int patchlen;
 	struct strbuf line_buf = STRBUF_INIT;
 
 	oidclr(&oid, the_repository->hash_algo);
+	flags |= GOPID_FIND_HEADER;
 	while (!feof(stdin)) {
-		patchlen = get_one_patchid(&n, &result, &line_buf, stable, verbatim);
-		flush_current_id(patchlen, &oid, &result);
+		patchlen = get_one_patchid(&n, &result, &line_buf, flags);
+		if (patchlen)
+			flush_current_id(&oid, &result);
 		oidcpy(&oid, &n);
+		flags &= ~GOPID_FIND_HEADER;
 	}
 	strbuf_release(&line_buf);
 }
@@ -219,6 +265,7 @@ int cmd_patch_id(int argc, const char **argv, const char *prefix)
 	/* if nothing is set, default to unstable */
 	struct patch_id_opts config = {0, 0};
 	int opts = 0;
+	unsigned flags = 0;
 	struct option builtin_patch_id_options[] = {
 		OPT_CMDMODE(0, "unstable", &opts,
 		    N_("use the unstable patch-id algorithm"), 1),
@@ -250,7 +297,11 @@ int cmd_patch_id(int argc, const char **argv, const char *prefix)
 	if (!the_hash_algo)
 		repo_set_hash_algo(the_repository, GIT_HASH_SHA1);
 
-	generate_id_list(opts ? opts > 1 : config.stable,
-			 opts ? opts == 3 : config.verbatim);
+	if (opts ? opts > 1 : config.stable)
+		flags |= GOPID_STABLE;
+	if (opts ? opts == 3 : config.verbatim)
+		flags |= GOPID_VERBATIM;
+	generate_id_list(flags);
+
 	return 0;
 }

t/t4204-patch-id.sh

@@ -114,6 +114,46 @@ test_expect_success 'patch-id supports git-format-patch output' '
 	test "$2" = $(git rev-parse HEAD)
 '
 
+test_expect_success 'patch-id computes the same for various formats' '
+	# This test happens to consider "git log -p -1" output
+	# the canonical input format, so use it as the norm.
+	git log -1 -p same >log-p.output &&
+	git patch-id <log-p.output >expect &&
+
+	# format-patch begins with "From <commit object name>"
+	git format-patch -1 --stdout same >format-patch.output &&
+	git patch-id <format-patch.output >actual &&
+	test_cmp actual expect &&
+
+	# "diff-tree --stdin -p" begins with "<commit object name>"
+	same=$(git rev-parse same) &&
+	echo $same | git diff-tree --stdin -p >diff-tree.output &&
+	git patch-id <diff-tree.output >actual &&
+	test_cmp actual expect &&
+
+	# "diff-tree --stdin -v -p" begins with "commit <commit object name>"
+	echo $same | git diff-tree --stdin -p -v >diff-tree-v.output &&
+	git patch-id <diff-tree-v.output >actual &&
+	test_cmp actual expect
+'
+
+hash=$(git rev-parse same:)
+for cruft in "$hash" "commit $hash is bad" "From $hash status"
+do
+	test_expect_success "patch-id with <$cruft> in log message" '
+		git format-patch -1 --stdout same >patch-0 &&
+		git patch-id <patch-0 >expect &&
+
+		{
+			sed -e "/^$/q" patch-0 &&
+			printf "random message\n%s\n\n" "$cruft" &&
+			sed -e "1,/^$/d" patch-0
+		} >patch-cruft &&
+		git patch-id <patch-cruft >actual &&
+		test_cmp actual expect
+	'
+done
+
 test_expect_success 'whitespace is irrelevant in footer' '
 	get_patch_id main &&
 	git checkout same &&