worktree: teach list --porcelain to annotate locked worktree

Commit c57b3367be (worktree: teach `list` to annotate locked worktree,
2020-10-11) taught "git worktree list" to annotate locked worktrees by
appending "locked" text to its output, however, this is not listed in
the --porcelain format.

Teach "list --porcelain" to do the same and add a "locked" attribute
followed by its reason, thus making both default and porcelain format
consistent. If the locked reason is not available then only "locked"
is shown.

The output of the "git worktree list --porcelain" becomes like so:

    $ git worktree list --porcelain
    ...
    worktree /path/to/locked
    HEAD 123abcdea123abcd123acbd123acbda123abcd12
    detached
    locked

    worktree /path/to/locked-with-reason
    HEAD abc123abc123abc123abc123abc123abc123abc1
    detached
    locked reason why it is locked
    ...

In porcelain mode, if the lock reason contains special characters
such as newlines, they are escaped with backslashes and the entire
reason is enclosed in double quotes. For example:

   $ git worktree list --porcelain
   ...
   locked "worktree's path mounted in\nremovable device"
   ...

Furthermore, let's update the documentation to state that some
attributes in the porcelain format might be listed alone or together
with its value depending whether the value is available or not. Thus
documenting the case of the new "locked" attribute.

Helped-by: Phillip Wood <phillip.wood@dunelm.org.uk>
Helped-by: Eric Sunshine <sunshine@sunshineco.com>
Signed-off-by: Rafael Silva <rafaeloliveira.cs@gmail.com>
Reviewed-by: Eric Sunshine <sunshine@sunshineco.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

Documentation/git-worktree.txt

@@ -377,8 +377,10 @@ Porcelain Format
 The porcelain format has a line per attribute.  Attributes are listed with a
 label and value separated by a single space.  Boolean attributes (like `bare`
 and `detached`) are listed as a label only, and are present only
-if the value is true.  The first attribute of a working tree is always
-`worktree`, an empty line indicates the end of the record.  For example:
+if the value is true.  Some attributes (like `locked`) can be listed as a label
+only or with a value depending upon whether a reason is available.  The first
+attribute of a working tree is always `worktree`, an empty line indicates the
+end of the record.  For example:
 
 ------------
 $ git worktree list --porcelain
@@ -393,6 +395,28 @@ worktree /path/to/other-linked-worktree
 HEAD 1234abc1234abc1234abc1234abc1234abc1234a
 detached
 
+worktree /path/to/linked-worktree-locked-no-reason
+HEAD 5678abc5678abc5678abc5678abc5678abc5678c
+branch refs/heads/locked-no-reason
+locked
+
+worktree /path/to/linked-worktree-locked-with-reason
+HEAD 3456def3456def3456def3456def3456def3456b
+branch refs/heads/locked-with-reason
+locked reason why is locked
+
+------------
+
+If the lock reason contains "unusual" characters such as newline, they
+are escaped and the entire reason is quoted as explained for the
+configuration variable `core.quotePath` (see linkgit:git-config[1]).
+For Example:
+
+------------
+$ git worktree list --porcelain
+...
+locked "reason\nwhy is locked"
+...
 ------------
 
 EXAMPLES

builtin/worktree.c

@@ -12,6 +12,7 @@
 #include "submodule.h"
 #include "utf8.h"
 #include "worktree.h"
+#include "quote.h"
 
 static const char * const worktree_usage[] = {
 	N_("git worktree add [<options>] <path> [<commit-ish>]"),
@@ -569,6 +570,8 @@ static int add(int ac, const char **av, const char *prefix)
 
 static void show_worktree_porcelain(struct worktree *wt)
 {
+	const char *reason;
+
 	printf("worktree %s\n", wt->path);
 	if (wt->is_bare)
 		printf("bare\n");
@@ -579,6 +582,16 @@ static void show_worktree_porcelain(struct worktree *wt)
 		else if (wt->head_ref)
 			printf("branch %s\n", wt->head_ref);
 	}
+
+	reason = worktree_lock_reason(wt);
+	if (reason && *reason) {
+		struct strbuf sb = STRBUF_INIT;
+		quote_c_style(reason, &sb, NULL, 0);
+		printf("locked %s\n", sb.buf);
+		strbuf_release(&sb);
+	} else if (reason)
+		printf("locked\n");
+
 	printf("\n");
 }
 

t/t2402-worktree-list.sh

@@ -72,6 +72,38 @@ test_expect_success '"list" all worktrees with locked annotation' '
 	! grep "/unlocked  *[0-9a-f].* locked$" out
 '
 
+test_expect_success '"list" all worktrees --porcelain with locked' '
+	test_when_finished "rm -rf locked1 locked2 unlocked out actual expect && git worktree prune" &&
+	echo "locked" >expect &&
+	echo "locked with reason" >>expect &&
+	git worktree add --detach locked1 &&
+	git worktree add --detach locked2 &&
+	# unlocked worktree should not be annotated with "locked"
+	git worktree add --detach unlocked &&
+	git worktree lock locked1 &&
+	test_when_finished "git worktree unlock locked1" &&
+	git worktree lock locked2 --reason "with reason" &&
+	test_when_finished "git worktree unlock locked2" &&
+	git worktree list --porcelain >out &&
+	grep "^locked" out >actual &&
+	test_cmp expect actual
+'
+
+test_expect_success '"list" all worktrees --porcelain with locked reason newline escaped' '
+	test_when_finished "rm -rf locked_lf locked_crlf out actual expect && git worktree prune" &&
+	printf "locked \"locked\\\\r\\\\nreason\"\n" >expect &&
+	printf "locked \"locked\\\\nreason\"\n" >>expect &&
+	git worktree add --detach locked_lf &&
+	git worktree add --detach locked_crlf &&
+	git worktree lock locked_lf --reason "$(printf "locked\nreason")" &&
+	test_when_finished "git worktree unlock locked_lf" &&
+	git worktree lock locked_crlf --reason "$(printf "locked\r\nreason")" &&
+	test_when_finished "git worktree unlock locked_crlf" &&
+	git worktree list --porcelain >out &&
+	grep "^locked" out >actual &&
+	test_cmp expect actual
+'
+
 test_expect_success 'bare repo setup' '
 	git init --bare bare1 &&
 	echo "data" >file1 &&