[PATCH v3] git-contacts: allow inputting patch via stdin

[Brigham Campbell <me@brighamcampbell.com>]

Make git-contacts accept patch contents via stdin for better
interoperability with other utilities. Read from stdin when the user
passes `-` at least once:

$ git contacts - <patch
$ git contacts patch1 - patch3 <patch2

Signed-off-by: Brigham Campbell <me@brighamcampbell.com>
---
This patch is motivated by an ongoing personal effort to allow b4 to
invoke git-contacts automatically.

This latest revision requires the user to pass '-' instead of implicitly
reading from stdin when stdin is not a tty and argv is empty. This
simplifies the change slightly and allows for input via files,
revisions, and stdin in a single invocation of git-contacts.
---
Changes in v3:
- Make user pass '-' instead of an empty argv and non-TTY stdin
- Link to v2: https://patch.msgid.link/20260915-git-contacts-stdin-v2-1-2005061d907a@brighamcampbell.com

Changes in v2:
- Minor variable cleanup / un-spaghettification
- Include update to usage comment
- Remove Cc trailers from commit message
- Link to v1: https://patch.msgid.link/20260914-git-contacts-stdin-v1-1-9ac628e6fd20@brighamcampbell.com
---
 contrib/contacts/git-contacts | 9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)

diff --git a/contrib/contacts/git-contacts b/contrib/contacts/git-contacts
index 85ad732fc0..74910496f4 100755
--- a/contrib/contacts/git-contacts
+++ b/contrib/contacts/git-contacts
@@ -162,9 +162,11 @@ if (!@ARGV) {
 	die "No input revisions or patch files\n";
 }
 
-my (@files, @rev_args);
+my (@files, @rev_args, $read_from_stdin);
 for (@ARGV) {
-	if (-e) {
+	if ($_ eq '-') {
+		$read_from_stdin = 1;
+	} elsif (-e) {
 		push @files, $_;
 	} else {
 		push @rev_args, $_;
@@ -178,6 +180,9 @@ for (@files) {
 if (@rev_args) {
 	scan_rev_args(\%sources, \@rev_args)
 }
+if ($read_from_stdin) {
+	scan_patches(\%sources, undef, \*STDIN);
+}
 
 my $toplevel = `git rev-parse --show-toplevel`;
 chomp $toplevel;

---
base-commit: f0ef1b96a076d08dc972a8d2cb0d1cfd60931eb6
change-id: 20260914-git-contacts-stdin-1e829930e19b

Thanks!
-- 
Brigham Campbell
https://brighamcampbell.com