From 96eac913ce32af23709e34ca224e4044fba34c93 Mon Sep 17 00:00:00 2001
From: Toddr Bot <toddbot@rinaldo.us>
Date: Tue, 21 Jul 2026 15:23:18 +0000
Subject: [PATCH] fix: add O_NONBLOCK, O_NOCTTY, O_CLOEXEC to
 SUPPORTED_SYSOPEN_MODES

sysopen() with O_NONBLOCK fatally croaked because the flag was absent
from the SUPPORTED_SYSOPEN_MODES whitelist. These flags are harmless
for in-memory mocked files (accept and ignore). O_CLOEXEC is guarded
with eval since it is not available on all platforms.

Closes #412

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
---
 lib/Test/MockFile.pm |  2 +-
 t/sysopen.t          | 40 ++++++++++++++++++++++++++++++++++++++++
 2 files changed, 41 insertions(+), 1 deletion(-)

diff --git a/lib/Test/MockFile.pm b/lib/Test/MockFile.pm
index 6c5d4cf..3b69df0 100644
--- a/lib/Test/MockFile.pm
+++ b/lib/Test/MockFile.pm
@@ -14,7 +14,7 @@ use warnings;
 # perl -MFcntl -E'eval "say q{$_: } . $_" foreach sort {eval "$a" <=> eval "$b"} qw/O_RDONLY O_WRONLY O_RDWR O_CREAT O_EXCL O_NOCTTY O_TRUNC O_APPEND O_NONBLOCK O_NDELAY O_EXLOCK O_SHLOCK O_DIRECTORY O_NOFOLLOW O_SYNC O_BINARY O_LARGEFILE/'
 use Fcntl;    # O_RDONLY, etc.
 
-use constant SUPPORTED_SYSOPEN_MODES => O_RDONLY | O_WRONLY | O_RDWR | O_APPEND | O_TRUNC | O_EXCL | O_CREAT | O_NOFOLLOW;
+use constant SUPPORTED_SYSOPEN_MODES => O_RDONLY | O_WRONLY | O_RDWR | O_APPEND | O_TRUNC | O_EXCL | O_CREAT | O_NOFOLLOW | O_NONBLOCK | O_NOCTTY | ( eval { O_CLOEXEC() } // 0 );
 
 use constant BROKEN_SYMLINK   => bless {}, "A::BROKEN::SYMLINK";
 use constant CIRCULAR_SYMLINK => bless {}, "A::CIRCULAR::SYMLINK";
diff --git a/t/sysopen.t b/t/sysopen.t
index ee18228..ff0e61d 100644
--- a/t/sysopen.t
+++ b/t/sysopen.t
@@ -303,5 +303,45 @@ note "sysopen failure returns undef in list context (single-element list)";
     ok( !defined $ret[0],        'sysopen failure element is undef (not "undef" string)' );
 }
 
+note "sysopen with O_NONBLOCK succeeds (flag accepted and ignored)";
+{
+    my $mock = Test::MockFile->file('/nonblock_test');
+    is( sysopen( my $fh, '/nonblock_test', O_WRONLY | O_CREAT | O_NONBLOCK, 0600 ), 1,
+        'sysopen O_WRONLY|O_CREAT|O_NONBLOCK succeeds' );
+    ok( -e '/nonblock_test', 'file created with O_NONBLOCK' );
+    is( syswrite( $fh, "hello" ), 5, 'write to O_NONBLOCK-opened file works' );
+    close $fh;
+    is( $mock->contents, "hello", 'contents correct after O_NONBLOCK open' );
+}
+
+note "sysopen with O_NOCTTY succeeds (flag accepted and ignored)";
+{
+    my $mock = Test::MockFile->file('/noctty_test');
+    is( sysopen( my $fh, '/noctty_test', O_WRONLY | O_CREAT | O_NOCTTY, 0600 ), 1,
+        'sysopen O_WRONLY|O_CREAT|O_NOCTTY succeeds' );
+    ok( -e '/noctty_test', 'file created with O_NOCTTY' );
+    close $fh;
+}
+
+note "sysopen with O_NONBLOCK|O_EXCL combined (issue #412 reproduction)";
+{
+    my $mock = Test::MockFile->file('/nonblock_excl_test');
+    is( sysopen( my $fh, '/nonblock_excl_test', O_WRONLY | O_CREAT | O_EXCL | O_NONBLOCK, 0600 ), 1,
+        'sysopen O_WRONLY|O_CREAT|O_EXCL|O_NONBLOCK succeeds' );
+    ok( -e '/nonblock_excl_test', 'file created with O_NONBLOCK|O_EXCL' );
+    close $fh;
+}
+
+SKIP: {
+    skip "O_CLOEXEC not available on this system", 2 unless eval { O_CLOEXEC(); 1 };
+
+    note "sysopen with O_CLOEXEC succeeds (flag accepted and ignored)";
+    my $mock = Test::MockFile->file('/cloexec_test');
+    is( sysopen( my $fh, '/cloexec_test', O_WRONLY | O_CREAT | O_CLOEXEC(), 0600 ), 1,
+        'sysopen O_WRONLY|O_CREAT|O_CLOEXEC succeeds' );
+    ok( -e '/cloexec_test', 'file created with O_CLOEXEC' );
+    close $fh;
+}
+
 done_testing();
 exit;