bug: path-based truncate() bypasses write permission check

[toddr-bot]

Description

When truncate('/path/to/file', $length) is called on a mocked read-only file with set_user() active, it succeeds instead of failing with EACCES.

The filehandle form (truncate($fh, $length)) correctly checks write permission (returns EINVAL if the handle isn't open for writing), but the path form skips permission checks entirely.

Expected behavior

Per POSIX truncate(2): "The calling process must have write permission for the file." Path-based truncate on a file without write permission should fail and set $! to EACCES.

Steps to reproduce

use Test::MockFile qw< nostrict >;
use Errno qw(EACCES);

my $mock = Test::MockFile->file('/tmp/readonly', 'data', { mode => 0444, uid => 99, gid => 99 });
Test::MockFile->set_user(1000, 1000);

# BUG: this succeeds when it should fail with EACCES
truncate('/tmp/readonly', 0);

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🤖 Created by Kōan from autonomous session