捕捉:小的与梅森不相容？

Question

作为一般策略，我避免使用后排，而是依赖于捕捉:微小和系统调用。

my ( $stdout, $stderr, @results ) = capture { system($command) };

然而，当我在Capture::Tiny下使用之前从未见过的异常时，我只是遇到了HTML::Mason内部的一个异常。

 Error from open(GLOB(0x555ef4527090), >&-1): Invalid argument at /usr/share/perl5/vendor_perl/Capture/Tiny.pm line 107.
    Capture::Tiny::_open(GLOB(0x555ef4527090), ">\\x{26}-1") called at /usr/share/perl5/vendor_perl/Capture/Tiny.pm line 194
    Capture::Tiny::_open_std(HASH(0x555ec25b12b8)) called at /usr/share/perl5/vendor_perl/Capture/Tiny.pm line 391
    Capture::Tiny::_capture_tee(1, 1, 0, 0, CODE(0x555f05d5ce70)) called at InternalModule.pm line 41
    ...
    InternalModule.pm called at /.../apache/htdocs/autohandler line 84
    HTML::Mason::Commands::__ANON__() called at /usr/share/perl5/vendor_perl/HTML/Mason/Component.pm line 135

这是一个遗留系统，所以模块版本有点旧。

• HTML::Mason 1.56
• 捕获:微小的0.44

在Capture::Tiny中执行一些内部操作显示，此方法正在引发异常

sub _open {
  open $_[0], $_[1] or Carp::confess "Error from open(" . join(q{, }, @_) . "): $!";   # Line 107
  # _debug( "# open " . join( ", " , map { defined $_ ? _name($_) : 'undef' } @_ ) . " as " . fileno( $_[0] ) . "\n" );
}

具体来说，调用_open并导致异常的是STDOUT的开放：

# In some cases we open all (prior to forking) and in others we only open
# the output handles (setting up redirection)
sub _open_std {
  my ($handles) = @_;
  _open \*STDIN, "<&" . fileno $handles->{stdin} if defined $handles->{stdin};
  _open \*STDOUT, ">&" . fileno $handles->{stdout} if defined $handles->{stdout};   # Line 194
  _open \*STDERR, ">&" . fileno $handles->{stderr} if defined $handles->{stderr};
}

我尝试过本地化*STDOUT，尽管看起来Capture::Tiny已经这样做了。

现在我的结论是，我应该用这样的解决方案

system("program args 1>program.stdout 2>program.stderr");

关于Capture::Tiny，我还缺少什么东西让它在Mason下工作吗？

Answer 1

在后台使用Capture::Tiny和system调用有几个好处

• 可以更详细地检查和报告错误情况。
• stdout和stderr的单独信息
• 没有任何东西被保存到磁盘上(因此，将敏感信息暂时保存在文件系统上)

但是，在本例中，我决定编写备份方法，以防Capture::Tiny在任何特定环境中不可用。如果不是，那么我们将只输出这些流来临时文件，并摄入它们的后缀。

# Capture::Tiny has an incompatibility with Mason.  Therefore we simply need to
# detect if it's safe to use, and if not we should do another mechanism for
# capturing the results.
state $is_safe_to_use_capture_tiny = eval {
    capture sub { };
    1;
};

my ( $stdout, $stderr, @result );

if ($is_safe_to_use_capture_tiny) {
    ( $stdout, $stderr, @result ) = capture { system($command) };

} else {
    # Backup equivalent to Capture::Tiny
    #     There is some risk to this approach, because we are choosing to cache
    # the stdout and stderr results to a file temporarily.  If these results
    # of the system call include sensitive information, then it would exist on
    # disk momentarily.
    #     However, given this is just a backup method that is only needed in
    # the case of system calls under Mason which is front end servers that do not
    # have access to sensitive information, it's an okay sacrifice.

    my $stdout_file = tempfile();
    my $stderr_file = tempfile();

    @result = system(qq{$command 1>$stdout_file 2>$stderr_file});
    $stdout = $stdout_file->exists ? $stdout_file->slurp : '';
    $stderr = $stderr_file->exists ? $stderr_file->slurp : '';
}