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Diffstat (limited to 'contrib/perl5/lib/IPC/Open2.pm')
| -rw-r--r-- | contrib/perl5/lib/IPC/Open2.pm | 118 |
1 files changed, 0 insertions, 118 deletions
diff --git a/contrib/perl5/lib/IPC/Open2.pm b/contrib/perl5/lib/IPC/Open2.pm deleted file mode 100644 index a5a3561..0000000 --- a/contrib/perl5/lib/IPC/Open2.pm +++ /dev/null @@ -1,118 +0,0 @@ -package IPC::Open2; - -use strict; -our ($VERSION, @ISA, @EXPORT); - -require 5.000; -require Exporter; - -$VERSION = 1.01; -@ISA = qw(Exporter); -@EXPORT = qw(open2); - -=head1 NAME - -IPC::Open2, open2 - open a process for both reading and writing - -=head1 SYNOPSIS - - use IPC::Open2; - - $pid = open2(\*RDRFH, \*WTRFH, 'some cmd and args'); - # or without using the shell - $pid = open2(\*RDRFH, \*WTRFH, 'some', 'cmd', 'and', 'args'); - - # or with handle autovivification - my($rdrfh, $wtrfh); - $pid = open2($rdrfh, $wtrfh, 'some cmd and args'); - # or without using the shell - $pid = open2($rdrfh, $wtrfh, 'some', 'cmd', 'and', 'args'); - -=head1 DESCRIPTION - -The open2() function runs the given $cmd and connects $rdrfh for -reading and $wtrfh for writing. It's what you think should work -when you try - - $pid = open(HANDLE, "|cmd args|"); - -The write filehandle will have autoflush turned on. - -If $rdrfh is a string (that is, a bareword filehandle rather than a glob -or a reference) and it begins with C<< >& >>, then the child will send output -directly to that file handle. If $wtrfh is a string that begins with -C<< <& >>, then $wtrfh will be closed in the parent, and the child will read -from it directly. In both cases, there will be a dup(2) instead of a -pipe(2) made. - -If either reader or writer is the null string, this will be replaced -by an autogenerated filehandle. If so, you must pass a valid lvalue -in the parameter slot so it can be overwritten in the caller, or -an exception will be raised. - -open2() returns the process ID of the child process. It doesn't return on -failure: it just raises an exception matching C</^open2:/>. However, -C<exec> failures in the child are not detected. You'll have to -trap SIGPIPE yourself. - -open2() does not wait for and reap the child process after it exits. -Except for short programs where it's acceptable to let the operating system -take care of this, you need to do this yourself. This is normally as -simple as calling C<waitpid $pid, 0> when you're done with the process. -Failing to do this can result in an accumulation of defunct or "zombie" -processes. See L<perlfunc/waitpid> for more information. - -This whole affair is quite dangerous, as you may block forever. It -assumes it's going to talk to something like B<bc>, both writing -to it and reading from it. This is presumably safe because you -"know" that commands like B<bc> will read a line at a time and -output a line at a time. Programs like B<sort> that read their -entire input stream first, however, are quite apt to cause deadlock. - -The big problem with this approach is that if you don't have control -over source code being run in the child process, you can't control -what it does with pipe buffering. Thus you can't just open a pipe to -C<cat -v> and continually read and write a line from it. - -The IO::Pty and Expect modules from CPAN can help with this, as they -provide a real tty (well, a pseudo-tty, actually), which gets you -back to line buffering in the invoked command again. - -=head1 WARNING - -The order of arguments differs from that of open3(). - -=head1 SEE ALSO - -See L<IPC::Open3> for an alternative that handles STDERR as well. This -function is really just a wrapper around open3(). - -=cut - -# &open2: tom christiansen, <tchrist@convex.com> -# -# usage: $pid = open2('rdr', 'wtr', 'some cmd and args'); -# or $pid = open2('rdr', 'wtr', 'some', 'cmd', 'and', 'args'); -# -# spawn the given $cmd and connect $rdr for -# reading and $wtr for writing. return pid -# of child, or 0 on failure. -# -# WARNING: this is dangerous, as you may block forever -# unless you are very careful. -# -# $wtr is left unbuffered. -# -# abort program if -# rdr or wtr are null -# a system call fails - -require IPC::Open3; - -sub open2 { - local $Carp::CarpLevel = $Carp::CarpLevel + 1; - return IPC::Open3::_open3('open2', scalar caller, - $_[1], $_[0], '>&STDERR', @_[2 .. $#_]); -} - -1 |
