NAME
    Spawn::Safe - Fork and exec a process "safely".

EXAMPLE
    A basic example:

     use Spawn::Safe;
     use Data::Dumper;
     my $results = spawn_safe({ argv => [qw{ ls -al /var/ }], timeout => 2 });
     die Dumper $results

    As a replacement for backticks:

     use Spawn::Safe;
     # $output = `ls -al /var/`;
     $output = spawn_safe(qw{ ls -al /var/ })->{stdout};

SYNOPSIS
    Spawn::Safe is a module designed to make "safe" calls to outside
    binaries easier and more reliable. Spawn::Safe never invokes a shell
    (unless the shell is explicitly requested), so escaping for the shell is
    not a concern. An optional timeout is made available, so scripts will
    not hang forever, and the caller is able to retrieve both stdout and
    stderr.

FUNCTIONS
  spawn_safe
    Spawn the specified binary, capture its output, and put a cap on its
    runtime.

    If passed a single scalar, spawn_safe will assume that to be the the
    target binary, and execute it without a limit on runtime.

    If passed an array, spawn_safe will execute the first element of the
    array as the target binary, with the remaining elements passed as
    parameters to the target binary, without a limit on runtime.

    If passed a hash reference, the following keys will be used:

    *   argv

        A scalar containing the name of the binary, or an array reference
        containing the binary and all of its parameters, to be executed.

    *   timeout

        The amount of time, in seconds, the binary will be allowed to run
        before being killed and a timeout error being returned. If false (or
        is otherwise undefined or unset), the timeout will be infinite.

    *   env

        A hash reference containing the new environment for the executed
        binary. If false (or otherwise undefined or unset), it will default
        to the current environment. You must specify the complete
        environment, as the current environment will be overwritten as a
        whole. To alter only one variable, a copy of the enviornment must be
        made, altered, and then passed in as a whole, eg:

         my %new_env = %ENV;
         %new_env{'TMP'} = '/var/tmp/';
         my $r = spawn_safe( { argv => 'ls', env => \%new_env } );

        Please note that if a new environment is specified, the new binary's
        environment will be altered before the call to exec() (but after the
        fork(), so the caller's environment will be unchanged), so the new
        environment will take effect before the new binary is launched. This
        means that if you alter a part of the environment needed to launch
        the binary (eg, by changing PATH, LD_LIBRARY_PATH, etc), these new
        variables will need to be set such that the binary can be executed
        successfully.

    The current PATH will be searched for the binary, if available. Open
    filehandles are subject to Perl's standard close-on-exec behavior. A
    shell will not be invoked unless explicitly defined as the target
    binary, as such output redirection and other shell features are
    unavailable.

    A hash reference will be returned containing one of the following sets
    of values:

    *   If the binary could not be spawned, the single key, 'error' will be
        set, which is a text description of the reason the binary could not
        be spawned.

    *   If the binary was executed successfully, but terminated due to a
        timeout, the keys 'error', 'stdout', and 'stderr', will be set. The
        value for 'error' will be set to 'timed out'. Any data collected
        from the executed binary's stdout or stderr will also be made
        available, but since the binary was forcefully terminated, the data
        may be incomplete.

    *   If the binary was executed successfully and ran to completion, the
        keys 'exit_code, 'stdout, and 'stderr', will all be available.

    If passed invalid parameters, spawn_safe will croak.

    Please note that when specifying a timeout, alarm() will be used in
    order to implement the timeout. If the caller has an active SIGALRM
    handler, it will be overwritten during the call to spawn_safe and then
    restored afterwards. Any pending alarms should be cleared before calling
    spawn_safe regardless of whether or not the there is an active SIGALRM
    handler.

CHANGES
  Version 1.7 - 2010-07-09, jeagle
    Clean up for release to CPAN.

  Version 0.4 - 2009-05-13, jeagle
    Correct a warning issued when using spawn_safe without a timeout.

    Fix compatibility with perl < 5.8.

  Version 0.3 - 2009-04-21, jeagle
    Clarify documentation regarding use of SIGALRM and for passing of a new
    environment.

    Correct a warning thrown by exec().

    Correct an issue with incorrectly handled timeouts.

  Version 0.2 - 2009-04-20, jeagle
    Modify API, breaking compatibility, for clarity and expandability.

    Add the ability to specify the target program's environment.

    Return the (partial) stdout and stderr on a timeout.

    Update and clarify documentation.

  Version 0.1 - 2009-04-11, jeagle
    Inital release.

