Commit | Line | Data |
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a0d0e21e | 1 | package IPC::Open3; |
7e1af8bc | 2 | |
3 | use strict; | |
4 | no strict 'refs'; # because users pass me bareword filehandles | |
5 | use vars qw($VERSION @ISA @EXPORT $Fh $Me); | |
6 | ||
4633a7c4 | 7 | require 5.001; |
a0d0e21e | 8 | require Exporter; |
7e1af8bc | 9 | |
a0d0e21e | 10 | use Carp; |
7e1af8bc | 11 | use Symbol 'qualify'; |
12 | ||
13 | $VERSION = 1.01; | |
14 | @ISA = qw(Exporter); | |
15 | @EXPORT = qw(open3); | |
a0d0e21e | 16 | |
f06db76b AD |
17 | =head1 NAME |
18 | ||
19 | IPC::Open3, open3 - open a process for reading, writing, and error handling | |
20 | ||
21 | =head1 SYNOPSIS | |
22 | ||
7e1af8bc | 23 | $pid = open3(\*WTRFH, \*RDRFH, \*ERRFH |
f06db76b AD |
24 | 'some cmd and args', 'optarg', ...); |
25 | ||
26 | =head1 DESCRIPTION | |
27 | ||
28 | Extremely similar to open2(), open3() spawns the given $cmd and | |
29 | connects RDRFH for reading, WTRFH for writing, and ERRFH for errors. If | |
30 | ERRFH is '', or the same as RDRFH, then STDOUT and STDERR of the child are | |
31 | on the same file handle. | |
32 | ||
1fef88e7 | 33 | If WTRFH begins with "E<lt>&", then WTRFH will be closed in the parent, and |
4633a7c4 | 34 | the child will read from it directly. If RDRFH or ERRFH begins with |
1fef88e7 | 35 | "E<gt>&", then the child will send output directly to that file handle. In both |
f06db76b AD |
36 | cases, there will be a dup(2) instead of a pipe(2) made. |
37 | ||
cb1a09d0 AD |
38 | If you try to read from the child's stdout writer and their stderr |
39 | writer, you'll have problems with blocking, which means you'll | |
40 | want to use select(), which means you'll have to use sysread() instead | |
41 | of normal stuff. | |
42 | ||
7e1af8bc | 43 | open3() returns the process ID of the child process. It doesn't return on |
44 | failure: it just raises an exception matching C</^open3:/>. | |
f06db76b | 45 | |
7e1af8bc | 46 | =head1 WARNING |
47 | ||
48 | It will not create these file handles for you. You have to do this | |
49 | yourself. So don't pass it empty variables expecting them to get filled | |
50 | in for you. | |
f06db76b | 51 | |
7e1af8bc | 52 | Additionally, this is very dangerous as you may block forever. It |
53 | assumes it's going to talk to something like B<bc>, both writing to it | |
54 | and reading from it. This is presumably safe because you "know" that | |
55 | commands like B<bc> will read a line at a time and output a line at a | |
56 | time. Programs like B<sort> that read their entire input stream first, | |
57 | however, are quite apt to cause deadlock. | |
58 | ||
59 | The big problem with this approach is that if you don't have control | |
60 | over source code being run in the the child process, you can't control | |
61 | what it does with pipe buffering. Thus you can't just open a pipe to | |
62 | C<cat -v> and continually read and write a line from it. | |
63 | ||
64 | =cut | |
a0d0e21e LW |
65 | |
66 | # &open3: Marc Horowitz <marc@mit.edu> | |
67 | # derived mostly from &open2 by tom christiansen, <tchrist@convex.com> | |
4633a7c4 | 68 | # fixed for 5.001 by Ulrich Kunitz <kunitz@mai-koeln.com> |
a0d0e21e LW |
69 | # |
70 | # $Id: open3.pl,v 1.1 1993/11/23 06:26:15 marc Exp $ | |
71 | # | |
72 | # usage: $pid = open3('wtr', 'rdr', 'err' 'some cmd and args', 'optarg', ...); | |
73 | # | |
74 | # spawn the given $cmd and connect rdr for | |
75 | # reading, wtr for writing, and err for errors. | |
76 | # if err is '', or the same as rdr, then stdout and | |
77 | # stderr of the child are on the same fh. returns pid | |
7e1af8bc | 78 | # of child (or dies on failure). |
a0d0e21e LW |
79 | |
80 | ||
4633a7c4 | 81 | # if wtr begins with '<&', then wtr will be closed in the parent, and |
a0d0e21e LW |
82 | # the child will read from it directly. if rdr or err begins with |
83 | # '>&', then the child will send output directly to that fd. In both | |
84 | # cases, there will be a dup() instead of a pipe() made. | |
85 | ||
86 | ||
87 | # WARNING: this is dangerous, as you may block forever | |
88 | # unless you are very careful. | |
89 | # | |
90 | # $wtr is left unbuffered. | |
91 | # | |
92 | # abort program if | |
93 | # rdr or wtr are null | |
7e1af8bc | 94 | # a system call fails |
a0d0e21e | 95 | |
7e1af8bc | 96 | $Fh = 'FHOPEN000'; # package static in case called more than once |
97 | $Me = 'open3 (bug)'; # you should never see this, it's always localized | |
a0d0e21e | 98 | |
7e1af8bc | 99 | # Fatal.pm needs to be fixed WRT prototypes. |
100 | ||
101 | sub xfork { | |
102 | my $pid = fork; | |
103 | defined $pid or croak "$Me: fork failed: $!"; | |
104 | return $pid; | |
105 | } | |
106 | ||
107 | sub xpipe { | |
108 | pipe $_[0], $_[1] or croak "$Me: pipe($_[0], $_[1]) failed: $!"; | |
109 | } | |
110 | ||
111 | # I tried using a * prototype character for the filehandle but it still | |
112 | # disallows a bearword while compiling under strict subs. | |
a0d0e21e | 113 | |
7e1af8bc | 114 | sub xopen { |
115 | open $_[0], $_[1] or croak "$Me: open($_[0], $_[1]) failed: $!"; | |
116 | } | |
117 | ||
118 | sub xclose { | |
119 | close $_[0] or croak "$Me: close($_[0]) failed: $!"; | |
120 | } | |
121 | ||
122 | sub _open3 { | |
123 | local $Me = shift; | |
124 | my($package, $dad_wtr, $dad_rdr, $dad_err, @cmd) = @_; | |
125 | my($dup_wtr, $dup_rdr, $dup_err, $kidpid); | |
126 | ||
127 | $dad_wtr or croak "$Me: wtr should not be null"; | |
128 | $dad_rdr or croak "$Me: rdr should not be null"; | |
a0d0e21e LW |
129 | $dad_err = $dad_rdr if ($dad_err eq ''); |
130 | ||
4633a7c4 LW |
131 | $dup_wtr = ($dad_wtr =~ s/^[<>]&//); |
132 | $dup_rdr = ($dad_rdr =~ s/^[<>]&//); | |
133 | $dup_err = ($dad_err =~ s/^[<>]&//); | |
a0d0e21e LW |
134 | |
135 | # force unqualified filehandles into callers' package | |
7e1af8bc | 136 | $dad_wtr = qualify $dad_wtr, $package; |
137 | $dad_rdr = qualify $dad_rdr, $package; | |
138 | $dad_err = qualify $dad_err, $package; | |
139 | ||
140 | my $kid_rdr = ++$Fh; | |
141 | my $kid_wtr = ++$Fh; | |
142 | my $kid_err = ++$Fh; | |
143 | ||
144 | xpipe $kid_rdr, $dad_wtr if !$dup_wtr; | |
145 | xpipe $dad_rdr, $kid_wtr if !$dup_rdr; | |
146 | xpipe $dad_err, $kid_err if !$dup_err && $dad_err ne $dad_rdr; | |
147 | ||
148 | $kidpid = xfork; | |
149 | if ($kidpid == 0) { | |
150 | # If she wants to dup the kid's stderr onto her stdout I need to | |
151 | # save a copy of her stdout before I put something else there. | |
152 | if ($dad_rdr ne $dad_err && $dup_err | |
153 | && fileno($dad_err) == fileno(STDOUT)) { | |
154 | my $tmp = ++$Fh; | |
155 | xopen($tmp, ">&$dad_err"); | |
156 | $dad_err = $tmp; | |
157 | } | |
a0d0e21e | 158 | |
a0d0e21e | 159 | if ($dup_wtr) { |
8ebc5c01 | 160 | xopen \*STDIN, "<&$dad_wtr" if fileno(STDIN) != fileno($dad_wtr); |
a0d0e21e | 161 | } else { |
8ebc5c01 | 162 | xclose $dad_wtr; |
163 | xopen \*STDIN, "<&$kid_rdr"; | |
164 | xclose $kid_rdr; | |
a0d0e21e LW |
165 | } |
166 | if ($dup_rdr) { | |
8ebc5c01 | 167 | xopen \*STDOUT, ">&$dad_rdr" if fileno(STDOUT) != fileno($dad_rdr); |
a0d0e21e | 168 | } else { |
8ebc5c01 | 169 | xclose $dad_rdr; |
170 | xopen \*STDOUT, ">&$kid_wtr"; | |
171 | xclose $kid_wtr; | |
a0d0e21e LW |
172 | } |
173 | if ($dad_rdr ne $dad_err) { | |
174 | if ($dup_err) { | |
8ebc5c01 | 175 | xopen \*STDERR, ">&$dad_err" |
176 | if fileno(STDERR) != fileno($dad_err); | |
a0d0e21e | 177 | } else { |
8ebc5c01 | 178 | xclose $dad_err; |
179 | xopen \*STDERR, ">&$kid_err"; | |
180 | xclose $kid_err; | |
a0d0e21e LW |
181 | } |
182 | } else { | |
8ebc5c01 | 183 | xopen \*STDERR, ">&STDOUT" if fileno(STDERR) != fileno(STDOUT); |
a0d0e21e LW |
184 | } |
185 | local($")=(" "); | |
c07a80fd | 186 | exec @cmd |
187 | or croak "open3: exec of @cmd failed"; | |
a0d0e21e LW |
188 | } |
189 | ||
7e1af8bc | 190 | xclose $kid_rdr if !$dup_wtr; |
191 | xclose $kid_wtr if !$dup_rdr; | |
192 | xclose $kid_err if !$dup_err && $dad_rdr ne $dad_err; | |
193 | # If the write handle is a dup give it away entirely, close my copy | |
194 | # of it. | |
195 | xclose $dad_wtr if $dup_wtr; | |
a0d0e21e LW |
196 | |
197 | select((select($dad_wtr), $| = 1)[0]); # unbuffer pipe | |
198 | $kidpid; | |
199 | } | |
7e1af8bc | 200 | |
201 | sub open3 { | |
202 | return _open3 'open3', scalar caller, @_ | |
203 | } | |
a0d0e21e LW |
204 | 1; # so require is happy |
205 |