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1 | package IPC::Open3; |
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2 | |
3 | use strict; |
4 | no strict 'refs'; # because users pass me bareword filehandles |
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5 | use vars qw($VERSION @ISA @EXPORT $Me); |
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6 | |
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7 | require 5.001; |
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8 | require Exporter; |
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9 | |
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10 | use Carp; |
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11 | use Symbol qw(gensym qualify); |
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12 | |
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13 | $VERSION = 1.0103; |
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14 | @ISA = qw(Exporter); |
15 | @EXPORT = qw(open3); |
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16 | |
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17 | =head1 NAME |
18 | |
19 | IPC::Open3, open3 - open a process for reading, writing, and error handling |
20 | |
21 | =head1 SYNOPSIS |
22 | |
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23 | $pid = open3(\*WTRFH, \*RDRFH, \*ERRFH, |
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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 |
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31 | on the same file handle. The WTRFH will have autoflush turned on. |
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32 | |
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33 | If WTRFH begins with "E<lt>&", then WTRFH will be closed in the parent, and |
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34 | the child will read from it directly. If RDRFH or ERRFH begins with |
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35 | "E<gt>&", then the child will send output directly to that file handle. |
36 | In both cases, there will be a dup(2) instead of a pipe(2) made. |
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37 | |
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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 | |
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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:/>. |
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45 | |
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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. |
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51 | |
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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 |
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60 | over source code being run in the child process, you can't control |
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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 |
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65 | |
66 | # &open3: Marc Horowitz <marc@mit.edu> |
67 | # derived mostly from &open2 by tom christiansen, <tchrist@convex.com> |
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68 | # fixed for 5.001 by Ulrich Kunitz <kunitz@mai-koeln.com> |
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69 | # ported to Win32 by Ron Schmidt, Merrill Lynch almost ended my career |
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70 | # |
71 | # $Id: open3.pl,v 1.1 1993/11/23 06:26:15 marc Exp $ |
72 | # |
73 | # usage: $pid = open3('wtr', 'rdr', 'err' 'some cmd and args', 'optarg', ...); |
74 | # |
75 | # spawn the given $cmd and connect rdr for |
76 | # reading, wtr for writing, and err for errors. |
77 | # if err is '', or the same as rdr, then stdout and |
78 | # stderr of the child are on the same fh. returns pid |
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79 | # of child (or dies on failure). |
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80 | |
81 | |
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82 | # if wtr begins with '<&', then wtr will be closed in the parent, and |
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83 | # the child will read from it directly. if rdr or err begins with |
84 | # '>&', then the child will send output directly to that fd. In both |
85 | # cases, there will be a dup() instead of a pipe() made. |
86 | |
87 | |
88 | # WARNING: this is dangerous, as you may block forever |
89 | # unless you are very careful. |
90 | # |
91 | # $wtr is left unbuffered. |
92 | # |
93 | # abort program if |
94 | # rdr or wtr are null |
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95 | # a system call fails |
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96 | |
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97 | $Me = 'open3 (bug)'; # you should never see this, it's always localized |
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98 | |
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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. |
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113 | |
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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 | |
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122 | my $do_spawn = $^O eq 'os2' || $^O eq 'MSWin32'; |
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123 | |
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124 | sub _open3 { |
125 | local $Me = shift; |
126 | my($package, $dad_wtr, $dad_rdr, $dad_err, @cmd) = @_; |
127 | my($dup_wtr, $dup_rdr, $dup_err, $kidpid); |
128 | |
129 | $dad_wtr or croak "$Me: wtr should not be null"; |
130 | $dad_rdr or croak "$Me: rdr should not be null"; |
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131 | $dad_err = $dad_rdr if ($dad_err eq ''); |
132 | |
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133 | $dup_wtr = ($dad_wtr =~ s/^[<>]&//); |
134 | $dup_rdr = ($dad_rdr =~ s/^[<>]&//); |
135 | $dup_err = ($dad_err =~ s/^[<>]&//); |
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136 | |
137 | # force unqualified filehandles into callers' package |
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138 | $dad_wtr = qualify $dad_wtr, $package; |
139 | $dad_rdr = qualify $dad_rdr, $package; |
140 | $dad_err = qualify $dad_err, $package; |
141 | |
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142 | my $kid_rdr = gensym; |
143 | my $kid_wtr = gensym; |
144 | my $kid_err = gensym; |
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145 | |
146 | xpipe $kid_rdr, $dad_wtr if !$dup_wtr; |
147 | xpipe $dad_rdr, $kid_wtr if !$dup_rdr; |
148 | xpipe $dad_err, $kid_err if !$dup_err && $dad_err ne $dad_rdr; |
149 | |
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150 | $kidpid = $do_spawn ? -1 : xfork; |
151 | if ($kidpid == 0) { # Kid |
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152 | # If she wants to dup the kid's stderr onto her stdout I need to |
153 | # save a copy of her stdout before I put something else there. |
154 | if ($dad_rdr ne $dad_err && $dup_err |
155 | && fileno($dad_err) == fileno(STDOUT)) { |
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156 | my $tmp = gensym; |
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157 | xopen($tmp, ">&$dad_err"); |
158 | $dad_err = $tmp; |
159 | } |
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160 | |
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161 | if ($dup_wtr) { |
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162 | xopen \*STDIN, "<&$dad_wtr" if fileno(STDIN) != fileno($dad_wtr); |
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163 | } else { |
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164 | xclose $dad_wtr; |
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165 | xopen \*STDIN, "<&=" . fileno $kid_rdr; |
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166 | } |
167 | if ($dup_rdr) { |
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168 | xopen \*STDOUT, ">&$dad_rdr" if fileno(STDOUT) != fileno($dad_rdr); |
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169 | } else { |
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170 | xclose $dad_rdr; |
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171 | xopen \*STDOUT, ">&=" . fileno $kid_wtr; |
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172 | } |
173 | if ($dad_rdr ne $dad_err) { |
174 | if ($dup_err) { |
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175 | # I have to use a fileno here because in this one case |
176 | # I'm doing a dup but the filehandle might be a reference |
177 | # (from the special case above). |
178 | xopen \*STDERR, ">&" . fileno $dad_err |
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179 | if fileno(STDERR) != fileno($dad_err); |
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180 | } else { |
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181 | xclose $dad_err; |
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182 | xopen \*STDERR, ">&=" . fileno $kid_err; |
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183 | } |
184 | } else { |
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185 | xopen \*STDERR, ">&STDOUT" if fileno(STDERR) != fileno(STDOUT); |
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186 | } |
187 | local($")=(" "); |
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188 | exec @cmd |
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189 | or croak "$Me: exec of @cmd failed"; |
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190 | } elsif ($do_spawn) { |
191 | # All the bookkeeping of coincidence between handles is |
192 | # handled in spawn_with_handles. |
193 | |
194 | my @close; |
195 | if ($dup_wtr) { |
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196 | $kid_rdr = \*{$dad_wtr}; |
197 | push @close, $kid_rdr; |
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198 | } else { |
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199 | push @close, \*{$dad_wtr}, $kid_rdr; |
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200 | } |
201 | if ($dup_rdr) { |
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202 | $kid_wtr = \*{$dad_rdr}; |
203 | push @close, $kid_wtr; |
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204 | } else { |
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205 | push @close, \*{$dad_rdr}, $kid_wtr; |
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206 | } |
207 | if ($dad_rdr ne $dad_err) { |
208 | if ($dup_err) { |
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209 | $kid_err = \*{$dad_err}; |
210 | push @close, $kid_err; |
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211 | } else { |
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212 | push @close, \*{$dad_err}, $kid_err; |
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213 | } |
214 | } else { |
215 | $kid_err = $kid_wtr; |
216 | } |
217 | require IO::Pipe; |
218 | $kidpid = eval { |
219 | spawn_with_handles( [ { mode => 'r', |
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220 | open_as => $kid_rdr, |
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221 | handle => \*STDIN }, |
222 | { mode => 'w', |
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223 | open_as => $kid_wtr, |
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224 | handle => \*STDOUT }, |
225 | { mode => 'w', |
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226 | open_as => $kid_err, |
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227 | handle => \*STDERR }, |
228 | ], \@close, @cmd); |
229 | }; |
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230 | die "$Me: $@" if $@; |
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231 | } |
232 | |
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233 | xclose $kid_rdr if !$dup_wtr; |
234 | xclose $kid_wtr if !$dup_rdr; |
235 | xclose $kid_err if !$dup_err && $dad_rdr ne $dad_err; |
236 | # If the write handle is a dup give it away entirely, close my copy |
237 | # of it. |
238 | xclose $dad_wtr if $dup_wtr; |
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239 | |
240 | select((select($dad_wtr), $| = 1)[0]); # unbuffer pipe |
241 | $kidpid; |
242 | } |
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243 | |
244 | sub open3 { |
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245 | if (@_ < 4) { |
246 | local $" = ', '; |
247 | croak "open3(@_): not enough arguments"; |
248 | } |
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249 | return _open3 'open3', scalar caller, @_ |
250 | } |
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251 | |
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252 | sub spawn_with_handles { |
253 | my $fds = shift; # Fields: handle, mode, open_as |
254 | my $close_in_child = shift; |
255 | my ($fd, $pid, @saved_fh, $saved, %saved, @errs); |
256 | require Fcntl; |
257 | |
258 | foreach $fd (@$fds) { |
259 | $fd->{tmp_copy} = IO::Handle->new_from_fd($fd->{handle}, $fd->{mode}); |
260 | $saved{fileno $fd->{handle}} = $fd->{tmp_copy}; |
261 | } |
262 | foreach $fd (@$fds) { |
263 | bless $fd->{handle}, 'IO::Handle' |
264 | unless eval { $fd->{handle}->isa('IO::Handle') } ; |
265 | # If some of handles to redirect-to coincide with handles to |
266 | # redirect, we need to use saved variants: |
267 | $fd->{handle}->fdopen($saved{fileno $fd->{open_as}} || $fd->{open_as}, |
268 | $fd->{mode}); |
269 | } |
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270 | unless ($^O eq 'MSWin32') { |
271 | # Stderr may be redirected below, so we save the err text: |
272 | foreach $fd (@$close_in_child) { |
273 | fcntl($fd, Fcntl::F_SETFD(), 1) or push @errs, "fcntl $fd: $!" |
274 | unless $saved{fileno $fd}; # Do not close what we redirect! |
275 | } |
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276 | } |
277 | |
278 | unless (@errs) { |
279 | $pid = eval { system 1, @_ }; # 1 == P_NOWAIT |
280 | push @errs, "IO::Pipe: Can't spawn-NOWAIT: $!" if !$pid || $pid < 0; |
281 | } |
282 | |
283 | foreach $fd (@$fds) { |
284 | $fd->{handle}->fdopen($fd->{tmp_copy}, $fd->{mode}); |
285 | $fd->{tmp_copy}->close or croak "Can't close: $!"; |
286 | } |
287 | croak join "\n", @errs if @errs; |
288 | return $pid; |
289 | } |
290 | |
291 | 1; # so require is happy |