SIGPIPE delay on open2 exec failure

[George Glynn]

Perl 5.8.5 on Fedora Core 3...

Can anyone tell me why my SIGPIPE handler doesn't run until I hit the enter
key when running this program from a TTY?

1: #!/usr/bin/perl
2:
3: use FileHandle;
4: use IPC::Open2;
5:
6: sub pipeHandler {
7: die("I piped");
8: }
9:
10: $SIG{PIPE} = \&pipeHandler;
11:
12: $pid = open2( \*FROMPROC, \*TOPROC, "/path/to/nonexistent/program");
13: TOPROC->autoflush();
14:
15: print TOPROC "Garbage in...";
16: print <FROMPROC>;
17:
18: while(<STDIN>) {
19: print TOPROC $_;
20: print <FROMPROC>;
21: }

I get the error message:

open2: exec of /path/to/nonexistent/program failed at foowrap line 12

right away, but the program sits waiting until I hit the enter key, then
dies and prints on STDERR:

I piped at script_name line 7, <STDIN> line 1.

Why didn't it hit the SIGPIPE handler trying to write to TOPROC on line 15?

I've also tried trapping __DIE__ with the following handler:

a: sub dieHandler {
b: die("I died");
c: }

This handler runs right away, and the message:

I died at script_name line b.

prints instead of the "open2: exec ... failed ..." message, as one would
expect, but then it still sits there waiting for me to hit enter again, at
which point it prints:

I died at script_name line b, <STDIN> line 1.

I'm sure I'm just missing the subtleties of IPC, so can anyone clue me in as
to what's happening here?

In case you're wondering, I ultimately want to have the program die right
away if the exec in the open2() program fails.

 

[xhoster]

Perl 5.8.5 on Fedora Core 3...
....
Why didn't it hit the SIGPIPE handler trying to write to TOPROC on line
15? ....

I'm sure I'm just missing the subtleties of IPC, so can anyone clue me in
as to what's happening here?

For me on 5.8.0 it does SIGPIPE on line 15, so this may be a bug
rather than some expected behavior.

Xho