Re: patch: make tcpdump cleanup on SIGPIPE

[Guy Harris <guy () alum mit edu>]

On Mon, Jul 28, 2003 at 12:48:52PM +1200, Jesper Peterson wrote:
> The attached patch

Checked in.

> conditionally applies to non-Win32 only, I presume that is 
> the way to do it. I'm not sure exactly what the Win32 implications
> are.

The Windows NT (NT 4.0, W2K, WXP, etc.) command line supports pipes, and
I think the Windows OT (95, 98, Me) command line supports them as well. 
I don't know whether they're actually implemented *as* pipes, i.e.
multiple processes with the output of one sent to an anonymousppppppp pipe which
is also the input of another, or whether either NT or OT implements them
the way I think they might have been done in at least some versions of
the DOS command line, i.e. run the first process and send its output to
a file, and then run the second process reading from the file.

If they're done as pipes (which I suspect NT might do; OT is another
matter, as its command interpreter might be similar to the old DOS one),
then it appears from

        http://msdn.microsoft.com/library/default.asp?url=/library/en-us/fileio/base/writefile.asp

that if you write to a pipe that's closed, the WriteFile() call returns
an error indication (returns FALSE) and the error value is
ERROR_BROKEN_PIPE; this is similar to what happens in UNIX if you're
ignoring SIGPIPE.

"tcpdump" doesn't check for write errors when printing, and WinDump
inherits that, so it'll probably keep writing to the dead pipe, and
eventually exit (or get terminated by a SIGINT if you ^C it).  If it did
check for errors, it'd just exit more quickly.

As such, doing the SIGPIPE stuff only on UNIX is probably the right
thing to do.
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