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Re: gawk 3.1.6 bug in /inet/tcp/lport/0/0
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From: |
Corinna Vinschen |
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Subject: |
Re: gawk 3.1.6 bug in /inet/tcp/lport/0/0 |
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Date: |
Thu, 15 Nov 2007 22:45:01 +0100 |
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User-agent: |
Mutt/1.5.16 (2007-06-09) |
On Nov 15 23:07, Aharon Robbins wrote:
> Greetings. Re the below. I don't get any such message under Linux.
> Please talk to the cygwin people directly. I have bcc'ed the Cygwin
> contact for gawk, so I hope she will be in touch w/you directly.
>
> Thanks,
>
> Arnold
>
> > From: Richard Narum
> > FYI,
> >
> > I believe I have encountered a bug in gawk 3.1.6 with the special file
> > name /inet/tcp using lport != 0 and rhost = rport = 0. I am running
> > Cygwin on Windows XP version "CYGWIN_NT-5.1 1.5.24(0.156/4/2) 2007-01-31
> > 10:57". I had version "GNU Awk 3.1.6", Cygwin install calls it 3.1.6-1,
> > and had to roll back to "GNU Awk 3.1.5", Cygwin's 3.1.5-4 . Version
> > 3.1.6 fails and 3.1.5 seems to work fine.
> >
> > I am running the following script.
> >
> >
> > #!/bin/sh
> >
> > gawk '
> > BEGIN {
> > RS = ORS = "\r\n"
> > HttpService = "/inet/tcp/8080/0/0"
> > Hello = "<HTML><HEAD></HEAD><BODY><PRE>Hello World!</PRE></BODY></HTML>"
> > Len = length(Hello) + length(ORS)
> > while ("awk" != "complex") {
> > print "HTTP/1.0 200 OK" |& HttpService
> > print "Content-Length: " Len ORS |& HttpService
> > print Hello |& HttpService
> > while ((HttpService |& getline) > 0)
> > continue;
> > close(HttpService)
> > }
> > }
> > '
> >
> > I get the following error.
> >
> >
> > gawk: cmd. line:8: fatal: remote host and port information (0, 0) invalid
That's a regression in io.c, function socketopen. The 3.1.5 code
called gethostbyname on a hostname "0", which leads to gethostbyname
returning NULL. However, this wasn't a problem because the code
explicitely checked for an input remote address of "0" and, if so,
allowed gethostbyname to fail without socketopen to fail:
io.c:
1137 struct hostent *hp = gethostbyname(remotehostname);
[...]
1140 int any_remote_host = strcmp(remotehostname, "0");
[...]
1180 if (socket_fd < 0 || socket_fd == INVALID_HANDLE
* 1181 || (hp == NULL && any_remote_host != 0))
1182 return INVALID_HANDLE;
In 3.1.6, the function getaddrinfo is used. If getaddrinfo returns -1,
gawk fails to open the socket, because there's no further test for
any_remote_host. I don't know why this works on Linux, but it certainly
fails on Cygwin, because Cygwin doesn't have (so far) a getaddrinfo
function and so the fallback function in missing_d is used, which in turn
uses gethostbyname. Since gethostbyname fails with the remote hostname
"0", the whole socketopen function fails now. I'm sure this isn't a
problem only on Cygwin, though, but on any platform not having its own
getaddrinfo function.
Since the socketopen function has changed so enormously, I don't see an
easy patch for this.
Corinna