Re: [gawk-stable] bug: fatal error when getline from directory

[Aharon Robbins]

Greetings. Re this:

> Date: Thu, 01 Jan 2009 21:18:29 +0100
> To: address@hidden
> CC: James Troup <address@hidden>, Paolo <address@hidden>
> Subject: [gawk-stable] bug: fatal error when getline from directory
>
> Happy New Year Arnold,
>
> I want to inform you about a bug in gawk-stable (current CVS version)
> and in earlier versions which Paolo has reported to the Debian
> bug-tracking system. (The current Debian gawk-maintainer is James
> Troup.)
> I
> Look at:
>
> http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=407454
>
> If you like it, I write a patch versus gawk-stable (according your
> advices.)
>
> I think the suggestions of Paolo are the right way.
> --
> Steffen

I have to decide what "the right thing" is here. Just to close the loop
w/o needing to look at the Debian file, the reported problem is that
getline from a directory is fatal, instead of an error.

Different awks do different things when handed a directory. Brian
Kernighan's awk treats a read of a directory as EOF; I think that's wrong.
For example:

        $ for i in nawk mawk mksawk gawk
        > do echo ==== $i
        > $i 'BEGIN { x = 4; print (getline x < "/tmp") ; print x }'
        > done
        ==== nawk
        0
        4
        ==== mawk
        mawk: read error (Is a directory)
        ==== mksawk
        -1
        
        ==== gawk
        gawk: fatal: file `/tmp' is a directory

In the same vein, each awk behaves differently when given a
directory on the command line. BWK awk and mksawk (used in Solaris
as /usr/xpg4/bin/awk) ignore the directory, mawk gives an error, as
does gawk:

        $ for i in nawk mawk mksawk gawk
        > do echo ==== $i
        > $i '{ print FILENAME }' a /tmp b
        > done
        ==== nawk
        a
        b
        ==== mawk
        a
        mawk: read error (Is a directory)
        ==== mksawk
        a
        b
        ==== gawk
        a
        gawk: (FILENAME=a FNR=1) fatal: cannot open file `/tmp' for reading 
(Success)

I will consult with the other awk authors before I decide what to do.

Thanks,

Arnold