Re: fopen()-pclose() bug in install-info

[Hans-Bernhard Bröker]

Am 09.02.2021 um 21:55 schrieb Gavin Smith:

> Yes, it is clearly wrong in this case.  It's just a question now of
> understanding the changes in the two earlier commits and making
> sure that we don't break anything that those commits were supposed to
> fix.

I'm pretty sure it's 2d03d088d945a9dc0dd9318a32fe4e74ca51dfbc that broke 
this.  Before, all fopen()s in there were freopen( , , stdin) calls.
I.e. in the case of a non-compressed file, 'f' would be equal to stdin 
at all times.  Only for detected compressed files would it then be 
overwritten by a popen()ed one.  The change turned all those freopens to 
plain fopen(), and failed to add one back in for the non-compressed file 
case.  So open_possibly_compressed_file() now doesn't match it's 
documented behaviour.

> One way to fix it would be reinstate the is_pipe argument and
> only call pclose if it's a pipe.

No need for an additional argument. The "compression program" output 
parameter already holds that information:

        if (*compression_program)
          pclose();
        else
          fclose();