[Bug libc/10511] New: popen() returns fp on non existing file

["wharms at bfs dot de" <sourceware-bugzilla at sourceware dot org>]

popen() returns a filepointer even when the file in question does not exists.
that makes complicated for subsequenting code to check for success.
I am aware that the posix specs say nothing about using a non existing file and
an error msg from the shell is shown. ntl all programmers i ask where not aware
that popen may fail this way and simply assume that a filepointer means that
everything works.

 /lib/libc.so.6 
GNU C Library stable release version 2.9 (20081117), by Roland McGrath et al.
Copyright (C) 2008 Free Software Foundation, Inc.
This is free software; see the source for copying conditions.
There is NO warranty; not even for MERCHANTABILITY or FITNESS FOR A
PARTICULAR PURPOSE.
Configured for i686-suse-linux.
Compiled by GNU CC version 4.3.2 [gcc-4_3-branch revision 141291].
Compiled on a Linux 2.6.27 system on 2009-02-22.
Available extensions:
        crypt add-on version 2.1 by Michael Glad and others
        GNU Libidn by Simon Josefsson
        NoVersion patch for broken glibc 2.0 binaries
        Native POSIX Threads Library by Ulrich Drepper et al
        BIND-8.2.3-T5B


#include <stdio.h>
int main()
{
        FILE *fp=popen("blub","w");
        if (!fp)
                printf("popen failed\n");
        else
                printf("popen worked\n");
        return 0;
}

result;
sh: blub: command not found
popen worked

-- 
           Summary: popen() returns fp on non existing file
           Product: glibc
           Version: 2.9
            Status: NEW
          Severity: normal
          Priority: P2
         Component: libc
        AssignedTo: drepper at redhat dot com
        ReportedBy: wharms at bfs dot de
                CC: glibc-bugs at sources dot redhat dot com


http://sourceware.org/bugzilla/show_bug.cgi?id=10511

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