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From: "jussilehtola at fedoraproject dot org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug fortran/96486] get_environment_variable crashes for environment
 variables that are empty strings
Date: Fri, 07 Aug 2020 20:36:51 +0000
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D96486

Susi Lehtola <jussilehtola at fedoraproject dot org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
            Summary|get_environment_variable    |get_environment_variable
                   |fails for zero-length       |crashes for environment
                   |values                      |variables that are empty
                   |                            |strings

--- Comment #22 from Susi Lehtola <jussilehtola at fedoraproject dot org> -=
--
to repeat: libgfortran crashes when you try to read an environment variable
that is an empty string, in the case you have preallocated an array that is=
 the
proper size i.e. zero characters.

I don't get any more backtrace than what I've reported above; I guess gdb
doesn't debug libgfortran intrinsics by default. The procedure I used was

$ gfortran -g -Wall readvar2.f90=20
$ export HOSTNAME=3D
$ gdb ./a.out
(gdb) r
Starting program: /tmp/a.out=20
Fortran runtime error: Zero-length string passed as value to
get_environment_variable.

Error termination. Backtrace:
#0  0x401267 in zerolen_value
        at /tmp/readvar2.f90:17
#1  0x4012c4 in main
        at /tmp/readvar2.f90:22
[Inferior 1 (process 152269) exited with code 02]=