[Bug fortran/54678] New: second call to get_environment_variable gives valgrind warning with 8-byte integers

[Bug fortran/54678] New: second call to get_environment_variable gives valgrind warning with 8-byte integers

[ajmay81 at googlemail dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=54678

             Bug #: 54678
           Summary: second call to get_environment_variable gives valgrind
                    warning with 8-byte integers
    Classification: Unclassified
           Product: gcc
           Version: 4.7.1
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: fortran
        AssignedTo: unassigned@gcc.gnu.org
        ReportedBy: ajmay81@googlemail.com


Seen with this cut-down example (test.f90):

program test
implicit none
character(len=1024) :: a
call get_environment_variable("HOME",a)
write(6,*)'HOME=',trim(a)
call get_environment_variable("HOME",a)
write(6,*)'HOME=',trim(a)
end

Compiling with:

gfortran -g -fdefault-integer-8 test.f90

and running valgrind on the resulting executable gives a warning about an
uninitialized variable on the second call to get_environment_variable:

==13919== Conditional jump or move depends on uninitialised value(s)
==13919==    at 0x4F14DF4: _gfortran_get_environment_variable_i4 (in
/usr/lib64/libgfortran.so.3.0.0)
==13919==    by 0x4F14F62: _gfortran_get_environment_variable_i8 (in
/usr/lib64/libgfortran.so.3.0.0)
==13919==    by 0x4009AC: MAIN__ (test.f90:6)
==13919==    by 0x400AA4: main (test.f90:8)

Compiling with default (4-byte) integers does not show the problem, i.e.:

gfortran -g test.f90

[Bug fortran/54678] second call to get_environment_variable gives valgrind warning with 8-byte integers

[burnus at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=54678

Tobias Burnus <burnus at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |burnus at gcc dot gnu.org

--- Comment #1 from Tobias Burnus <burnus at gcc dot gnu.org> 2012-09-24 06:37:26 UTC ---
Draft patch:

--- a/libgfortran/intrinsics/env.c
+++ b/libgfortran/intrinsics/env.c
@@ -186,5 +186,6 @@ get_environment_variable_i8 (char *name, char *value,
GFC_INTEGER_8 *length,

   get_environment_variable_i4 (name, value, &length4, &status4, 
-                              &trim_name4, name_len, value_len);
+                              trim_name ? &trim_name4 : NULL,
+                              name_len, value_len);

   if (length)

[Bug fortran/54678] second call to get_environment_variable gives valgrind warning with 8-byte integers

[tkoenig at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=54678

Thomas Koenig <tkoenig at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |NEW
   Last reconfirmed|                            |2013-01-05
                 CC|                            |tkoenig at gcc dot gnu.org
     Ever Confirmed|0                           |1

--- Comment #2 from Thomas Koenig <tkoenig at gcc dot gnu.org> 2013-01-05 20:54:57 UTC ---
Hi Tobias,

do you plan to commit the patch from Comment #1?
It looks obvious to me.

[Bug fortran/54678] second call to get_environment_variable gives valgrind warning with 8-byte integers

[burnus at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=54678

--- Comment #3 from Tobias Burnus <burnus at gcc dot gnu.org> 2013-01-06 12:43:49 UTC ---
Author: burnus
Date: Sun Jan  6 12:43:45 2013
New Revision: 194948

URL: http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=194948
Log:
2013-01-06  Tobias Burnus  <burnus@net-b.de>

        PR fortran/54678
        * intrinsics/env.c (get_environment_variable_i8): Don't use
        uninitialized variable.


Modified:
    trunk/libgfortran/ChangeLog
    trunk/libgfortran/intrinsics/env.c

[Bug fortran/54678] second call to get_environment_variable gives valgrind warning with 8-byte integers

[burnus at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=54678

Tobias Burnus <burnus at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |RESOLVED
         Resolution|                            |FIXED

--- Comment #4 from Tobias Burnus <burnus at gcc dot gnu.org> 2013-01-06 12:46:16 UTC ---
FIXED on the trunk (4.8).

Thanks for the report - and sorry for the delay.

Thomas: Thanks for the reminder.