Fortran : get_environment_variable runtime error PR96486

Runtime error occurs when the type of the value argument is
character(0):  "Zero-length string passed as value...".
The status argument, intent(out), will contain -1 if the value
of the environment is too large to fit in the value argument, this
is the case if the type is character(0) so there is no reason to
produce a runtime error if the value argument is zero length.

2020-08-24  Mark Eggleston  <markeggleston@gcc.gnu.org>

libgfortran/

	PR fortran/96486
	* intrinsics/env.c: If value_len is > 0 blank the string.
	Copy the result only if its length is > 0.

2020-08-24  Mark Eggleston  <markeggleston@gcc.gnu.org>

gcc/testsuite/

	PR fortran/96486
	* gfortran.dg/pr96486.f90: New test.

diff --git a/gcc/testsuite/gfortran.dg/pr96486.f90 b/gcc/testsuite/gfortran.dg/pr96486.f90
new file mode 100644 (file)
index 0000000..fdc7025
--- /dev/null
+++ b/gcc/testsuite/gfortran.dg/pr96486.f90
@@ -0,0 +1,9 @@
+! { dg-do run }
+
+program test
+  implicit none
+  character(0) :: value
+  integer :: l, stat
+  call get_environment_variable("HOME",value,length=l,status=stat)
+  if (stat.ne.-1) stop 1
+end program test

diff --git a/libgfortran/intrinsics/env.c b/libgfortran/intrinsics/env.c
index b7837b30873c51b6a698ec2970f1ab052fbe0ce9..7ab0b44389707e60797f47aee94c965acf74ba88 100644 (file)
--- a/libgfortran/intrinsics/env.c
+++ b/libgfortran/intrinsics/env.c
@@ -110,10 +110,7 @@ get_environment_variable_i4 (char *name, char *value, GFC_INTEGER_4 *length,
 
   if (value != NULL)
     { 
-      if (value_len < 1)
-       runtime_error ("Zero-length string passed as value to "
-                      "get_environment_variable.");
-      else
+      if (value_len > 0)
        memset (value, ' ', value_len); /* Blank the string.  */
     }
 
@@ -138,7 +135,7 @@ get_environment_variable_i4 (char *name, char *value, GFC_INTEGER_4 *length,
              memcpy (value, res, value_len);
              stat = GFC_VALUE_TOO_SHORT;
            }
-         else
+         else if (res_len > 0)
            memcpy (value, res, res_len);
        }
     }