real: Eliminate access to uninitialized memory.

When compiling this program with gcobol:

        identification division.
        program-id. prog.
        data division.
        working-storage section.
        01 val pic v9(5) value .001.
        procedure division.
            display val
            goback.

the rounding up of .99999...9999 to 1.000...0000 causes a read of the
first byte of the output buffer.  Although harmless, it generates a
valgrind warning.  The following change clears that warning.

gcc/ChangeLog:

	* real.cc (real_to_decimal_for_mode): Set str[0] to known value.

diff --git a/gcc/real.cc b/gcc/real.cc
index 1f987d48889f44687a045547cecd405d07cfd3c9..43d25246ed7c10c9644d758f20213e98a95e5b84 100644 (file)
--- a/gcc/real.cc
+++ b/gcc/real.cc
@@ -1629,6 +1629,11 @@ real_to_decimal_for_mode (char *str, const REAL_VALUE_TYPE *r_orig,
       strcpy (str, (r.sign ? "-0.0" : "0.0"));
       return;
     case rvc_normal:
+      /*  When r_orig is a positive value that converts to all nines and is
+          rounded up to 1.0, str[0] is harmlessly accessed before being set to
+          '1'.  That read access triggers a valgrind warning.  Setting str[0]
+          to any value quiets the warning. */
+      str[0] = ' ';
       break;
     case rvc_inf:
       strcpy (str, (r.sign ? "-Inf" : "+Inf"));