Re: [ID 20011101.069] \stat('.') gives "Attempt to free unreferenced scalar"

[Radu Greab]

On Thu, 1 Nov 2001 12:09 -0600, Tye McQueen wrote:
 > perl -e "print \stat('.')"
 > 
 > on perl 5.6.0 and 5.6.1 on several platforms (including the one
 > documented here by perlbug as well as Linux on intel and Sparc,
 > Solaris, and AIX) gives "Attempt to free unreferenced scalar" or
 > just throws SIGSEGV.  This bug appears to have been introduced
 > between 5.005_02 and 5.005_03.

The patch below fixes the bug.

The OPf_REF flag signals OP_STAT and the other file test operators
that the argument is a filehandle. When a reference is constructed,
Perl_mod() always sets the OPf_REF flag and stat() will consider the
argument to be a filehandle even when it is an expression.


Thanks,
Radu Greab


--- op.c~       Fri Oct 26 17:09:53 2001
+++ op.c        Fri Nov  2 15:11:24 2001
@@ -1670,19 +1670,22 @@
            goto nomod;
        break; /* mod()ing was handled by ck_return() */
     }
-    if (type != OP_LEAVESUBLV)
-        o->op_flags |= OPf_MOD;
+    if (type != OP_REFGEN ||
+       PL_check[o->op_type] != MEMBER_TO_FPTR(Perl_ck_ftst)) {
+       if (type != OP_LEAVESUBLV)
+           o->op_flags |= OPf_MOD;
 
-    if (type == OP_AASSIGN || type == OP_SASSIGN)
-       o->op_flags |= OPf_SPECIAL|OPf_REF;
-    else if (!type) {
-       o->op_private |= OPpLVAL_INTRO;
-       o->op_flags &= ~OPf_SPECIAL;
-       PL_hints |= HINT_BLOCK_SCOPE;
+       if (type == OP_AASSIGN || type == OP_SASSIGN)
+           o->op_flags |= OPf_SPECIAL|OPf_REF;
+       else if (!type) {
+           o->op_private |= OPpLVAL_INTRO;
+           o->op_flags &= ~OPf_SPECIAL;
+           PL_hints |= HINT_BLOCK_SCOPE;
+       }
+       else if (type != OP_GREPSTART && type != OP_ENTERSUB
+                && type != OP_LEAVESUBLV)
+           o->op_flags |= OPf_REF;
     }
-    else if (type != OP_GREPSTART && type != OP_ENTERSUB
-             && type != OP_LEAVESUBLV)
-       o->op_flags |= OPf_REF;
     return o;
 }
 
--- t/op/stat.t~        Fri Sep 14 18:49:59 2001
+++ t/op/stat.t Fri Nov  2 15:10:47 2001
@@ -9,7 +9,7 @@
 
 use Config;
 
-print "1..58\n";
+print "1..59\n";
 
 $Is_MSWin32 = $^O eq 'MSWin32';
 $Is_NetWare = $^O eq 'NetWare';
@@ -281,3 +281,7 @@
 if (-f()) {print "ok 58\n";} else {print "not ok 58\n";}
 
 unlink 'Op.stat.tmp' or print "# unlink failed: $!\n";
+
+# bug id 20011101.069
+my @r = \stat(".");
+if (@r == 13) { print "ok 59\n" } else { print "not ok 59\n" }