Fix #72850 - reading $! shouldn't SEGV if Strerror(errno) returns NULL.

This can happen on some OSes for out of range errno values. The bug was
introduced with 0097b436152452e4, which in turn fixed #61976.

Test case by Steve Peters.

diff --git a/mg.c b/mg.c
index cc01547..06c899e 100644 (file)
--- a/mg.c
+++ b/mg.c
@@ -1048,7 +1048,8 @@ Perl_magic_get(pTHX_ SV *sv, MAGIC *mg)
        else
 #endif
        sv_setpv(sv, errno ? Strerror(errno) : "");
-       SvPOK_on(sv);   /* may have got removed during taint processing */
+       if (SvPOKp(sv))
+           SvPOK_on(sv);    /* may have got removed during taint processing */
        RESTORE_ERRNO;
        }
 

diff --git a/t/op/magic.t b/t/op/magic.t
index 975be11..3df3e4b 100644 (file)
--- a/t/op/magic.t
+++ b/t/op/magic.t
@@ -12,7 +12,7 @@ BEGIN {
 use warnings;
 use Config;
 
-plan (tests => 79);
+plan (tests => 80);
 
 $Is_MSWin32  = $^O eq 'MSWin32';
 $Is_NetWare  = $^O eq 'NetWare';
@@ -491,3 +491,9 @@ foreach my $sig (qw(__DIE__ _BOGUS_HOOK KILL THIRSTY)) {
     is $SIG{$sig}, undef, "$sig is not present";
     is delete $SIG{$sig}, undef, "delete of $sig returns undef";
 }
+
+{
+    $! = 9999;
+    is int $!, 9999, q{[perl #72850] Core dump in bleadperl from perl -e '$! = 9999; $a = $!;'};
+
+}