[PATCH] fix for [perl #61976] Errno ($!) not evaluated to a error message string (5.10.0 in taint mode)

[David Mitchell]

Change 27176 / 2a509ed3c095f7d712013e653f68821f6bb2d6db fixed a taint
bug, which as a side effect, meant that $! used within a tainted expression
failed to have a string value.

This quick fix just makes sure the POK flag is set (prior to it being
shifted back to pPOK).
---
 mg.c         |    1 +
 t/op/taint.t |   13 ++++++++++++-
 2 files changed, 13 insertions(+), 1 deletions(-)

diff --git a/mg.c b/mg.c
index fb91325..ddfc2ff 100644
--- a/mg.c
+++ b/mg.c
@@ -1048,6 +1048,7 @@ 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 */
 	RESTORE_ERRNO;
 	}
 #endif
diff --git a/t/op/taint.t b/t/op/taint.t
index 796b6fa..161073d 100644
--- a/t/op/taint.t
+++ b/t/op/taint.t
@@ -17,7 +17,7 @@ use Config;
 use File::Spec::Functions;
 
 BEGIN { require './test.pl'; }
-plan tests => 301;
+plan tests => 302;
 
 $| = 1;
 
@@ -1308,6 +1308,17 @@ foreach my $ord (78, 163, 256) {
     ok(tainted($zz), "pack a*a* preserves tainting");
 }
 
+# Bug RT #61976 tainted $! would show numeric rather than string value
+
+{
+    my $tainted_path = substr($^X,0,0) . "/no/such/file";
+    my $err;
+    # $! is used in a tainted expression, so gets tainted
+    open my $fh, $tainted_path or $err= "$!";
+    unlike($err, qr/^\d+$/, 'tainted $!');
+}
+
+
 # This may bomb out with the alarm signal so keep it last
 SKIP: {
     skip "No alarm()"  unless $Config{d_alarm};
-- 
1.7.0


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