Allow syswrite with offset same as length of string [perl #70095]

You are not really outside of the string then, but the effect will
always be a noop since the number of bytes written will be capped
to not exceed the length of the string as for other offsets.

1 files changed, 7 insertions, 3 deletions

diff --git a/t/op/sysio.t b/t/op/sysio.t
index 966a516997..f2c269ebaf 100644
--- a/t/op/sysio.t
+++ b/t/op/sysio.t
@@ -70,12 +70,16 @@ is($x, 'abc');
 ok(!-s $outfile);
 
 # should not be able to write from after the buffer
-eval { syswrite(O, $x, 1, 3) };
+eval { syswrite(O, $x, 1, 4) };
 like($@, qr/^Offset outside string /);
 
 # $x still intact
 is($x, 'abc');
 
+# but it should be ok to write from the end of the buffer
+syswrite(O, $x, 0, 3);
+syswrite(O, $x, 1, 3);
+
 # $outfile still intact
 if ($reopen) {  # must close file to update EOF marker for stat
   close O; open(O, ">>$outfile") || die "sysio.t: cannot write $outfile: $!";
@@ -97,7 +101,7 @@ if ($reopen) {  # must close file to update EOF marker for stat
 ok(!-s $outfile);
 
 # [perl #67912] syswrite prints garbage if called with empty scalar and non-zero offset
-eval { my $buf = ''; syswrite(O, $buf, 1, 0) };
+eval { my $buf = ''; syswrite(O, $buf, 1, 1) };
 like($@, qr/^Offset outside string /);
 
 # $x still intact
@@ -109,7 +113,7 @@ if ($reopen) {  # must close file to update EOF marker for stat
 }
 ok(!-s $outfile);
 
-eval { my $buf = 'x'; syswrite(O, $buf, 1, 1) };
+eval { my $buf = 'x'; syswrite(O, $buf, 1, 2) };
 like($@, qr/^Offset outside string /);
 
 # $x still intact