Perl_mode_from_discipline must update len. (else SEGV)

Diagnosis and patch from clkao

p4raw-id: //depot/perl@23076

diff --git a/doio.c b/doio.c
index 98e7204..a551d05 100644 (file)
--- a/doio.c
+++ b/doio.c
@@ -1172,6 +1172,7 @@ fail_discipline:
 #ifndef PERLIO_LAYERS
                Perl_croak(aTHX_ "IO layers (like '%.*s') unavailable", end-s, s);
 #else
+               len -= end-s;
                s = end;
 #endif
            }