Cope with brain damage in PerlIO::via, which will let you fclose() the

same FILE * twice, thanks to it calling out to Perl space inside the
close call tree, with the underlying PerlIO * already closed, but not
unlinked.

p4raw-id: //depot/perl@34596

diff --git a/perlio.c b/perlio.c
index 466dd13..faf8147 100644 (file)
--- a/perlio.c
+++ b/perlio.c
@@ -3144,8 +3144,15 @@ PerlIOStdio_close(pTHX_ PerlIO *f)
        if (getsockopt(fd, SOL_SOCKET, SO_TYPE, (void *) &optval, &optlen) == 0)
            invalidate = 1;
 #endif
-       if (PerlIOUnix_refcnt_dec(fd) > 0) /* File descriptor still in use */
+       /* Test for -1, as *BSD stdio (at least) on fclose sets the FILE* such
+          that a subsequent fileno() on it returns -1. Don't want to croak()
+          from within PerlIOUnix_refcnt_dec() if some buggy caller code is
+          trying to close an already closed handle which somehow it still has
+          a reference to. (via.xs, I'm looking at you).  */
+       if (fd != -1 && PerlIOUnix_refcnt_dec(fd) > 0) {
+           /* File descriptor still in use */
            invalidate = 1;
+       }
        if (invalidate) {
            /* For STD* handles, don't close stdio, since we shared the FILE *, too. */
            if (stdio == stdin) /* Some stdios are buggy fflush-ing inputs */