Fix bug where insert-file-contents closes a file twice.

* fileio.c (close_file_unwind): Don't close if FD is negative;
this can happen when unwinding a zapped file descriptor.
(Finsert_file_contents): Unwind-protect the fd before the point marker,
in case Emacs runs out of memory between the two unwind-protects.
Don't trash errno when closing FD.
Zap the FD in the specpdl when closing it, instead of deferring
the removal of the unwind-protect; this fixes a bug where a child
function unwinds the stack past us.

Fixes: debbugs:14839

1 files changed, 6 insertions, 0 deletions

diff --git a/src/lisp.h b/src/lisp.h
index 38413f831dc..26e9e18ec9a 100644
--- a/src/lisp.h
+++ b/src/lisp.h
@@ -2750,6 +2750,12 @@ set_unwind_protect_ptr (ptrdiff_t count, void *arg)
   specpdl[count].unwind_ptr.arg = arg;
 }
 
+LISP_INLINE void
+set_unwind_protect_int (ptrdiff_t count, int arg)
+{
+  specpdl[count].unwind_int.arg = arg;
+}
+
 /* Everything needed to describe an active condition case.
 
    Members are volatile if their values need to survive _longjmp when