glibc/libio/vtables.c
Paul Eggert 581c785bf3 Update copyright dates with scripts/update-copyrights
I used these shell commands:

../glibc/scripts/update-copyrights $PWD/../gnulib/build-aux/update-copyright
(cd ../glibc && git commit -am"[this commit message]")

and then ignored the output, which consisted lines saying "FOO: warning:
copyright statement not found" for each of 7061 files FOO.

I then removed trailing white space from math/tgmath.h,
support/tst-support-open-dev-null-range.c, and
sysdeps/x86_64/multiarch/strlen-vec.S, to work around the following
obscure pre-commit check failure diagnostics from Savannah.  I don't
know why I run into these diagnostics whereas others evidently do not.

remote: *** 912-#endif
remote: *** 913:
remote: *** 914-
remote: *** error: lines with trailing whitespace found
...
remote: *** error: sysdeps/unix/sysv/linux/statx_cp.c: trailing lines
2022-01-01 11:40:24 -08:00

90 lines
2.7 KiB
C

/* libio vtable validation.
Copyright (C) 2016-2022 Free Software Foundation, Inc.
This file is part of the GNU C Library.
The GNU C Library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public
License as published by the Free Software Foundation; either
version 2.1 of the License, or (at your option) any later version.
The GNU C Library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public
License along with the GNU C Library; if not, see
<https://www.gnu.org/licenses/>. */
#include <dlfcn.h>
#include <libioP.h>
#include <stdio.h>
#include <ldsodefs.h>
#ifdef SHARED
void (*IO_accept_foreign_vtables) (void) attribute_hidden;
/* Used to detected multiple libcs. */
extern struct dl_open_hook *_dl_open_hook;
libc_hidden_proto (_dl_open_hook);
#else /* !SHARED */
/* Used to check whether static dlopen support is needed. */
# pragma weak __dlopen
#endif
void attribute_hidden
_IO_vtable_check (void)
{
#ifdef SHARED
/* Honor the compatibility flag. */
void (*flag) (void) = atomic_load_relaxed (&IO_accept_foreign_vtables);
#ifdef PTR_DEMANGLE
PTR_DEMANGLE (flag);
#endif
if (flag == &_IO_vtable_check)
return;
/* In case this libc copy is in a non-default namespace, we always
need to accept foreign vtables because there is always a
possibility that FILE * objects are passed across the linking
boundary. */
{
Dl_info di;
struct link_map *l;
if (!rtld_active ()
|| (_dl_addr (_IO_vtable_check, &di, &l, NULL) != 0
&& l->l_ns != LM_ID_BASE))
return;
}
#else /* !SHARED */
/* We cannot perform vtable validation in the static dlopen case
because FILE * handles might be passed back and forth across the
boundary. Therefore, we disable checking in this case. */
if (__dlopen != NULL)
return;
#endif
__libc_fatal ("Fatal error: glibc detected an invalid stdio handle\n");
}
/* Some variants of libstdc++ interpose _IO_2_1_stdin_ etc. and
install their own vtables directly, without calling _IO_init or
other functions. Detect this by looking at the vtables values
during startup, and disable vtable validation in this case. */
#ifdef SHARED
__attribute__ ((constructor))
static void
check_stdfiles_vtables (void)
{
if (_IO_2_1_stdin_.vtable != &_IO_file_jumps
|| _IO_2_1_stdout_.vtable != &_IO_file_jumps
|| _IO_2_1_stderr_.vtable != &_IO_file_jumps)
IO_set_accept_foreign_vtables (&_IO_vtable_check);
}
#endif