glibc/libio/iofopncook.c
Adhemerval Zanella Netto 3020f72618 libio: Remove the usage of __libc_IO_vtables
Instead of using a special ELF section along with a linker script
directive to put the IO vtables within the RELRO section, the libio
vtables are all moved to an array marked as data.relro (so linker
will place in the RELRO segment without the need of extra directives).

To avoid static linking namespace issues and including all vtable
referenced objects, all required function pointers are set to weak alias.

Checked on x86_64-linux-gnu, i686-linux-gnu, and aarch64-linux-gnu.

Reviewed-by: Carlos O'Donell <carlos@redhat.com>
2023-03-27 13:57:55 -03:00

221 lines
5.8 KiB
C

/* Copyright (C) 1993-2023 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/>.
As a special exception, if you link the code in this file with
files compiled with a GNU compiler to produce an executable,
that does not cause the resulting executable to be covered by
the GNU Lesser General Public License. This exception does not
however invalidate any other reasons why the executable file
might be covered by the GNU Lesser General Public License.
This exception applies to code released by its copyright holders
in files containing the exception. */
#include <libioP.h>
#include <stdio.h>
#include <stdlib.h>
#include <shlib-compat.h>
#include <pointer_guard.h>
ssize_t
_IO_cookie_read (FILE *fp, void *buf, ssize_t size)
{
struct _IO_cookie_file *cfile = (struct _IO_cookie_file *) fp;
cookie_read_function_t *read_cb = cfile->__io_functions.read;
PTR_DEMANGLE (read_cb);
if (read_cb == NULL)
return -1;
return read_cb (cfile->__cookie, buf, size);
}
ssize_t
_IO_cookie_write (FILE *fp, const void *buf, ssize_t size)
{
struct _IO_cookie_file *cfile = (struct _IO_cookie_file *) fp;
cookie_write_function_t *write_cb = cfile->__io_functions.write;
PTR_DEMANGLE (write_cb);
if (write_cb == NULL)
{
fp->_flags |= _IO_ERR_SEEN;
return 0;
}
ssize_t n = write_cb (cfile->__cookie, buf, size);
if (n < size)
fp->_flags |= _IO_ERR_SEEN;
return n;
}
off64_t
_IO_cookie_seek (FILE *fp, off64_t offset, int dir)
{
struct _IO_cookie_file *cfile = (struct _IO_cookie_file *) fp;
cookie_seek_function_t *seek_cb = cfile->__io_functions.seek;
PTR_DEMANGLE (seek_cb);
return ((seek_cb == NULL
|| (seek_cb (cfile->__cookie, &offset, dir)
== -1)
|| offset == (off64_t) -1)
? _IO_pos_BAD : offset);
}
int
_IO_cookie_close (FILE *fp)
{
struct _IO_cookie_file *cfile = (struct _IO_cookie_file *) fp;
cookie_close_function_t *close_cb = cfile->__io_functions.close;
PTR_DEMANGLE (close_cb);
if (close_cb == NULL)
return 0;
return close_cb (cfile->__cookie);
}
off64_t
_IO_cookie_seekoff (FILE *fp, off64_t offset, int dir, int mode)
{
/* We must force the fileops code to always use seek to determine
the position. */
fp->_offset = _IO_pos_BAD;
return _IO_file_seekoff (fp, offset, dir, mode);
}
/* Copy the callbacks from SOURCE to *TARGET, with pointer
mangling. */
static void
set_callbacks (cookie_io_functions_t *target,
cookie_io_functions_t source)
{
PTR_MANGLE (source.read);
PTR_MANGLE (source.write);
PTR_MANGLE (source.seek);
PTR_MANGLE (source.close);
*target = source;
}
void
_IO_cookie_init (struct _IO_cookie_file *cfile, int read_write,
void *cookie, cookie_io_functions_t io_functions)
{
_IO_init_internal (&cfile->__fp.file, 0);
_IO_JUMPS (&cfile->__fp) = &_IO_cookie_jumps;
cfile->__cookie = cookie;
set_callbacks (&cfile->__io_functions, io_functions);
_IO_new_file_init_internal (&cfile->__fp);
_IO_mask_flags (&cfile->__fp.file, read_write,
_IO_NO_READS+_IO_NO_WRITES+_IO_IS_APPENDING);
cfile->__fp.file._flags2 |= _IO_FLAGS2_NEED_LOCK;
/* We use a negative number different from -1 for _fileno to mark that
this special stream is not associated with a real file, but still has
to be treated as such. */
cfile->__fp.file._fileno = -2;
}
FILE *
_IO_fopencookie (void *cookie, const char *mode,
cookie_io_functions_t io_functions)
{
int read_write;
struct locked_FILE
{
struct _IO_cookie_file cfile;
#ifdef _IO_MTSAFE_IO
_IO_lock_t lock;
#endif
} *new_f;
switch (*mode++)
{
case 'r':
read_write = _IO_NO_WRITES;
break;
case 'w':
read_write = _IO_NO_READS;
break;
case 'a':
read_write = _IO_NO_READS|_IO_IS_APPENDING;
break;
default:
__set_errno (EINVAL);
return NULL;
}
if (mode[0] == '+' || (mode[0] == 'b' && mode[1] == '+'))
read_write &= _IO_IS_APPENDING;
new_f = (struct locked_FILE *) malloc (sizeof (struct locked_FILE));
if (new_f == NULL)
return NULL;
#ifdef _IO_MTSAFE_IO
new_f->cfile.__fp.file._lock = &new_f->lock;
#endif
_IO_cookie_init (&new_f->cfile, read_write, cookie, io_functions);
return (FILE *) &new_f->cfile.__fp;
}
versioned_symbol (libc, _IO_fopencookie, fopencookie, GLIBC_2_2);
#if SHLIB_COMPAT (libc, GLIBC_2_0, GLIBC_2_2)
off64_t
attribute_compat_text_section
_IO_old_cookie_seek (FILE *fp, off64_t offset, int dir)
{
struct _IO_cookie_file *cfile = (struct _IO_cookie_file *) fp;
int (*seek_cb) (FILE *, off_t, int)
= (int (*) (FILE *, off_t, int)) cfile->__io_functions.seek;
PTR_DEMANGLE (seek_cb);
if (seek_cb == NULL)
return _IO_pos_BAD;
int ret = seek_cb (cfile->__cookie, offset, dir);
return (ret == -1) ? _IO_pos_BAD : ret;
}
FILE *
attribute_compat_text_section
_IO_old_fopencookie (void *cookie, const char *mode,
cookie_io_functions_t io_functions)
{
FILE *ret;
ret = _IO_fopencookie (cookie, mode, io_functions);
if (ret != NULL)
_IO_JUMPS_FILE_plus (ret) = &_IO_old_cookie_jumps;
return ret;
}
compat_symbol (libc, _IO_old_fopencookie, fopencookie, GLIBC_2_0);
#endif