glibc/sysdeps/unix/sysv/linux/fexecve.c
Joseph Myers d82468d100 Fix fexecve build where syscall macros call sizeof.
The recent fexecve changes broke the build on (at least) alpha (maybe
other configurations, that was the first breakage I saw in my
build-many-glibcs.py run):

In file included from ../sysdeps/unix/sysv/linux/alpha/sysdep.h:29:0,
                 from ../sysdeps/alpha/nptl/tls.h:31,
                 from ../include/errno.h:25,
                 from ../sysdeps/unix/sysv/linux/fexecve.c:18:
../sysdeps/unix/sysv/linux/fexecve.c: In function 'fexecve':
../sysdeps/unix/alpha/sysdep.h:203:10: error: 'sizeof' on array function parameter 'argv' will return size of 'char * const*' [-Werror=sizeof-array-argument]
   (sizeof(arg) == 4 ? (long)(int)(long)(arg) : (long)(arg))
          ^
../sysdeps/unix/alpha/sysdep.h:302:26: note: in expansion of macro 'syscall_promote'
  register long _tmp_18 = syscall_promote (arg3);  \
                          ^~~~~~~~~~~~~~~
../sysdeps/unix/alpha/sysdep.h:173:2: note: in expansion of macro 'inline_syscall5'
  inline_syscall##nr(__NR_##name, args); \
  ^~~~~~~~~~~~~~
../sysdeps/unix/sysv/linux/alpha/sysdep.h:85:2: note: in expansion of macro 'INLINE_SYSCALL1'
  INLINE_SYSCALL1(name, nr, args);    \
  ^~~~~~~~~~~~~~~
../sysdeps/unix/sysv/linux/fexecve.c:42:3: note: in expansion of macro 'INLINE_SYSCALL'
   INLINE_SYSCALL (execveat, 5, fd, "", argv, envp, AT_EMPTY_PATH);
   ^~~~~~~~~~~~~~
../sysdeps/unix/sysv/linux/fexecve.c:33:30: note: declared here
 fexecve (int fd, char *const argv[], char *const envp[])
                              ^~~~

This patch fixes this similarly to previous fixes for such issues: use
&argv[0] and &envp[0] as the syscall macro arguments.  Tested
(compilation only) for alpha-linux-gnu with build-many-glibcs.py.

	* sysdeps/unix/sysv/linux/fexecve.c (fexecve) [__NR_execveat]:
	Explicitly take address of first element of array arguments in
	call to INLINE_SYSCALL.
2017-09-19 15:50:38 +00:00

72 lines
2.1 KiB
C

/* Copyright (C) 1994-2017 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
<http://www.gnu.org/licenses/>. */
#include <errno.h>
#include <stddef.h>
#include <stdio.h>
#include <unistd.h>
#include <fcntl.h>
#include <sys/stat.h>
#include <sysdep.h>
#include <sys/syscall.h>
#include <kernel-features.h>
/* Execute the file FD refers to, overlaying the running program image.
ARGV and ENVP are passed to the new program, as for `execve'. */
int
fexecve (int fd, char *const argv[], char *const envp[])
{
if (fd < 0 || argv == NULL || envp == NULL)
{
__set_errno (EINVAL);
return -1;
}
#ifdef __NR_execveat
/* Avoid implicit array coercion in syscall macros. */
INLINE_SYSCALL (execveat, 5, fd, "", &argv[0], &envp[0], AT_EMPTY_PATH);
# ifndef __ASSUME_EXECVEAT
if (errno != ENOSYS)
return -1;
# endif
#endif
#ifndef __ASSUME_EXECVEAT
/* We use the /proc filesystem to get the information. If it is not
mounted we fail. */
char buf[sizeof "/proc/self/fd/" + sizeof (int) * 3];
__snprintf (buf, sizeof (buf), "/proc/self/fd/%d", fd);
/* We do not need the return value. */
__execve (buf, argv, envp);
int save = errno;
/* We come here only if the 'execve' call fails. Determine whether
/proc is mounted. If not we return ENOSYS. */
struct stat st;
if (stat ("/proc/self/fd", &st) != 0 && errno == ENOENT)
save = ENOSYS;
__set_errno (save);
#endif
return -1;
}