1/* Copyright (C) 1994-2023 Free Software Foundation, Inc.
2 This file is part of the GNU C Library.
3
4 The GNU C Library is free software; you can redistribute it and/or
5 modify it under the terms of the GNU Lesser General Public
6 License as published by the Free Software Foundation; either
7 version 2.1 of the License, or (at your option) any later version.
8
9 The GNU C Library is distributed in the hope that it will be useful,
10 but WITHOUT ANY WARRANTY; without even the implied warranty of
11 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
12 Lesser General Public License for more details.
13
14 You should have received a copy of the GNU Lesser General Public
15 License along with the GNU C Library; if not, see
16 <https://www.gnu.org/licenses/>. */
17
18#include <errno.h>
19#include <stddef.h>
20#include <stdio.h>
21#include <unistd.h>
22#include <fcntl.h>
23#include <sys/stat.h>
24
25#include <fd_to_filename.h>
26#include <sysdep.h>
27#include <sys/syscall.h>
28#include <kernel-features.h>
29
30
31/* Execute the file FD refers to, overlaying the running program image.
32 ARGV and ENVP are passed to the new program, as for `execve'. */
33int
34fexecve (int fd, char *const argv[], char *const envp[])
35{
36 if (fd < 0 || argv == NULL || envp == NULL)
37 {
38 __set_errno (EINVAL);
39 return -1;
40 }
41
42#ifdef __NR_execveat
43 /* Avoid implicit array coercion in syscall macros. */
44 INLINE_SYSCALL (execveat, 5, fd, "", &argv[0], &envp[0], AT_EMPTY_PATH);
45# ifndef __ASSUME_EXECVEAT
46 if (errno != ENOSYS)
47 return -1;
48# endif
49#endif
50
51#ifndef __ASSUME_EXECVEAT
52 /* We use the /proc filesystem to get the information. If it is not
53 mounted we fail. We do not need the return value. */
54 struct fd_to_filename filename;
55 __execve (__fd_to_filename (fd, &filename), argv, envp);
56
57 int save = errno;
58
59 /* We come here only if the 'execve' call fails. Determine whether
60 /proc is mounted. If not we return ENOSYS. */
61 struct __stat64_t64 st;
62 if (__stat64_time64 ("/proc/self/fd", &st) != 0 && errno == ENOENT)
63 save = ENOSYS;
64
65 __set_errno (save);
66#endif
67
68 return -1;
69}
70