1 files changed, 79 insertions, 0 deletions
diff --git a/sysdeps/unix/sysv/linux/execveat.c b/sysdeps/unix/sysv/linux/execveat.c
new file mode 100644
index 0000000000..62f3f0514e
--- /dev/null
+++ b/sysdeps/unix/sysv/linux/execveat.c
@@ -0,0 +1,79 @@
+/* Copyright (C) 1994-2020 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 <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>
+#include <fd_to_filename.h>
+#include <not-cancel.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
+execveat (int dirfd, const char *path, char *const argv[], char *const envp[],
+          int flags)
+{
+  /* Avoid implicit array coercion in syscall macros.  */
+  INLINE_SYSCALL_CALL (execveat, dirfd, path, &argv[0], &envp[0], flags);
+#ifndef __ASSUME_EXECVEAT
+  if (errno != ENOSYS)
+    return -1;
+
+  if ((flags & ~(AT_EMPTY_PATH | AT_SYMLINK_NOFOLLOW)) != 0)
+    return EINVAL;
+
+  int fd;
+  if (path[0] == '\0' && (flags & AT_EMPTY_PATH) && dirfd >= 0)
+    fd = dirfd;
+  else
+    {
+      int oflags = O_CLOEXEC;
+      if (flags & AT_SYMLINK_NOFOLLOW)
+        oflags |= O_NOFOLLOW;
+      fd = openat (dirfd, path, oflags);
+    }
+  if (fd < 0)
+    return -1;
+
+  struct fd_to_filename fdfilename;
+  const char *gfilename = __fd_to_filename (fd, &fdfilename);
+
+  /* We do not need the return value.  */
+  __execve (gfilename, 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;
+
+  if (fd != dirfd)
+    __close_nocancel (fd);
+  __set_errno (save);
+#endif
+
+  return -1;
+}