+
−/* provide a replacement openat function
+
−   Copyright (C) 2004-2013 Free Software Foundation, Inc.
+
−
+
−   This program is free software: you can redistribute it and/or modify
+
−   it under the terms of the GNU General Public License as published by
+
−   the Free Software Foundation; either version 3 of the License, or
+
−   (at your option) any later version.
+
−
+
−   This program 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 General Public License for more details.
+
−
+
−   You should have received a copy of the GNU General Public License
+
−   along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
+
−
+
−/* written by Jim Meyering */
+
−
+
−/* If the user's config.h happens to include <fcntl.h>, let it include only
+
−   the system's <fcntl.h> here, so that orig_openat doesn't recurse to
+
−   rpl_openat.  */
+
−#define __need_system_fcntl_h
+
−#include <config.h>
+
−
+
−/* Get the original definition of open.  It might be defined as a macro.  */
+
−#include <fcntl.h>
+
−#include <sys/types.h>
+
−#undef __need_system_fcntl_h
+
−
+
−#if HAVE_OPENAT
+
−static int
+
−orig_openat (int fd, char const *filename, int flags, mode_t mode)
+
−{
+
−  return openat (fd, filename, flags, mode);
+
−}
+
−#endif
+
−
+
−/* Write "fcntl.h" here, not <fcntl.h>, otherwise OSF/1 5.1 DTK cc eliminates
+
−   this include because of the preliminary #include <fcntl.h> above.  */
+
−#include "fcntl.h"
+
−
+
−#include "openat.h"
+
−
+
−#include <stdarg.h>
+
−#include <stdbool.h>
+
−#include <stddef.h>
+
−#include <string.h>
+
−#include <sys/stat.h>
+
−#include <errno.h>
+
−
+
−#if HAVE_OPENAT
+
−
+
−/* Like openat, but work around Solaris 9 bugs with trailing slash.  */
+
−int
+
−rpl_openat (int dfd, char const *filename, int flags, ...)
+
−{
+
−  mode_t mode;
+
−  int fd;
+
−
+
−  mode = 0;
+
−  if (flags & O_CREAT)
+
−    {
+
−      va_list arg;
+
−      va_start (arg, flags);
+
−
+
−      /* We have to use PROMOTED_MODE_T instead of mode_t, otherwise GCC 4
+
−         creates crashing code when 'mode_t' is smaller than 'int'.  */
+
−      mode = va_arg (arg, PROMOTED_MODE_T);
+
−
+
−      va_end (arg);
+
−    }
+
−
+
−# if OPEN_TRAILING_SLASH_BUG
+
−  /* If the filename ends in a slash and one of O_CREAT, O_WRONLY, O_RDWR
+
−     is specified, then fail.
+
−     Rationale: POSIX <http://www.opengroup.org/susv3/basedefs/xbd_chap04.html>
+
−     says that
+
−       "A pathname that contains at least one non-slash character and that
+
−        ends with one or more trailing slashes shall be resolved as if a
+
−        single dot character ( '.' ) were appended to the pathname."
+
−     and
+
−       "The special filename dot shall refer to the directory specified by
+
−        its predecessor."
+
−     If the named file already exists as a directory, then
+
−       - if O_CREAT is specified, open() must fail because of the semantics
+
−         of O_CREAT,
+
−       - if O_WRONLY or O_RDWR is specified, open() must fail because POSIX
+
−         <http://www.opengroup.org/susv3/functions/open.html> says that it
+
−         fails with errno = EISDIR in this case.
+
−     If the named file does not exist or does not name a directory, then
+
−       - if O_CREAT is specified, open() must fail since open() cannot create
+
−         directories,
+
−       - if O_WRONLY or O_RDWR is specified, open() must fail because the
+
−         file does not contain a '.' directory.  */
+
−  if (flags & (O_CREAT | O_WRONLY | O_RDWR))
+
−    {
+
−      size_t len = strlen (filename);
+
−      if (len > 0 && filename[len - 1] == '/')
+
−        {
+
−          errno = EISDIR;
+
−          return -1;
+
−        }
+
−    }
+
−# endif
+
−
+
−  fd = orig_openat (dfd, filename, flags, mode);
+
−
+
−# if OPEN_TRAILING_SLASH_BUG
+
−  /* If the filename ends in a slash and fd does not refer to a directory,
+
−     then fail.
+
−     Rationale: POSIX <http://www.opengroup.org/susv3/basedefs/xbd_chap04.html>
+
−     says that
+
−       "A pathname that contains at least one non-slash character and that
+
−        ends with one or more trailing slashes shall be resolved as if a
+
−        single dot character ( '.' ) were appended to the pathname."
+
−     and
+
−       "The special filename dot shall refer to the directory specified by
+
−        its predecessor."
+
−     If the named file without the slash is not a directory, open() must fail
+
−     with ENOTDIR.  */
+
−  if (fd >= 0)
+
−    {
+
−      /* We know len is positive, since open did not fail with ENOENT.  */
+
−      size_t len = strlen (filename);
+
−      if (filename[len - 1] == '/')
+
−        {
+
−          struct stat statbuf;
+
−
+
−          if (fstat (fd, &statbuf) >= 0 && !S_ISDIR (statbuf.st_mode))
+
−            {
+
−              close (fd);
+
−              errno = ENOTDIR;
+
−              return -1;
+
−            }
+
−        }
+
−    }
+
−# endif
+
−
+
−  return fd;
+
−}
+
−
+
−#else /* !HAVE_OPENAT */
+
−
+
−# include "dosname.h" /* solely for definition of IS_ABSOLUTE_FILE_NAME */
+
−# include "openat-priv.h"
+
−# include "save-cwd.h"
+
−
+
−/* Replacement for Solaris' openat function.
+
−   <http://www.google.com/search?q=openat+site:docs.sun.com>
+
−   First, try to simulate it via open ("/proc/self/fd/FD/FILE").
+
−   Failing that, simulate it by doing save_cwd/fchdir/open/restore_cwd.
+
−   If either the save_cwd or the restore_cwd fails (relatively unlikely),
+
−   then give a diagnostic and exit nonzero.
+
−   Otherwise, upon failure, set errno and return -1, as openat does.
+
−   Upon successful completion, return a file descriptor.  */
+
−int
+
−openat (int fd, char const *file, int flags, ...)
+
−{
+
−  mode_t mode = 0;
+
−
+
−  if (flags & O_CREAT)
+
−    {
+
−      va_list arg;
+
−      va_start (arg, flags);
+
−
+
−      /* We have to use PROMOTED_MODE_T instead of mode_t, otherwise GCC 4
+
−         creates crashing code when 'mode_t' is smaller than 'int'.  */
+
−      mode = va_arg (arg, PROMOTED_MODE_T);
+
−
+
−      va_end (arg);
+
−    }
+
−
+
−  return openat_permissive (fd, file, flags, mode, NULL);
+
−}
+
−
+
−/* Like openat (FD, FILE, FLAGS, MODE), but if CWD_ERRNO is
+
−   nonnull, set *CWD_ERRNO to an errno value if unable to save
+
−   or restore the initial working directory.  This is needed only
+
−   the first time remove.c's remove_dir opens a command-line
+
−   directory argument.
+
−
+
−   If a previous attempt to restore the current working directory
+
−   failed, then we must not even try to access a '.'-relative name.
+
−   It is the caller's responsibility not to call this function
+
−   in that case.  */
+
−
+
−int
+
−openat_permissive (int fd, char const *file, int flags, mode_t mode,
+
−                   int *cwd_errno)
+
−{
+
−  struct saved_cwd saved_cwd;
+
−  int saved_errno;
+
−  int err;
+
−  bool save_ok;
+
−
+
−  if (fd == AT_FDCWD || IS_ABSOLUTE_FILE_NAME (file))
+
−    return open (file, flags, mode);
+
−
+
−  {
+
−    char buf[OPENAT_BUFFER_SIZE];
+
−    char *proc_file = openat_proc_name (buf, fd, file);
+
−    if (proc_file)
+
−      {
+
−        int open_result = open (proc_file, flags, mode);
+
−        int open_errno = errno;
+
−        if (proc_file != buf)
+
−          free (proc_file);
+
−        /* If the syscall succeeds, or if it fails with an unexpected
+
−           errno value, then return right away.  Otherwise, fall through
+
−           and resort to using save_cwd/restore_cwd.  */
+
−        if (0 <= open_result || ! EXPECTED_ERRNO (open_errno))
+
−          {
+
−            errno = open_errno;
+
−            return open_result;
+
−          }
+
−      }
+
−  }
+
−
+
−  save_ok = (save_cwd (&saved_cwd) == 0);
+
−  if (! save_ok)
+
−    {
+
−      if (! cwd_errno)
+
−        openat_save_fail (errno);
+
−      *cwd_errno = errno;
+
−    }
+
−  if (0 <= fd && fd == saved_cwd.desc)
+
−    {
+
−      /* If saving the working directory collides with the user's
+
−         requested fd, then the user's fd must have been closed to
+
−         begin with.  */
+
−      free_cwd (&saved_cwd);
+
−      errno = EBADF;
+
−      return -1;
+
−    }
+
−
+
−  err = fchdir (fd);
+
−  saved_errno = errno;
+
−
+
−  if (! err)
+
−    {
+
−      err = open (file, flags, mode);
+
−      saved_errno = errno;
+
−      if (save_ok && restore_cwd (&saved_cwd) != 0)
+
−        {
+
−          if (! cwd_errno)
+
−            {
+
−              /* Don't write a message to just-created fd 2.  */
+
−              saved_errno = errno;
+
−              if (err == STDERR_FILENO)
+
−                close (err);
+
−              openat_restore_fail (saved_errno);
+
−            }
+
−          *cwd_errno = errno;
+
−        }
+
−    }
+
−
+
−  free_cwd (&saved_cwd);
+
−  errno = saved_errno;
+
−  return err;
+
−}
+
−
+
−/* Return true if our openat implementation must resort to
+
−   using save_cwd and restore_cwd.  */
+
−bool
+
−openat_needs_fchdir (void)
+
−{
+
−  bool needs_fchdir = true;
+
−  int fd = open ("/", O_SEARCH);
+
−
+
−  if (0 <= fd)
+
−    {
+
−      char buf[OPENAT_BUFFER_SIZE];
+
−      char *proc_file = openat_proc_name (buf, fd, ".");
+
−      if (proc_file)
+
−        {
+
−          needs_fchdir = false;
+
−          if (proc_file != buf)
+
−            free (proc_file);
+
−        }
+
−      close (fd);
+
−    }
+
−
+
−  return needs_fchdir;
+
−}
+
−
+
−#endif /* !HAVE_OPENAT */