open.c

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Hash : 26fd3545
Author :
Date : 2025-09-16T23:08:01

stringeq: prefer streq to strcmp in other modules

* lib/acl-internal.c, lib/argmatch.c, lib/argp-help.c:
* lib/argp-parse.c, lib/bcp47.c, lib/c32_get_mapping.c:
* lib/c32_get_type_test.c, lib/concat-filename.c:
* lib/cpu-supports.h, lib/dfa.c, lib/duplocale.c, lib/exclude.c:
* lib/findprog-in.c, lib/findprog.c, lib/fopen.c, lib/freopen.c:
* lib/fts.c, lib/gen-uni-tables.c, lib/getfilecon.c:
* lib/getlogin.c, lib/getugroups.c, lib/hard-locale.c:
* lib/hashcode-named-file.c, lib/hashkey-string.c:
* lib/iconv_open.c, lib/idcache.c, lib/lc-charset-unicode.c:
* lib/localcharset.c, lib/localename-environ.c:
* lib/localename-unsafe.c, lib/mbs_endswith.c, lib/mountlist.c:
* lib/newlocale.c, lib/nl_langinfo.c, lib/nproc.c, lib/open.c:
* lib/os2-spawn.c, lib/parse-datetime.y, lib/popen.c:
* lib/progreloc.c, lib/propername.c, lib/pt_chown.c, lib/putenv.c:
* lib/qcopy-acl.c, lib/readutmp.c, lib/rpmatch.c:
* lib/setlocale-fixes.c, lib/setlocale.c, lib/sig2str.c:
* lib/spawni.c, lib/stat.c, lib/str_endswith.c, lib/streq.h:
* lib/striconveha.c, lib/struniq.h, lib/supersede.c:
* lib/time_rz.c, lib/unicodeio.c, lib/vasnprintf.c:
* lib/vc-mtime.c, lib/wctrans-impl.h, lib/wctype-impl.h:
Prefer streq to strcmp when either will do.
Do not make this change to files shared with glibc.
Do not make the change to test files, at least not for now.
* lib/gen-uni-tables.c (streq): New static function, in same style.
* modules/acl-permissions, modules/argp, modules/c32_get_mapping:
* modules/c32_get_type_test, modules/concat-filename:
* modules/cpu-supports, modules/dfa, modules/duplocale:
* modules/exclude, modules/findprog, modules/findprog-in:
* modules/fopen, modules/fopen-gnu, modules/freopen, modules/fts:
* modules/getlocalename_l-simple, modules/getlocalename_l-unsafe:
* modules/getlogin, modules/getugroups, modules/hard-locale:
* modules/hashcode-named-file, modules/hashkey-string:
* modules/iconv_open, modules/idcache, modules/localcharset:
* modules/localename, modules/localename-unsafe:
* modules/mbs_endswith, modules/mountlist, modules/newlocale:
* modules/nl_langinfo, modules/nproc, modules/open:
* modules/parse-datetime, modules/popen:
* modules/posix_spawn-internal, modules/propername:
* modules/pt_chown, modules/putenv-gnu, modules/qcopy-acl:
* modules/rpmatch, modules/selinux-h, modules/setenv:
* modules/setlocale, modules/setlocale-fixes, modules/sig2str:
* modules/spawn-pipe, modules/stat, modules/str_endswith:
* modules/streq, modules/striconveha, modules/supersede:
* modules/time_rz, modules/uchar-h, modules/unicodeio:
* modules/uniconv/base, modules/wctrans, modules/wctype:
(Depends-on): Add stringeq.

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lib/open.c

/* Open a descriptor to a file.
   Copyright (C) 2007-2025 Free Software Foundation, Inc.

   This file 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.

   This file 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 this program.  If not, see <https://www.gnu.org/licenses/>.  */

/* Written by Bruno Haible <bruno@clisp.org>, 2007.  */

/* If the user's config.h happens to include <fcntl.h>, let it include only
   the system's <fcntl.h> here, so that orig_open doesn't recurse to
   rpl_open.  */
#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

static int
orig_open (const char *filename, int flags, mode_t mode)
{
#if defined _WIN32 && !defined __CYGWIN__
  return _open (filename, flags, mode);
#else
  return open (filename, flags, mode);
#endif
}

/* Specification.  */
#include <fcntl.h>

#include "cloexec.h"

#include <errno.h>
#include <stdarg.h>
#include <string.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <unistd.h>

#ifndef HAVE_WORKING_O_DIRECTORY
# define HAVE_WORKING_O_DIRECTORY false
#endif

#ifndef OPEN_TRAILING_SLASH_BUG
# define OPEN_TRAILING_SLASH_BUG false
#endif

#ifndef REPLACE_OPEN_DIRECTORY
# define REPLACE_OPEN_DIRECTORY false
#endif

static int
lstatif (char const *filename, struct stat *st, int flags)
{
  return flags & O_NOFOLLOW ? lstat (filename, st) : stat (filename, st);
}

int
open (const char *filename, 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);
    }

#if GNULIB_defined_O_NONBLOCK
  /* The only known platform that lacks O_NONBLOCK is mingw, but it
     also lacks named pipes and Unix sockets, which are the only two
     file types that require non-blocking handling in open().
     Therefore, it is safe to ignore O_NONBLOCK here.  It is handy
     that mingw also lacks openat(), so that is also covered here.  */
  flags &= ~O_NONBLOCK;
#endif

#if defined _WIN32 && ! defined __CYGWIN__
  if (streq (filename, "/dev/null"))
    filename = "NUL";
#endif

  /* Fail if one of O_CREAT, O_WRONLY, O_RDWR is specified and the filename
     ends in a slash, as POSIX says such a filename must name a directory
     <https://pubs.opengroup.org/onlinepubs/9699919799/basedefs/V1_chap04.html#tag_04_13>:
       "A pathname that contains at least one non-<slash> character and that
        ends with one or more trailing <slash> characters shall not be resolved
        successfully unless the last pathname component before the trailing
        <slash> characters names an existing directory"
     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
         <https://pubs.opengroup.org/onlinepubs/9699919799/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.  */
  bool check_for_slash_bug;
  if (OPEN_TRAILING_SLASH_BUG)
    {
      size_t len = strlen (filename);
      check_for_slash_bug = len && filename[len - 1] == '/';
    }
  else
    check_for_slash_bug = false;

  if (check_for_slash_bug
      && (flags & O_CREAT
          || (flags & O_ACCMODE) == O_RDWR
          || (flags & O_ACCMODE) == O_WRONLY))
    {
      errno = EISDIR;
      return -1;
    }

  /* With the trailing slash bug or without working O_DIRECTORY, check with
     stat first lest we hang trying to open a fifo.  Although there is
     a race between this and opening the file, we can do no better.
     After opening the file we will check again with fstat.  */
  bool check_directory =
    (check_for_slash_bug
     || (!HAVE_WORKING_O_DIRECTORY && flags & O_DIRECTORY));
  if (check_directory)
    {
      struct stat statbuf;
      if (lstatif (filename, &statbuf, flags) < 0)
        {
          if (! (flags & O_CREAT && errno == ENOENT))
            return -1;
        }
      else if (!S_ISDIR (statbuf.st_mode))
        {
          errno = ENOTDIR;
          return -1;
        }
    }

  /* 0 = unknown, 1 = yes, -1 = no.  */
#if GNULIB_defined_O_CLOEXEC
  int have_cloexec = -1;
#else
  static int have_cloexec;
#endif

  int fd = orig_open (filename,
                      flags & ~(have_cloexec < 0 ? O_CLOEXEC : 0), mode);

  if (flags & O_CLOEXEC)
    {
      if (! have_cloexec)
        {
          if (0 <= fd)
            have_cloexec = 1;
          else if (errno == EINVAL)
            {
              fd = orig_open (filename, flags & ~O_CLOEXEC, mode);
              have_cloexec = -1;
            }
        }
      if (have_cloexec < 0 && 0 <= fd)
        set_cloexec_flag (fd, true);
    }


#if REPLACE_FCHDIR
  /* Implementing fchdir and fdopendir requires the ability to open a
     directory file descriptor.  If open doesn't support that (as on
     mingw), use a dummy file that behaves the same as directories
     on Linux (ie. always reports EOF on attempts to read()), and
     override fstat in fchdir.c to hide the dummy.  */
  if (REPLACE_OPEN_DIRECTORY && fd < 0 && errno == EACCES
      && ((flags & (O_ACCMODE | O_CREAT)) == O_RDONLY
          || (O_SEARCH != O_RDONLY
              && (flags & (O_ACCMODE | O_CREAT)) == O_SEARCH)))
    {
      struct stat statbuf;
      if (check_directory
          || (lstatif (filename, &statbuf, flags) == 0
              && S_ISDIR (statbuf.st_mode)))
        {
          /* Maximum recursion depth of 1.  */
          fd = open ("/dev/null", flags & ~O_DIRECTORY, mode);
          if (0 <= fd)
            fd = _gl_register_fd (fd, filename);
        }
      else
        errno = EACCES;
    }
#endif

  /* If checking for directories, fail if fd does not refer to a directory.
     Rationale: A filename ending in slash cannot name a non-directory
     <https://pubs.opengroup.org/onlinepubs/9699919799/basedefs/V1_chap04.html#tag_04_13>:
       "A pathname that contains at least one non-<slash> character and that
        ends with one or more trailing <slash> characters shall not be resolved
        successfully unless the last pathname component before the trailing
        <slash> characters names an existing directory"
     If the named file without the slash is not a directory, open() must fail
     with ENOTDIR.  */
  if (check_directory && 0 <= fd)
    {
      struct stat statbuf;
      int r = fstat (fd, &statbuf);
      if (r < 0 || !S_ISDIR (statbuf.st_mode))
        {
          int err = r < 0 ? errno : ENOTDIR;
          close (fd);
          errno = err;
          return -1;
        }
    }

#if REPLACE_FCHDIR
  if (!REPLACE_OPEN_DIRECTORY && 0 <= fd)
    fd = _gl_register_fd (fd, filename);
#endif

  return fd;
}

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kc3-lang/gnulib/lib/open.c

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lib/open.c