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/* Open a descriptor to a file.
Copyright (C) 2007-2024 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. */
#ifdef __osf__
/* 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"
#else
# include <fcntl.h>
#endif
#include "cloexec.h"
#include <errno.h>
#include <stdarg.h>
#include <string.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <unistd.h>
#ifndef REPLACE_OPEN_DIRECTORY
# define REPLACE_OPEN_DIRECTORY 0
#endif
int
open (const char *filename, int flags, ...)
{
/* 0 = unknown, 1 = yes, -1 = no. */
#if GNULIB_defined_O_CLOEXEC
int have_cloexec = -1;
#else
static int have_cloexec;
#endif
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 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 (strcmp (filename, "/dev/null") == 0)
filename = "NUL";
#endif
#if OPEN_TRAILING_SLASH_BUG
/* 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. */
if ((flags & O_CREAT)
|| (flags & O_ACCMODE) == O_RDWR
|| (flags & O_ACCMODE) == O_WRONLY)
{
size_t len = strlen (filename);
if (len > 0 && filename[len - 1] == '/')
{
errno = EISDIR;
return -1;
}
}
#endif
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), we 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 fact that we have a
dummy. */
if (REPLACE_OPEN_DIRECTORY && fd < 0 && errno == EACCES
&& ((flags & O_ACCMODE) == O_RDONLY
|| (O_SEARCH != O_RDONLY && (flags & O_ACCMODE) == O_SEARCH)))
{
struct stat statbuf;
if (stat (filename, &statbuf) == 0 && S_ISDIR (statbuf.st_mode))
{
/* Maximum recursion depth of 1. */
fd = open ("/dev/null", flags, mode);
if (0 <= fd)
fd = _gl_register_fd (fd, filename);
}
else
errno = EACCES;
}
#endif
#if OPEN_TRAILING_SLASH_BUG
/* If the filename ends in a slash and fd does not refer to a directory,
then fail.
Rationale: 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 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
#if REPLACE_FCHDIR
if (!REPLACE_OPEN_DIRECTORY && 0 <= fd)
fd = _gl_register_fd (fd, filename);
#endif
return fd;
}
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