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/* Open a stream to a file.
Copyright (C) 2007-2023 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 <stdio.h>, let it include only
the system's <stdio.h> here, so that orig_fopen doesn't recurse to
rpl_fopen. */
#define _GL_ALREADY_INCLUDING_STDIO_H
#include <config.h>
/* Get the original definition of fopen. It might be defined as a macro. */
#include <stdio.h>
#undef _GL_ALREADY_INCLUDING_STDIO_H
static FILE *
orig_fopen (const char *filename, const char *mode)
{
return fopen (filename, mode);
}
/* Specification. */
/* Write "stdio.h" here, not <stdio.h>, otherwise OSF/1 5.1 DTK cc eliminates
this include because of the preliminary #include <stdio.h> above. */
#include "stdio.h"
#include <errno.h>
#include <fcntl.h>
#include <string.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/stat.h>
FILE *
rpl_fopen (const char *filename, const char *mode)
{
int open_direction;
int open_flags;
#if GNULIB_FOPEN_GNU
bool open_flags_gnu;
# define BUF_SIZE 80
char fdopen_mode_buf[BUF_SIZE + 1];
#endif
#if defined _WIN32 && ! defined __CYGWIN__
if (strcmp (filename, "/dev/null") == 0)
filename = "NUL";
#endif
/* Parse the mode. */
open_direction = 0;
open_flags = 0;
#if GNULIB_FOPEN_GNU
open_flags_gnu = false;
#endif
{
const char *p = mode;
#if GNULIB_FOPEN_GNU
char *q = fdopen_mode_buf;
#endif
for (; *p != '\0'; p++)
{
switch (*p)
{
case 'r':
open_direction = O_RDONLY;
#if GNULIB_FOPEN_GNU
if (q < fdopen_mode_buf + BUF_SIZE)
*q++ = *p;
#endif
continue;
case 'w':
open_direction = O_WRONLY;
open_flags |= O_CREAT | O_TRUNC;
#if GNULIB_FOPEN_GNU
if (q < fdopen_mode_buf + BUF_SIZE)
*q++ = *p;
#endif
continue;
case 'a':
open_direction = O_WRONLY;
open_flags |= O_CREAT | O_APPEND;
#if GNULIB_FOPEN_GNU
if (q < fdopen_mode_buf + BUF_SIZE)
*q++ = *p;
#endif
continue;
case 'b':
/* While it is non-standard, O_BINARY is guaranteed by
gnulib <fcntl.h>. We can also assume that orig_fopen
supports the 'b' flag. */
open_flags |= O_BINARY;
#if GNULIB_FOPEN_GNU
if (q < fdopen_mode_buf + BUF_SIZE)
*q++ = *p;
#endif
continue;
case '+':
open_direction = O_RDWR;
#if GNULIB_FOPEN_GNU
if (q < fdopen_mode_buf + BUF_SIZE)
*q++ = *p;
#endif
continue;
#if GNULIB_FOPEN_GNU
case 'x':
open_flags |= O_EXCL;
open_flags_gnu = true;
continue;
case 'e':
open_flags |= O_CLOEXEC;
open_flags_gnu = true;
continue;
#endif
default:
break;
}
#if GNULIB_FOPEN_GNU
/* The rest of the mode string can be a platform-dependent extension.
Copy it unmodified. */
{
size_t len = strlen (p);
if (len > fdopen_mode_buf + BUF_SIZE - q)
len = fdopen_mode_buf + BUF_SIZE - q;
memcpy (q, p, len);
q += len;
}
#endif
break;
}
#if GNULIB_FOPEN_GNU
*q = '\0';
#endif
}
#if FOPEN_TRAILING_SLASH_BUG
/* Fail if the mode requires write access 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 a mode that
requires write access is specified, fopen() must fail because POSIX
<https://pubs.opengroup.org/onlinepubs/9699919799/functions/fopen.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
fopen() must fail since the file does not contain a '.' directory. */
{
size_t len = strlen (filename);
if (len > 0 && filename[len - 1] == '/')
{
int fd;
struct stat statbuf;
FILE *fp;
if (open_direction != O_RDONLY)
{
errno = EISDIR;
return NULL;
}
fd = open (filename, open_direction | open_flags,
S_IRUSR | S_IWUSR | S_IRGRP | S_IWGRP | S_IROTH | S_IWOTH);
if (fd < 0)
return NULL;
if (fstat (fd, &statbuf) >= 0 && !S_ISDIR (statbuf.st_mode))
{
close (fd);
errno = ENOTDIR;
return NULL;
}
# if GNULIB_FOPEN_GNU
fp = fdopen (fd, fdopen_mode_buf);
# else
fp = fdopen (fd, mode);
# endif
if (fp == NULL)
{
int saved_errno = errno;
close (fd);
errno = saved_errno;
}
return fp;
}
}
#endif
#if GNULIB_FOPEN_GNU
if (open_flags_gnu)
{
int fd;
FILE *fp;
fd = open (filename, open_direction | open_flags,
S_IRUSR | S_IWUSR | S_IRGRP | S_IWGRP | S_IROTH | S_IWOTH);
if (fd < 0)
return NULL;
fp = fdopen (fd, fdopen_mode_buf);
if (fp == NULL)
{
int saved_errno = errno;
close (fd);
errno = saved_errno;
}
return fp;
}
#endif
/* open_direction is sometimes used, sometimes unused.
Silence gcc's warning about this situation. */
(void) open_direction;
return orig_fopen (filename, mode);
}
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