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/* Utility to pick a temporary filename prefix.
Copyright (C) 1996 Free Software Foundation, Inc.
This file is part of the libiberty library.
Libiberty is free software; you can redistribute it and/or
modify it under the terms of the GNU Library General Public
License as published by the Free Software Foundation; either
version 2 of the License, or (at your option) any later version.
Libiberty 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
Library General Public License for more details.
You should have received a copy of the GNU Library General Public
License along with libiberty; see the file COPYING.LIB. If not,
write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
Boston, MA 02111-1307, USA. */
/* This file exports one function: choose_temp_base. */
/* This file lives in at least two places: libiberty and gcc.
Don't change one without the other. */
#ifndef NO_SYS_FILE_H
#include <sys/types.h>
#include <sys/file.h> /* May get R_OK, etc. on some systems. */
#endif
#ifndef R_OK
#define R_OK 4
#define W_OK 2
#define X_OK 1
#endif
#include <stdio.h> /* May get P_tmpdir. */
#ifdef IN_GCC
#include "config.h"
#include "gansidecl.h"
extern char *xmalloc ();
#else
#include "ansidecl.h"
#include "libiberty.h"
#if defined (__MSDOS__) || defined (_WIN32)
#define DIR_SEPARATOR '\\'
#endif
#endif
#ifndef DIR_SEPARATOR
#define DIR_SEPARATOR '/'
#endif
/* On MSDOS, write temp files in current dir
because there's no place else we can expect to use. */
/* ??? Although the current directory is tried as a last resort,
this is left in so that on MSDOS it is prefered to /tmp on the
off chance that someone requires this, since that was the previous
behaviour. */
#ifdef __MSDOS__
#ifndef P_tmpdir
#define P_tmpdir "."
#endif
#endif
/* Name of temporary file.
mktemp requires 6 trailing X's. */
#define TEMP_FILE "ccXXXXXX"
/* Subroutine of choose_temp_base.
If BASE is non-NULL, return it.
Otherwise it checks if DIR is a usable directory.
If success, DIR is returned.
Otherwise NULL is returned. */
static char *
try (dir, base)
char *dir, *base;
{
if (base != 0)
return base;
if (dir != 0
&& access (dir, R_OK | W_OK | X_OK) == 0)
return dir;
return 0;
}
/* Return a prefix for temporary file names or NULL if unable to find one.
The current directory is chosen if all else fails so the program is
exited if a temporary directory can't be found (mktemp fails).
The buffer for the result is obtained with xmalloc. */
char *
choose_temp_base ()
{
char *base = 0;
char *temp_filename;
int len;
static char tmp[] = { DIR_SEPARATOR, 't', 'm', 'p', 0 };
static char usrtmp[] = { DIR_SEPARATOR, 'u', 's', 'r', DIR_SEPARATOR, 't', 'm', 'p', 0 };
#ifndef MPW
base = try (getenv ("TMPDIR"), base);
base = try (getenv ("TMP"), base);
base = try (getenv ("TEMP"), base);
#ifdef P_tmpdir
base = try (P_tmpdir, base);
#endif
/* Try /usr/tmp, then /tmp. */
base = try (usrtmp, base);
base = try (tmp, base);
/* If all else fails, use the current directory! */
if (base == 0)
#ifdef VMS
base = "[";
#else
base = ".";
#endif
#else /* MPW */
base = ":";
#endif
len = strlen (base);
temp_filename = xmalloc (len + 1 /*DIR_SEPARATOR*/
+ strlen (TEMP_FILE) + 1);
strcpy (temp_filename, base);
#ifndef MPW
if (len != 0
&& temp_filename[len-1] != '/'
&& temp_filename[len-1] != DIR_SEPARATOR)
temp_filename[len++] = DIR_SEPARATOR;
#else /* MPW */
if (temp_filename[len-1] != ':')
temp_filename[len++] = ':';
#endif /* MPW */
strcpy (temp_filename + len, TEMP_FILE);
#ifndef HAVE_MKSTEMP
/* old behaviour - this can be abused through a symlink attack */
mktemp (temp_filename);
if (strlen (temp_filename) == 0)
abort ();
#else
/* mktemp is insecure; mkstemp isn't. According to the GNU libc docs:
* Unlike `mktemp', `mkstemp' is actually guaranteed to create a unique
* file that cannot possibly clash with any other program trying to
* create a temporary file. This is because it works by calling `open'
* with the `O_EXCL' flag bit, which says you want to always create a new
* file, and get an error if the file already exists.
* This is of course assuming the tempdir used has proper Unix filesystem
* semantics - if not (e.g. NFS), we're still lost.
*
* We assume mkstemp(3) is properly implemented (not like mkstemp from glibc
* 2.0.6 and earlier which creates the tempfile mode 0666, according to
* mkstemp(3) from the Linux manpages release 1.19)
*/
{
int fd;
fd = mkstemp (temp_filename);
if (fd == -1)
abort ();
if (close(fd))
abort ();
}
#endif /* HAVE_MKSTEMP */
return temp_filename;
}
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