+
−/* tempname.c - generate the name of a temporary file.
+
−
+
−   Copyright (C) 1991-2003, 2005-2007, 2009-2013 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/>.  */
+
−
+
−/* Extracted from glibc sysdeps/posix/tempname.c.  See also tmpdir.c.  */
+
−
+
−#if !_LIBC
+
−# include <config.h>
+
−# include "tempname.h"
+
−#endif
+
−
+
−#include <sys/types.h>
+
−#include <assert.h>
+
−
+
−#include <errno.h>
+
−#ifndef __set_errno
+
−# define __set_errno(Val) errno = (Val)
+
−#endif
+
−
+
−#include <stdio.h>
+
−#ifndef P_tmpdir
+
−# define P_tmpdir "/tmp"
+
−#endif
+
−#ifndef TMP_MAX
+
−# define TMP_MAX 238328
+
−#endif
+
−#ifndef __GT_FILE
+
−# define __GT_FILE      0
+
−# define __GT_DIR       1
+
−# define __GT_NOCREATE  2
+
−#endif
+
−#if !_LIBC && (GT_FILE != __GT_FILE || GT_DIR != __GT_DIR       \
+
−               || GT_NOCREATE != __GT_NOCREATE)
+
−# error report this to bug-gnulib@gnu.org
+
−#endif
+
−
+
−#include <stddef.h>
+
−#include <stdlib.h>
+
−#include <string.h>
+
−
+
−#include <fcntl.h>
+
−#include <sys/time.h>
+
−#include <stdint.h>
+
−#include <unistd.h>
+
−
+
−#include <sys/stat.h>
+
−
+
−#if _LIBC
+
−# define struct_stat64 struct stat64
+
−#else
+
−# define struct_stat64 struct stat
+
−# define __gen_tempname gen_tempname
+
−# define __getpid getpid
+
−# define __gettimeofday gettimeofday
+
−# define __mkdir mkdir
+
−# define __open open
+
−# define __lxstat64(version, file, buf) lstat (file, buf)
+
−# define __secure_getenv secure_getenv
+
−#endif
+
−
+
−#ifdef _LIBC
+
−# include <hp-timing.h>
+
−# if HP_TIMING_AVAIL
+
−#  define RANDOM_BITS(Var) \
+
−  if (__builtin_expect (value == UINT64_C (0), 0))                            \
+
−    {                                                                         \
+
−      /* If this is the first time this function is used initialize           \
+
−         the variable we accumulate the value in to some somewhat             \
+
−         random value.  If we'd not do this programs at startup time          \
+
−         might have a reduced set of possible names, at least on slow         \
+
−         machines.  */                                                        \
+
−      struct timeval tv;                                                      \
+
−      __gettimeofday (&tv, NULL);                                             \
+
−      value = ((uint64_t) tv.tv_usec << 16) ^ tv.tv_sec;                      \
+
−    }                                                                         \
+
−  HP_TIMING_NOW (Var)
+
−# endif
+
−#endif
+
−
+
−/* Use the widest available unsigned type if uint64_t is not
+
−   available.  The algorithm below extracts a number less than 62**6
+
−   (approximately 2**35.725) from uint64_t, so ancient hosts where
+
−   uintmax_t is only 32 bits lose about 3.725 bits of randomness,
+
−   which is better than not having mkstemp at all.  */
+
−#if !defined UINT64_MAX && !defined uint64_t
+
−# define uint64_t uintmax_t
+
−#endif
+
−
+
−#if _LIBC
+
−/* Return nonzero if DIR is an existent directory.  */
+
−static int
+
−direxists (const char *dir)
+
−{
+
−  struct_stat64 buf;
+
−  return __xstat64 (_STAT_VER, dir, &buf) == 0 && S_ISDIR (buf.st_mode);
+
−}
+
−
+
−/* Path search algorithm, for tmpnam, tmpfile, etc.  If DIR is
+
−   non-null and exists, uses it; otherwise uses the first of $TMPDIR,
+
−   P_tmpdir, /tmp that exists.  Copies into TMPL a template suitable
+
−   for use with mk[s]temp.  Will fail (-1) if DIR is non-null and
+
−   doesn't exist, none of the searched dirs exists, or there's not
+
−   enough space in TMPL. */
+
−int
+
−__path_search (char *tmpl, size_t tmpl_len, const char *dir, const char *pfx,
+
−               int try_tmpdir)
+
−{
+
−  const char *d;
+
−  size_t dlen, plen;
+
−
+
−  if (!pfx || !pfx[0])
+
−    {
+
−      pfx = "file";
+
−      plen = 4;
+
−    }
+
−  else
+
−    {
+
−      plen = strlen (pfx);
+
−      if (plen > 5)
+
−        plen = 5;
+
−    }
+
−
+
−  if (try_tmpdir)
+
−    {
+
−      d = __secure_getenv ("TMPDIR");
+
−      if (d != NULL && direxists (d))
+
−        dir = d;
+
−      else if (dir != NULL && direxists (dir))
+
−        /* nothing */ ;
+
−      else
+
−        dir = NULL;
+
−    }
+
−  if (dir == NULL)
+
−    {
+
−      if (direxists (P_tmpdir))
+
−        dir = P_tmpdir;
+
−      else if (strcmp (P_tmpdir, "/tmp") != 0 && direxists ("/tmp"))
+
−        dir = "/tmp";
+
−      else
+
−        {
+
−          __set_errno (ENOENT);
+
−          return -1;
+
−        }
+
−    }
+
−
+
−  dlen = strlen (dir);
+
−  while (dlen > 1 && dir[dlen - 1] == '/')
+
−    dlen--;                     /* remove trailing slashes */
+
−
+
−  /* check we have room for "${dir}/${pfx}XXXXXX\0" */
+
−  if (tmpl_len < dlen + 1 + plen + 6 + 1)
+
−    {
+
−      __set_errno (EINVAL);
+
−      return -1;
+
−    }
+
−
+
−  sprintf (tmpl, "%.*s/%.*sXXXXXX", (int) dlen, dir, (int) plen, pfx);
+
−  return 0;
+
−}
+
−#endif /* _LIBC */
+
−
+
−/* These are the characters used in temporary file names.  */
+
−static const char letters[] =
+
−"abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789";
+
−
+
−/* Generate a temporary file name based on TMPL.  TMPL must match the
+
−   rules for mk[s]temp (i.e. end in "XXXXXX", possibly with a suffix).
+
−   The name constructed does not exist at the time of the call to
+
−   __gen_tempname.  TMPL is overwritten with the result.
+
−
+
−   KIND may be one of:
+
−   __GT_NOCREATE:       simply verify that the name does not exist
+
−                        at the time of the call.
+
−   __GT_FILE:           create the file using open(O_CREAT|O_EXCL)
+
−                        and return a read-write fd.  The file is mode 0600.
+
−   __GT_DIR:            create a directory, which will be mode 0700.
+
−
+
−   We use a clever algorithm to get hard-to-predict names. */
+
−int
+
−__gen_tempname (char *tmpl, int suffixlen, int flags, int kind)
+
−{
+
−  int len;
+
−  char *XXXXXX;
+
−  static uint64_t value;
+
−  uint64_t random_time_bits;
+
−  unsigned int count;
+
−  int fd = -1;
+
−  int save_errno = errno;
+
−  struct_stat64 st;
+
−
+
−  /* A lower bound on the number of temporary files to attempt to
+
−     generate.  The maximum total number of temporary file names that
+
−     can exist for a given template is 62**6.  It should never be
+
−     necessary to try all of these combinations.  Instead if a reasonable
+
−     number of names is tried (we define reasonable as 62**3) fail to
+
−     give the system administrator the chance to remove the problems.  */
+
−#define ATTEMPTS_MIN (62 * 62 * 62)
+
−
+
−  /* The number of times to attempt to generate a temporary file.  To
+
−     conform to POSIX, this must be no smaller than TMP_MAX.  */
+
−#if ATTEMPTS_MIN < TMP_MAX
+
−  unsigned int attempts = TMP_MAX;
+
−#else
+
−  unsigned int attempts = ATTEMPTS_MIN;
+
−#endif
+
−
+
−  len = strlen (tmpl);
+
−  if (len < 6 + suffixlen || memcmp (&tmpl[len - 6 - suffixlen], "XXXXXX", 6))
+
−    {
+
−      __set_errno (EINVAL);
+
−      return -1;
+
−    }
+
−
+
−  /* This is where the Xs start.  */
+
−  XXXXXX = &tmpl[len - 6 - suffixlen];
+
−
+
−  /* Get some more or less random data.  */
+
−#ifdef RANDOM_BITS
+
−  RANDOM_BITS (random_time_bits);
+
−#else
+
−  {
+
−    struct timeval tv;
+
−    __gettimeofday (&tv, NULL);
+
−    random_time_bits = ((uint64_t) tv.tv_usec << 16) ^ tv.tv_sec;
+
−  }
+
−#endif
+
−  value += random_time_bits ^ __getpid ();
+
−
+
−  for (count = 0; count < attempts; value += 7777, ++count)
+
−    {
+
−      uint64_t v = value;
+
−
+
−      /* Fill in the random bits.  */
+
−      XXXXXX[0] = letters[v % 62];
+
−      v /= 62;
+
−      XXXXXX[1] = letters[v % 62];
+
−      v /= 62;
+
−      XXXXXX[2] = letters[v % 62];
+
−      v /= 62;
+
−      XXXXXX[3] = letters[v % 62];
+
−      v /= 62;
+
−      XXXXXX[4] = letters[v % 62];
+
−      v /= 62;
+
−      XXXXXX[5] = letters[v % 62];
+
−
+
−      switch (kind)
+
−        {
+
−        case __GT_FILE:
+
−          fd = __open (tmpl,
+
−                       (flags & ~O_ACCMODE)
+
−                       | O_RDWR | O_CREAT | O_EXCL, S_IRUSR | S_IWUSR);
+
−          break;
+
−
+
−        case __GT_DIR:
+
−          fd = __mkdir (tmpl, S_IRUSR | S_IWUSR | S_IXUSR);
+
−          break;
+
−
+
−        case __GT_NOCREATE:
+
−          /* This case is backward from the other three.  __gen_tempname
+
−             succeeds if __xstat fails because the name does not exist.
+
−             Note the continue to bypass the common logic at the bottom
+
−             of the loop.  */
+
−          if (__lxstat64 (_STAT_VER, tmpl, &st) < 0)
+
−            {
+
−              if (errno == ENOENT)
+
−                {
+
−                  __set_errno (save_errno);
+
−                  return 0;
+
−                }
+
−              else
+
−                /* Give up now. */
+
−                return -1;
+
−            }
+
−          continue;
+
−
+
−        default:
+
−          assert (! "invalid KIND in __gen_tempname");
+
−          abort ();
+
−        }
+
−
+
−      if (fd >= 0)
+
−        {
+
−          __set_errno (save_errno);
+
−          return fd;
+
−        }
+
−      else if (errno != EEXIST)
+
−        return -1;
+
−    }
+
−
+
−  /* We got out of the loop because we ran out of combinations to try.  */
+
−  __set_errno (EEXIST);
+
−  return -1;
+
−}