diff options
Diffstat (limited to 'sysdeps')
| -rw-r--r-- | sysdeps/posix/tempname.c | 17 | ||||
| -rw-r--r-- | sysdeps/unix/i386/i686/tempname.c | 35 |
2 files changed, 50 insertions, 2 deletions
diff --git a/sysdeps/posix/tempname.c b/sysdeps/posix/tempname.c index ae22f10df9..088da95758 100644 --- a/sysdeps/posix/tempname.c +++ b/sysdeps/posix/tempname.c @@ -107,6 +107,15 @@ # define __secure_getenv getenv #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 + /* Return nonzero if DIR is an existent directory. */ static int direxists (const char *dir) @@ -218,14 +227,18 @@ __gen_tempname (char *tmpl, int kind) XXXXXX = &tmpl[len - 6]; /* Get some more or less random data. */ -#if HAVE_GETTIMEOFDAY || _LIBC +#ifdef RANDOM_BITS + RANDOM_BITS (random_time_bits); +#else +# if HAVE_GETTIMEOFDAY || _LIBC { struct timeval tv; __gettimeofday (&tv, NULL); random_time_bits = ((uint64_t) tv.tv_usec << 16) ^ tv.tv_sec; } -#else +# else random_time_bits = time (NULL); +# endif #endif value += random_time_bits ^ __getpid (); diff --git a/sysdeps/unix/i386/i686/tempname.c b/sysdeps/unix/i386/i686/tempname.c new file mode 100644 index 0000000000..3d2476e612 --- /dev/null +++ b/sysdeps/unix/i386/i686/tempname.c @@ -0,0 +1,35 @@ +/* Copyright (C) 2001 Free Software Foundation, Inc. + This file is part of the GNU C Library. + + The GNU C Library 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. + + The GNU C Library 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 the GNU C Library; see the file COPYING.LIB. If not, + write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330, + Boston, MA 02111-1307, USA. */ + +/* For i686 and up we have a better and faster source of random bits in the + form of the time stamp counter. */ +#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; \ + } \ + __asm__ __volatile__ ("rdtsc" : "=A" (Var)) + +#include_next <tempname.c> |