1 /* $NetBSD: tmpname.cpp,v 1.1.1.1 2016/01/13 18:41:48 christos Exp $ */ 2 3 /* Copyright (C) 2001, 2003, 2004 Free Software Foundation, Inc. 4 Written by Werner Lemberg (wl@gnu.org) 5 6 This file is part of groff. 7 8 groff is free software; you can redistribute it and/or modify it under 9 the terms of the GNU General Public License as published by the Free 10 Software Foundation; either version 2, or (at your option) any later 11 version. 12 13 groff is distributed in the hope that it will be useful, but WITHOUT ANY 14 WARRANTY; without even the implied warranty of MERCHANTABILITY or 15 FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 16 for more details. 17 18 You should have received a copy of the GNU General Public License along 19 with groff; see the file COPYING. If not, write to the Free Software 20 Foundation, 51 Franklin St - Fifth Floor, Boston, MA 02110-1301, USA. */ 21 22 23 /* This file is heavily based on the function __gen_tempname() in the 24 file tempname.c which is part of the fileutils package. */ 25 26 27 #include "lib.h" 28 29 #include <stddef.h> 30 #include <stdlib.h> 31 #include <errno.h> 32 #include <time.h> 33 34 #include "posix.h" 35 #include "nonposix.h" 36 37 #ifndef TMP_MAX 38 # define TMP_MAX 238328 39 #endif 40 41 #if HAVE_SYS_TIME_H 42 # include <sys/time.h> 43 #endif 44 45 #ifdef HAVE_GETTIMEOFDAY 46 #ifdef NEED_DECLARATION_GETTIMEOFDAY 47 extern "C" { 48 int gettimeofday(struct timeval *, void *); 49 } 50 #endif 51 #endif 52 53 #if HAVE_CC_INTTYPES_H 54 # include <inttypes.h> 55 #endif 56 57 /* Use the widest available unsigned type if uint64_t is not 58 available. The algorithm below extracts a number less than 62**6 59 (approximately 2**35.725) from uint64_t, so ancient hosts where 60 uintmax_t is only 32 bits lose about 3.725 bits of randomness, 61 which is better than not having mkstemp at all. */ 62 #if !defined UINT64_MAX && !defined uint64_t 63 # define uint64_t uintmax_t 64 #endif 65 66 /* These are the characters used in temporary filenames. */ 67 static const char letters[] = 68 "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789"; 69 70 int gen_tempname(char *tmpl, int dir) 71 { 72 static uint64_t value; 73 74 size_t len = strlen(tmpl); 75 if (len < 6 || strcmp(&tmpl[len - 6], "XXXXXX")) 76 return -1; /* EINVAL */ 77 78 /* This is where the Xs start. */ 79 char *XXXXXX = &tmpl[len - 6]; 80 81 /* Get some more or less random data. */ 82 #if HAVE_GETTIMEOFDAY 83 timeval tv; 84 gettimeofday(&tv, NULL); 85 uint64_t random_time_bits = ((uint64_t)tv.tv_usec << 16) ^ tv.tv_sec; 86 #else 87 uint64_t random_time_bits = time(NULL); 88 #endif 89 value += random_time_bits ^ getpid(); 90 91 for (int count = 0; count < TMP_MAX; value += 7777, ++count) { 92 uint64_t v = value; 93 94 /* Fill in the random bits. */ 95 XXXXXX[0] = letters[v % 62]; 96 v /= 62; 97 XXXXXX[1] = letters[v % 62]; 98 v /= 62; 99 XXXXXX[2] = letters[v % 62]; 100 v /= 62; 101 XXXXXX[3] = letters[v % 62]; 102 v /= 62; 103 XXXXXX[4] = letters[v % 62]; 104 v /= 62; 105 XXXXXX[5] = letters[v % 62]; 106 107 int fd = dir ? mkdir(tmpl, S_IRUSR | S_IWUSR | S_IXUSR) 108 : open(tmpl, O_RDWR | O_CREAT | O_EXCL, S_IRUSR | S_IWUSR); 109 110 if (fd >= 0) 111 return fd; 112 else if (errno != EEXIST) 113 return -1; 114 } 115 116 /* We got out of the loop because we ran out of combinations to try. */ 117 return -1; /* EEXIST */ 118 } 119