1 /* $NetBSD: cmpbuf.c,v 1.1.1.1 2016/01/13 03:15:30 christos Exp $ */ 2 3 /* Buffer primitives for comparison operations. 4 5 Copyright (C) 1993, 1995, 1998, 2001, 2002 Free Software Foundation, Inc. 6 7 This program is free software; you can redistribute it and/or modify 8 it under the terms of the GNU General Public License as published by 9 the Free Software Foundation; either version 2, or (at your option) 10 any later version. 11 12 This program is distributed in the hope that it will be useful, 13 but WITHOUT ANY WARRANTY; without even the implied warranty of 14 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 15 GNU General Public License for more details. 16 17 You should have received a copy of the GNU General Public License 18 along with this program; see the file COPYING. 19 If not, write to the Free Software Foundation, 20 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. */ 21 22 #if HAVE_CONFIG_H 23 # include <config.h> 24 #endif 25 26 #include <errno.h> 27 #include <limits.h> 28 29 #include <signal.h> 30 #ifndef SA_RESTART 31 # ifdef SA_INTERRUPT /* e.g. SunOS 4.1.x */ 32 # define SA_RESTART SA_INTERRUPT 33 # else 34 # define SA_RESTART 0 35 # endif 36 #endif 37 38 #if HAVE_UNISTD_H 39 # include <unistd.h> 40 #endif 41 42 #if HAVE_INTTYPES_H 43 # include <inttypes.h> 44 #endif 45 46 #include <sys/types.h> 47 #include "cmpbuf.h" 48 49 /* Determine whether an integer type is signed, and its bounds. 50 This code assumes two's (or one's!) complement with no holes. */ 51 52 /* The extra casts work around common compiler bugs, 53 e.g. Cray C 5.0.3.0 when t == time_t. */ 54 #ifndef TYPE_SIGNED 55 # define TYPE_SIGNED(t) (! ((t) 0 < (t) -1)) 56 #endif 57 #ifndef TYPE_MINIMUM 58 # define TYPE_MINIMUM(t) ((t) (TYPE_SIGNED (t) \ 59 ? ~ (t) 0 << (sizeof (t) * CHAR_BIT - 1) \ 60 : (t) 0)) 61 #endif 62 #ifndef TYPE_MAXIMUM 63 # define TYPE_MAXIMUM(t) ((t) (~ (t) 0 - TYPE_MINIMUM (t))) 64 #endif 65 66 #ifndef PTRDIFF_MAX 67 # define PTRDIFF_MAX TYPE_MAXIMUM (ptrdiff_t) 68 #endif 69 #ifndef SIZE_MAX 70 # define SIZE_MAX TYPE_MAXIMUM (size_t) 71 #endif 72 #ifndef SSIZE_MAX 73 # define SSIZE_MAX TYPE_MAXIMUM (ssize_t) 74 #endif 75 76 #undef MIN 77 #define MIN(a, b) ((a) <= (b) ? (a) : (b)) 78 79 /* Read NBYTES bytes from descriptor FD into BUF. 80 NBYTES must not be SIZE_MAX. 81 Return the number of characters successfully read. 82 On error, return SIZE_MAX, setting errno. 83 The number returned is always NBYTES unless end-of-file or error. */ 84 85 size_t 86 block_read (int fd, char *buf, size_t nbytes) 87 { 88 char *bp = buf; 89 char const *buflim = buf + nbytes; 90 size_t readlim = SSIZE_MAX; 91 92 do 93 { 94 size_t bytes_to_read = MIN (buflim - bp, readlim); 95 ssize_t nread = read (fd, bp, bytes_to_read); 96 if (nread <= 0) 97 { 98 if (nread == 0) 99 break; 100 101 /* Accommodate Tru64 5.1, which can't read more than INT_MAX 102 bytes at a time. They call that a 64-bit OS? */ 103 if (errno == EINVAL && INT_MAX < bytes_to_read) 104 { 105 readlim = INT_MAX; 106 continue; 107 } 108 109 /* This is needed for programs that have signal handlers on 110 older hosts without SA_RESTART. It also accommodates 111 ancient AIX hosts that set errno to EINTR after uncaught 112 SIGCONT. See <news:1r77ojINN85n@ftp.UU.NET> 113 (1993-04-22). */ 114 if (! SA_RESTART && errno == EINTR) 115 continue; 116 117 return SIZE_MAX; 118 } 119 bp += nread; 120 } 121 while (bp < buflim); 122 123 return bp - buf; 124 } 125 126 /* Least common multiple of two buffer sizes A and B. However, if 127 either A or B is zero, or if the multiple is greater than LCM_MAX, 128 return a reasonable buffer size. */ 129 130 size_t 131 buffer_lcm (size_t a, size_t b, size_t lcm_max) 132 { 133 size_t lcm, m, n, q, r; 134 135 /* Yield reasonable values if buffer sizes are zero. */ 136 if (!a) 137 return b ? b : 8 * 1024; 138 if (!b) 139 return a; 140 141 /* n = gcd (a, b) */ 142 for (m = a, n = b; (r = m % n) != 0; m = n, n = r) 143 continue; 144 145 /* Yield a if there is an overflow. */ 146 q = a / n; 147 lcm = q * b; 148 return lcm <= lcm_max && lcm / b == q ? lcm : a; 149 } 150