150 lines
3.8 KiB
C
150 lines
3.8 KiB
C
/* $NetBSD: cmpbuf.c,v 1.1.1.1 2003/01/26 00:43:15 wiz Exp $ */
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/* Buffer primitives for comparison operations.
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Copyright (C) 1993, 1995, 1998, 2001, 2002 Free Software Foundation, Inc.
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This program is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 2, or (at your option)
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any later version.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program; see the file COPYING.
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If not, write to the Free Software Foundation,
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59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. */
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#if HAVE_CONFIG_H
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# include <config.h>
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#endif
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#include <errno.h>
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#include <limits.h>
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#include <signal.h>
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#ifndef SA_RESTART
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# ifdef SA_INTERRUPT /* e.g. SunOS 4.1.x */
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# define SA_RESTART SA_INTERRUPT
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# else
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# define SA_RESTART 0
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# endif
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#endif
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#if HAVE_UNISTD_H
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# include <unistd.h>
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#endif
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#if HAVE_INTTYPES_H
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# include <inttypes.h>
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#endif
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#include <sys/types.h>
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#include "cmpbuf.h"
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/* Determine whether an integer type is signed, and its bounds.
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This code assumes two's (or one's!) complement with no holes. */
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/* The extra casts work around common compiler bugs,
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e.g. Cray C 5.0.3.0 when t == time_t. */
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#ifndef TYPE_SIGNED
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# define TYPE_SIGNED(t) (! ((t) 0 < (t) -1))
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#endif
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#ifndef TYPE_MINIMUM
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# define TYPE_MINIMUM(t) ((t) (TYPE_SIGNED (t) \
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? ~ (t) 0 << (sizeof (t) * CHAR_BIT - 1) \
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: (t) 0))
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#endif
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#ifndef TYPE_MAXIMUM
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# define TYPE_MAXIMUM(t) ((t) (~ (t) 0 - TYPE_MINIMUM (t)))
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#endif
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#ifndef PTRDIFF_MAX
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# define PTRDIFF_MAX TYPE_MAXIMUM (ptrdiff_t)
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#endif
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#ifndef SIZE_MAX
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# define SIZE_MAX TYPE_MAXIMUM (size_t)
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#endif
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#ifndef SSIZE_MAX
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# define SSIZE_MAX TYPE_MAXIMUM (ssize_t)
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#endif
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#undef MIN
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#define MIN(a, b) ((a) <= (b) ? (a) : (b))
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/* Read NBYTES bytes from descriptor FD into BUF.
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NBYTES must not be SIZE_MAX.
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Return the number of characters successfully read.
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On error, return SIZE_MAX, setting errno.
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The number returned is always NBYTES unless end-of-file or error. */
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size_t
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block_read (int fd, char *buf, size_t nbytes)
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{
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char *bp = buf;
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char const *buflim = buf + nbytes;
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size_t readlim = SSIZE_MAX;
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do
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{
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size_t bytes_to_read = MIN (buflim - bp, readlim);
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ssize_t nread = read (fd, bp, bytes_to_read);
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if (nread <= 0)
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{
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if (nread == 0)
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break;
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/* Accommodate Tru64 5.1, which can't read more than INT_MAX
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bytes at a time. They call that a 64-bit OS? */
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if (errno == EINVAL && INT_MAX < bytes_to_read)
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{
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readlim = INT_MAX;
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continue;
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}
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/* This is needed for programs that have signal handlers on
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older hosts without SA_RESTART. It also accommodates
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ancient AIX hosts that set errno to EINTR after uncaught
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SIGCONT. See <news:1r77ojINN85n@ftp.UU.NET>
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(1993-04-22). */
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if (! SA_RESTART && errno == EINTR)
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continue;
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return SIZE_MAX;
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}
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bp += nread;
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}
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while (bp < buflim);
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return bp - buf;
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}
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/* Least common multiple of two buffer sizes A and B. However, if
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either A or B is zero, or if the multiple is greater than LCM_MAX,
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return a reasonable buffer size. */
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size_t
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buffer_lcm (size_t a, size_t b, size_t lcm_max)
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{
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size_t lcm, m, n, q, r;
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/* Yield reasonable values if buffer sizes are zero. */
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if (!a)
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return b ? b : 8 * 1024;
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if (!b)
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return a;
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/* n = gcd (a, b) */
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for (m = a, n = b; (r = m % n) != 0; m = n, n = r)
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continue;
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/* Yield a if there is an overflow. */
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q = a / n;
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lcm = q * b;
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return lcm <= lcm_max && lcm / b == q ? lcm : a;
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}
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