/* Buffer primitives for comparison operations. Copyright (C) 1993, 1995, 1998, 2001, 2002 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 2, 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; see the file COPYING. If not, write to the Free Software Foundation, 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. */ #if HAVE_CONFIG_H # include <config.h> #endif #include <errno.h> #include <limits.h> #include <signal.h> #ifndef SA_RESTART # ifdef SA_INTERRUPT /* e.g. SunOS 4.1.x */ # define SA_RESTART SA_INTERRUPT # else # define SA_RESTART 0 # endif #endif #if HAVE_UNISTD_H # include <unistd.h> #endif #if HAVE_INTTYPES_H # include <inttypes.h> #endif #include <sys/types.h> #include "cmpbuf.h" /* Determine whether an integer type is signed, and its bounds. This code assumes two's (or one's!) complement with no holes. */ /* The extra casts work around common compiler bugs, e.g. Cray C 5.0.3.0 when t == time_t. */ #ifndef TYPE_SIGNED # define TYPE_SIGNED(t) (! ((t) 0 < (t) -1)) #endif #ifndef TYPE_MINIMUM # define TYPE_MINIMUM(t) ((t) (TYPE_SIGNED (t) \ ? ~ (t) 0 << (sizeof (t) * CHAR_BIT - 1) \ : (t) 0)) #endif #ifndef TYPE_MAXIMUM # define TYPE_MAXIMUM(t) ((t) (~ (t) 0 - TYPE_MINIMUM (t))) #endif #ifndef PTRDIFF_MAX # define PTRDIFF_MAX TYPE_MAXIMUM (ptrdiff_t) #endif #ifndef SIZE_MAX # define SIZE_MAX TYPE_MAXIMUM (size_t) #endif #ifndef SSIZE_MAX # define SSIZE_MAX TYPE_MAXIMUM (ssize_t) #endif #undef MIN #define MIN(a, b) ((a) <= (b) ? (a) : (b)) /* Read NBYTES bytes from descriptor FD into BUF. NBYTES must not be SIZE_MAX. Return the number of characters successfully read. On error, return SIZE_MAX, setting errno. The number returned is always NBYTES unless end-of-file or error. */ size_t block_read (int fd, char *buf, size_t nbytes) { char *bp = buf; char const *buflim = buf + nbytes; size_t readlim = SSIZE_MAX; do { size_t bytes_to_read = MIN (buflim - bp, readlim); ssize_t nread = read (fd, bp, bytes_to_read); if (nread <= 0) { if (nread == 0) break; /* Accommodate Tru64 5.1, which can't read more than INT_MAX bytes at a time. They call that a 64-bit OS? */ if (errno == EINVAL && INT_MAX < bytes_to_read) { readlim = INT_MAX; continue; } /* This is needed for programs that have signal handlers on older hosts without SA_RESTART. It also accommodates ancient AIX hosts that set errno to EINTR after uncaught SIGCONT. See <news:1r77ojINN85n@ftp.UU.NET> (1993-04-22). */ if (! SA_RESTART && errno == EINTR) continue; return SIZE_MAX; } bp += nread; } while (bp < buflim); return bp - buf; } /* Least common multiple of two buffer sizes A and B. However, if either A or B is zero, or if the multiple is greater than LCM_MAX, return a reasonable buffer size. */ size_t buffer_lcm (size_t a, size_t b, size_t lcm_max) { size_t lcm, m, n, q, r; /* Yield reasonable values if buffer sizes are zero. */ if (!a) return b ? b : 8 * 1024; if (!b) return a; /* n = gcd (a, b) */ for (m = a, n = b; (r = m % n) != 0; m = n, n = r) continue; /* Yield a if there is an overflow. */ q = a / n; lcm = q * b; return lcm <= lcm_max && lcm / b == q ? lcm : a; }