/* An interface to read and write that retries after interrupts. Copyright (C) 1993, 1994, 1998, 2002, 2003, 2004, 2005, 2006 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; if not, write to the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA. */ #include <config.h> /* Specification. */ #ifdef SAFE_WRITE # include "safe-write.h" #else # include "safe-read.h" #endif /* Get ssize_t. */ #include <sys/types.h> #include <unistd.h> #include <errno.h> #ifdef EINTR # define IS_EINTR(x) ((x) == EINTR) #else # define IS_EINTR(x) 0 #endif #include <limits.h> #ifdef SAFE_WRITE # define safe_rw safe_write # define rw write #else # define safe_rw safe_read # define rw read # undef const # define const /* empty */ #endif /* Read(write) up to COUNT bytes at BUF from(to) descriptor FD, retrying if interrupted. Return the actual number of bytes read(written), zero for EOF, or SAFE_READ_ERROR(SAFE_WRITE_ERROR) upon error. */ size_t safe_rw (int fd, void const *buf, size_t count) { /* Work around a bug in Tru64 5.1. Attempting to read more than INT_MAX bytes fails with errno == EINVAL. See <http://lists.gnu.org/archive/html/bug-gnu-utils/2002-04/msg00010.html>. When decreasing COUNT, keep it block-aligned. */ enum { BUGGY_READ_MAXIMUM = INT_MAX & ~8191 }; for (;;) { ssize_t result = rw (fd, buf, count); if (0 <= result) return result; else if (IS_EINTR (errno)) continue; else if (errno == EINVAL && BUGGY_READ_MAXIMUM < count) count = BUGGY_READ_MAXIMUM; else return result; } } |