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/* An interface to read and write that retries after interrupts.
Copyright (C) 1993, 1994, 1998, 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; if not, write to the Free Software Foundation,
Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. */
#if HAVE_CONFIG_H
# include <config.h>
#endif
/* Get ssize_t. */
#include <sys/types.h>
#if HAVE_UNISTD_H
# include <unistd.h>
#endif
#include <errno.h>
#ifndef errno
extern int errno;
#endif
#ifdef EINTR
# define IS_EINTR(x) ((x) == EINTR)
#else
# define IS_EINTR(x) 0
#endif
#include <limits.h>
#ifndef CHAR_BIT
# define CHAR_BIT 8
#endif
/* The extra casts work around common compiler bugs. */
#define TYPE_SIGNED(t) (! ((t) 0 < (t) -1))
/* The outer cast is needed to work around a bug in Cray C 5.0.3.0.
It is necessary at least when t == time_t. */
#define TYPE_MINIMUM(t) ((t) (TYPE_SIGNED (t) \
? ~ (t) 0 << (sizeof (t) * CHAR_BIT - 1) : (t) 0))
#define TYPE_MAXIMUM(t) ((t) (~ (t) 0 - TYPE_MINIMUM (t)))
#ifndef INT_MAX
# define INT_MAX TYPE_MAXIMUM (int)
#endif
#ifdef SAFE_WRITE
# include "safe-write.h"
# define safe_rw safe_write
# define rw write
#else
# include "safe-read.h"
# 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)
{
ssize_t result;
/* POSIX limits COUNT to SSIZE_MAX, but we limit it further, requiring
that COUNT <= INT_MAX, to avoid triggering a bug in Tru64 5.1.
When decreasing COUNT, keep the file pointer block-aligned.
Note that in any case, read(write) may succeed, yet read(write)
fewer than COUNT bytes, so the caller must be prepared to handle
partial results. */
if (count > INT_MAX)
count = INT_MAX & ~8191;
do
{
result = rw (fd, buf, count);
}
while (result < 0 && IS_EINTR (errno));
return (size_t) result;
}
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