83 lines
2.2 KiB
C
83 lines
2.2 KiB
C
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/* An interface to read and write that retries after interrupts.
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Copyright (C) 1993, 1994, 1998, 2002-2003 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; if not, write to the Free Software Foundation,
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Inc., 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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/* Specification. */
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#ifdef SAFE_WRITE
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# include "safe-write.h"
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#else
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# include "safe-read.h"
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#endif
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/* Get ssize_t. */
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#include <sys/types.h>
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#if HAVE_UNISTD_H
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# include <unistd.h>
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#endif
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#include <errno.h>
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#ifndef errno
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extern int errno;
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#endif
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#ifdef EINTR
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# define IS_EINTR(x) ((x) == EINTR)
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#else
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# define IS_EINTR(x) 0
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#endif
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#include <limits.h>
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#ifdef SAFE_WRITE
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# define safe_rw safe_write
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# define rw write
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#else
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# define safe_rw safe_read
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# define rw read
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# undef const
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# define const /* empty */
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#endif
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/* Read(write) up to COUNT bytes at BUF from(to) descriptor FD, retrying if
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interrupted. Return the actual number of bytes read(written), zero for EOF,
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or SAFE_READ_ERROR(SAFE_WRITE_ERROR) upon error. */
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size_t
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safe_rw (int fd, void const *buf, size_t count)
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{
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ssize_t result;
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/* POSIX limits COUNT to SSIZE_MAX, but we limit it further, requiring
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that COUNT <= INT_MAX, to avoid triggering a bug in Tru64 5.1.
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When decreasing COUNT, keep the file pointer block-aligned.
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Note that in any case, read(write) may succeed, yet read(write)
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fewer than COUNT bytes, so the caller must be prepared to handle
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partial results. */
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if (count > INT_MAX)
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count = INT_MAX & ~8191;
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do
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{
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result = rw (fd, buf, count);
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}
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while (result < 0 && IS_EINTR (errno));
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return (size_t) result;
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}
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