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96 lines
2.8 KiB
C
96 lines
2.8 KiB
C
/* Copyright (C) 2009-2017 Free Software Foundation, Inc.
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This file is part of the GNU C Library.
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The GNU C Library is free software; you can redistribute it and/or
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modify it under the terms of the GNU Lesser General Public
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License as published by the Free Software Foundation; either
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version 2.1 of the License, or (at your option) any later version.
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The GNU C Library 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 GNU
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Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public
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License along with the GNU C Library; if not, see
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<http://www.gnu.org/licenses/>. */
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#include <errno.h>
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#include <stdlib.h>
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#include <unistd.h>
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#include <string.h>
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#include <limits.h>
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#include <stdbool.h>
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#include <sys/param.h>
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#if __WORDSIZE == 64 && !defined PWRITEV
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/* Hide the pwritev64 declaration. */
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# define pwritev64 __redirect_pwritev64
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#endif
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#include <sys/uio.h>
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#include <bits/wordsize.h>
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#ifndef PWRITEV
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# define PWRITEV pwritev
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# define PWRITE __pwrite
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# define OFF_T off_t
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#endif
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static void
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ifree (char **ptrp)
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{
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free (*ptrp);
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}
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/* Write data pointed by the buffers described by IOVEC, which is a
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vector of COUNT 'struct iovec's, to file descriptor FD at the given
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position OFFSET without change the file pointer. The data is
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written in the order specified. Operates just like 'write' (see
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<unistd.h>) except that the data are taken from IOVEC instead of a
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contiguous buffer. */
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ssize_t
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PWRITEV (int fd, const struct iovec *vector, int count, OFF_T offset)
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{
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/* Find the total number of bytes to be read. */
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size_t bytes = 0;
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for (int i = 0; i < count; ++i)
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{
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/* Check for ssize_t overflow. */
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if (SSIZE_MAX - bytes < vector[i].iov_len)
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{
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__set_errno (EINVAL);
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return -1;
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}
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bytes += vector[i].iov_len;
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}
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/* Allocate a temporary buffer to hold the data. We should normally
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use alloca since it's faster and does not require synchronization
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with other threads. But we cannot if the amount of memory
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required is too large. */
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char *buffer;
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char *malloced_buffer __attribute__ ((__cleanup__ (ifree))) = NULL;
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if (__libc_use_alloca (bytes))
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buffer = (char *) __alloca (bytes);
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else
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{
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malloced_buffer = buffer = (char *) malloc (bytes);
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if (buffer == NULL)
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return -1;
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}
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/* Copy the data from BUFFER into the memory specified by VECTOR. */
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char *ptr = buffer;
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for (int i = 0; i < count; ++i)
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ptr = __mempcpy ((void *) ptr, (void *) vector[i].iov_base,
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vector[i].iov_len);
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/* Write the data. */
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return PWRITE (fd, buffer, bytes, offset);
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}
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#if __WORDSIZE == 64 && defined pwritev64
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# undef pwritev64
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strong_alias (pwritev, pwritev64)
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#endif
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