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69 lines
2.1 KiB
C
69 lines
2.1 KiB
C
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/* Copyright (C) 1991, 1992 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 Library General Public License as
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published by the Free Software Foundation; either version 2 of the
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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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Library General Public License for more details.
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You should have received a copy of the GNU Library General Public
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License along with the GNU C Library; see the file COPYING.LIB. If
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not, write to the Free Software Foundation, Inc., 675 Mass Ave,
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Cambridge, MA 02139, USA. */
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#include <ansidecl.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 <sys/uio.h>
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/* Read data from file descriptor FD, and put the result in the
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buffers described by VECTOR, which is a vector of COUNT `struct iovec's.
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The buffers are filled in the order specified.
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Operates just like `read' (see <unistd.h>) except that data are
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put in VECTOR instead of a contiguous buffer. */
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int
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DEFUN(readv, (fd, vector, count),
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int fd AND CONST struct iovec *vector AND size_t count)
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{
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char *buffer;
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size_t bytes;
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int bytes_read;
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register size_t i;
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/* Find the total number of bytes to be read. */
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bytes = 0;
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for (i = 0; i < count; ++i)
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bytes += vector[i].iov_len;
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/* Allocate a temporary buffer to hold the data. */
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buffer = (char *) __alloca(bytes);
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/* Read the data. */
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bytes_read = read(fd, buffer, bytes);
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if (bytes_read <= 0)
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return -1;
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/* Copy the data from BUFFER into the memory specified by VECTOR. */
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bytes = bytes_read;
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for (i = 0; i < count; ++i)
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{
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#define min(a, b) ((a) > (b) ? (b) : (a))
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size_t copy = min(vector[i].iov_len, bytes);
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(void) memcpy((PTR) vector[i].iov_base, (PTR) buffer, copy);
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buffer += copy;
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bytes -= copy;
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if (bytes == 0)
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break;
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}
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return bytes_read;
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}
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