101 lines
2.5 KiB
C
101 lines
2.5 KiB
C
/* ****************************************************************************
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* stream/builtin/streams/read.c -- read from a STREAMS stream.
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* Copyright (C) 2016-2017 Thomas "Cakeisalie5" Touhey <thomas@touhey.fr>
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*
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* This file is part of libcasio.
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* libcasio is free software; you can redistribute it and/or modify it
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* under the terms of the GNU Lesser General Public License as published by
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* the Free Software Foundation; either version 3.0 of the License,
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* or (at your option) any later version.
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*
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* libcasio 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.
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* See the GNU Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public License
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* along with libcasio; if not, see <http://www.gnu.org/licenses/>.
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* ************************************************************************* */
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#include "streams.h"
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#ifndef LIBCASIO_DISABLED_STREAMS
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/**
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* casio_streams_read:
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* Read from a terminal.
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*
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* @arg cookie the cookie.
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* @arg data the data pointer.
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* @arg size the data size.
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* @return the size written and -1 if error (error code is in errno).
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*/
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size_t CASIO_EXPORT casio_streams_read(streams_cookie_t *cookie,
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unsigned char *dest, size_t size)
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{
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int fd = cookie->_readfd;
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size_t copiedsize = 0;
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/* Transmit what's already in the buffer. */
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if (cookie->_start <= cookie->_end) {
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size_t tocopy = cookie->_end - cookie->_start + 1;
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if (tocopy > size) tocopy = size;
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memcpy(dest, &cookie->_buffer[cookie->_start], tocopy);
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cookie->_start += tocopy;
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dest += tocopy;
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size -= tocopy;
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copiedsize += tocopy;
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}
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/* Main receiving loop. */
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while (size) {
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ssize_t recv;
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size_t tocopy;
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/* Receive. */
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recv = read(fd, cookie->_buffer, BUFSIZE);
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if (!recv)
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continue;
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/* Check error. */
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if (recv < 0) switch (errno) {
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case 0: continue;
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case ENODEV: case EIO:
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return (casio_error_nocalc);
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default:
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msg((ll_fatal, "error was %d: %s",
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errno, strerror(errno)));
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errno = casio_error_unknown;
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return (-1);
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}
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/* Get the current size to copy. */
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tocopy = (size_t)recv;
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if (tocopy > size) tocopy = size;
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/* Copy to destination. */
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memcpy(dest, cookie->_buffer, tocopy);
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dest += tocopy;
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size -= tocopy;
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/* Increment total size copied */
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copiedsize += tocopy;
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/* Correct start and end points. */
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cookie->_start = tocopy;
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cookie->_end = (size_t)recv - 1;
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}
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return copiedsize;
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}
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#endif
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