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Add lib_libfgets() to better support the small differences between gets(), gets_s(), and fgets()
This commit is contained in:
Gregory Nutt
@@ -0,0 +1,252 @@
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/****************************************************************************
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* libc/stdio/lib_libfgets.c
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*
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* Copyright (C) 2007-2008, 2011-2014 Gregory Nutt. All rights reserved.
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* Author: Gregory Nutt <gnutt@nuttx.org>
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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*
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in
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* the documentation and/or other materials provided with the
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* distribution.
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* 3. Neither the name NuttX nor the names of its contributors may be
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* used to endorse or promote products derived from this software
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* without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
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* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
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* COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
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* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
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* BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
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* OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
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* AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
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* ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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* POSSIBILITY OF SUCH DAMAGE.
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*
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****************************************************************************/
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/****************************************************************************
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* Included Files
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****************************************************************************/
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#include <nuttx/config.h>
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#include <stdbool.h>
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#include <stdio.h>
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#include <unistd.h>
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#include <string.h>
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#include <ctype.h>
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#include <assert.h>
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#include <debug.h>
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/****************************************************************************
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* Pre-processor Definitions
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****************************************************************************/
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/* Some environments may return CR as end-of-line, others LF, and others
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* both. If not specified, the logic here assumes either (but not both) as
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* the default.
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*/
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#if defined(CONFIG_EOL_IS_CR)
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# undef CONFIG_EOL_IS_LF
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# undef CONFIG_EOL_IS_BOTH_CRLF
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# undef CONFIG_EOL_IS_EITHER_CRLF
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#elif defined(CONFIG_EOL_IS_LF)
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# undef CONFIG_EOL_IS_CR
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# undef CONFIG_EOL_IS_BOTH_CRLF
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# undef CONFIG_EOL_IS_EITHER_CRLF
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#elif defined(CONFIG_EOL_IS_BOTH_CRLF)
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# undef CONFIG_EOL_IS_CR
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# undef CONFIG_EOL_IS_LF
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# undef CONFIG_EOL_IS_EITHER_CRLF
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#elif defined(CONFIG_EOL_IS_EITHER_CRLF)
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# undef CONFIG_EOL_IS_CR
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# undef CONFIG_EOL_IS_LF
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# undef CONFIG_EOL_IS_BOTH_CRLF
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#else
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# undef CONFIG_EOL_IS_CR
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# undef CONFIG_EOL_IS_LF
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# undef CONFIG_EOL_IS_BOTH_CRLF
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# define CONFIG_EOL_IS_EITHER_CRLF 1
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#endif
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/****************************************************************************
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* Private Functions
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****************************************************************************/
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/****************************************************************************
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* Name: consume_eol
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*
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* Description:
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* If 'consume' is true, then consume_eol() will read and discard bytes from
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* 'stream' until an EOF or a newline encountered or until a read error
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* occurs.
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*
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**************************************************************************/
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static void consume_eol(FILE *stream, bool consume)
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{
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if (consume)
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{
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int ch;
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do
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{
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ch = fgetc(stream);
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}
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#if defined(CONFIG_EOL_IS_LF) || defined(CONFIG_EOL_IS_BOTH_CRLF)
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while (ch != EOF && ch != '\n');
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#elif defined(CONFIG_EOL_IS_CR)
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while (ch != EOF && ch != '\r');
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#else /* elif defined(CONFIG_EOL_IS_EITHER_CRLF) */
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while (ch != EOF && ch != '\n' && ch != '\r');
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#endif
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}
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}
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/****************************************************************************
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* Public Functions
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****************************************************************************/
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/****************************************************************************
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* Name: lib_fgets
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*
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* Description:
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* lib_fgets() implements the core logic for both fgets() and gets_s().
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* lib_fgets() reads in at most one less than 'buflen' characters from
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* stream and stores them into the buffer pointed to by 'buf'. Reading
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* stops after an EOF or a newline encountered or after a read error
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* occurs.
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*
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* If a newline is read, it is stored into the buffer only if 'keepnl' is
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* set true. A null terminator is always stored after the last character
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* in the buffer.
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*
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* If 'buflen'-1 bytes were read into 'buf' without encountering an EOF
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* or newline then the following behavior depends on the value of
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* 'consume': If consume is true, then lib_fgets() will continue reading
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* bytes and discarding them until an EOF or a newline encountered or
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* until a read error occurs. Otherwise, lib_fgets() returns with the
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* remaining of the incoming stream buffer.
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*
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**************************************************************************/
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FAR char *lib_fgets(FAR char *buf, int buflen, FILE *stream,
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bool keepnl, bool consume)
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{
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int nch = 0;
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/* Sanity checks */
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if (!stream || !buf || stream->fs_fd < 0)
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{
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return NULL;
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}
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/* Make sure that we have a buffer and space for at least one character */
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if (buflen < 1)
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{
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consume_eol(stream, consume);
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return NULL;
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}
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/* Make sure that we have space for something in addition to the NUL
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* terminator.
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*/
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if (buflen < 2)
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{
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*buf = '\0';
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consume_eol(stream, consume);
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return buf;
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}
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/* Read characters until we have a full line. On each the loop we must
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* be assured that there are two free bytes in the line buffer: One for
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* the next character and one for the null terminator.
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*/
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for(;;)
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{
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/* Get the next character */
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int ch = fgetc(stream);
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/* Check for end-of-line. This is tricky only in that some
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* environments may return CR as end-of-line, others LF, and
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* others both.
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*/
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#if defined(CONFIG_EOL_IS_LF) || defined(CONFIG_EOL_IS_BOTH_CRLF)
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if (ch == '\n')
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#elif defined(CONFIG_EOL_IS_CR)
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if (ch == '\r')
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#else /* elif defined(CONFIG_EOL_IS_EITHER_CRLF) */
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if (ch == '\n' || ch == '\r')
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#endif
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{
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if (keepnl)
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{
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/* Store newline is stored in the buffer */
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buf[nch++] = '\n';
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}
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/* Terminate the string */
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buf[nch] = '\0';
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return buf;
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}
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/* Check for end-of-file */
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else if (ch == EOF)
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{
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/* End of file with no data? */
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if (!nch)
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{
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/* Yes.. return NULL as the end of file mark */
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return NULL;
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}
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else
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{
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/* No, terminate the accumulated string */
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buf[nch] = '\0';
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return buf;
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}
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}
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/* Otherwise, check if the character is printable and, if so, put the
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* character in the line buffer
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*/
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else if (isprint(ch))
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{
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buf[nch++] = ch;
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/* Check if there is room for another character and the line's
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* NUL terminator. If not then we have to end the line now,
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* perhaps consuming any data up to the end-of-line.
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*/
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if (nch + 1 >= buflen)
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{
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buf[nch] = '\0';
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consume_eol(stream, consume);
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return buf;
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}
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}
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}
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}
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