/****************************************************************************
* libs/libc/stdio/lib_libfgets.c
*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership. The
* ASF licenses this file to you under the Apache License, Version 2.0 (the
* "License"); you may not use this file except in compliance with the
* License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
* License for the specific language governing permissions and limitations
* under the License.
*
****************************************************************************/
/****************************************************************************
* Included Files
****************************************************************************/
#include <nuttx/config.h>
#include <stdbool.h>
#include <stdio.h>
#include <unistd.h>
#include <string.h>
#include <ctype.h>
#include <assert.h>
#include <debug.h>
#include "libc.h"
/****************************************************************************
* Pre-processor Definitions
****************************************************************************/
/* Some environments may return CR as end-of-line, others LF, and others
* both. If not specified, the logic here assumes either (but not both) as
* the default.
*/
#if defined(CONFIG_EOL_IS_CR)
# undef CONFIG_EOL_IS_LF
# undef CONFIG_EOL_IS_BOTH_CRLF
# undef CONFIG_EOL_IS_EITHER_CRLF
#elif defined(CONFIG_EOL_IS_LF)
# undef CONFIG_EOL_IS_CR
# undef CONFIG_EOL_IS_BOTH_CRLF
# undef CONFIG_EOL_IS_EITHER_CRLF
#elif defined(CONFIG_EOL_IS_BOTH_CRLF)
# undef CONFIG_EOL_IS_CR
# undef CONFIG_EOL_IS_LF
# undef CONFIG_EOL_IS_EITHER_CRLF
#elif defined(CONFIG_EOL_IS_EITHER_CRLF)
# undef CONFIG_EOL_IS_CR
# undef CONFIG_EOL_IS_LF
# undef CONFIG_EOL_IS_BOTH_CRLF
#else
# undef CONFIG_EOL_IS_CR
# undef CONFIG_EOL_IS_LF
# undef CONFIG_EOL_IS_BOTH_CRLF
# define CONFIG_EOL_IS_EITHER_CRLF 1
#endif
/****************************************************************************
* Private Functions
****************************************************************************/
/****************************************************************************
* Name: consume_eol
*
* Description:
* If 'consume' is true, then consume_eol() will read and discard bytes
* from 'stream' until an EOF or a newline encountered or until a read
* error occurs.
*
****************************************************************************/
static void consume_eol(FILE *stream, bool consume)
{
if (consume)
{
int ch;
do
{
ch = fgetc(stream);
}
#if defined(CONFIG_EOL_IS_LF) || defined(CONFIG_EOL_IS_BOTH_CRLF)
while (ch != EOF && ch != '\n');
#elif defined(CONFIG_EOL_IS_CR)
while (ch != EOF && ch != '\r');
#else /* elif defined(CONFIG_EOL_IS_EITHER_CRLF) */
while (ch != EOF && ch != '\n' && ch != '\r');
#endif
}
}
/****************************************************************************
* Public Functions
****************************************************************************/
/****************************************************************************
* Name: lib_fgets
*
* Description:
* lib_fgets() implements the core logic for both fgets() and gets_s().
* lib_fgets() reads in at most one less than 'buflen' characters from
* stream and stores them into the buffer pointed to by 'buf'. Reading
* stops after an EOF or a newline encountered or after a read error
* occurs.
*
* If a newline is read, it is stored into the buffer only if 'keepnl' is
* set true. A null terminator is always stored after the last character
* in the buffer.
*
* If 'buflen'-1 bytes were read into 'buf' without encountering an EOF
* or newline then the following behavior depends on the value of
* 'consume': If consume is true, then lib_fgets() will continue reading
* bytes and discarding them until an EOF or a newline encountered or
* until a read error occurs. Otherwise, lib_fgets() returns with the
* remaining of the incoming stream buffer.
*
****************************************************************************/
FAR char *lib_fgets(FAR char *buf, size_t buflen, FILE *stream,
bool keepnl, bool consume)
{
size_t nch = 0;
/* Sanity checks */
if (!stream || !buf || stream->fs_fd < 0)
{
return NULL;
}
/* Make sure that we have a buffer and space for at least one character */
if (buflen < 1)
{
consume_eol(stream, consume);
return NULL;
}
/* Make sure that we have space for something in addition to the NUL
* terminator.
*/
if (buflen < 2)
{
*buf = '\0';
consume_eol(stream, consume);
return buf;
}
/* Read characters until we have a full line. On each the loop we must
* be assured that there are two free bytes in the line buffer: One for
* the next character and one for the null terminator.
*/
for (; ; )
{
/* Get the next character */
int ch = fgetc(stream);
/* Check for end-of-line. This is tricky only in that some
* environments may return CR as end-of-line, others LF, and
* others both.
*/
#if defined(CONFIG_EOL_IS_LF) || defined(CONFIG_EOL_IS_BOTH_CRLF)
if (ch == '\n')
#elif defined(CONFIG_EOL_IS_CR)
if (ch == '\r')
#else /* elif defined(CONFIG_EOL_IS_EITHER_CRLF) */
if (ch == '\n' || ch == '\r')
#endif
{
if (keepnl)
{
/* Store newline is stored in the buffer */
buf[nch++] = '\n';
}
/* Terminate the string */
buf[nch] = '\0';
return buf;
}
/* Check for end-of-file */
else if (ch == EOF)
{
/* End of file with no data? */
if (!nch)
{
/* Yes.. return NULL as the end of file mark */
return NULL;
}
else
{
/* No, terminate the accumulated string */
buf[nch] = '\0';
return buf;
}
}
/* Otherwise, put the character in the line buffer */
else
{
buf[nch++] = ch;
/* Check if there is room for another character and the line's
* NUL terminator. If not then we have to end the line now,
* perhaps consuming any data up to the end-of-line.
*/
if (nch + 1 >= buflen)
{
buf[nch] = '\0';
consume_eol(stream, consume);
return buf;
}
}
}
}