/****************************************************************************
* lib/lib_fgets.c
*
* Copyright (C) 2007, 2008 Gregory Nutt. All rights reserved.
* Author: Gregory Nutt <spudmonkey@racsa.co.cr>
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in
* the documentation and/or other materials provided with the
* distribution.
* 3. Neither the name NuttX nor the names of its contributors may be
* used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
* COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
* BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
* OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
* AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
* ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
* POSSIBILITY OF SUCH DAMAGE.
*
****************************************************************************/
/****************************************************************************
* Included Files
****************************************************************************/
#include <nuttx/config.h>
#include <stdio.h>
#include <unistd.h>
#include <string.h>
#include <ctype.h>
#include <debug.h>
/****************************************************************************
* Definitions
****************************************************************************/
/* In some systems, the underlying serial logic may
* automatically echo characters back to the console. We
* will assume that that is not the case here
*/
#define CONFIG_FGETS_ECHO 1
/* Some environments may return CR as end-of-line, others LF, and
* others both. The logic here assumes either but not both.
*/
#undef CONFIG_EOL_IS_CR
#undef CONFIG_EOL_IS_LF
#undef CONFIG_EOL_IS_BOTH_CRLF
#define CONFIG_EOL_IS_EITHER_CRLF 1
/****************************************************************************
* Private Type Declarations
****************************************************************************/
/****************************************************************************
* Private Function Prototypes
****************************************************************************/
/****************************************************************************
* Public Data
****************************************************************************/
/****************************************************************************
* Private Data
****************************************************************************/
/* <esc>[K is the VT100 command erases to the end of the line. */
static const char g_erasetoeol[] = "\033[K";
/****************************************************************************
* Private Functions
****************************************************************************/
/****************************************************************************
* Name: _lib_rawgetc
****************************************************************************/
static inline int _lib_rawgetc(int fd)
{
char buffer;
if (read(fd, &buffer, 1) < 1)
{
/* Return EOF if the end of file (0) or error (-1) occurs */
return EOF;
}
return (int)buffer;
}
/****************************************************************************
* Name: _lib_consoleputc
****************************************************************************/
#ifdef CONFIG_FGETS_ECHO
static inline void _lib_consoleputc(int ch)
{
char buffer = ch;
(void)write(1, &buffer, 1);
}
#endif
/****************************************************************************
* Name: _lib_consoleputs
****************************************************************************/
#ifdef CONFIG_FGETS_ECHO
static inline void _lib_consoleputs(FAR const char *str)
{
(void)write(1, str, strlen(str));
}
#endif
/****************************************************************************
* Global Functions
****************************************************************************/
/****************************************************************************
* Name: fgets
*
* Description:
* 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. If a
* newline is read, it is stored into the buffer. A null
* terminator is stored after the last character in the
* buffer.
*
* Assumptions:
* If the stream corresponds to stdin (fd=0) this version
* will assume that we are reading characters from a
* VT100 console and that stdout (fd=1) is also available.
* This will not work well if fd=0 corresponds to a raw
* byte steam.
*
**************************************************************************/
char *fgets(FAR char *buf, int buflen, FILE *stream)
{
#ifdef CONFIG_FGETS_ECHO
boolean console;
#endif
int escape = 0;
int nch = 0;
/* Sanity checks */
if (!stream || !buf || buflen < 1 || stream->fs_filedes < 0)
{
return NULL;
}
if (buflen < 2)
{
*buf = '\0';
return buf;
}
/* Check if the stream is stdin */
#ifdef CONFIG_FGETS_ECHO
console = (stream->fs_filedes == 0);
/* <esc>[K is the VT100 command that erases to the end of the line. */
if (console)
{
_lib_consoleputs(g_erasetoeol);
}
#endif
/* 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 = _lib_rawgetc(stream->fs_filedes);
/* Are we processing a VT100 escape sequence */
if (escape)
{
/* Yes, is it an <esc>[, 3 byte sequence */
if (ch != 0x5b || escape == 2)
{
/* We are finished with the escape sequence */
escape = 0;
ch = 'a';
}
else
{
/* The next character is the end of a 3-byte sequence.
* NOTE: Some of the <esc>[ sequences are longer than
* 3-bytes, but I have not encountered any in normal use
* yet and, so, have not provided the decoding logic.
*/
escape = 2;
}
}
/* Check for backspace */
else if (ch == 0x08)
{
/* Eliminate that last character in the buffer. */
if (nch > 0)
{
nch--;
#ifdef CONFIG_FGETS_ECHO
if (console)
{
/* Echo the backspace character on the console */
_lib_consoleputc(ch);
_lib_consoleputs(g_erasetoeol);
}
#endif
}
}
/* Check for the beginning of a VT100 escape sequence */
else if (console && ch == 0x1b)
{
/* The next character is escaped */
escape = 1;
}
/* 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)
else if (ch == '\n')
#elif defined(CONFIG_EOL_IS_CR)
else if (ch == '\r')
#elif CONFIG_EOL_IS_EITHER_CRLF
else if (ch == '\n' || ch == '\r')
#endif
{
/* The newline is stored in the buffer along
* with the null terminator.
*/
buf[nch++] = '\n';
buf[nch] = '\0';
#ifdef CONFIG_FGETS_ECHO
if (console)
{
/* Echo the newline to the console */
_lib_consoleputc('\n');
}
#endif
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
{
/* Terminate the line */
buf[nch] = '\0';
return buf;
}
}
/* Otherwise, check if the character is printable and,
* if so, put the character in the line buffer
*/
else if (isprint(ch))
{
buf[nch++] = ch;
#ifdef CONFIG_FGETS_ECHO
if (console)
{
/* Echo the character to the console */
_lib_consoleputc(ch);
}
#endif
/* Check if there is room for another character
* and the line's null terminator. If not then
* we have to end the line now.
*/
if (nch + 1 >= buflen)
{
buf[nch] = '\0';
return buf;
}
}
}
}
