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px4_autopilot/apps/system/readline/readline.c

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/****************************************************************************
* lib/stdio/lib_fgets.c
*
* Copyright (C) 2007-2008, 2011-2012 Gregory Nutt. All rights reserved.
* Author: Gregory Nutt <gnutt@nuttx.org>
*
* 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 <stdbool.h>
#include <stdio.h>
#include <unistd.h>
#include <string.h>
#include <ctype.h>
#include <errno.h>
#include <debug.h>
#include <apps/readline.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_READLINE_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
/* Some special characters */
#define BS 0x08 /* Backspace */
#define ESC 0x1b /* Escape */
#define LBRACKET 0x5b /* Left bracket */
#define DEL 0x7f /* DEL */
/****************************************************************************
* 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: readline_rawgetc
****************************************************************************/
static inline int readline_rawgetc(int infd)
{
char buffer;
ssize_t nread;
nread = read(infd, &buffer, 1);
if (nread < 1)
{
/* Return EOF if the end of file (0) or error (-1) occurs */
return EOF;
}
return (int)buffer;
}
/****************************************************************************
* Name: readline_consoleputc
****************************************************************************/
#ifdef CONFIG_READLINE_ECHO
static inline void readline_consoleputc(int ch, int outfd)
{
char buffer = ch;
(void)write(outfd, &buffer, 1);
}
#endif
/****************************************************************************
* Name: readline_consoleputs
****************************************************************************/
#ifdef CONFIG_READLINE_ECHO
static inline void readline_consoleputs(FAR const char *str, int outfd)
{
(void)write(outfd, str, strlen(str));
}
#endif
/****************************************************************************
* Global Functions
****************************************************************************/
/****************************************************************************
* Name: readline
*
* readline() reads in at most one less than 'buflen' characters from
* 'instream' and stores them into the buffer pointed to by 'buf'.
* Characters are echoed on 'outstream'. 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.
*
* This version of realine assumes that we are reading and writing to
* a VT100 console. This will not work well if 'instream' or 'outstream'
* corresponds to a raw byte steam.
*
* This function is inspired by the GNU readline but is an entirely
* different creature.
*
* Input Parameters:
* buf - The user allocated buffer to be filled.
* buflen - the size of the buffer.
* instream - The stream to read characters from
* outstream - The stream to each characters to.
*
* Returned values:
* On success, the (positive) number of bytes transferred is returned.
* A length of zero would indicated an end of file condition. An failure,
* a negated errno value is returned.
*
**************************************************************************/
ssize_t readline(FAR char *buf, int buflen, FILE *instream, FILE *outstream)
{
int infd;
int outfd;
int escape;
int nch;
/* Sanity checks */
if (!instream || !outstream || !buf || buflen < 1)
{
return -EINVAL;
}
if (buflen < 2)
{
*buf = '\0';
return 0;
}
/* Extract the file descriptions. This is cheating (and horribly non-
* standard)
*/
infd = instream->fs_filedes;
outfd = outstream->fs_filedes;
/* <esc>[K is the VT100 command that erases to the end of the line. */
#ifdef CONFIG_READLINE_ECHO
readline_consoleputs(g_erasetoeol, outfd);
#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.
*/
escape = 0;
nch = 0;
for(;;)
{
/* Get the next character */
int ch = readline_rawgetc(infd);
/* Are we processing a VT100 escape sequence */
if (escape)
{
/* Yes, is it an <esc>[, 3 byte sequence */
if (ch != LBRACKET || 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
*
* There are several notions of backspace, for an elaborate summary see
* http://www.ibb.net/~anne/keyboard.html. There is no clean solution.
* Here both DEL and backspace are treated like backspace here. The
* Unix/Linux screen terminal by default outputs DEL (0x7f) when the
* backspace key is pressed.
*/
else if (ch == BS || ch == DEL)
{
/* Eliminate that last character in the buffer. */
if (nch > 0)
{
nch--;
#ifdef CONFIG_READLINE_ECHO
/* Echo the backspace character on the console. Always output
* the backspace character because the VT100 terminal doesn't
* understand DEL properly.
*/
readline_consoleputc(BS, outfd);
readline_consoleputs(g_erasetoeol, outfd);
#endif
}
}
/* Check for the beginning of a VT100 escape sequence */
else if (ch == ESC)
{
/* 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_READLINE_ECHO
/* Echo the newline to the console */
readline_consoleputc('\n', outfd);
#endif
return nch;
}
/* Check for end-of-file */
else if (ch == EOF)
{
/* Terminate the line (which might be zero length) */
buf[nch] = '\0';
return nch;
}
/* 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_READLINE_ECHO
/* Echo the character to the console */
readline_consoleputc(ch, outfd);
#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 nch;
}
}
}
}