in system/readline/readline_common.c [474:738]
ssize_t readline_common(FAR struct rl_common_s *vtbl, FAR char *buf,
int buflen)
{
int escape;
int nch;
#ifdef CONFIG_READLINE_CMD_HISTORY
int i;
#endif
/* Sanity checks */
DEBUGASSERT(buf && buflen > 0);
if (buflen < 2)
{
*buf = '\0';
return 0;
}
/* <esc>[K is the VT100 command that erases to the end of the line. */
#ifdef CONFIG_READLINE_ECHO
RL_WRITE(vtbl, g_erasetoeol, sizeof(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.
*/
escape = 0;
nch = 0;
for (; ; )
{
/* Get the next character. readline_rawgetc() returns EOF on any
* errors or at the end of file.
*/
int ch = RL_GETC(vtbl);
/* Check for end-of-file or read error */
if (ch == EOF)
{
/* Did we already received some data? */
if (nch > 0)
{
/* Yes.. Terminate the line (which might be zero length)
* and return the data that was received. The end-of-file
* or error condition will be reported next time.
*/
buf[nch] = '\0';
return nch;
}
return EOF;
}
/* Are we processing a VT100 escape sequence */
else if (escape)
{
/* Yes, is it an <esc>[, 3 byte sequence */
if (ch != ASCII_LBRACKET || escape == 2)
{
/* We are finished with the escape sequence */
#ifdef CONFIG_READLINE_CMD_HISTORY
/* Intercept up and down arrow keys */
if (g_cmdhist.len > 0)
{
if (ch == 'A') /* up arrow */
{
/* Go to the past command in history */
g_cmdhist.offset--;
if (-g_cmdhist.offset >= g_cmdhist.len)
{
g_cmdhist.offset = -(g_cmdhist.len - 1);
}
}
else if (ch == 'B') /* down arrow */
{
/* Go to the recent command in history */
g_cmdhist.offset++;
if (g_cmdhist.offset > 1)
{
g_cmdhist.offset = 1;
}
}
/* Clear out current command from the prompt */
while (nch > 0)
{
nch--;
#ifdef CONFIG_READLINE_ECHO
RL_PUTC(vtbl, ASCII_BS);
RL_WRITE(vtbl, g_erasetoeol, sizeof(g_erasetoeol));
#endif
}
if (g_cmdhist.offset != 1)
{
int idx = g_cmdhist.head + g_cmdhist.offset;
/* Circular buffer wrap around */
if (idx < 0)
{
idx = idx + RL_CMDHIST_LEN;
}
else if (idx >= RL_CMDHIST_LEN)
{
idx = idx - RL_CMDHIST_LEN;
}
for (i = 0; g_cmdhist.buf[idx][i] != '\0'; i++)
{
buf[nch++] = g_cmdhist.buf[idx][i];
RL_PUTC(vtbl, g_cmdhist.buf[idx][i]);
}
buf[nch] = '\0';
}
}
#endif /* CONFIG_READLINE_CMD_HISTORY */
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 == ASCII_BS || ch == ASCII_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.
*/
RL_PUTC(vtbl, ASCII_BS);
RL_WRITE(vtbl, g_erasetoeol, sizeof(g_erasetoeol));
#endif
}
}
/* Check for the beginning of a VT100 escape sequence */
else if (ch == ASCII_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.
*/
else if (ch == '\n')
{
#ifdef CONFIG_READLINE_CMD_HISTORY
/* Save history of command, only if there was something
* typed besides return character.
*/
if (nch >= 1)
{
/* If this command is the one at the top of the circular
* buffer, don't save it again.
*/
if (strncmp(buf, g_cmdhist.buf[g_cmdhist.head], nch + 1) != 0)
{
g_cmdhist.head = (g_cmdhist.head + 1) % RL_CMDHIST_LEN;
for (i = 0; (i < nch) && i < (RL_CMDHIST_LINELEN - 1); i++)
{
g_cmdhist.buf[g_cmdhist.head][i] = buf[i];
}
g_cmdhist.buf[g_cmdhist.head][i] = '\0';
if (g_cmdhist.len < RL_CMDHIST_LEN)
{
g_cmdhist.len++;
}
}
g_cmdhist.offset = 1;
}
#endif /* CONFIG_READLINE_CMD_HISTORY */
/* The newline is stored in the buffer along with the null
* terminator.
*/
buf[nch++] = '\n';
buf[nch] = '\0';
return nch;
}
/* Otherwise, put the character in the line buffer if the
* character is not a control byte
*/
else if (!iscntrl(ch & 0xff))
{
buf[nch++] = ch;
/* 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;
}
}
#ifdef CONFIG_READLINE_TABCOMPLETION
else if (ch == '\t') /* TAB character */
{
tab_completion(vtbl, buf, buflen, &nch);
}
#endif
}
}