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putty-source/ldisc.c
Simon Tatham 9f0e7d2915 Backends: notify ldisc when sendok becomes true. (NFC) 
I've introduced a function ldisc_notify_sendok(), which backends
should call on their ldisc (if they have one) when anything changes
that might cause backend_sendok() to start returning true.

At the moment, the function does nothing. But in future, I'm going to
make ldisc start buffering typed-ahead input data not yet sent to the
backend, and then the effect of this function will be to trigger
flushing all that data into the backend.

Backends only have to call this function if sendok was previously
false: backends requiring no network connection stage (like pty and
serial) can safely return true from sendok, and in that case, they
don't also have to immediately call this function.
2021-09-14 11:23:20 +01:00

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/*
* ldisc.c: PuTTY line discipline. Sits between the input coming
* from keypresses in the window, and the output channel leading to
* the back end. Implements echo and/or local line editing,
* depending on what's currently configured.
*/
#include <stdio.h>
#include <ctype.h>
#include <assert.h>
#include "putty.h"
#include "terminal.h"
struct Ldisc_tag {
Terminal *term;
Backend *backend;
Seat *seat;
/*
* Values cached out of conf.
*/
bool telnet_keyboard, telnet_newline;
int protocol, localecho, localedit;
char *buf;
size_t buflen, bufsiz;
bool quotenext;
};
#define ECHOING (ldisc->localecho == FORCE_ON || \
(ldisc->localecho == AUTO && \
(backend_ldisc_option_state(ldisc->backend, LD_ECHO))))
#define EDITING (ldisc->localedit == FORCE_ON || \
(ldisc->localedit == AUTO && \
(backend_ldisc_option_state(ldisc->backend, LD_EDIT))))
static void c_write(Ldisc *ldisc, const void *buf, int len)
{
seat_stdout(ldisc->seat, buf, len);
}
static int plen(Ldisc *ldisc, unsigned char c)
{
if ((c >= 32 && c <= 126) || (c >= 160 && !in_utf(ldisc->term)))
return 1;
else if (c < 128)
return 2; /* ^x for some x */
else if (in_utf(ldisc->term) && c >= 0xC0)
return 1; /* UTF-8 introducer character
* (FIXME: combining / wide chars) */
else if (in_utf(ldisc->term) && c >= 0x80 && c < 0xC0)
return 0; /* UTF-8 followup character */
else
return 4; /* <XY> hex representation */
}
static void pwrite(Ldisc *ldisc, unsigned char c)
{
if ((c >= 32 && c <= 126) ||
(!in_utf(ldisc->term) && c >= 0xA0) ||
(in_utf(ldisc->term) && c >= 0x80)) {
c_write(ldisc, &c, 1);
} else if (c < 128) {
char cc[2];
cc[1] = (c == 127 ? '?' : c + 0x40);
cc[0] = '^';
c_write(ldisc, cc, 2);
} else {
char cc[5];
sprintf(cc, "<%02X>", c);
c_write(ldisc, cc, 4);
}
}
static bool char_start(Ldisc *ldisc, unsigned char c)
{
if (in_utf(ldisc->term))
return (c < 0x80 || c >= 0xC0);
else
return true;
}
static void bsb(Ldisc *ldisc, int n)
{
while (n--)
c_write(ldisc, "\010 \010", 3);
}
#define CTRL(x) (x^'@')
#define KCTRL(x) ((x^'@') | 0x100)
Ldisc *ldisc_create(Conf *conf, Terminal *term, Backend *backend, Seat *seat)
{
Ldisc *ldisc = snew(Ldisc);
ldisc->buf = NULL;
ldisc->buflen = 0;
ldisc->bufsiz = 0;
ldisc->quotenext = false;
ldisc->backend = backend;
ldisc->term = term;
ldisc->seat = seat;
ldisc_configure(ldisc, conf);
/* Link ourselves into the backend and the terminal */
if (term)
term->ldisc = ldisc;
if (backend)
backend_provide_ldisc(backend, ldisc);
return ldisc;
}
void ldisc_configure(Ldisc *ldisc, Conf *conf)
{
ldisc->telnet_keyboard = conf_get_bool(conf, CONF_telnet_keyboard);
ldisc->telnet_newline = conf_get_bool(conf, CONF_telnet_newline);
ldisc->protocol = conf_get_int(conf, CONF_protocol);
ldisc->localecho = conf_get_int(conf, CONF_localecho);
ldisc->localedit = conf_get_int(conf, CONF_localedit);
}
void ldisc_free(Ldisc *ldisc)
{
if (ldisc->term)
ldisc->term->ldisc = NULL;
if (ldisc->backend)
backend_provide_ldisc(ldisc->backend, NULL);
if (ldisc->buf)
sfree(ldisc->buf);
sfree(ldisc);
}
void ldisc_echoedit_update(Ldisc *ldisc)
{
seat_echoedit_update(ldisc->seat, ECHOING, EDITING);
}
void ldisc_check_sendok(Ldisc *ldisc)
{
}
void ldisc_send(Ldisc *ldisc, const void *vbuf, int len, bool interactive)
{
const char *buf = (const char *)vbuf;
int keyflag = 0;
assert(ldisc->term);
if (interactive) {
/*
* Interrupt a paste from the clipboard, if one was in
* progress when the user pressed a key. This is easier than
* buffering the current piece of data and saving it until the
* terminal has finished pasting, and has the potential side
* benefit of permitting a user to cancel an accidental huge
* paste.
*/
term_nopaste(ldisc->term);
}
/*
* Less than zero means null terminated special string.
*/
if (len < 0) {
len = strlen(buf);
keyflag = KCTRL('@');
}
/*
* Either perform local editing, or just send characters.
*/
if (EDITING) {
while (len--) {
int c;
c = (unsigned char)(*buf++) + keyflag;
if (!interactive && c == '\r')
c += KCTRL('@');
switch (ldisc->quotenext ? ' ' : c) {
/*
* ^h/^?: delete, and output BSBs, to return to
* last character boundary (in UTF-8 mode this may
* be more than one byte)
* ^w: delete, and output BSBs, to return to last
* space/nonspace boundary
* ^u: delete, and output BSBs, to return to BOL
* ^c: Do a ^u then send a telnet IP
* ^z: Do a ^u then send a telnet SUSP
* ^\: Do a ^u then send a telnet ABORT
* ^r: echo "^R\n" and redraw line
* ^v: quote next char
* ^d: if at BOL, end of file and close connection,
* else send line and reset to BOL
* ^m: send line-plus-\r\n and reset to BOL
*/
case KCTRL('H'):
case KCTRL('?'): /* backspace/delete */
if (ldisc->buflen > 0) {
do {
if (ECHOING)
bsb(ldisc, plen(ldisc, ldisc->buf[ldisc->buflen - 1]));
ldisc->buflen--;
} while (!char_start(ldisc, ldisc->buf[ldisc->buflen]));
}
break;
case CTRL('W'): /* delete word */
while (ldisc->buflen > 0) {
if (ECHOING)
bsb(ldisc, plen(ldisc, ldisc->buf[ldisc->buflen - 1]));
ldisc->buflen--;
if (ldisc->buflen > 0 &&
isspace((unsigned char)ldisc->buf[ldisc->buflen-1]) &&
!isspace((unsigned char)ldisc->buf[ldisc->buflen]))
break;
}
break;
case CTRL('U'): /* delete line */
case CTRL('C'): /* Send IP */
case CTRL('\\'): /* Quit */
case CTRL('Z'): /* Suspend */
while (ldisc->buflen > 0) {
if (ECHOING)
bsb(ldisc, plen(ldisc, ldisc->buf[ldisc->buflen - 1]));
ldisc->buflen--;
}
backend_special(ldisc->backend, SS_EL, 0);
/*
* We don't send IP, SUSP or ABORT if the user has
* configured telnet specials off! This breaks
* talkers otherwise.
*/
if (!ldisc->telnet_keyboard)
goto default_case;
if (c == CTRL('C'))
backend_special(ldisc->backend, SS_IP, 0);
if (c == CTRL('Z'))
backend_special(ldisc->backend, SS_SUSP, 0);
if (c == CTRL('\\'))
backend_special(ldisc->backend, SS_ABORT, 0);
break;
case CTRL('R'): /* redraw line */
if (ECHOING) {
int i;
c_write(ldisc, "^R\r\n", 4);
for (i = 0; i < ldisc->buflen; i++)
pwrite(ldisc, ldisc->buf[i]);
}
break;
case CTRL('V'): /* quote next char */
ldisc->quotenext = true;
break;
case CTRL('D'): /* logout or send */
if (ldisc->buflen == 0) {
backend_special(ldisc->backend, SS_EOF, 0);
} else {
backend_send(ldisc->backend, ldisc->buf, ldisc->buflen);
ldisc->buflen = 0;
}
break;
/*
* This particularly hideous bit of code from RDB
* allows ordinary ^M^J to do the same thing as
* magic-^M when in Raw protocol. The line `case
* KCTRL('M'):' is _inside_ the if block. Thus:
*
* - receiving regular ^M goes straight to the
* default clause and inserts as a literal ^M.
* - receiving regular ^J _not_ directly after a
* literal ^M (or not in Raw protocol) fails the
* if condition, leaps to the bottom of the if,
* and falls through into the default clause
* again.
* - receiving regular ^J just after a literal ^M
* in Raw protocol passes the if condition,
* deletes the literal ^M, and falls through
* into the magic-^M code
* - receiving a magic-^M empties the line buffer,
* signals end-of-line in one of the various
* entertaining ways, and _doesn't_ fall out of
* the bottom of the if and through to the
* default clause because of the break.
*/
case CTRL('J'):
if (ldisc->protocol == PROT_RAW &&
ldisc->buflen > 0 && ldisc->buf[ldisc->buflen - 1] == '\r') {
if (ECHOING)
bsb(ldisc, plen(ldisc, ldisc->buf[ldisc->buflen - 1]));
ldisc->buflen--;
/* FALLTHROUGH */
case KCTRL('M'): /* send with newline */
if (ldisc->buflen > 0)
backend_send(ldisc->backend,
ldisc->buf, ldisc->buflen);
if (ldisc->protocol == PROT_RAW)
backend_send(ldisc->backend, "\r\n", 2);
else if (ldisc->protocol == PROT_TELNET && ldisc->telnet_newline)
backend_special(ldisc->backend, SS_EOL, 0);
else
backend_send(ldisc->backend, "\r", 1);
if (ECHOING)
c_write(ldisc, "\r\n", 2);
ldisc->buflen = 0;
break;
}
/* FALLTHROUGH */
default: /* get to this label from ^V handler */
default_case:
sgrowarray(ldisc->buf, ldisc->bufsiz, ldisc->buflen);
ldisc->buf[ldisc->buflen++] = c;
if (ECHOING)
pwrite(ldisc, (unsigned char) c);
ldisc->quotenext = false;
break;
}
}
} else {
if (ldisc->buflen != 0) {
backend_send(ldisc->backend, ldisc->buf, ldisc->buflen);
while (ldisc->buflen > 0) {
bsb(ldisc, plen(ldisc, ldisc->buf[ldisc->buflen - 1]));
ldisc->buflen--;
}
}
if (len > 0) {
if (ECHOING)
c_write(ldisc, buf, len);
if (keyflag && ldisc->protocol == PROT_TELNET && len == 1) {
switch (buf[0]) {
case CTRL('M'):
if (ldisc->protocol == PROT_TELNET && ldisc->telnet_newline)
backend_special(ldisc->backend, SS_EOL, 0);
else
backend_send(ldisc->backend, "\r", 1);
break;
case CTRL('?'):
case CTRL('H'):
if (ldisc->telnet_keyboard) {
backend_special(ldisc->backend, SS_EC, 0);
break;
}
case CTRL('C'):
if (ldisc->telnet_keyboard) {
backend_special(ldisc->backend, SS_IP, 0);
break;
}
case CTRL('Z'):
if (ldisc->telnet_keyboard) {
backend_special(ldisc->backend, SS_SUSP, 0);
break;
}
default:
backend_send(ldisc->backend, buf, len);
break;
}
} else
backend_send(ldisc->backend, buf, len);
}
}
}
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