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getty: document bits we don't set - maybe we should set some of them?

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Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
This commit is contained in:
Denys Vlasenko 2011-01-26 11:28:43 +01:00
parent d7c25e98bf
commit 3ff9be31be
1 changed files with 59 additions and 7 deletions
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66
loginutils/getty.c
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@ -264,10 +264,17 @@ static void termios_init(int speed)
if (option_mask32 & F_RTSCTS)
G.termios.c_cflag |= CRTSCTS; /* flow control using RTS/CTS pins */
#endif
/* Other bits in c_cflag:
* CSTOPB 2 stop bits (1 otherwise)
* PARENB Enable parity bit
* PARODD Use odd parity (else even)
* LOBLK Block job control output (??)
*/
G.termios.c_iflag = 0;
G.termios.c_lflag = 0;
/* non-raw output; add CR to each NL */
G.termios.c_oflag = OPOST | ONLCR;
G.termios.c_cc[VMIN] = 1; /* block reads if < 1 char is available */
G.termios.c_cc[VTIME] = 0; /* no timeout (reads block forever) */
#ifdef __linux__
@ -281,18 +288,55 @@ static void termios_init(int speed)
static void termios_final(void)
{
/* software flow control on output; and on input */
/* software flow control on output (stop sending if XOFF is recvd);
* and on input (send XOFF when buffer is full)
*/
G.termios.c_iflag |= IXON | IXOFF;
if (G.eol == '\r') {
G.termios.c_iflag |= ICRNL; /* map CR on input to NL */
}
/* non-raw input; enable SIGINT/QUIT/etc sigs; echo;
* echo erase character as BS-space-BS;
* echo NL on kill char;
* erase entire line via BS-space-BS on kill char */
/* Other bits in c_iflag:
* IXANY Any recvd char enables output (any char is also a XON)
* INPCK Enable parity check
* IGNPAR Ignore parity errors (drop bad bytes)
* PARMRK Mark parity errors with 0xff, 0x00 prefix
* (else bad byte is received as 0x00)
* ISTRIP Strip parity bit
* IGNBRK Ignore break condition
* BRKINT Send SIGINT on break - maybe set this?
* INLCR Map NL to CR
* IGNCR Ignore CR
* ICRNL Map CR to NL
* IUCLC Map uppercase to lowercase
* IMAXBEL Echo BEL on input line too long
* IUTF8 [Appears to affect tty's idea of char widths,
* observed to improve backspacing through Unicode chars]
*/
/* line buffered input (NL or EOL or EOF chars end a line);
* recognize INT/QUIT/SUSP chars;
* echo input chars;
* echo BS-SP-BS on erase character;
* echo kill char specially, not as ^c (ECHOKE controls how exactly);
* erase all input via BS-SP-BS on kill char (else go to next line)
*/
G.termios.c_lflag |= ICANON | ISIG | ECHO | ECHOE | ECHOK | ECHOKE;
/* echo ctrl chars as ^c; (what is ECHOPRT?) */
/* no longer in c_lflag: | ECHOCTL | ECHOPRT */
/* Other bits in c_lflag:
* XCASE Map uppercase to \lowercase [tried, doesn't work]
* ECHONL Echo NL even if ECHO is not set
* NOFLSH Don't flush input buffer after interrupt or quit chars
* IEXTEN Enable extended functions (??)
* [glibc says it enables c_cc[LNEXT] "enter literal char"
* and c_cc[VDISCARD] "toggle discard buffered output" chars]
* ECHOCTL Echo ctrl chars as ^c (else don't echo) - maybe set this?
* ECHOPRT On erase, echo erased chars
* [qwe<BS><BS><BS> input looks like "qwe\ewq/" on screen]
* FLUSHO Output being flushed (c_cc[VDISCARD] is in effect)
* PENDIN Retype pending input at next read or input char
* (c_cc[VREPRINT] is being processes)
* TOSTOP Send SIGTTOU for background output
* (why "stty sane" unsets this bit?)
*/
G.termios.c_cc[VINTR] = DEF_INTR;
G.termios.c_cc[VQUIT] = DEF_QUIT;
@ -305,6 +349,14 @@ static void termios_final(void)
G.termios.c_cc[VSWTCH] = DEF_SWITCH;
#endif
G.termios.c_cc[VKILL] = DEF_KILL;
/* Other control chars:
* VEOL2
* VERASE, VWERASE - (word) erase. we may set VERASE in get_logname
* VREPRINT - reprint current input buffer
* VLNEXT, VDISCARD, VSTATUS
* VSUSP, VDSUSP - send (delayed) SIGTSTP
* VSTART, VSTOP - chars used for IXON/IXOFF
*/
if (tcsetattr_stdin_TCSANOW(&G.termios) < 0)
bb_perror_msg_and_die("tcsetattr");