From d8494934a7b7cb8063282b03a6b996c9b7cec42a Mon Sep 17 00:00:00 2001 From: Denys Vlasenko Date: Wed, 26 Jan 2011 03:26:38 +0100 Subject: getty: explain every bit in termios; remove redundant stuff in termios_final Signed-off-by: Denys Vlasenko --- loginutils/getty.c | 67 +++++++++++++++++++++++++----------------------------- 1 file changed, 31 insertions(+), 36 deletions(-) (limited to 'loginutils/getty.c') diff --git a/loginutils/getty.c b/loginutils/getty.c index b71d68a1f..29d889f43 100644 --- a/loginutils/getty.c +++ b/loginutils/getty.c @@ -106,15 +106,15 @@ struct globals { //usage:#define getty_full_usage "\n\n" //usage: "Open a tty, prompt for a login name, then invoke /bin/login\n" //usage: "\nOptions:" -//usage: "\n -h Enable hardware (RTS/CTS) flow control" -//usage: "\n -i Don't display /etc/issue" -//usage: "\n -L Local line, set CLOCAL on it" +//usage: "\n -h Enable hardware RTS/CTS flow control" +//usage: "\n -L Set CLOCAL (ignore Carrier Detect state)" //usage: "\n -m Get baud rate from modem's CONNECT status message" +//usage: "\n -n Don't prompt for login name" //usage: "\n -w Wait for CR or LF before sending /etc/issue" -//usage: "\n -n Don't prompt for a login name" +//usage: "\n -i Don't display /etc/issue" //usage: "\n -f ISSUE_FILE Display ISSUE_FILE instead of /etc/issue" //usage: "\n -l LOGIN Invoke LOGIN instead of /bin/login" -//usage: "\n -t SEC Terminate after SEC if no username is read" +//usage: "\n -t SEC Terminate after SEC if no login name is read" //usage: "\n -I INITSTR Send INITSTR before anything else" //usage: "\n -H HOST Log HOST into the utmp file as the hostname" //usage: "\n" @@ -251,21 +251,28 @@ static void termios_init(int speed) * reads will be done in raw mode anyway. Errors will be dealt with * later on. */ + /* 8 bits; hangup (drop DTR) on last close; enable receive */ G.termios.c_cflag = CS8 | HUPCL | CREAD; - if (option_mask32 & F_LOCAL) + if (option_mask32 & F_LOCAL) { + /* ignore Carrier Detect pin: + * opens don't block when CD is low, + * losing CD doesn't hang up processes whose ctty is this tty + */ G.termios.c_cflag |= CLOCAL; + } +#ifdef CRTSCTS + if (option_mask32 & F_RTSCTS) + G.termios.c_cflag |= CRTSCTS; /* flow control using RTS/CTS pins */ +#endif 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; - G.termios.c_cc[VTIME] = 0; + 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__ G.termios.c_line = 0; #endif -#ifdef CRTSCTS - if (option_mask32 & F_RTSCTS) - G.termios.c_cflag |= CRTSCTS; -#endif tcsetattr_stdin_TCSANOW(&G.termios); @@ -274,12 +281,17 @@ static void termios_init(int speed) static void termios_final(void) { - /* General terminal-independent stuff */ - G.termios.c_iflag |= IXON | IXOFF; /* 2-way flow control */ + /* software flow control on output; and on input */ + 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/ec sigs; echo; echo NL on kill char; + * erase entire line via BS-space-BS on kill char */ G.termios.c_lflag |= ICANON | ISIG | ECHO | ECHOE | ECHOK | ECHOKE; - /* no longer in lflag: | ECHOCTL | ECHOPRT */ - G.termios.c_oflag |= OPOST; - /* G.termios.c_cflag = 0; */ + /* echo ctrl chars as ^c; (what is ECHOPRT?) */ + /* no longer in c_lflag: | ECHOCTL | ECHOPRT */ + G.termios.c_cc[VINTR] = DEF_INTR; G.termios.c_cc[VQUIT] = DEF_QUIT; G.termios.c_cc[VEOF] = DEF_EOF; @@ -290,22 +302,8 @@ static void termios_final(void) #ifdef VSWTCH G.termios.c_cc[VSWTCH] = DEF_SWITCH; #endif - - /* Account for special characters seen in input */ - if (G.eol == '\r') { - G.termios.c_iflag |= ICRNL; /* map CR in input to NL */ - /* already done by termios_init */ - /* G.termios.c_oflag |= ONLCR; map NL in output to CR-NL */ - } G.termios.c_cc[VKILL] = DEF_KILL; -#ifdef CRTSCTS - /* Optionally enable hardware flow control */ - if (option_mask32 & F_RTSCTS) - G.termios.c_cflag |= CRTSCTS; -#endif - - /* Finally, make the new settings effective */ if (tcsetattr_stdin_TCSANOW(&G.termios) < 0) bb_perror_msg_and_die("tcsetattr"); } @@ -330,11 +328,7 @@ static void auto_baud(void) * modem status messages is enabled. */ - /* - * Don't block if input queue is empty. - * Errors will be dealt with later on. - */ - G.termios.c_cc[VMIN] = 0; /* don't block if queue empty */ + G.termios.c_cc[VMIN] = 0; /* don't block reads (min read is 0 chars) */ tcsetattr_stdin_TCSANOW(&G.termios); /* @@ -538,6 +532,7 @@ int getty_main(int argc UNUSED_PARAM, char **argv) /* Set the optional timer */ alarm(G.timeout); /* if 0, alarm is not set */ +//BUG: death by signal won't restore termios /* Optionally wait for CR or LF before writing /etc/issue */ if (option_mask32 & F_WAITCRLF) { -- cgit v1.2.3