ddd1ec1c2
Peter Korsgaard
2011-01-26
Subject
getty: wait up to 5 seconds for the output buffer to drain
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loginutils/getty.c+33 -23
| @@ -224,6 +224,12 @@ static void open_tty(void) | |
| } | |
| } | |
| + | static void set_termios(void) |
| + | { |
| + | if (tcsetattr_stdin_TCSANOW(&G.termios) < 0) |
| + | bb_perror_msg_and_die("tcsetattr"); |
| + | } |
| + | |
| /* We manipulate termios this way: | |
| * - first, we read existing termios settings | |
| * - termios_init modifies some parts and sets it | |
| @@ -233,25 +239,31 @@ static void open_tty(void) | |
| */ | |
| static void termios_init(int speed) | |
| { | |
| - | /* Flush input and output queues, important for modems! |
| - | * Users report losing previously queued output chars, and I hesitate |
| - | * to use tcdrain here instead of tcflush - I imagine it can block. |
| - | * Using small sleep instead. |
| + | /* Try to drain output buffer, with 5 sec timeout. |
| + | * Added on request from users of ~600 baud serial interface |
| + | * with biggish buffer on a 90MHz CPU. |
| + | * They were losing hundreds of bytes of buffered output |
| + | * on tcflush. |
| */ | |
| - | usleep(100*1000); /* 0.1 sec */ |
| + | signal_no_SA_RESTART_empty_mask(SIGALRM, record_signo); |
| + | alarm(5); |
| + | tcdrain(STDIN_FILENO); |
| + | alarm(0); |
| + | signal(SIGALRM, SIG_DFL); /* do not break -t TIMEOUT! */ |
| + | |
| + | /* Flush input and output queues, important for modems! */ |
| tcflush(STDIN_FILENO, TCIOFLUSH); | |
| /* Set speed if it wasn't specified as "0" on command line */ | |
| if (speed != B0) | |
| cfsetspeed(&G.termios, speed); | |
| - | /* |
| - | * Initial termios settings: 8-bit characters, raw-mode, blocking i/o. |
| + | /* Initial termios settings: 8-bit characters, raw-mode, blocking i/o. |
| * Special characters are set after we have read the login name; all | |
| * 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 */ |
| + | /* 8 bits; hang up (drop DTR) on last close; enable receive */ |
| G.termios.c_cflag = CS8 | HUPCL | CREAD; | |
| if (option_mask32 & F_LOCAL) { | |
| /* ignore Carrier Detect pin: | |
| @@ -266,9 +278,8 @@ static void termios_init(int speed) | |
| #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 (??) |
| + | * PARENB Enable parity bit (both on input and output) |
| + | * PARODD Odd parity (else even) |
| */ | |
| G.termios.c_iflag = 0; | |
| G.termios.c_lflag = 0; | |
| @@ -281,7 +292,7 @@ static void termios_init(int speed) | |
| G.termios.c_line = 0; | |
| #endif | |
| - | tcsetattr_stdin_TCSANOW(&G.termios); |
| + | set_termios(); |
| debug("term_io 2\n"); | |
| } | |
| @@ -309,8 +320,8 @@ static void termios_final(void) | |
| * 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] |
| + | * 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); | |
| @@ -324,16 +335,16 @@ static void termios_final(void) | |
| /* Other bits in c_lflag: | |
| * XCASE Map uppercase to \lowercase [tried, doesn't work] | |
| * ECHONL Echo NL even if ECHO is not set | |
| + | * 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] |
| * 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) |
| + | * (c_cc[VREPRINT] is being processed) |
| * TOSTOP Send SIGTTOU for background output | |
| * (why "stty sane" unsets this bit?) | |
| */ | |
| @@ -358,8 +369,7 @@ static void termios_final(void) | |
| * VSTART, VSTOP - chars used for IXON/IXOFF | |
| */ | |
| - | if (tcsetattr_stdin_TCSANOW(&G.termios) < 0) |
| - | bb_perror_msg_and_die("tcsetattr"); |
| + | set_termios(); |
| } | |
| /* extract baud rate from modem status message */ | |
| @@ -383,7 +393,7 @@ static void auto_baud(void) | |
| */ | |
| G.termios.c_cc[VMIN] = 0; /* don't block reads (min read is 0 chars) */ | |
| - | tcsetattr_stdin_TCSANOW(&G.termios); |
| + | set_termios(); |
| /* | |
| * Wait for a while, then read everything the modem has said so far and | |
| @@ -407,7 +417,7 @@ static void auto_baud(void) | |
| /* Restore terminal settings. Errors will be dealt with later on */ | |
| G.termios.c_cc[VMIN] = 1; /* restore to value set by termios_init */ | |
| - | tcsetattr_stdin_TCSANOW(&G.termios); |
| + | set_termios(); |
| } | |
| /* get user name, establish parity, speed, erase, kill, eol; | |
| @@ -614,7 +624,7 @@ int getty_main(int argc UNUSED_PARAM, char **argv) | |
| /* We are here only if G.numspeed > 1 */ | |
| baud_index = (baud_index + 1) % G.numspeed; | |
| cfsetspeed(&G.termios, G.speeds[baud_index]); | |
| - | tcsetattr_stdin_TCSANOW(&G.termios); |
| + | set_termios(); |
| } | |
| } | |