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getty: wait up to 5 seconds for the output buffer to drain

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Signed-off-by: Peter Korsgaard <jacmet@sunsite.dk>
Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
This commit is contained in:
Peter Korsgaard
2011-01-26 15:15:19 +01:00
committed by Denys Vlasenko
parent e3d4c03852
commit ddd1ec1c27
1 changed files with 33 additions and 23 deletions
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56
loginutils/getty.c
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@@ -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: /* We manipulate termios this way:
* - first, we read existing termios settings * - first, we read existing termios settings
* - termios_init modifies some parts and sets it * - termios_init modifies some parts and sets it
@@ -233,25 +239,31 @@ static void open_tty(void)
*/ */
static void termios_init(int speed) static void termios_init(int speed)
{ {
/* Flush input and output queues, important for modems! /* Try to drain output buffer, with 5 sec timeout.
* Users report losing previously queued output chars, and I hesitate * Added on request from users of ~600 baud serial interface
* to use tcdrain here instead of tcflush - I imagine it can block. * with biggish buffer on a 90MHz CPU.
* Using small sleep instead. * 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); tcflush(STDIN_FILENO, TCIOFLUSH);
/* Set speed if it wasn't specified as "0" on command line */ /* Set speed if it wasn't specified as "0" on command line */
if (speed != B0) if (speed != B0)
cfsetspeed(&G.termios, speed); 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 * 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 * reads will be done in raw mode anyway. Errors will be dealt with
* later on. * 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; G.termios.c_cflag = CS8 | HUPCL | CREAD;
if (option_mask32 & F_LOCAL) { if (option_mask32 & F_LOCAL) {
/* ignore Carrier Detect pin: /* ignore Carrier Detect pin:
@@ -266,9 +278,8 @@ static void termios_init(int speed)
#endif #endif
/* Other bits in c_cflag: /* Other bits in c_cflag:
* CSTOPB 2 stop bits (1 otherwise) * CSTOPB 2 stop bits (1 otherwise)
* PARENB Enable parity bit * PARENB Enable parity bit (both on input and output)
* PARODD Use odd parity (else even) * PARODD Odd parity (else even)
* LOBLK Block job control output (??)
*/ */
G.termios.c_iflag = 0; G.termios.c_iflag = 0;
G.termios.c_lflag = 0; G.termios.c_lflag = 0;
@@ -281,7 +292,7 @@ static void termios_init(int speed)
G.termios.c_line = 0; G.termios.c_line = 0;
#endif #endif
tcsetattr_stdin_TCSANOW(&G.termios); set_termios();
debug("term_io 2\n"); debug("term_io 2\n");
} }
@@ -309,8 +320,8 @@ static void termios_final(void)
* ICRNL Map CR to NL * ICRNL Map CR to NL
* IUCLC Map uppercase to lowercase * IUCLC Map uppercase to lowercase
* IMAXBEL Echo BEL on input line too long * IMAXBEL Echo BEL on input line too long
* IUTF8 [Appears to affect tty's idea of char widths, * IUTF8 Appears to affect tty's idea of char widths,
* observed to improve backspacing through Unicode chars] * observed to improve backspacing through Unicode chars
*/ */
/* line buffered input (NL or EOL or EOF chars end a line); /* 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: /* Other bits in c_lflag:
* XCASE Map uppercase to \lowercase [tried, doesn't work] * XCASE Map uppercase to \lowercase [tried, doesn't work]
* ECHONL Echo NL even if ECHO is not set * 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 * NOFLSH Don't flush input buffer after interrupt or quit chars
* IEXTEN Enable extended functions (??) * IEXTEN Enable extended functions (??)
* [glibc says it enables c_cc[LNEXT] "enter literal char" * [glibc says it enables c_cc[LNEXT] "enter literal char"
* and c_cc[VDISCARD] "toggle discard buffered output" chars] * 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) * FLUSHO Output being flushed (c_cc[VDISCARD] is in effect)
* PENDIN Retype pending input at next read or input char * 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 * TOSTOP Send SIGTTOU for background output
* (why "stty sane" unsets this bit?) * (why "stty sane" unsets this bit?)
*/ */
@@ -358,8 +369,7 @@ static void termios_final(void)
* VSTART, VSTOP - chars used for IXON/IXOFF * VSTART, VSTOP - chars used for IXON/IXOFF
*/ */
if (tcsetattr_stdin_TCSANOW(&G.termios) < 0) set_termios();
bb_perror_msg_and_die("tcsetattr");
} }
/* extract baud rate from modem status message */ /* 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) */ 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 * 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 */ /* Restore terminal settings. Errors will be dealt with later on */
G.termios.c_cc[VMIN] = 1; /* restore to value set by termios_init */ 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; /* 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 */ /* We are here only if G.numspeed > 1 */
baud_index = (baud_index + 1) % G.numspeed; baud_index = (baud_index + 1) % G.numspeed;
cfsetspeed(&G.termios, G.speeds[baud_index]); cfsetspeed(&G.termios, G.speeds[baud_index]);
tcsetattr_stdin_TCSANOW(&G.termios); set_termios();
} }
} }