mirror of
https://github.com/topjohnwu/ndk-busybox.git
synced 2024-11-24 04:09:43 +00:00
getty,login: tighten up handling of ctty, pgrp, and tty attr restoring on timeout
Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
This commit is contained in:
Denys Vlasenko
parent
ef5a2d757a
commit
7449e18190
@ -279,6 +279,7 @@ and inspect it by
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Again, if TOSTOP is set but the background process ignores or blocks
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the SIGTTOU signal, or if its process group is orphaned (see below),
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then the write() returns an EIO error, and no signal is sent.
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[vda: correction. SUS says that if SIGTTOU is blocked/ignored, write succeeds. ]
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<p>
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</p><h3>Orphaned process groups</h3>
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@ -30,14 +30,23 @@ char* FAST_FUNC bb_ask(const int fd, int timeout, const char *prompt)
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struct sigaction sa, oldsa;
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struct termios tio, oldtio;
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tcgetattr(fd, &oldtio);
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fputs(prompt, stdout);
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fflush_all();
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tcflush(fd, TCIFLUSH);
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tcgetattr(fd, &oldtio);
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tio = oldtio;
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#ifndef IUCLC
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# define IUCLC 0
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#endif
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#if 0
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/* Switch off UPPERCASE->lowercase conversion (never used since 198x)
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* and XON/XOFF (why we want to mess with this??)
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*/
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# ifndef IUCLC
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# define IUCLC 0
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# endif
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tio.c_iflag &= ~(IUCLC|IXON|IXOFF|IXANY);
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tio.c_lflag &= ~(ECHO|ECHOE|ECHOK|ECHONL|TOSTOP);
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#endif
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/* Switch off echo */
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tio.c_lflag &= ~(ECHO|ECHOE|ECHOK|ECHONL);
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tcsetattr(fd, TCSANOW, &tio);
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memset(&sa, 0, sizeof(sa));
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@ -50,9 +59,6 @@ char* FAST_FUNC bb_ask(const int fd, int timeout, const char *prompt)
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alarm(timeout);
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}
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fputs(prompt, stdout);
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fflush_all();
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if (!passwd)
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passwd = xmalloc(sizeof_passwd);
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ret = passwd;
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@ -83,16 +83,16 @@ static FILE *dbf;
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#define MAX_SPEED 10 /* max. nr. of baud rates */
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struct globals {
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unsigned timeout; /* time-out period */
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unsigned timeout;
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const char *login; /* login program */
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const char *fakehost;
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const char *tty; /* name of tty */
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const char *tty_name;
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char *initstring; /* modem init string */
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const char *issue; /* alternative issue file */
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int numspeed; /* number of baud rates to try */
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int speeds[MAX_SPEED]; /* baud rates to be tried */
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unsigned char eol; /* end-of-line char seen (CR or NL) */
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struct termios termios; /* terminal mode bits */
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struct termios tty_attrs;
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char line_buf[128];
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};
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@ -181,15 +181,14 @@ static void parse_args(char **argv)
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debug("after getopt\n");
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/* We loosen up a bit and accept both "baudrate tty" and "tty baudrate" */
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G.tty = argv[0]; /* tty name */
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ts = argv[1]; /* baud rate(s) */
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G.tty_name = argv[0];
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ts = argv[1]; /* baud rate(s) */
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if (isdigit(argv[0][0])) {
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/* A number first, assume it's a speed (BSD style) */
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G.tty = ts; /* tty name is in argv[1] */
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ts = argv[0]; /* baud rate(s) */
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G.tty_name = ts; /* tty name is in argv[1] */
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ts = argv[0]; /* baud rate(s) */
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}
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parse_speeds(ts);
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applet_name = xasprintf("getty: %s", G.tty);
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if (argv[2])
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xsetenv("TERM", argv[2]);
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@ -201,42 +200,49 @@ static void parse_args(char **argv)
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static void open_tty(void)
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{
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/* Set up new standard input, unless we are given an already opened port */
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if (NOT_LONE_DASH(G.tty)) {
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if (G.tty[0] != '/')
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G.tty = xasprintf("/dev/%s", G.tty); /* will leak it */
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if (NOT_LONE_DASH(G.tty_name)) {
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if (G.tty_name[0] != '/')
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G.tty_name = xasprintf("/dev/%s", G.tty_name); /* will leak it */
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/* Open the tty as standard input */
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debug("open(2)\n");
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close(0);
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xopen(G.tty, O_RDWR | O_NONBLOCK); /* uses fd 0 */
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xopen(G.tty_name, O_RDWR | O_NONBLOCK); /* uses fd 0 */
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/* Set proper protections and ownership */
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fchown(0, 0, 0); /* 0:0 */
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fchmod(0, 0620); /* crw--w---- */
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} else {
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char *n;
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/*
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* Standard input should already be connected to an open port. Make
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* sure it is open for read/write.
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* Standard input should already be connected to an open port.
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* Make sure it is open for read/write.
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*/
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if ((fcntl(0, F_GETFL) & (O_RDWR|O_RDONLY|O_WRONLY)) != O_RDWR)
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bb_error_msg_and_die("stdin is not open for read/write");
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/* Try to get real tty name instead of "-" */
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n = xmalloc_ttyname(0);
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if (n)
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G.tty_name = n;
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}
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applet_name = xasprintf("getty: %s", skip_dev_pfx(G.tty_name));
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}
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static void set_termios(void)
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static void set_tty_attrs(void)
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{
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if (tcsetattr_stdin_TCSANOW(&G.termios) < 0)
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if (tcsetattr_stdin_TCSANOW(&G.tty_attrs) < 0)
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bb_perror_msg_and_die("tcsetattr");
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}
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/* We manipulate termios this way:
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* - first, we read existing termios settings
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* - termios_init modifies some parts and sets it
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* - auto_baud and/or BREAK processing can set different speed and set termios
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* - termios_final again modifies some parts and sets termios before
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/* We manipulate tty_attrs this way:
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* - first, we read existing tty_attrs
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* - init_tty_attrs modifies some parts and sets it
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* - auto_baud and/or BREAK processing can set different speed and set tty attrs
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* - finalize_tty_attrs again modifies some parts and sets tty attrs before
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* execing login
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*/
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static void termios_init(int speed)
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static void init_tty_attrs(int speed)
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{
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/* Try to drain output buffer, with 5 sec timeout.
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* Added on request from users of ~600 baud serial interface
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@ -255,14 +261,14 @@ static void termios_init(int speed)
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/* Set speed if it wasn't specified as "0" on command line */
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if (speed != B0)
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cfsetspeed(&G.termios, speed);
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cfsetspeed(&G.tty_attrs, speed);
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/* Initial termios settings: 8-bit characters, raw mode, blocking i/o.
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/* Initial settings: 8-bit characters, raw mode, blocking i/o.
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* Special characters are set after we have read the login name; all
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* reads will be done in raw mode anyway.
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*/
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/* Clear all bits except: */
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G.termios.c_cflag &= (0
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G.tty_attrs.c_cflag &= (0
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/* 2 stop bits (1 otherwise)
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* Enable parity bit (both on input and output)
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* Odd parity (else even)
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@ -280,42 +286,42 @@ static void termios_init(int speed)
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#endif
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);
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/* Set: 8 bits; hang up (drop DTR) on last close; enable receive */
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G.termios.c_cflag |= CS8 | HUPCL | CREAD;
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G.tty_attrs.c_cflag |= CS8 | HUPCL | CREAD;
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if (option_mask32 & F_LOCAL) {
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/* ignore Carrier Detect pin:
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* opens don't block when CD is low,
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* losing CD doesn't hang up processes whose ctty is this tty
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*/
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G.termios.c_cflag |= CLOCAL;
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G.tty_attrs.c_cflag |= CLOCAL;
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}
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#ifdef CRTSCTS
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if (option_mask32 & F_RTSCTS)
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G.termios.c_cflag |= CRTSCTS; /* flow control using RTS/CTS pins */
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G.tty_attrs.c_cflag |= CRTSCTS; /* flow control using RTS/CTS pins */
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#endif
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G.termios.c_iflag = 0;
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G.termios.c_lflag = 0;
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G.tty_attrs.c_iflag = 0;
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G.tty_attrs.c_lflag = 0;
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/* non-raw output; add CR to each NL */
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G.termios.c_oflag = OPOST | ONLCR;
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G.tty_attrs.c_oflag = OPOST | ONLCR;
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G.termios.c_cc[VMIN] = 1; /* block reads if < 1 char is available */
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G.termios.c_cc[VTIME] = 0; /* no timeout (reads block forever) */
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G.tty_attrs.c_cc[VMIN] = 1; /* block reads if < 1 char is available */
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G.tty_attrs.c_cc[VTIME] = 0; /* no timeout (reads block forever) */
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#ifdef __linux__
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G.termios.c_line = 0;
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G.tty_attrs.c_line = 0;
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#endif
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set_termios();
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set_tty_attrs();
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debug("term_io 2\n");
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}
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static void termios_final(void)
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static void finalize_tty_attrs(void)
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{
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/* software flow control on output (stop sending if XOFF is recvd);
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* and on input (send XOFF when buffer is full)
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*/
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G.termios.c_iflag |= IXON | IXOFF;
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G.tty_attrs.c_iflag |= IXON | IXOFF;
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if (G.eol == '\r') {
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G.termios.c_iflag |= ICRNL; /* map CR on input to NL */
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G.tty_attrs.c_iflag |= ICRNL; /* map CR on input to NL */
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}
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/* Other bits in c_iflag:
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* IXANY Any recvd char enables output (any char is also a XON)
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@ -342,7 +348,7 @@ static void termios_final(void)
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* echo kill char specially, not as ^c (ECHOKE controls how exactly);
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* erase all input via BS-SP-BS on kill char (else go to next line)
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*/
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G.termios.c_lflag |= ICANON | ISIG | ECHO | ECHOE | ECHOK | ECHOKE;
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G.tty_attrs.c_lflag |= ICANON | ISIG | ECHO | ECHOE | ECHOK | ECHOKE;
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/* Other bits in c_lflag:
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* XCASE Map uppercase to \lowercase [tried, doesn't work]
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* ECHONL Echo NL even if ECHO is not set
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@ -360,17 +366,17 @@ static void termios_final(void)
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* (why "stty sane" unsets this bit?)
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*/
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G.termios.c_cc[VINTR] = DEF_INTR;
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G.termios.c_cc[VQUIT] = DEF_QUIT;
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G.termios.c_cc[VEOF] = DEF_EOF;
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G.termios.c_cc[VEOL] = DEF_EOL;
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G.tty_attrs.c_cc[VINTR] = DEF_INTR;
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G.tty_attrs.c_cc[VQUIT] = DEF_QUIT;
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G.tty_attrs.c_cc[VEOF] = DEF_EOF;
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G.tty_attrs.c_cc[VEOL] = DEF_EOL;
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#ifdef VSWTC
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G.termios.c_cc[VSWTC] = DEF_SWITCH;
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G.tty_attrs.c_cc[VSWTC] = DEF_SWITCH;
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#endif
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#ifdef VSWTCH
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G.termios.c_cc[VSWTCH] = DEF_SWITCH;
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G.tty_attrs.c_cc[VSWTCH] = DEF_SWITCH;
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#endif
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G.termios.c_cc[VKILL] = DEF_KILL;
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G.tty_attrs.c_cc[VKILL] = DEF_KILL;
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/* Other control chars:
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* VEOL2
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* VERASE, VWERASE - (word) erase. we may set VERASE in get_logname
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@ -380,7 +386,7 @@ static void termios_final(void)
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* VSTART, VSTOP - chars used for IXON/IXOFF
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*/
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set_termios();
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set_tty_attrs();
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}
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/* extract baud rate from modem status message */
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@ -403,8 +409,8 @@ static void auto_baud(void)
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* modem status messages is enabled.
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*/
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G.termios.c_cc[VMIN] = 0; /* don't block reads (min read is 0 chars) */
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set_termios();
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G.tty_attrs.c_cc[VMIN] = 0; /* don't block reads (min read is 0 chars) */
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set_tty_attrs();
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/*
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* Wait for a while, then read everything the modem has said so far and
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@ -420,15 +426,15 @@ static void auto_baud(void)
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if (isdigit(*bp)) {
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speed = bcode(bp);
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if (speed > 0)
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cfsetspeed(&G.termios, speed);
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cfsetspeed(&G.tty_attrs, speed);
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break;
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}
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}
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}
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/* Restore terminal settings */
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G.termios.c_cc[VMIN] = 1; /* restore to value set by termios_init */
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set_termios();
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G.tty_attrs.c_cc[VMIN] = 1; /* restore to value set by init_tty_attrs */
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set_tty_attrs();
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}
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/* get user name, establish parity, speed, erase, kill, eol;
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@ -449,7 +455,7 @@ static char *get_logname(void)
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/* Write issue file and prompt */
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#ifdef ISSUE
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if (!(option_mask32 & F_NOISSUE))
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print_login_issue(G.issue, G.tty);
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print_login_issue(G.issue, G.tty_name);
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#endif
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print_login_prompt();
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@ -479,7 +485,7 @@ static char *get_logname(void)
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goto got_logname;
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case BS:
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case DEL:
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G.termios.c_cc[VERASE] = c;
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G.tty_attrs.c_cc[VERASE] = c;
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if (bp > G.line_buf) {
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full_write(STDOUT_FILENO, "\010 \010", 3);
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bp--;
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@ -510,11 +516,17 @@ static char *get_logname(void)
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return G.line_buf;
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}
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static void alarm_handler(int sig UNUSED_PARAM)
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{
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finalize_tty_attrs();
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_exit(EXIT_SUCCESS);
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}
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int getty_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
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int getty_main(int argc UNUSED_PARAM, char **argv)
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{
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int n;
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pid_t pid;
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pid_t pid, tsid;
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char *logname;
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INIT_G();
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@ -527,14 +539,35 @@ int getty_main(int argc UNUSED_PARAM, char **argv)
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/* Parse command-line arguments */
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parse_args(argv);
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logmode = LOGMODE_NONE;
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/* Create new session and pgrp, lose controlling tty */
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pid = setsid(); /* this also gives us our pid :) */
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if (pid < 0) {
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int fd;
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/* :(
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* docs/ctty.htm says:
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* "This is allowed only when the current process
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* is not a process group leader".
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* Thus, setsid() will fail if we _already_ are
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* a session leader - which is quite possible for getty!
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*/
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pid = getpid();
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if (getsid(0) != pid)
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bb_perror_msg_and_die("setsid");
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/* Looks like we are already a session leader.
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* In this case (setsid failed) we may still have ctty,
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* and it may be different from tty we need to control!
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* If we still have ctty, on Linux ioctl(TIOCSCTTY)
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* (which we are going to call a bit later) always fails.
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* Try to drop ctty now to prevent that.
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*/
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fd = open("/dev/tty", O_RDWR);
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if (fd >= 0) {
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ioctl(fd, TIOCNOTTY);
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close(fd);
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}
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}
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/* Create new session, lose controlling tty, if any */
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/* docs/ctty.htm says:
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* "This is allowed only when the current process
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* is not a process group leader" - is this a problem? */
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setsid();
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/* close stdio, and stray descriptors, just in case */
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/* Close stdio, and stray descriptors, just in case */
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n = xopen(bb_dev_null, O_RDWR);
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/* dup2(n, 0); - no, we need to handle "getty - 9600" too */
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xdup2(n, 1);
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@ -558,13 +591,25 @@ int getty_main(int argc UNUSED_PARAM, char **argv)
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#endif
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/* Open the tty as standard input, if it is not "-" */
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/* If it's not "-" and not taken yet, it will become our ctty */
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debug("calling open_tty\n");
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open_tty();
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ndelay_off(0);
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ndelay_off(STDIN_FILENO);
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debug("duping\n");
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xdup2(0, 1);
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xdup2(0, 2);
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xdup2(STDIN_FILENO, 1);
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xdup2(STDIN_FILENO, 2);
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/* Steal ctty if we don't have it yet */
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tsid = tcgetsid(STDIN_FILENO);
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if (tsid < 0 || pid != tsid) {
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if (ioctl(STDIN_FILENO, TIOCSCTTY, /*force:*/ (long)1) < 0)
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bb_perror_msg_and_die("TIOCSCTTY");
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}
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#ifdef __linux__
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/* Make ourself a foreground process group within our session */
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if (tcsetpgrp(STDIN_FILENO, pid) < 0)
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bb_perror_msg_and_die("tcsetpgrp");
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#endif
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/*
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* The following ioctl will fail if stdin is not a tty, but also when
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@ -574,25 +619,15 @@ int getty_main(int argc UNUSED_PARAM, char **argv)
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* by patching the SunOS kernel variable "zsadtrlow" to a larger value;
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* 5 seconds seems to be a good value.
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*/
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if (tcgetattr(STDIN_FILENO, &G.termios) < 0)
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if (tcgetattr(STDIN_FILENO, &G.tty_attrs) < 0)
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bb_perror_msg_and_die("tcgetattr");
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|
||||
pid = getpid();
|
||||
#ifdef __linux__
|
||||
// FIXME: do we need this? Otherwise "-" case seems to be broken...
|
||||
// /* Forcibly make fd 0 our controlling tty, even if another session
|
||||
// * has it as a ctty. (Another session loses ctty). */
|
||||
// ioctl(STDIN_FILENO, TIOCSCTTY, (void*)1);
|
||||
/* Make ourself a foreground process group within our session */
|
||||
tcsetpgrp(STDIN_FILENO, pid);
|
||||
#endif
|
||||
|
||||
/* Update the utmp file. This tty is ours now! */
|
||||
update_utmp(pid, LOGIN_PROCESS, G.tty, "LOGIN", G.fakehost);
|
||||
update_utmp(pid, LOGIN_PROCESS, G.tty_name, "LOGIN", G.fakehost);
|
||||
|
||||
/* Initialize the termios settings (raw mode, eight-bit, blocking i/o) */
|
||||
debug("calling termios_init\n");
|
||||
termios_init(G.speeds[0]);
|
||||
/* Initialize tty attrs (raw mode, eight-bit, blocking i/o) */
|
||||
debug("calling init_tty_attrs\n");
|
||||
init_tty_attrs(G.speeds[0]);
|
||||
|
||||
/* Write the modem init string and DON'T flush the buffers */
|
||||
if (option_mask32 & F_INITSTRING) {
|
||||
@ -606,8 +641,8 @@ int getty_main(int argc UNUSED_PARAM, char **argv)
|
||||
auto_baud();
|
||||
|
||||
/* Set the optional timer */
|
||||
signal(SIGALRM, alarm_handler);
|
||||
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) {
|
||||
@ -622,7 +657,7 @@ int getty_main(int argc UNUSED_PARAM, char **argv)
|
||||
|
||||
logname = NULL;
|
||||
if (!(option_mask32 & F_NOPROMPT)) {
|
||||
/* NB: termios_init already set line speed
|
||||
/* NB: init_tty_attrs already set line speed
|
||||
* to G.speeds[0] */
|
||||
int baud_index = 0;
|
||||
|
||||
@ -634,16 +669,15 @@ int getty_main(int argc UNUSED_PARAM, char **argv)
|
||||
break;
|
||||
/* We are here only if G.numspeed > 1 */
|
||||
baud_index = (baud_index + 1) % G.numspeed;
|
||||
cfsetspeed(&G.termios, G.speeds[baud_index]);
|
||||
set_termios();
|
||||
cfsetspeed(&G.tty_attrs, G.speeds[baud_index]);
|
||||
set_tty_attrs();
|
||||
}
|
||||
}
|
||||
|
||||
/* Disable timer */
|
||||
alarm(0);
|
||||
|
||||
/* Finalize the termios settings */
|
||||
termios_final();
|
||||
finalize_tty_attrs();
|
||||
|
||||
/* Now the newline character should be properly written */
|
||||
full_write(STDOUT_FILENO, "\n", 1);
|
||||
|
||||
@ -41,6 +41,13 @@ enum {
|
||||
TTYNAME_SIZE = 32,
|
||||
};
|
||||
|
||||
struct globals {
|
||||
struct termios tty_attrs;
|
||||
} FIX_ALIASING;
|
||||
#define G (*(struct globals*)&bb_common_bufsiz1)
|
||||
#define INIT_G() do { } while (0)
|
||||
|
||||
|
||||
#if ENABLE_FEATURE_NOLOGIN
|
||||
static void die_if_nologin(void)
|
||||
{
|
||||
@ -206,15 +213,21 @@ static void motd(void)
|
||||
|
||||
static void alarm_handler(int sig UNUSED_PARAM)
|
||||
{
|
||||
/* This is the escape hatch! Poor serial line users and the like
|
||||
/* This is the escape hatch! Poor serial line users and the like
|
||||
* arrive here when their connection is broken.
|
||||
* We don't want to block here */
|
||||
ndelay_on(1);
|
||||
printf("\r\nLogin timed out after %d seconds\r\n", TIMEOUT);
|
||||
ndelay_on(STDOUT_FILENO);
|
||||
/* Test for correct attr restoring:
|
||||
* run "getty 0 -" from a shell, enter bogus username, stop at
|
||||
* password prompt, let it time out. Without the tcsetattr below,
|
||||
* when you are back at shell prompt, echo will be still off.
|
||||
*/
|
||||
tcsetattr_stdin_TCSANOW(&G.tty_attrs);
|
||||
printf("\r\nLogin timed out after %u seconds\r\n", TIMEOUT);
|
||||
fflush_all();
|
||||
/* unix API is brain damaged regarding O_NONBLOCK,
|
||||
* we should undo it, or else we can affect other processes */
|
||||
ndelay_off(1);
|
||||
ndelay_off(STDOUT_FILENO);
|
||||
_exit(EXIT_SUCCESS);
|
||||
}
|
||||
|
||||
@ -250,9 +263,7 @@ int login_main(int argc UNUSED_PARAM, char **argv)
|
||||
pid_t child_pid;
|
||||
#endif
|
||||
|
||||
username[0] = '\0';
|
||||
signal(SIGALRM, alarm_handler);
|
||||
alarm(TIMEOUT);
|
||||
INIT_G();
|
||||
|
||||
/* More of suid paranoia if called by non-root: */
|
||||
/* Clear dangerous stuff, set PATH */
|
||||
@ -264,6 +275,7 @@ int login_main(int argc UNUSED_PARAM, char **argv)
|
||||
* (The name of the function is misleading. Not daemonizing here.) */
|
||||
bb_daemonize_or_rexec(DAEMON_ONLY_SANITIZE | DAEMON_CLOSE_EXTRA_FDS, NULL);
|
||||
|
||||
username[0] = '\0';
|
||||
opt = getopt32(argv, "f:h:p", &opt_user, &opt_host);
|
||||
if (opt & LOGIN_OPT_f) {
|
||||
if (!run_by_root)
|
||||
@ -274,9 +286,19 @@ int login_main(int argc UNUSED_PARAM, char **argv)
|
||||
if (argv[0]) /* user from command line (getty) */
|
||||
safe_strncpy(username, argv[0], sizeof(username));
|
||||
|
||||
/* Let's find out and memorize our tty */
|
||||
if (!isatty(STDIN_FILENO) || !isatty(STDOUT_FILENO) || !isatty(STDERR_FILENO))
|
||||
/* Save tty attributes - and by doing it, check that it's indeed a tty */
|
||||
if (tcgetattr(STDIN_FILENO, &G.tty_attrs) < 0
|
||||
|| !isatty(STDOUT_FILENO)
|
||||
/*|| !isatty(STDERR_FILENO) - no, guess some people might want to redirect this */
|
||||
) {
|
||||
return EXIT_FAILURE; /* Must be a terminal */
|
||||
}
|
||||
|
||||
/* We install timeout handler only _after_ we saved G.tty_attrs */
|
||||
signal(SIGALRM, alarm_handler);
|
||||
alarm(TIMEOUT);
|
||||
|
||||
/* Find out and memorize our tty name */
|
||||
full_tty = xmalloc_ttyname(STDIN_FILENO);
|
||||
if (!full_tty)
|
||||
full_tty = xstrdup("UNKNOWN");
|
||||
@ -391,7 +413,10 @@ int login_main(int argc UNUSED_PARAM, char **argv)
|
||||
if (!pw->pw_passwd[0])
|
||||
break;
|
||||
fake_it:
|
||||
/* authorization takes place here */
|
||||
/* Password reading and authorization takes place here.
|
||||
* Note that reads (in no-echo mode) trash tty attributes.
|
||||
* If we get interrupted by SIGALRM, we need to restore attrs.
|
||||
*/
|
||||
if (correct_password(pw))
|
||||
break;
|
||||
#endif /* ENABLE_PAM */
|
||||
|
||||
Loading…
Reference in New Issue
Block a user