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faaf8cb3f

Denys Vlasenko
Denys Vlasenko
2011-01-24
FAILED Duration: 237s

Subject

getty: more simplifications; explain how we treat parity now

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Architecture & Compiler Flags

Architecture: x86_64-linux-gnu Compiler: gcc (Ubuntu 11.4.0-1ubuntu1~22.04.3) 11.4.0

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Commit Diff GitHub →

loginutils/getty.c +93 -95
loginutils/getty.c+93 -95
@@ -1,15 +1,23 @@
/* vi: set sw=4 ts=4: */
-/* Based on agetty - another getty program for Linux. By W. Z. Venema 1989
+/*
+ * Based on agetty - another getty program for Linux. By W. Z. Venema 1989
* Ported to Linux by Peter Orbaek <[email protected]>
* This program is freely distributable.
*
* option added by Eric Rasmussen <[email protected]> - 12/28/95
*
* 1999-02-22 Arkadiusz Mickiewicz <[email protected]>
- * - added Native Language Support
+ * - Added Native Language Support
*
* 1999-05-05 Thorsten Kranzkowski <[email protected]>
- * - enable hardware flow control before displaying /etc/issue
+ * - Enabled hardware flow control before displaying /etc/issue
+ *
+ * 2011-01 Venys Vlasenko
+ * - Removed parity detection code. It can't work reliably:
+ * if all chars received have bit 7 cleared and odd (or even) parity,
+ * it is impossible to determine whether other side is 8-bit,no-parity
+ * or 7-bit,odd(even)-parity. It also interferes with non-ASCII usernames.
+ * - From now on, we assume that parity is correctly set.
*
* Licensed under GPLv2 or later, see file LICENSE in this source tree.
*/
@@ -23,13 +31,7 @@
# define IUCLC 0
#endif
-/*
- * Some heuristics to find out what environment we are in: if it is not
- * System V, assume it is SunOS 4.
- */
-#ifdef LOGIN_PROCESS /* defined in System V utmp.h */
-# include <sys/utsname.h>
-#else /* if !sysV style, wtmp/utmp code is off */
+#ifndef LOGIN_PROCESS
# undef ENABLE_FEATURE_UTMP
# undef ENABLE_FEATURE_WTMP
# define ENABLE_FEATURE_UTMP 0
@@ -37,7 +39,7 @@
#endif
-/* The following is used for understandable diagnostics. */
+/* The following is used for understandable diagnostics */
#ifdef DEBUGGING
static FILE *dbf;
# define DEBUGTERM "/dev/ttyp0"
@@ -64,14 +66,14 @@ static FILE *dbf;
*/
#define ISSUE "/etc/issue"
-/* Some shorthands for control characters. */
+/* Some shorthands for control characters */
#define CTL(x) ((x) ^ 0100) /* Assumes ASCII dialect */
#define CR CTL('M') /* carriage return */
#define NL CTL('J') /* line feed */
#define BS CTL('H') /* back space */
#define DEL CTL('?') /* delete */
-/* Defaults for line-editing etc. characters; you may want to change this. */
+/* Defaults for line-editing etc. characters; you may want to change this */
#define DEF_ERASE DEL /* default erase character */
#define DEF_INTR CTL('C') /* default interrupt character */
#define DEF_QUIT CTL('\\') /* default quit char */
@@ -81,23 +83,22 @@ static FILE *dbf;
#define DEF_SWITCH 0 /* default switch char */
/*
- * When multiple baud rates are specified on the command line, the first one
- * we will try is the first one specified.
+ * When multiple baud rates are specified on the command line,
+ * the first one we will try is the first one specified.
*/
#define MAX_SPEED 10 /* max. nr. of baud rates */
struct globals {
unsigned timeout; /* time-out period */
const char *login; /* login program */
+ const char *fakehost;
const char *tty; /* name of tty */
const char *initstring; /* modem init string */
const char *issue; /* alternative issue file */
int numspeed; /* number of baud rates to try */
int speeds[MAX_SPEED]; /* baud rates to be tried */
+ unsigned char eol; /* end-of-line char seen (CR or NL) */
struct termios termios; /* terminal mode bits */
- /* Storage for things detected while the login name was read. */
- unsigned char erase; /* erase character */
- unsigned char eol; /* end-of-line character */
char line_buf[128];
};
@@ -168,14 +169,14 @@ static void parse_speeds(char *arg)
}
/* parse command-line arguments */
-static void parse_args(char **argv, char **fakehost_p)
+static void parse_args(char **argv)
{
char *ts;
int flags;
opt_complementary = "-2:t+"; /* at least 2 args; -t N */
flags = getopt32(argv, opt_string,
- &G.initstring, fakehost_p, &G.issue,
+ &G.initstring, &G.fakehost, &G.issue,
&G.login, &G.timeout
);
if (flags & F_INITSTRING) {
@@ -206,17 +207,17 @@ static void parse_args(char **argv, char **fakehost_p)
/* set up tty as standard input, output, error */
static void open_tty(void)
{
- /* Set up new standard input, unless we are given an already opened port. */
+ /* Set up new standard input, unless we are given an already opened port */
if (NOT_LONE_DASH(G.tty)) {
if (G.tty[0] != '/')
G.tty = xasprintf("/dev/%s", G.tty); /* will leak it */
- /* Open the tty as standard input. */
+ /* Open the tty as standard input */
debug("open(2)\n");
close(0);
xopen(G.tty, O_RDWR | O_NONBLOCK); /* uses fd 0 */
- /* Set proper protections and ownership. */
+ /* Set proper protections and ownership */
fchown(0, 0, 0); /* 0:0 */
fchmod(0, 0620); /* crw--w---- */
} else {
@@ -229,7 +230,13 @@ static void open_tty(void)
}
}
-/* initialize termios settings */
+/* We manipulate termios this way:
+ * - first, we read existing termios settings
+ * - termios_init modifies some parts and sets it
+ * - auto_baud and/or BREAK processing can set different speed and set termios
+ * - termios_final again modifies some parts and sets termios before
+ * execing login
+ */
static void termios_init(int speed)
{
/* Flush input and output queues, important for modems!
@@ -240,7 +247,7 @@ static void termios_init(int speed)
usleep(100*1000); /* 0.1 sec */
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)
cfsetspeed(&G.termios, speed);
@@ -271,13 +278,44 @@ static void termios_init(int speed)
debug("term_io 2\n");
}
+static void termios_final(void)
+{
+ /* General terminal-independent stuff */
+ G.termios.c_iflag |= IXON | IXOFF; /* 2-way flow control */
+ 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; */
+ G.termios.c_cc[VINTR] = DEF_INTR;
+ G.termios.c_cc[VQUIT] = DEF_QUIT;
+ G.termios.c_cc[VEOF] = DEF_EOF;
+ G.termios.c_cc[VEOL] = DEF_EOL;
+#ifdef VSWTC
+ G.termios.c_cc[VSWTC] = DEF_SWITCH;
+#endif
+
+ /* Account for special characters seen in input */
+ if (G.eol == CR) {
+ 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");
+}
+
/* extract baud rate from modem status message */
static void auto_baud(void)
{
- int speed;
- int vmin;
- unsigned iflag;
- char *bp;
int nread;
/*
@@ -296,12 +334,9 @@ static void auto_baud(void)
*/
/*
- * Use 7-bit characters, don't block if input queue is empty. Errors will
- * be dealt with later on.
+ * Don't block if input queue is empty.
+ * Errors will be dealt with later on.
*/
- iflag = G.termios.c_iflag;
- G.termios.c_iflag |= ISTRIP; /* enable 8th-bit stripping */
- vmin = G.termios.c_cc[VMIN];
G.termios.c_cc[VMIN] = 0; /* don't block if queue empty */
tcsetattr_stdin_TCSANOW(&G.termios);
@@ -312,6 +347,8 @@ static void auto_baud(void)
sleep(1);
nread = safe_read(STDIN_FILENO, G.line_buf, sizeof(G.line_buf) - 1);
if (nread > 0) {
+ int speed;
+ char *bp;
G.line_buf[nread] = '\0';
for (bp = G.line_buf; bp < G.line_buf + nread; bp++) {
if (isdigit(*bp)) {
@@ -323,38 +360,38 @@ static void auto_baud(void)
}
}
- /* Restore terminal settings. Errors will be dealt with later on. */
- G.termios.c_iflag = iflag;
- G.termios.c_cc[VMIN] = vmin;
+ /* 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);
}
/* get user name, establish parity, speed, erase, kill, eol;
- * return NULL on BREAK, logname on success */
+ * return NULL on BREAK, logname on success
+ */
static char *get_logname(void)
{
char *bp;
char c;
- /* Flush pending input (esp. after parsing or switching the baud rate). */
+ /* Flush pending input (esp. after parsing or switching the baud rate) */
usleep(100*1000); /* 0.1 sec */
tcflush(STDIN_FILENO, TCIOFLUSH);
- /* Prompt for and read a login name. */
+ /* Prompt for and read a login name */
G.line_buf[0] = '\0';
while (!G.line_buf[0]) {
- /* Write issue file and prompt. */
+ /* Write issue file and prompt */
#ifdef ISSUE
if (!(option_mask32 & F_NOISSUE))
print_login_issue(G.issue, G.tty);
#endif
print_login_prompt();
- /* Read name, watch for break, parity, erase, kill, end-of-line. */
+ /* Read name, watch for break, parity, erase, kill, end-of-line */
bp = G.line_buf;
G.eol = '\0';
while (1) {
- /* Do not report trivial EINTR/EIO errors. */
+ /* Do not report trivial EINTR/EIO errors */
errno = EINTR; /* make read of 0 bytes be silent too */
if (read(STDIN_FILENO, &c, 1) < 1) {
if (errno == EINTR || errno == EIO)
@@ -367,7 +404,7 @@ static char *get_logname(void)
if (c == '\0' && G.numspeed > 1)
return NULL;
- /* Do erase, kill and end-of-line processing. */
+ /* Do erase, kill and end-of-line processing */
switch (c) {
case CR:
case NL:
@@ -376,7 +413,7 @@ static char *get_logname(void)
goto got_logname;
case BS:
case DEL:
- G.erase = c;
+ G.termios.c_cc[VERASE] = c;
if (bp > G.line_buf) {
full_write(STDOUT_FILENO, "\010 \010", 3);
bp--;
@@ -407,61 +444,22 @@ static char *get_logname(void)
return G.line_buf;
}
-/* set the final tty mode bits */
-static void termios_final(void)
-{
- /* General terminal-independent stuff. */
- G.termios.c_iflag |= IXON | IXOFF; /* 2-way flow control */
- 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; */
- G.termios.c_cc[VINTR] = DEF_INTR; /* default interrupt */
- G.termios.c_cc[VQUIT] = DEF_QUIT; /* default quit */
- G.termios.c_cc[VEOF] = DEF_EOF; /* default EOF character */
- G.termios.c_cc[VEOL] = DEF_EOL;
-#ifdef VSWTC
- G.termios.c_cc[VSWTC] = DEF_SWITCH; /* default switch character */
-#endif
-
- /* Account for special characters seen in input. */
- if (G.eol == CR) {
- G.termios.c_iflag |= ICRNL; /* map CR in input to NL */
- G.termios.c_oflag |= ONLCR; /* map NL in output to CR-NL */
- }
- G.termios.c_cc[VERASE] = G.erase; /* set erase character */
- G.termios.c_cc[VKILL] = DEF_KILL; /* set kill character */
-
-#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");
-}
-
int getty_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
int getty_main(int argc UNUSED_PARAM, char **argv)
{
int n;
pid_t pid;
- char *fakehost = NULL; /* Fake hostname for ut_host */
char *logname;
INIT_G();
G.login = _PATH_LOGIN; /* default login program */
- G.initstring = ""; /* modem init string */
#ifdef ISSUE
G.issue = ISSUE; /* default issue file */
#endif
- G.erase = DEF_ERASE;
G.eol = CR;
- /* Parse command-line arguments. */
- parse_args(argv, &fakehost);
+ /* Parse command-line arguments */
+ parse_args(argv);
logmode = LOGMODE_NONE;
@@ -524,9 +522,9 @@ int getty_main(int argc UNUSED_PARAM, char **argv)
#endif
/* Update the utmp file. This tty is ours now! */
- update_utmp(pid, LOGIN_PROCESS, G.tty, "LOGIN", fakehost);
+ update_utmp(pid, LOGIN_PROCESS, G.tty, "LOGIN", G.fakehost);
- /* Initialize the termios settings (raw mode, eight-bit, blocking i/o). */
+ /* Initialize the termios settings (raw mode, eight-bit, blocking i/o) */
debug("calling termios_init\n");
termios_init(G.speeds[0]);
@@ -563,30 +561,30 @@ int getty_main(int argc UNUSED_PARAM, char **argv)
int baud_index = 0;
while (1) {
- /* Read the login name. */
+ /* Read the login name */
debug("reading login name\n");
logname = get_logname();
if (logname)
break;
- /* We are here only if G.numspeed > 1. */
+ /* 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);
}
}
- /* Disable timer. */
+ /* Disable timer */
alarm(0);
- /* Finalize the termios settings. */
+ /* Finalize the termios settings */
termios_final();
- /* Now the newline character should be properly written. */
+ /* Now the newline character should be properly written */
full_write(STDOUT_FILENO, "\n", 1);
- /* Let the login program take care of password validation. */
+ /* Let the login program take care of password validation */
/* We use PATH because we trust that root doesn't set "bad" PATH,
- * and getty is not suid-root applet. */
+ * and getty is not suid-root applet */
/* With -n, logname == NULL, and login will ask for username instead */
BB_EXECLP(G.login, G.login, "--", logname, NULL);
bb_error_msg_and_die("can't execute '%s'", G.login);