7 files changed, 134 insertions, 56 deletions

diff --git a/include/libbb.h b/include/libbb.h
index ea61701b7..f3121eb47 100644
--- a/include/libbb.h
+++ b/include/libbb.h
@@ -797,9 +797,11 @@ void die_if_bad_username(const char* name) FAST_FUNC;
 #endif
 
 #if ENABLE_FEATURE_UTMP
-void FAST_FUNC update_utmp(int new_type, const char *short_tty, const char *username, const char *opt_host);
+void FAST_FUNC write_new_utmp(pid_t pid, int new_type, const char *tty_name, const char *username, const char *hostname);
+void FAST_FUNC update_utmp(pid_t pid, int new_type, const char *tty_name, const char *username, const char *hostname);
 #else
-# define update_utmp(new_type, short_tty, username, opt_host) ((void)0)
+# define write_new_utmp(pid, new_type, tty_name, username, hostname) ((void)0)
+# define update_utmp(pid, new_type, tty_name, username, hostname) ((void)0)
 #endif
 
 int execable_file(const char *name) FAST_FUNC;
diff --git a/init/halt.c b/init/halt.c
index a3459ee48..f1bb2c4a8 100644
--- a/init/halt.c
+++ b/init/halt.c
@@ -18,17 +18,18 @@ static void write_wtmp(void)
 {
         struct utmp utmp;
         struct utsname uts;
-        if (access(bb_path_wtmp_file, R_OK|W_OK) == -1) {
+        /* "man utmp" says wtmp file should *not* be created automagically */
+        /*if (access(bb_path_wtmp_file, R_OK|W_OK) == -1) {
                 close(creat(bb_path_wtmp_file, 0664));
-        }
+        }*/
         memset(&utmp, 0, sizeof(utmp));
         utmp.ut_tv.tv_sec = time(NULL);
-        safe_strncpy(utmp.ut_user, "shutdown", UT_NAMESIZE);
+        strcpy(utmp.ut_user, "shutdown"); /* it is wide enough */
         utmp.ut_type = RUN_LVL;
-        safe_strncpy(utmp.ut_id, "~~", sizeof(utmp.ut_id));
-        safe_strncpy(utmp.ut_line, "~~", UT_LINESIZE);
-        if (uname(&uts) == 0)
-                safe_strncpy(utmp.ut_host, uts.release, sizeof(utmp.ut_host));
+        utmp.ut_id[0] = '~'; utmp.ut_id[1] = '~'; /* = strcpy(utmp.ut_id, "~~"); */
+        utmp.ut_line[0] = '~'; utmp.ut_line[1] = '~'; /* = strcpy(utmp.ut_line, "~~"); */
+        uname(&uts);
+        safe_strncpy(utmp.ut_host, uts.release, sizeof(utmp.ut_host));
         updwtmp(bb_path_wtmp_file, &utmp);
 }
 #else
diff --git a/libbb/utmp.c b/libbb/utmp.c
index 06b939b9d..d6ba336e3 100644
--- a/libbb/utmp.c
+++ b/libbb/utmp.c
@@ -15,37 +15,87 @@ static void touch(const char *filename)
                 close(open(filename, O_WRONLY | O_CREAT, 0664));
 }
 
+// TODO: move to libbb
+static const char* skip_dev_pfx(const char *tty_name)
+{
+        if (strncmp(tty_name, "/dev/", 5) == 0)
+                tty_name += 5;
+        return tty_name;
+}
+
+void FAST_FUNC write_new_utmp(pid_t pid, int new_type, const char *tty_name, const char *username, const char *hostname)
+{
+        struct utmp utent;
+        char *id;
+        unsigned width;
+
+        memset(&utent, 0, sizeof(utent));
+        utent.ut_pid = pid;
+        utent.ut_type = new_type;
+        tty_name = skip_dev_pfx(tty_name);
+        safe_strncpy(utent.ut_line, tty_name, sizeof(utent.ut_line));
+        if (username)
+                safe_strncpy(utent.ut_user, username, sizeof(utent.ut_user));
+        if (hostname)
+                safe_strncpy(utent.ut_host, hostname, sizeof(utent.ut_host));
+        utent.ut_tv.tv_sec = time(NULL);
+
+        /* Invent our own ut_id. ut_id is only 4 chars wide.
+         * Try to fit something remotely meaningful... */
+        id = utent.ut_id;
+        width = sizeof(utent.ut_id);
+        if (tty_name[0] == 'p') {
+                /* if "ptyXXX", map to "pXXX" */
+                /* if "pts/XX", map to "p/XX" */
+                *id++ = 'p';
+                width--;
+        } /* else: usually it's "ttyXXXX", map to "XXXX" */
+        if (strlen(tty_name) > 3)
+                tty_name += 3;
+        strncpy(id, tty_name, width);
+
+        touch(_PATH_UTMP);
+        //utmpname(_PATH_UTMP);
+        setutent();
+        /* Append new one (hopefully, unless we collide on ut_id) */
+        pututline(&utent);
+        endutent();
+
+#if ENABLE_FEATURE_WTMP
+        /* "man utmp" says wtmp file should *not* be created automagically */
+        /*touch(bb_path_wtmp_file);*/
+        updwtmp(bb_path_wtmp_file, &utent);
+#endif
+}
+
 /*
  * Read "man utmp" to make sense out of it.
  */
-void FAST_FUNC update_utmp(int new_type, const char *short_tty, const char *username, const char *opt_host)
+void FAST_FUNC update_utmp(pid_t pid, int new_type, const char *tty_name, const char *username, const char *hostname)
 {
         struct utmp utent;
-        struct utmp *ut;
-        pid_t pid;
+        struct utmp *utp;
 
         touch(_PATH_UTMP);
-        utmpname(_PATH_UTMP);
+        //utmpname(_PATH_UTMP);
         setutent();
 
-        pid = getpid();
         /* Did init/getty/telnetd/sshd/... create an entry for us?
          * It should be (new_type-1), but we'd also reuse
          * any other potentially stale xxx_PROCESS entry */
-        while ((ut = getutent()) != NULL) {
-                if (ut->ut_pid == pid
+        while ((utp = getutent()) != NULL) {
+                if (utp->ut_pid == pid
                 // && ut->ut_line[0]
-                 && ut->ut_id[0] /* must have nonzero id */
-                 && (  ut->ut_type == INIT_PROCESS
-                    || ut->ut_type == LOGIN_PROCESS
-                    || ut->ut_type == USER_PROCESS
-                    || ut->ut_type == DEAD_PROCESS
+                 && utp->ut_id[0] /* must have nonzero id */
+                 && (  utp->ut_type == INIT_PROCESS
+                    || utp->ut_type == LOGIN_PROCESS
+                    || utp->ut_type == USER_PROCESS
+                    || utp->ut_type == DEAD_PROCESS
                     )
                 ) {
-                        utent = *ut; /* struct copy */
-                        if (ut->ut_type >= new_type) {
+                        if (utp->ut_type >= new_type) {
                                 /* Stale record. Nuke hostname */
-                                memset(utent.ut_host, 0, sizeof(utent.ut_host));
+                                memset(utp->ut_host, 0, sizeof(utp->ut_host));
                         }
                         /* NB: pututline (see later) searches for matching utent
                          * using getutid(utent) - we must not change ut_id
@@ -54,39 +104,38 @@ void FAST_FUNC update_utmp(int new_type, const char *short_tty, const char *user
                         break;
                 }
         }
-        endutent();
+        //endutent(); - no need, pututline can deal with (and actually likes)
+        //the situation when utmp file is positioned on found record
 
-        if (!ut) {
-                /* Didn't find anything, create new one */
-                memset(&utent, 0, sizeof(utent));
-                utent.ut_pid = pid;
-                /* Invent our own ut_id. ut_id is only 4 chars wide.
-                 * Try to fit something remotely meaningful... */
-                if (short_tty[0] == 'p') {
-                        /* if "ptyXXX", map to "pXXX" */
-                        /* if "pts/XX", map to "p/XX" */
-                        utent.ut_id[0] = 'p';
-                        strncpy(utent.ut_id + 1, short_tty + 3, sizeof(utent.ut_id)-1);
-                } else {
-                        /* assuming it's "ttyXXXX", map to "XXXX" */
-                        strncpy(utent.ut_id, short_tty + 3, sizeof(utent.ut_id));
-                }
+        if (!utp) {
+                if (new_type != DEAD_PROCESS)
+                        write_new_utmp(pid, new_type, tty_name, username, hostname);
+                else
+                        endutent();
+                return;
         }
 
+        /* Make a copy. We can't use *utp, pututline's internal getutid
+         * will overwrite it before it is used! */
+        utent = *utp;
+
         utent.ut_type = new_type;
-        safe_strncpy(utent.ut_line, short_tty, sizeof(utent.ut_line));
-        safe_strncpy(utent.ut_user, username, sizeof(utent.ut_user));
-        if (opt_host)
-                safe_strncpy(utent.ut_host, opt_host, sizeof(utent.ut_host));
+        if (tty_name)
+                safe_strncpy(utent.ut_line, skip_dev_pfx(tty_name), sizeof(utent.ut_line));
+        if (username)
+                safe_strncpy(utent.ut_user, username, sizeof(utent.ut_user));
+        if (hostname)
+                safe_strncpy(utent.ut_host, hostname, sizeof(utent.ut_host));
         utent.ut_tv.tv_sec = time(NULL);
 
         /* Update, or append new one */
-        setutent();
+        //setutent();
         pututline(&utent);
         endutent();
 
 #if ENABLE_FEATURE_WTMP
-        touch(bb_path_wtmp_file);
+        /* "man utmp" says wtmp file should *not* be created automagically */
+        /*touch(bb_path_wtmp_file);*/
         updwtmp(bb_path_wtmp_file, &utent);
 #endif
 }
diff --git a/loginutils/getty.c b/loginutils/getty.c
index 8d1d5254e..d032357e2 100644
--- a/loginutils/getty.c
+++ b/loginutils/getty.c
@@ -19,7 +19,7 @@
 #include <syslog.h>
 
 #if ENABLE_FEATURE_UTMP
-#include <utmp.h> /* LOGIN_PROCESS */
+# include <utmp.h> /* LOGIN_PROCESS */
 #endif
 
 #ifndef IUCLC
@@ -579,6 +579,7 @@ 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;                  /* login name, given to /bin/login */
         /* Merging these into "struct local" may _seem_ to reduce
@@ -651,17 +652,18 @@ int getty_main(int argc UNUSED_PARAM, char **argv)
         /* tcgetattr() + error check */
         ioctl_or_perror_and_die(0, TCGETS, &termios, "%s: TCGETS", options.tty);
 
+        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(0, TIOCSCTTY, (void*)1);
         /* Make ourself a foreground process group within our session */
-        tcsetpgrp(0, getpid());
+        tcsetpgrp(0, pid);
 #endif
 
         /* Update the utmp file. This tty is ours now! */
-        update_utmp(LOGIN_PROCESS, options.tty, "LOGIN", fakehost);
+        update_utmp(pid, LOGIN_PROCESS, options.tty, "LOGIN", fakehost);
 
         /* Initialize the termios settings (raw mode, eight-bit, blocking i/o). */
         debug("calling termios_init\n");
diff --git a/loginutils/login.c b/loginutils/login.c
index 4a820379d..bf21d6121 100644
--- a/loginutils/login.c
+++ b/loginutils/login.c
@@ -384,7 +384,7 @@ int login_main(int argc UNUSED_PARAM, char **argv)
         fchown(0, pw->pw_uid, pw->pw_gid);
         fchmod(0, 0600);
 
-        update_utmp(USER_PROCESS, short_tty, username, run_by_root ? opt_host : NULL);
+        update_utmp(getpid(), USER_PROCESS, short_tty, username, run_by_root ? opt_host : NULL);
 
         /* We trust environment only if we run by root */
         if (ENABLE_LOGIN_SCRIPTS && run_by_root)
diff --git a/miscutils/last.c b/miscutils/last.c
index 6e3ed9093..55c03ae41 100644
--- a/miscutils/last.c
+++ b/miscutils/last.c
@@ -92,7 +92,8 @@ int last_main(int argc UNUSED_PARAM, char **argv UNUSED_PARAM)
                                 goto next;
                         }
                         if (ut.ut_type != DEAD_PROCESS
-                         && ut.ut_user[0] && ut.ut_line[0]
+                         && ut.ut_user[0]
+                         && ut.ut_line[0]
                         ) {
                                 ut.ut_type = USER_PROCESS;
                         }
diff --git a/networking/telnetd.c b/networking/telnetd.c
index cab94f0f7..b3e66eb4b 100644
--- a/networking/telnetd.c
+++ b/networking/telnetd.c
@@ -20,18 +20,22 @@
  * Vladimir Oleynik <dzo@simtreas.ru> 2001
  * Set process group corrections, initial busybox port
  */
-
 #define DEBUG 0
 
 #include "libbb.h"
 #include <syslog.h>
 
 #if DEBUG
-#define TELCMDS
-#define TELOPTS
+# define TELCMDS
+# define TELOPTS
 #endif
 #include <arpa/telnet.h>
 
+#if ENABLE_FEATURE_UTMP
+# include <utmp.h> /* LOGIN_PROCESS */
+#endif
+
+
 struct tsession {
         struct tsession *next;
         pid_t shell_pid;
@@ -319,7 +323,11 @@ make_new_session(
         xopen(tty_name, O_RDWR); /* becomes our ctty */
         xdup2(0, 1);
         xdup2(0, 2);
-        tcsetpgrp(0, getpid()); /* switch this tty's process group to us */
+        pid = getpid();
+        tcsetpgrp(0, pid); /* switch this tty's process group to us */
+
+//TODO: fetch remote addr via getpeername (see ftpd.c)
+        write_new_utmp(pid, LOGIN_PROCESS, tty_name, /*username:*/ "LOGIN", /*hostname:*/ NULL);
 
         /* The pseudo-terminal allocated to the client is configured to operate
          * in cooked mode, and with XTABS CRMOD enabled (see tty(4)) */
@@ -358,12 +366,13 @@ make_new_session(
 static void
 free_session(struct tsession *ts)
 {
-        struct tsession *t = G.sessions;
+        struct tsession *t;
 
         if (option_mask32 & OPT_INETD)
                 exit(EXIT_SUCCESS);
 
         /* Unlink this telnet session from the session list */
+        t = G.sessions;
         if (t == ts)
                 G.sessions = ts->next;
         else {
@@ -414,6 +423,7 @@ static void handle_sigchld(int sig UNUSED_PARAM)
 {
         pid_t pid;
         struct tsession *ts;
+        int save_errno = errno;
 
         /* Looping: more than one child may have exited */
         while (1) {
@@ -424,11 +434,22 @@ static void handle_sigchld(int sig UNUSED_PARAM)
                 while (ts) {
                         if (ts->shell_pid == pid) {
                                 ts->shell_pid = -1;
+// man utmp:
+// When init(8) finds that a process has exited, it locates its utmp entry
+// by ut_pid, sets ut_type to DEAD_PROCESS, and clears ut_user, ut_host
+// and ut_time with null bytes.
+// [same applies to other processes which maintain utmp entries, like telnetd]
+//
+// We do not bother actually clearing fields:
+// it might be interesting to know who was logged in and from where
+                                update_utmp(pid, DEAD_PROCESS, /*tty_name:*/ NULL, /*username:*/ NULL, /*hostname:*/ NULL);
                                 break;
                         }
                         ts = ts->next;
                 }
         }
+
+        errno = save_errno;
 }
 
 int telnetd_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
@@ -689,6 +710,8 @@ int telnetd_main(int argc UNUSED_PARAM, char **argv)
                 ts = next;
                 continue;
  kill_session:
+                if (ts->shell_pid > 0)
+                        update_utmp(ts->shell_pid, DEAD_PROCESS, /*tty_name:*/ NULL, /*username:*/ NULL, /*hostname:*/ NULL);
                 free_session(ts);
                 ts = next;
         }