libbb: split update_utmp from login/getty in preparation to use it for telnetd
function old new delta
update_utent - 339 +339
login_main 1498 1128 -370
------------------------------------------------------------------------------
(add/remove: 1/0 grow/shrink: 0/1 up/down: 339/-370) Total: -31 bytes
function old new delta
update_utmp 246 337 +91
login_main 1128 1140 +12
getty_main 1908 1918 +10
...
update_utent 339 - -339
------------------------------------------------------------------------------
(add/remove: 1/1 grow/shrink: 5/6 up/down: 119/-368) Total: -249 bytes
Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
diff --git a/libbb/Kbuild b/libbb/Kbuild
index 4606d5a..1b11d5d 100644
--- a/libbb/Kbuild
+++ b/libbb/Kbuild
@@ -120,6 +120,8 @@
lib-y += xreadlink.o
lib-y += xrealloc_vector.o
+lib-$(CONFIG_FEATURE_UTMP) += utmp.o
+
# A mix of optimizations (why build stuff we know won't be used)
# and objects which may fail to build (SELinux on selinux-less system)
lib-$(CONFIG_SELINUX) += selinux_common.o
diff --git a/libbb/utmp.c b/libbb/utmp.c
new file mode 100644
index 0000000..06b939b
--- /dev/null
+++ b/libbb/utmp.c
@@ -0,0 +1,92 @@
+/* vi: set sw=4 ts=4: */
+/*
+ * utmp/wtmp support routines.
+ *
+ * Copyright (C) 2010 Denys Vlasenko
+ *
+ * Licensed under GPL version 2, see file LICENSE in this tarball for details.
+ */
+#include "libbb.h"
+#include <utmp.h>
+
+static void touch(const char *filename)
+{
+ if (access(filename, R_OK | W_OK) == -1)
+ close(open(filename, O_WRONLY | O_CREAT, 0664));
+}
+
+/*
+ * 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)
+{
+ struct utmp utent;
+ struct utmp *ut;
+ pid_t pid;
+
+ touch(_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
+ // && 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
+ )
+ ) {
+ utent = *ut; /* struct copy */
+ if (ut->ut_type >= new_type) {
+ /* Stale record. Nuke hostname */
+ memset(utent.ut_host, 0, sizeof(utent.ut_host));
+ }
+ /* NB: pututline (see later) searches for matching utent
+ * using getutid(utent) - we must not change ut_id
+ * if we want *exactly this* record to be overwritten!
+ */
+ break;
+ }
+ }
+ endutent();
+
+ 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));
+ }
+ }
+
+ 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));
+ utent.ut_tv.tv_sec = time(NULL);
+
+ /* Update, or append new one */
+ setutent();
+ pututline(&utent);
+ endutent();
+
+#if ENABLE_FEATURE_WTMP
+ touch(bb_path_wtmp_file);
+ updwtmp(bb_path_wtmp_file, &utent);
+#endif
+}