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/* 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));
}
// 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(pid_t pid, int new_type, const char *tty_name, const char *username, const char *hostname)
{
struct utmp utent;
struct utmp *utp;
touch(_PATH_UTMP);
//utmpname(_PATH_UTMP);
setutent();
/* 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 ((utp = getutent()) != NULL) {
if (utp->ut_pid == pid
// && ut->ut_line[0]
&& 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
)
) {
if (utp->ut_type >= new_type) {
/* Stale record. Nuke hostname */
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
* if we want *exactly this* record to be overwritten!
*/
break;
}
}
//endutent(); - no need, pututline can deal with (and actually likes)
//the situation when utmp file is positioned on found record
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;
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();
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
}
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