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libbb: split update_utmp from login/getty in preparation to use it for telnetd

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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>
This commit is contained in:
Denys Vlasenko
2010-04-05 03:18:40 +02:00
parent 4c721049c3
commit 37f5bef63c
7 changed files with 117 additions and 159 deletions
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2
libbb/Kbuild
View File

@@ -120,6 +120,8 @@ lib-y += xgethostbyname.o
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

92
libbb/utmp.c Normal file
View File

@@ -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
}