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lib/, src/, configure.ac: Use utmpx instead of utmp

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utmpx is specified by POSIX as an XSI extension.  That's more portable
than utmp, which is unavailable for example in musl libc.  The manual
page specifies that in Linux (but it probably means in glibc), utmp and
utmpx (and the functions that use them) are identical, so this commit
shouldn't affect glibc systems.

Assume utmpx is always present.

Also, if utmpx is present, POSIX guarantees that some members exist:

-  ut_user
-  ut_id
-  ut_line
-  ut_pid
-  ut_type
-  ut_tv

So, rely on them unconditionally.

Fixes: 170b76cdd1 ("Disable utmpx permanently")
Closes: <https://github.com/shadow-maint/shadow/issues/945>
Reported-by: Firas Khalil Khana <firasuke@gmail.com>
Reported-by: "A. Wilfox" <https://github.com/awilfox>
Tested-by: Firas Khalil Khana <firasuke@gmail.com>
Reviewed-by: Iker Pedrosa <ipedrosa@redhat.com>
Signed-off-by: Alejandro Colomar <alx@kernel.org>
Cherry-picked-from: 64bcb54fa9 ("lib/, src/, configure.ac: Use utmpx instead of utmp")
Signed-off-by: Alejandro Colomar <alx@kernel.org>
This commit is contained in:
Alejandro Colomar
2024-02-17 15:15:38 +01:00
parent 2128715ede
commit bec925d29d
5 changed files with 97 additions and 97 deletions
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src/logoutd.c
+19 -15
View File
@@ -15,7 +15,7 @@
#include <stdio.h>
#include <sys/stat.h>
#include <sys/types.h>
#include <utmp.h>
#include <utmpx.h>
#include "defines.h"
#include "prototypes.h"
#include "shadowlog.h"
@@ -32,14 +32,17 @@ const char *Prog;
#define HUP_MESG_FILE "/etc/logoutd.mesg"
#endif
/* local function prototypes */
static int check_login (const struct utmp *ut);
static int check_login (const struct utmpx *ut);
static void send_mesg_to_tty (int tty_fd);
/*
* check_login - check if user (struct utmp) allowed to stay logged in
* check_login - check if user (struct utmpx) allowed to stay logged in
*/
static int check_login (const struct utmp *ut)
static int
check_login(const struct utmpx *ut)
{
char user[sizeof (ut->ut_user) + 1];
time_t now;
@@ -112,16 +115,17 @@ static void send_mesg_to_tty (int tty_fd)
* utmp file is periodically scanned and offending users are logged
* off from the system.
*/
int main (int argc, char **argv)
int
main(int argc, char **argv)
{
int i;
int status;
pid_t pid;
int i;
int status;
pid_t pid;
struct utmp *ut;
char user[sizeof (ut->ut_user) + 1]; /* terminating NUL */
char tty_name[sizeof (ut->ut_line) + 6]; /* /dev/ + NUL */
int tty_fd;
struct utmpx *ut;
char user[sizeof (ut->ut_user) + 1]; /* terminating NUL */
char tty_name[sizeof (ut->ut_line) + 6]; /* /dev/ + NUL */
int tty_fd;
if (1 != argc) {
(void) fputs (_("Usage: logoutd\n"), stderr);
@@ -169,14 +173,14 @@ int main (int argc, char **argv)
* Attempt to re-open the utmp file. The file is only
* open while it is being used.
*/
setutent ();
setutxent();
/*
* Read all of the entries in the utmp file. The entries
* for login sessions will be checked to see if the user
* is permitted to be signed on at this time.
*/
while ((ut = getutent ()) != NULL) {
while ((ut = getutxent()) != NULL) {
if (ut->ut_type != USER_PROCESS) {
continue;
}
@@ -239,7 +243,7 @@ int main (int argc, char **argv)
exit (EXIT_SUCCESS);
}
endutent ();
endutxent();
#ifndef DEBUG
sleep (60);