Thorsten Kukuk wrote:
> If you haven't seen yet, I made some time ago a mapping
> between utmp struct entries and libsystemd functions:
> https://github.com/thkukuk/utmpx/blob/main/utmp-to-logind.md
Thanks. This is helpful.
The only problem with this mapping is for the ut_line row, which
used to contain, for inbound ssh, the pty device name. It is not easy
to find the pty name in this situation; at least, none of the systemd
APIs and /run/systemd/** files that I looked at helped.
> But be aware:
> 1. you need to extend ut_tv from 32bit time_t to 64bit time_t, or your
> patch will not survive 2038.
This is already done by the 'year2038' module of Gnulib, which
coreutils and many other packages use.
> 2. the string entries are size limited in struct utmp, but are not with
> libsystemd. So could be that you need to truncate device names, user
> names and host names.
Thanks for the hint. Truncating would mean to introduce arbitrary limits,
which is against the GNU Coding Standards
<https://www.gnu.org/prep/standards/html_node/Semantics.html>. Hence
we'll happily use arbitrary-length strings in our code.
Paul Eggert wrote:
> This suggests that Gnulib needs to redo the readutmp API so that it's
> not tied to struct utmpx's fixed string lengths. That's a bit of a
> hassle but should be doable (change char array to char *). An advantage
> is that Gnulib is a source-code library and so we can make binary- (and
> even source-) incompatible changes to the API without too much trouble.
For the moment, I've extended the 'readutmp' module to use arbitrary-
length strings only when compiling with libsystemd.
Here are the changes I committed in gnulib.
2023-08-01 Bruno Haible <br...@clisp.org>
readutmp: Small changes to reduce the code size on the coreutils side.
* m4/readutmp.m4 (gl_READUTMP): Test also for the ut_host field in
'struct utmpx' and 'struct utmp'.
* lib/readutmp.h (HAVE_STRUCT_XTMP_UT_HOST): New macro.
(UT_USER_SIZE): Define also as a macro. Set to -1 if
READUTMP_USE_SYSTEMD.
(UT_LINE_SIZE, UT_HOST_SIZE): New constants and macros.
2023-08-01 Bruno Haible <br...@clisp.org>
readutmp: For year-2038 safety on Linux/{x86,arm}, use systemd APIs.
Suggested by Thorsten Kukuk <ku...@suse.com> in
<https://www.thkukuk.de/blog/Y2038_glibc_utmp_64bit/> and
<https://github.com/thkukuk/utmpx/blob/main/utmp-to-logind.md>.
* m4/systemd.m4: New file.
* m4/readutmp.m4 (gl_READUTMP): Require gl_SYSTEMD_CHOICE. Set
READUTMP_LIB. Conditionally define READUTMP_USE_SYSTEMD.
* lib/readutmp.h: For READUTMP_USE_SYSTEMD, include <sys/time.h> and
<utmpx.h>.
(struct gl_utmp): New type.
(UTMP_STRUCT_NAME, UT_TIME_MEMBER, UT_EXIT_E_TERMINATION,
UT_EXIT_E_EXIT, UT_USER, HAVE_STRUCT_XTMP_UT_EXIT,
HAVE_STRUCT_XTMP_UT_ID, HAVE_STRUCT_XTMP_UT_PID): Define differently for
READUTMP_USE_SYSTEMD.
(UT_USER_SIZE): Don't define for READUTMP_USE_SYSTEMD.
(UT_TYPE_EQ, UT_TYPE_NOT_DEFINED, READ_UTMP_SUPPORTED): Define also for
READUTMP_USE_SYSTEMD.
(free_utmp): New declaration.
* lib/readutmp.c: Add new includes for READUTMP_USE_SYSTEMD.
(extract_trimmed_name): Adapt to READUTMP_USE_SYSTEMD.
(get_boot_time_uncached, get_boot_time, guess_pty_name): New functions.
(read_utmp): New implementation for READUTMP_USE_SYSTEMD.
(free_utmp): New function.
* tests/test-readutmp.c (main): At the end, invoke free_utmp.
* modules/readutmp (Files): Add m4/systemd.m4.
(Link): New section.
* modules/readutmp-tests (Makefile.am): Link test-readutmp with
READUTMP_LIB.
* NEWS: Mention the free_utmp function and the READUTMP_LIB link
requirement.
When the output of the 'test-readutmp' program without libsystemd is
==============================================================================
Here are the read_utmp results.
Flags: B = Boot, U = User Process
Termi‐ Flags
Time (GMT) User Device PID nation Exit B U
------------------- ------------------ ----------- ---------- ------ ---- - -
2023-07-30 09:25:15 reboot ~ 0 0 0 X
2023-07-30 09:25:31 runlevel ~ 53 0 0
2023-07-30 09:25:48 bruno seat0 1663 0 0 X
2023-07-30 09:25:48 bruno tty2 1663 0 0 X
2023-07-30 09:31:17 pts/1 3210 0 0
2023-07-31 23:36:52 bruno pts/3 30619 0 0 X
2023-08-01 15:19:26 other pts/4 40513 0 0 X
2023-08-01 19:02:20 pts/5 43376 0 1
==============================================================================
with libsystemd it is:
==============================================================================
Here are the read_utmp results.
Flags: B = Boot, U = User Process
Termi‐ Flags
Time (GMT) User Device PID nation Exit B U
------------------- ------------------ ----------- ---------- ------ ---- - -
2023-07-30 09:25:14 reboot ~ 0 0 0 X
2023-07-30 09:25:47 bruno seat0 1593 0 0 X
2023-07-30 09:25:47 bruno tty2 1593 0 0 X
2023-08-01 15:19:25 other sshd pts/4 40513 0 0 X
==============================================================================
The major changes are:
* Entries without BOOT_TIME or USER_PROCESS flag are gone. This includes
- runlevel and possibly "old time" / "new time" entries, which I don't know
how to get from systemd,
- entries for pseudo-terminals (xterm etc.) that are not login shells;
I don't know how to get them from systemd either, and (IMO) they were
uninteresting anyway,
- login shells that have exited.
* The reboot time is a little more precise, since the systemd code uses
the /proc/uptime virtual file.
* The pids now refer to the session leader, which is a parent (or ancestor)
of the process which has allocated the pty.
* In the ut_line field ("Device" column) I added extra info about the
service name, in this case "sshd". I imagine that is at least as useful as
knowing the pty name ("pts/4").
>From 0b71ff37a7cb0ce546975796f9366eee25be5fb7 Mon Sep 17 00:00:00 2001
From: Bruno Haible <br...@clisp.org>
Date: Tue, 1 Aug 2023 21:44:07 +0200
Subject: [PATCH 1/2] readutmp: For year-2038 safety on Linux/{x86,arm}, use
systemd APIs.
Suggested by Thorsten Kukuk <ku...@suse.com> in
<https://www.thkukuk.de/blog/Y2038_glibc_utmp_64bit/> and
<https://github.com/thkukuk/utmpx/blob/main/utmp-to-logind.md>.
* m4/systemd.m4: New file.
* m4/readutmp.m4 (gl_READUTMP): Require gl_SYSTEMD_CHOICE. Set
READUTMP_LIB. Conditionally define READUTMP_USE_SYSTEMD.
* lib/readutmp.h: For READUTMP_USE_SYSTEMD, include <sys/time.h> and
<utmpx.h>.
(struct gl_utmp): New type.
(UTMP_STRUCT_NAME, UT_TIME_MEMBER, UT_EXIT_E_TERMINATION,
UT_EXIT_E_EXIT, UT_USER, HAVE_STRUCT_XTMP_UT_EXIT,
HAVE_STRUCT_XTMP_UT_ID, HAVE_STRUCT_XTMP_UT_PID): Define differently for
READUTMP_USE_SYSTEMD.
(UT_USER_SIZE): Don't define for READUTMP_USE_SYSTEMD.
(UT_TYPE_EQ, UT_TYPE_NOT_DEFINED, READ_UTMP_SUPPORTED): Define also for
READUTMP_USE_SYSTEMD.
(free_utmp): New declaration.
* lib/readutmp.c: Add new includes for READUTMP_USE_SYSTEMD.
(extract_trimmed_name): Adapt to READUTMP_USE_SYSTEMD.
(get_boot_time_uncached, get_boot_time, guess_pty_name): New functions.
(read_utmp): New implementation for READUTMP_USE_SYSTEMD.
(free_utmp): New function.
* tests/test-readutmp.c (main): At the end, invoke free_utmp.
* modules/readutmp (Files): Add m4/systemd.m4.
(Link): New section.
* modules/readutmp-tests (Makefile.am): Link test-readutmp with
READUTMP_LIB.
* NEWS: Mention the free_utmp function and the READUTMP_LIB link
requirement.
---
ChangeLog | 33 ++++
NEWS | 4 +
lib/readutmp.c | 350 ++++++++++++++++++++++++++++++++++++++++-
lib/readutmp.h | 75 +++++++--
m4/readutmp.m4 | 36 +++++
m4/systemd.m4 | 23 +++
modules/readutmp | 4 +
modules/readutmp-tests | 1 +
tests/test-readutmp.c | 2 +
9 files changed, 511 insertions(+), 17 deletions(-)
create mode 100644 m4/systemd.m4
diff --git a/ChangeLog b/ChangeLog
index a96252f2a0..16bf75a66d 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,36 @@
+2023-08-01 Bruno Haible <br...@clisp.org>
+
+ readutmp: For year-2038 safety on Linux/{x86,arm}, use systemd APIs.
+ Suggested by Thorsten Kukuk <ku...@suse.com> in
+ <https://www.thkukuk.de/blog/Y2038_glibc_utmp_64bit/> and
+ <https://github.com/thkukuk/utmpx/blob/main/utmp-to-logind.md>.
+ * m4/systemd.m4: New file.
+ * m4/readutmp.m4 (gl_READUTMP): Require gl_SYSTEMD_CHOICE. Set
+ READUTMP_LIB. Conditionally define READUTMP_USE_SYSTEMD.
+ * lib/readutmp.h: For READUTMP_USE_SYSTEMD, include <sys/time.h> and
+ <utmpx.h>.
+ (struct gl_utmp): New type.
+ (UTMP_STRUCT_NAME, UT_TIME_MEMBER, UT_EXIT_E_TERMINATION,
+ UT_EXIT_E_EXIT, UT_USER, HAVE_STRUCT_XTMP_UT_EXIT,
+ HAVE_STRUCT_XTMP_UT_ID, HAVE_STRUCT_XTMP_UT_PID): Define differently for
+ READUTMP_USE_SYSTEMD.
+ (UT_USER_SIZE): Don't define for READUTMP_USE_SYSTEMD.
+ (UT_TYPE_EQ, UT_TYPE_NOT_DEFINED, READ_UTMP_SUPPORTED): Define also for
+ READUTMP_USE_SYSTEMD.
+ (free_utmp): New declaration.
+ * lib/readutmp.c: Add new includes for READUTMP_USE_SYSTEMD.
+ (extract_trimmed_name): Adapt to READUTMP_USE_SYSTEMD.
+ (get_boot_time_uncached, get_boot_time, guess_pty_name): New functions.
+ (read_utmp): New implementation for READUTMP_USE_SYSTEMD.
+ (free_utmp): New function.
+ * tests/test-readutmp.c (main): At the end, invoke free_utmp.
+ * modules/readutmp (Files): Add m4/systemd.m4.
+ (Link): New section.
+ * modules/readutmp-tests (Makefile.am): Link test-readutmp with
+ READUTMP_LIB.
+ * NEWS: Mention the free_utmp function and the READUTMP_LIB link
+ requirement.
+
2023-08-01 Bruno Haible <br...@clisp.org>
readutmp: Trivial simplification.
diff --git a/NEWS b/NEWS
index 9aa243182c..87d49ffbe2 100644
--- a/NEWS
+++ b/NEWS
@@ -74,6 +74,10 @@ User visible incompatible changes
Date Modules Changes
+2023-08-01 readutmp After processing the read_utmp() results, call
+ free_utmp() in order to avoid a memory leak.
+ Link additionally with $(READUTMP_LIB).
+
2023-07-10 dfa The signature of the function
case_folded_counterparts, declared in localeinfo.h,
has changed.
diff --git a/lib/readutmp.c b/lib/readutmp.c
index 34b96d999e..ba4b0eadb1 100644
--- a/lib/readutmp.c
+++ b/lib/readutmp.c
@@ -31,6 +31,13 @@
#include <stdlib.h>
#include <stdint.h>
+#if READUTMP_USE_SYSTEMD
+# include <dirent.h>
+# include <sys/sysinfo.h>
+# include <systemd/sd-login.h>
+# include <time.h>
+#endif
+
#include "xalloc.h"
/* Each of the FILE streams in this file is only used in a single thread. */
@@ -48,16 +55,20 @@ extract_trimmed_name (const STRUCT_UTMP *ut)
{
char *p, *trimmed_name;
+#if READUTMP_USE_SYSTEMD
+ trimmed_name = xstrdup (UT_USER (ut));
+#else
trimmed_name = xmalloc (UT_USER_SIZE + 1);
strncpy (trimmed_name, UT_USER (ut), UT_USER_SIZE);
/* Append a trailing NUL. Some systems pad names shorter than the
- maximum with spaces, others pad with NULs. Remove any trailing
- spaces. */
+ maximum with spaces, others pad with NULs. */
trimmed_name[UT_USER_SIZE] = '\0';
+#endif
+ /* Remove any trailing spaces. */
for (p = trimmed_name + strlen (trimmed_name);
trimmed_name < p && p[-1] == ' ';
*--p = '\0')
- continue;
+ ;
return trimmed_name;
}
@@ -85,7 +96,322 @@ desirable_utmp_entry (STRUCT_UTMP const *ut, int options)
return true;
}
-# if defined UTMP_NAME_FUNCTION
+# if READUTMP_USE_SYSTEMD
+/* Use systemd and Linux /proc and kernel APIs. */
+
+static struct timeval
+get_boot_time_uncached ()
+{
+ /* /proc/uptime contains the uptime with a resolution of 0.01 sec. */
+ FILE *fp = fopen ("/proc/uptime", "re");
+ if (fp != NULL)
+ {
+ char buf[32 + 1];
+ size_t n = fread (buf, 1, sizeof (buf) - 1, fp);
+ fclose (fp);
+ if (n > 0)
+ {
+ buf[n] = '\0';
+ /* buf now contains two values: the uptime and the idle time. */
+ char *endptr;
+ double uptime = strtod (buf, &endptr);
+ if (endptr > buf)
+ {
+ struct timeval result;
+ if (gettimeofday (&result, NULL) >= 0)
+ {
+ long uptime_sec = (long) uptime;
+ int uptime_usec =
+ (int) ((uptime - (double) uptime_sec) * 1000000.0 + 0.5);
+ if (result.tv_usec < uptime_usec)
+ {
+ result.tv_usec += 1000000;
+ result.tv_sec -= 1;
+ }
+ result.tv_sec -= uptime_sec;
+ result.tv_usec -= uptime_usec;
+ return result;
+ }
+ }
+ }
+ }
+
+ /* The sysinfo call returns the uptime with a resolution of 1 sec only. */
+ struct sysinfo info;
+ if (sysinfo (&info) >= 0)
+ {
+ struct timeval result;
+ if (gettimeofday (&result, NULL) >= 0)
+ {
+ result.tv_sec -= info.uptime;
+ return result;
+ }
+ }
+
+ /* We shouldn't get here. */
+ return (struct timeval) { .tv_sec = 0, .tv_usec = 0 };
+}
+
+static struct timeval
+get_boot_time ()
+{
+ static int cached;
+ static struct timeval boot_time;
+
+ if (!cached)
+ {
+ boot_time = get_boot_time_uncached ();
+ cached = 1;
+ }
+ return boot_time;
+}
+
+/* Guess the pty name that was opened for the given user right after
+ the given time AT. */
+static char *
+guess_pty_name (uid_t uid, const struct timespec at)
+{
+ /* Traverse the entries of the /dev/pts/ directory, looking for devices
+ which are owned by UID and whose ctime is shortly after AT. */
+ DIR *dirp = opendir ("/dev/pts");
+ if (dirp != NULL)
+ {
+ /* Buffer containing /dev/pts/N. */
+ char name_buf[9 + 10 + 1];
+ memcpy (name_buf, "/dev/pts/", 9);
+
+ char best_name[9 + 10 + 1];
+ struct timespec best_time = { .tv_sec = 0, .tv_nsec = 0 };
+
+ for (;;)
+ {
+ struct dirent *dp = readdir (dirp);
+ if (dp == NULL)
+ break;
+ if (dp->d_name[0] != '.' && strlen (dp->d_name) <= 10)
+ {
+ /* Compose the absolute file name /dev/pts/N. */
+ strcpy (name_buf + 9, dp->d_name);
+
+ /* Find its owner and ctime. */
+ struct stat st;
+ if (stat (name_buf, &st) >= 0
+ && st.st_uid == uid
+ && (st.st_ctim.tv_sec > at.tv_sec
+ || (st.st_ctim.tv_sec == at.tv_sec
+ && st.st_ctim.tv_nsec >= at.tv_nsec)))
+ {
+ /* This entry has the owner UID and a ctime >= AT. */
+ /* Is this entry the best one so far? */
+ if ((best_time.tv_sec == 0 && best_time.tv_nsec == 0)
+ || (st.st_ctim.tv_sec < best_time.tv_sec
+ || (st.st_ctim.tv_sec == best_time.tv_sec
+ && st.st_ctim.tv_nsec < best_time.tv_nsec)))
+ {
+ strcpy (best_name, name_buf);
+ best_time = st.st_ctim;
+ }
+ }
+ }
+ }
+
+ closedir (dirp);
+
+ /* Did we find an entry owned by ID, and is it at most 5 seconds
+ after AT? */
+ if (!(best_time.tv_sec == 0 && best_time.tv_nsec == 0)
+ && (best_time.tv_sec < at.tv_sec + 5
+ || (best_time.tv_sec == at.tv_sec + 5
+ && best_time.tv_nsec <= at.tv_nsec)))
+ return xstrdup (best_name + 5);
+ }
+
+ return NULL;
+}
+
+int
+read_utmp (char const *file, size_t *n_entries, STRUCT_UTMP **utmp_buf,
+ int options)
+{
+ /* Fill entries, simulating what an utmp file would contain. */
+ idx_t n_filled = 0;
+ idx_t n_alloc = 0;
+ STRUCT_UTMP *utmp = NULL;
+
+ /* Synthesize a BOOT_TIME entry. */
+ if (!(options & READ_UTMP_USER_PROCESS))
+ {
+ if (n_filled == n_alloc)
+ utmp = xpalloc (utmp, &n_alloc, 1, -1, sizeof (STRUCT_UTMP));
+ STRUCT_UTMP *ut = &utmp[n_filled];
+ ut->ut_user = xstrdup ("reboot");
+ ut->ut_id = xstrdup ("");
+ ut->ut_line = xstrdup ("~");
+ ut->ut_pid = 0;
+ ut->ut_type = BOOT_TIME;
+ ut->ut_tv = get_boot_time ();
+ ut->ut_host = xstrdup ("");
+ ut->ut_session = 0;
+ if (desirable_utmp_entry (ut, options))
+ n_filled++;
+ else
+ free_utmp (1, ut);
+ }
+
+ /* Synthesize USER_PROCESS entries. */
+ char **sessions;
+ int num_sessions = sd_get_sessions (&sessions);
+ if (num_sessions >= 0)
+ {
+ char **session_ptr;
+ for (session_ptr = sessions; *session_ptr != NULL; session_ptr++)
+ {
+ char *session = *session_ptr;
+
+ uint64_t start_usec;
+ if (sd_session_get_start_time (session, &start_usec) < 0)
+ start_usec = 0;
+ struct timeval start_tv;
+ start_tv.tv_sec = start_usec / 1000000;
+ start_tv.tv_usec = start_usec % 1000000;
+
+ char *seat;
+ if (sd_session_get_seat (session, &seat) < 0)
+ seat = NULL;
+
+ char *tty;
+ if (sd_session_get_tty (session, &tty) < 0)
+ {
+ tty = NULL;
+ /* Try harder to get a sensible value for the tty. */
+ char *type;
+ if (sd_session_get_type (session, &type) >= 0)
+ {
+ if (strcmp (type, "tty") == 0)
+ {
+ char *service;
+ if (sd_session_get_service (session, &service) < 0)
+ service = NULL;
+
+ char *pty;
+ uid_t uid;
+ if (sd_session_get_uid (session, &uid) >= 0)
+ {
+ struct timespec start_ts =
+ {
+ .tv_sec = start_tv.tv_sec,
+ .tv_nsec = start_tv.tv_usec * 1000
+ };
+ pty = guess_pty_name (uid, start_ts);
+ }
+ else
+ pty = NULL;
+
+ if (service != NULL && pty != NULL)
+ {
+ tty = xmalloc (strlen (service) + 1 + strlen (pty) + 1);
+ stpcpy (stpcpy (stpcpy (tty, service), " "), pty);
+ }
+ else if (service != NULL)
+ tty = xstrdup (service);
+ else if (pty != NULL)
+ tty = xstrdup (pty);
+
+ free (pty);
+ free (service);
+ }
+ free (type);
+ }
+ }
+
+ /* Create up to two USER_PROCESS entries: one for the seat,
+ one for the tty. */
+ if (seat != NULL || tty != NULL)
+ {
+ char *user;
+ if (sd_session_get_username (session, &user) < 0)
+ user = xstrdup ("");
+
+ pid_t leader_pid;
+ if (sd_session_get_leader (session, &leader_pid) < 0)
+ leader_pid = 0;
+
+ char *remote_host;
+ if (sd_session_get_remote_host (session, &remote_host) < 0)
+ remote_host = NULL;
+ char *remote_user;
+ if (sd_session_get_remote_user (session, &remote_user) < 0)
+ remote_user = NULL;
+ char *host;
+ if (remote_host != NULL)
+ {
+ if (remote_user != NULL)
+ {
+ host = xmalloc (strlen (remote_user) + 1 + strlen (remote_host) + 1);
+ stpcpy (stpcpy (stpcpy (host, remote_user), "@"), remote_host);
+ }
+ else
+ host = xstrdup (remote_host);
+ }
+ else
+ host = xstrdup ("");
+
+ size_t n_filled_after = n_filled + (seat != NULL) + (tty != NULL);
+ if (n_filled_after > n_alloc)
+ utmp = xpalloc (utmp, &n_alloc, n_filled_after - n_alloc, -1,
+ sizeof (STRUCT_UTMP));
+ if (seat != NULL)
+ {
+ STRUCT_UTMP *ut = &utmp[n_filled];
+ ut->ut_user = xstrdup (user);
+ ut->ut_id = xstrdup (session);
+ ut->ut_line = xstrdup (seat);
+ ut->ut_pid = leader_pid; /* this is the best we have */
+ ut->ut_type = USER_PROCESS;
+ ut->ut_tv = start_tv;
+ ut->ut_host = xstrdup (host);
+ ut->ut_session = leader_pid;
+ if (desirable_utmp_entry (ut, options))
+ n_filled++;
+ else
+ free_utmp (1, ut);
+ }
+ if (tty != NULL)
+ {
+ STRUCT_UTMP *ut = &utmp[n_filled];
+ ut->ut_user = xstrdup (user);
+ ut->ut_id = xstrdup (session);
+ ut->ut_line = xstrdup (tty);
+ ut->ut_pid = leader_pid; /* this is the best we have */
+ ut->ut_type = USER_PROCESS;
+ ut->ut_tv = start_tv;
+ ut->ut_host = xstrdup (host);
+ ut->ut_session = leader_pid;
+ if (desirable_utmp_entry (ut, options))
+ n_filled++;
+ else
+ free_utmp (1, ut);
+ }
+
+ free (host);
+ free (remote_user);
+ free (remote_host);
+ free (user);
+ }
+ free (tty);
+ free (seat);
+ free (session);
+ }
+ free (sessions);
+ }
+
+ *n_entries = n_filled;
+ *utmp_buf = utmp;
+
+ return 0;
+}
+
+# elif defined UTMP_NAME_FUNCTION
static void
copy_utmp_entry (STRUCT_UTMP *dst, STRUCT_UTMP *src)
@@ -219,3 +545,19 @@ read_utmp (char const *file, size_t *n_entries, STRUCT_UTMP **utmp_buf,
}
#endif
+
+void
+free_utmp (size_t n_entries, STRUCT_UTMP *entries)
+{
+#if READUTMP_USE_SYSTEMD
+ size_t i;
+ for (i = 0; i < n_entries; i++)
+ {
+ STRUCT_UTMP *ut = &entries[i];
+ free (ut->ut_user);
+ free (ut->ut_id);
+ free (ut->ut_line);
+ free (ut->ut_host);
+ }
+#endif
+}
diff --git a/lib/readutmp.h b/lib/readutmp.h
index 271dd4921a..e03e0b0a32 100644
--- a/lib/readutmp.h
+++ b/lib/readutmp.h
@@ -37,7 +37,34 @@
# undef HAVE_UTMPX_H
# endif
-# if HAVE_UTMPX_H
+# if READUTMP_USE_SYSTEMD
+
+/* Get 'struct timeval'. */
+# include <sys/time.h>
+
+/* Type for the entries returned by read_utmp. */
+struct gl_utmp
+{
+ /* All 'char *' here are of arbitrary length and malloc-allocated. */
+ char *ut_user; /* User name */
+ char *ut_id; /* Session ID */
+ char *ut_line; /* seat / device */
+ pid_t ut_pid; /* process ID of ? */
+ short ut_type; /* BOOT_TIME or USER_PROCESS */
+ struct timeval ut_tv; /* time */
+ char *ut_host; /* for remote sessions: user@host or host */
+ long ut_session; /* process ID of session leader */
+};
+
+/* Get values for ut_type: BOOT_TIME, USER_PROCESS. */
+# include <utmpx.h>
+
+# define UTMP_STRUCT_NAME gl_utmp
+# define UT_TIME_MEMBER(UT) ((UT)->ut_tv.tv_sec)
+# define UT_EXIT_E_TERMINATION(UT) 0
+# define UT_EXIT_E_EXIT(UT) 0
+
+# elif HAVE_UTMPX_H
/* <utmpx.h> defines 'struct utmpx' with the following fields:
@@ -171,7 +198,11 @@ struct gl_utmp
# endif
/* Accessor macro for the member named ut_user or ut_name. */
-# if HAVE_UTMPX_H
+# if READUTMP_USE_SYSTEMD
+
+# define UT_USER(UT) ((UT)->ut_user)
+
+# elif HAVE_UTMPX_H
# if HAVE_STRUCT_UTMPX_UT_USER
# define UT_USER(UT) ((UT)->ut_user)
@@ -197,23 +228,37 @@ struct gl_utmp
# endif
-# define HAVE_STRUCT_XTMP_UT_EXIT \
- (HAVE_STRUCT_UTMP_UT_EXIT \
- || HAVE_STRUCT_UTMPX_UT_EXIT)
+# if READUTMP_USE_SYSTEMD
+# define HAVE_STRUCT_XTMP_UT_EXIT 0
+# else
+# define HAVE_STRUCT_XTMP_UT_EXIT \
+ (HAVE_STRUCT_UTMP_UT_EXIT \
+ || HAVE_STRUCT_UTMPX_UT_EXIT)
+# endif
-# define HAVE_STRUCT_XTMP_UT_ID \
- (HAVE_STRUCT_UTMP_UT_ID \
- || HAVE_STRUCT_UTMPX_UT_ID)
+# if READUTMP_USE_SYSTEMD
+# define HAVE_STRUCT_XTMP_UT_ID 1
+# else
+# define HAVE_STRUCT_XTMP_UT_ID \
+ (HAVE_STRUCT_UTMP_UT_ID \
+ || HAVE_STRUCT_UTMPX_UT_ID)
+# endif
-# define HAVE_STRUCT_XTMP_UT_PID \
- (HAVE_STRUCT_UTMP_UT_PID \
- || HAVE_STRUCT_UTMPX_UT_PID)
+# if READUTMP_USE_SYSTEMD
+# define HAVE_STRUCT_XTMP_UT_PID 1
+# else
+# define HAVE_STRUCT_XTMP_UT_PID \
+ (HAVE_STRUCT_UTMP_UT_PID \
+ || HAVE_STRUCT_UTMPX_UT_PID)
+# endif
/* Type of entry returned by read_utmp(). */
typedef struct UTMP_STRUCT_NAME STRUCT_UTMP;
/* Size of the UT_USER (ut) member. */
+# if !READUTMP_USE_SYSTEMD
enum { UT_USER_SIZE = sizeof UT_USER ((STRUCT_UTMP *) 0) };
+# endif
/* Definition of UTMP_FILE and WTMP_FILE. */
@@ -252,7 +297,7 @@ enum { UT_USER_SIZE = sizeof UT_USER ((STRUCT_UTMP *) 0) };
/* Accessor macros for the member named ut_type. */
-# if HAVE_STRUCT_UTMP_UT_TYPE || HAVE_STRUCT_UTMPX_UT_TYPE
+# if READUTMP_USE_SYSTEMD || HAVE_STRUCT_UTMP_UT_TYPE || HAVE_STRUCT_UTMPX_UT_TYPE
# define UT_TYPE_EQ(UT, V) ((UT)->ut_type == (V))
# define UT_TYPE_NOT_DEFINED 0
# else
@@ -279,7 +324,7 @@ enum { UT_USER_SIZE = sizeof UT_USER ((STRUCT_UTMP *) 0) };
|| (UT_TYPE_NOT_DEFINED && UT_TIME_MEMBER (UT) != 0)))
/* Define if read_utmp is not just a dummy. */
-# if HAVE_UTMPX_H || HAVE_UTMP_H
+# if READUTMP_USE_SYSTEMD || HAVE_UTMPX_H || HAVE_UTMP_H
# define READ_UTMP_SUPPORTED 1
# endif
@@ -309,4 +354,8 @@ char *extract_trimmed_name (const STRUCT_UTMP *ut)
int read_utmp (char const *file, size_t *n_entries, STRUCT_UTMP **utmp_buf,
int options);
+/* Free the memory allocated by the N_ENTRIES utmp entries, starting
+ at ENTRIES. */
+void free_utmp (size_t n_entries, STRUCT_UTMP *entries);
+
#endif /* __READUTMP_H__ */
diff --git a/m4/readutmp.m4 b/m4/readutmp.m4
index 44fcc6151b..2dfd3fe8d0 100644
--- a/m4/readutmp.m4
+++ b/m4/readutmp.m4
@@ -9,6 +9,42 @@ AC_DEFUN([gl_READUTMP]
dnl Persuade utmpx.h to declare utmpxname
AC_REQUIRE([AC_USE_SYSTEM_EXTENSIONS])
+ AC_REQUIRE([gl_SYSTEMD_CHOICE])
+
+ dnl Set READUTMP_LIB to '-lsystemd' or '', depending on whether use of
+ dnl systemd APIs is possible and desired (only the systemd login API, here).
+ dnl AC_LIB_LINKFLAGS_BODY would be overkill here, since few people install
+ dnl libsystemd in non-system directories.
+ READUTMP_LIB=
+ if test "$SYSTEMD_CHOICE" = yes; then
+ AC_CHECK_HEADER([systemd/sd-login.h])
+ if test $ac_cv_header_systemd_sd_login_h = yes; then
+ AC_CACHE_CHECK([for libsystemd version >= 254],
+ [gl_cv_lib_readutmp_systemd],
+ [gl_save_LIBS="$LIBS"
+ LIBS="$LIBS -lsystemd"
+ AC_LINK_IFELSE(
+ [AC_LANG_PROGRAM([[
+ #include <stdint.h>
+ #include <systemd/sd-login.h>
+ ]], [[
+ uint64_t st;
+ sd_session_get_start_time ("1", &st);
+ ]])
+ ],
+ [gl_cv_lib_readutmp_systemd=yes],
+ [gl_cv_lib_readutmp_systemd=no])
+ LIBS="$gl_save_LIBS"
+ ])
+ if test $gl_cv_lib_readutmp_systemd = yes; then
+ AC_DEFINE([READUTMP_USE_SYSTEMD], [1],
+ [Define if the readutmp module should use the systemd login API.])
+ READUTMP_LIB='-lsystemd'
+ fi
+ fi
+ fi
+ AC_SUBST([READUTMP_LIB])
+
AC_CHECK_HEADERS_ONCE([utmp.h utmpx.h])
if test $ac_cv_header_utmp_h = yes || test $ac_cv_header_utmpx_h = yes; then
dnl Prerequisites of lib/readutmp.h and lib/readutmp.c.
diff --git a/m4/systemd.m4 b/m4/systemd.m4
new file mode 100644
index 0000000000..0c919385b2
--- /dev/null
+++ b/m4/systemd.m4
@@ -0,0 +1,23 @@
+# systemd.m4 serial 1
+dnl Copyright (C) 2023 Free Software Foundation, Inc.
+dnl This file is free software; the Free Software Foundation
+dnl gives unlimited permission to copy and/or distribute it,
+dnl with or without modifications, as long as this notice is preserved.
+
+# Sets SYSTEMD_CHOICE to 'yes' or 'no', depending on the preferred use of
+# systemd APIs.
+AC_DEFUN([gl_SYSTEMD_CHOICE],
+[
+ AC_MSG_CHECKING([whether to use systemd APIs])
+ AC_ARG_ENABLE([systemd],
+ [ --disable-systemd do not use systemd APIs],
+ [SYSTEMD_CHOICE="$enableval"],
+ [SYSTEMD_CHOICE=yes])
+ AC_MSG_RESULT([$SYSTEMD_CHOICE])
+ AC_SUBST([SYSTEMD_CHOICE])
+])
+
+# Pre-built package name for the libsystemd library:
+# - On Debian and Debian-based systems: libsystemd-dev
+# - On Red Hat distributions: systemd-devel
+# - Other: https://repology.org/project/systemd/versions
diff --git a/modules/readutmp b/modules/readutmp
index 4b2de331dc..04893a4487 100644
--- a/modules/readutmp
+++ b/modules/readutmp
@@ -5,6 +5,7 @@ Files:
lib/readutmp.h
lib/readutmp.c
m4/readutmp.m4
+m4/systemd.m4
Depends-on:
extensions
@@ -24,6 +25,9 @@ lib_SOURCES += readutmp.c
Include:
"readutmp.h"
+Link:
+$(READUTMP_LIB)
+
License:
GPL
diff --git a/modules/readutmp-tests b/modules/readutmp-tests
index 792a80e792..06f06a7c3c 100644
--- a/modules/readutmp-tests
+++ b/modules/readutmp-tests
@@ -11,3 +11,4 @@ configure.ac:
Makefile.am:
TESTS += test-readutmp
check_PROGRAMS += test-readutmp
+test_readutmp_LDADD = $(LDADD) @READUTMP_LIB@
diff --git a/tests/test-readutmp.c b/tests/test-readutmp.c
index b806b47116..ae17087a81 100644
--- a/tests/test-readutmp.c
+++ b/tests/test-readutmp.c
@@ -138,6 +138,8 @@ main (int argc, char *argv[])
time_t now = time (NULL);
ASSERT (first >= now - 157680000);
ASSERT (last <= now + 604800);
+
+ free_utmp (num_entries, entries);
}
return 0;
--
2.34.1
>From a6d192b9608516430d95c0255594aa4b003d5ebb Mon Sep 17 00:00:00 2001
From: Bruno Haible <br...@clisp.org>
Date: Wed, 2 Aug 2023 00:56:25 +0200
Subject: [PATCH 2/2] readutmp: Small changes to reduce the code size on the
coreutils side.
* m4/readutmp.m4 (gl_READUTMP): Test also for the ut_host field in
'struct utmpx' and 'struct utmp'.
* lib/readutmp.h (HAVE_STRUCT_XTMP_UT_HOST): New macro.
(UT_USER_SIZE): Define also as a macro. Set to -1 if
READUTMP_USE_SYSTEMD.
(UT_LINE_SIZE, UT_HOST_SIZE): New constants and macros.
---
ChangeLog | 10 ++++++++++
lib/readutmp.h | 31 +++++++++++++++++++++++++++++--
m4/readutmp.m4 | 4 +++-
3 files changed, 42 insertions(+), 3 deletions(-)
diff --git a/ChangeLog b/ChangeLog
index 16bf75a66d..e7fd56e609 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,13 @@
+2023-08-01 Bruno Haible <br...@clisp.org>
+
+ readutmp: Small changes to reduce the code size on the coreutils side.
+ * m4/readutmp.m4 (gl_READUTMP): Test also for the ut_host field in
+ 'struct utmpx' and 'struct utmp'.
+ * lib/readutmp.h (HAVE_STRUCT_XTMP_UT_HOST): New macro.
+ (UT_USER_SIZE): Define also as a macro. Set to -1 if
+ READUTMP_USE_SYSTEMD.
+ (UT_LINE_SIZE, UT_HOST_SIZE): New constants and macros.
+
2023-08-01 Bruno Haible <br...@clisp.org>
readutmp: For year-2038 safety on Linux/{x86,arm}, use systemd APIs.
diff --git a/lib/readutmp.h b/lib/readutmp.h
index e03e0b0a32..06d2a69daf 100644
--- a/lib/readutmp.h
+++ b/lib/readutmp.h
@@ -252,12 +252,39 @@ struct gl_utmp
|| HAVE_STRUCT_UTMPX_UT_PID)
# endif
+# if READUTMP_USE_SYSTEMD
+# define HAVE_STRUCT_XTMP_UT_HOST 1
+# else
+# define HAVE_STRUCT_XTMP_UT_HOST \
+ (HAVE_STRUCT_UTMP_UT_HOST \
+ || HAVE_STRUCT_UTMPX_UT_HOST)
+# endif
+
/* Type of entry returned by read_utmp(). */
typedef struct UTMP_STRUCT_NAME STRUCT_UTMP;
-/* Size of the UT_USER (ut) member. */
-# if !READUTMP_USE_SYSTEMD
+/* Size of the UT_USER (ut) member, or -1 if unbounded. */
+# if READUTMP_USE_SYSTEMD
+enum { UT_USER_SIZE = -1 };
+# else
enum { UT_USER_SIZE = sizeof UT_USER ((STRUCT_UTMP *) 0) };
+# define UT_USER_SIZE UT_USER_SIZE
+# endif
+
+/* Size of the ut->ut_line member, or -1 if unbounded. */
+# if READUTMP_USE_SYSTEMD
+enum { UT_LINE_SIZE = -1 };
+# else
+enum { UT_LINE_SIZE = sizeof (((STRUCT_UTMP *) 0)->ut_line) };
+# define UT_LINE_SIZE UT_LINE_SIZE
+# endif
+
+/* Size of the ut->ut_host member, or -1 if unbounded. */
+# if READUTMP_USE_SYSTEMD
+enum { UT_HOST_SIZE = -1 };
+# else
+enum { UT_HOST_SIZE = sizeof (((STRUCT_UTMP *) 0)->ut_host) };
+# define UT_HOST_SIZE UT_HOST_SIZE
# endif
/* Definition of UTMP_FILE and WTMP_FILE. */
diff --git a/m4/readutmp.m4 b/m4/readutmp.m4
index 2dfd3fe8d0..a4b1cb4642 100644
--- a/m4/readutmp.m4
+++ b/m4/readutmp.m4
@@ -1,4 +1,4 @@
-# readutmp.m4 serial 21
+# readutmp.m4 serial 22
dnl Copyright (C) 2002-2023 Free Software Foundation, Inc.
dnl This file is free software; the Free Software Foundation
dnl gives unlimited permission to copy and/or distribute it,
@@ -78,6 +78,8 @@ AC_DEFUN([gl_READUTMP]
AC_CHECK_MEMBERS([struct utmp.ut_type],,,[$utmp_includes])
AC_CHECK_MEMBERS([struct utmpx.ut_pid],,,[$utmp_includes])
AC_CHECK_MEMBERS([struct utmp.ut_pid],,,[$utmp_includes])
+ AC_CHECK_MEMBERS([struct utmpx.ut_host],,,[$utmp_includes])
+ AC_CHECK_MEMBERS([struct utmp.ut_host],,,[$utmp_includes])
AC_CHECK_MEMBERS([struct utmpx.ut_id],,,[$utmp_includes])
AC_CHECK_MEMBERS([struct utmp.ut_id],,,[$utmp_includes])
AC_CHECK_MEMBERS([struct utmpx.ut_exit],,,[$utmp_includes])
--
2.34.1
