This set of patches straightens the code of the 'boot-time' module:
Determining the boot time does require iterating through the /var/run/utmpx
file, but it does not require
- memory allocation,
- copying of strings,
- evaluating an options parameter,
- linking with libsystemd.
So, let me replace the code of this module with a simplified copy of
lib/readutmp.c, while at the same time avoiding large amounts of code
duplication.
Paul: With this simplification, you may consider using the 'boot-time' module
in Emacs. I bet that it produces a better result than Emacs' src/filelock.c
on many platforms. (I haven't tested it, but I could test it if you give me
a manual testing recipe.)
2023-08-11 Bruno Haible <br...@clisp.org>
boot-time: Add comment about multithread-safety.
* lib/boot-time.h (get_boot_time): Add comment, same as in readutmp.h.
2023-08-11 Bruno Haible <br...@clisp.org>
boot-time: Simplify execution.
* lib/boot-time.c: Include <stdio.h>, <string.h>, <sys/types.h>,
<sys/stat.h>, <sys/sysinfo.h>, <time.h>, stat-time.h, unlocked-io.h,
boot-time-aux.h.
(UT_USER): New macro, from lib/readutmp.c.
(getutent): New declaration.
(get_boot_time_uncached): New function, containing a simplified code
from lib/readutmp.c.
(get_boot_time): Don't invoke read_utmp. Instead, invoke
get_boot_time_uncached and cache the result.
* modules/boot-time (Files): Add lib/boot-time-aux.h, lib/readutmp.h,
m4/readutmp.m4.
(Depends-on): Remove readutmp. Add extensions, fopen-gnu, stat-time,
stdbool, time-h, timespec_get, unlocked-io-internal.
(configure.ac): Invoke gl_PREREQ_READUTMP_H.
(Link): Remove $(READUTMP_LIB). Add $(CLOCK_TIME_LIB).
* modules/boot-time-tests (Makefile.am): Link test-boot-time with
$(CLOCK_TIME_LIB), not with $(READUTMP_LIB).
2023-08-11 Bruno Haible <br...@clisp.org>
readutmp: Refactor boot time determination code.
* lib/boot-time-aux.h: New file, extracted from lib/readutmp.c.
* lib/readutmp.c: On Linux, include <sys/sysinfo.h> even if
!READUTMP_USE_SYSTEMD.
Include boot-time-aux.h.
(SIZEOF): Remove macro, moved to boot-time-aux.h.
(get_linux_uptime): Remove function, moved to boot-time-aux.h.
(read_utmp_from_file): Invoke get_linux_boot_time_fallback,
get_android_boot_time, get_openbsd_boot_time, get_windows_boot_time.
Code moved to boot-time-aux.h.
(get_boot_time_uncached: Invoke get_linux_boot_time_final_fallback.
Code moved to boot-time-aux.h.
* m4/readutmp.m4 (gl_PREREQ_READUTMP_H): New macro, extracted from
gl_READUTMP.
(gl_READUTMP): Invoke it.
* modules/readutmp (Files): Add lib/boot-time-aux.h.
2023-08-11 Bruno Haible <br...@clisp.org>
readutmp: Make 'struct utmpx32' usable by other code.
* lib/readutmp.h (struct utmpx32): Moved to here from lib/readutmp.c.
(UTMP_STRUCT_NAME): Define as utmpx32 if needed.
* lib/readutmp.c (read_utmp_from_file): Simply use UTMP_STRUCT_NAME.
From cdbe33c428a82d42ff6fdcb48815edeb9d9d7fd8 Mon Sep 17 00:00:00 2001
From: Bruno Haible <br...@clisp.org>
Date: Fri, 11 Aug 2023 16:09:22 +0200
Subject: [PATCH 1/4] readutmp: Make 'struct utmpx32' usable by other code.
* lib/readutmp.h (struct utmpx32): Moved to here from lib/readutmp.c.
(UTMP_STRUCT_NAME): Define as utmpx32 if needed.
* lib/readutmp.c (read_utmp_from_file): Simply use UTMP_STRUCT_NAME.
---
ChangeLog | 7 +++++++
lib/readutmp.c | 33 ---------------------------------
lib/readutmp.h | 35 ++++++++++++++++++++++++++++++++++-
3 files changed, 41 insertions(+), 34 deletions(-)
diff --git a/ChangeLog b/ChangeLog
index 526e5cb4be..6836ca6308 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,10 @@
+2023-08-11 Bruno Haible <br...@clisp.org>
+
+ readutmp: Make 'struct utmpx32' usable by other code.
+ * lib/readutmp.h (struct utmpx32): Moved to here from lib/readutmp.c.
+ (UTMP_STRUCT_NAME): Define as utmpx32 if needed.
+ * lib/readutmp.c (read_utmp_from_file): Simply use UTMP_STRUCT_NAME.
+
2023-08-11 Bruno Haible <br...@clisp.org>
readutmp tests: Fix link error.
diff --git a/lib/readutmp.c b/lib/readutmp.c
index 40cee0e58c..00dbbcea48 100644
--- a/lib/readutmp.c
+++ b/lib/readutmp.c
@@ -383,40 +383,7 @@ read_utmp_from_file (char const *file, idx_t *n_entries, STRUCT_UTMP **utmp_buf,
while ((entry = GET_UTMP_ENT ()) != NULL)
{
-# if __GLIBC__ && _TIME_BITS == 64
- /* This is a near-copy of glibc's struct utmpx, which stops working
- after the year 2038. Unlike the glibc version, struct utmpx32
- describes the file format even if time_t is 64 bits. */
- struct utmpx32
- {
- short int ut_type; /* Type of login. */
- pid_t ut_pid; /* Process ID of login process. */
- char ut_line[UT_LINE_SIZE]; /* Devicename. */
- char ut_id[UT_ID_SIZE]; /* Inittab ID. */
- char ut_user[UT_USER_SIZE]; /* Username. */
- char ut_host[UT_HOST_SIZE]; /* Hostname for remote login. */
- struct __exit_status ut_exit; /* Exit status of a process marked
- as DEAD_PROCESS. */
- /* The fields ut_session and ut_tv must be the same size when compiled
- 32- and 64-bit. This allows files and shared memory to be shared
- between 32- and 64-bit applications. */
- int ut_session; /* Session ID, used for windowing. */
- struct
- {
- /* Seconds. Unsigned not signed, as glibc did not exist before 1970,
- and if the format is still in use after 2038 its timestamps
- will surely have the sign bit on. This hack stops working
- at 2106-02-07 06:28:16 UTC. */
- unsigned int tv_sec;
- int tv_usec; /* Microseconds. */
- } ut_tv; /* Time entry was made. */
- int ut_addr_v6[4]; /* Internet address of remote host. */
- char ut_reserved[20]; /* Reserved for future use. */
- };
- struct utmpx32 const *ut = (struct utmpx32 const *) entry;
-# else
struct UTMP_STRUCT_NAME const *ut = (struct UTMP_STRUCT_NAME const *) entry;
-# endif
struct timespec ts =
#if (HAVE_UTMPX_H ? 1 : HAVE_STRUCT_UTMP_UT_TV)
diff --git a/lib/readutmp.h b/lib/readutmp.h
index 70cd3801db..1cf588d265 100644
--- a/lib/readutmp.h
+++ b/lib/readutmp.h
@@ -132,7 +132,40 @@ enum { UT_HOST_SIZE = -1 };
⎣ ut_ss struct sockaddr_storage NetBSD, Minix
*/
-# define UTMP_STRUCT_NAME utmpx
+# if __GLIBC__ && _TIME_BITS == 64
+/* This is a near-copy of glibc's struct utmpx, which stops working
+ after the year 2038. Unlike the glibc version, struct utmpx32
+ describes the file format even if time_t is 64 bits. */
+struct utmpx32
+{
+ short int ut_type; /* Type of login. */
+ pid_t ut_pid; /* Process ID of login process. */
+ char ut_line[__UT_LINESIZE]; /* Devicename. */
+ char ut_id[4]; /* Inittab ID. */
+ char ut_user[__UT_USERSIZE]; /* Username. */
+ char ut_host[__UT_HOSTSIZE]; /* Hostname for remote login. */
+ struct __exit_status ut_exit; /* Exit status of a process marked
+ as DEAD_PROCESS. */
+ /* The fields ut_session and ut_tv must be the same size when compiled
+ 32- and 64-bit. This allows files and shared memory to be shared
+ between 32- and 64-bit applications. */
+ int ut_session; /* Session ID, used for windowing. */
+ struct
+ {
+ /* Seconds. Unsigned not signed, as glibc did not exist before 1970,
+ and if the format is still in use after 2038 its timestamps
+ will surely have the sign bit on. This hack stops working
+ at 2106-02-07 06:28:16 UTC. */
+ unsigned int tv_sec;
+ int tv_usec; /* Microseconds. */
+ } ut_tv; /* Time entry was made. */
+ int ut_addr_v6[4]; /* Internet address of remote host. */
+ char ut_reserved[20]; /* Reserved for future use. */
+};
+# define UTMP_STRUCT_NAME utmpx32
+# else
+# define UTMP_STRUCT_NAME utmpx
+# endif
# define SET_UTMP_ENT setutxent
# define GET_UTMP_ENT getutxent
# define END_UTMP_ENT endutxent
--
2.34.1
From 1657e67fe3f4be3cd572430358991bc12c62b193 Mon Sep 17 00:00:00 2001
From: Bruno Haible <br...@clisp.org>
Date: Fri, 11 Aug 2023 23:20:44 +0200
Subject: [PATCH 2/4] readutmp: Refactor boot time determination code.
* lib/boot-time-aux.h: New file, extracted from lib/readutmp.c.
* lib/readutmp.c: On Linux, include <sys/sysinfo.h> even if
!READUTMP_USE_SYSTEMD.
Include boot-time-aux.h.
(SIZEOF): Remove macro, moved to boot-time-aux.h.
(get_linux_uptime): Remove function, moved to boot-time-aux.h.
(read_utmp_from_file): Invoke get_linux_boot_time_fallback,
get_android_boot_time, get_openbsd_boot_time, get_windows_boot_time.
Code moved to boot-time-aux.h.
(get_boot_time_uncached: Invoke get_linux_boot_time_final_fallback.
Code moved to boot-time-aux.h.
* m4/readutmp.m4 (gl_PREREQ_READUTMP_H): New macro, extracted from
gl_READUTMP.
(gl_READUTMP): Invoke it.
* modules/readutmp (Files): Add lib/boot-time-aux.h.
---
ChangeLog | 19 ++++
lib/boot-time-aux.h | 228 ++++++++++++++++++++++++++++++++++++++++++++
lib/readutmp.c | 208 ++++++++--------------------------------
m4/readutmp.m4 | 14 ++-
modules/readutmp | 1 +
5 files changed, 299 insertions(+), 171 deletions(-)
create mode 100644 lib/boot-time-aux.h
diff --git a/ChangeLog b/ChangeLog
index 6836ca6308..29d5c73907 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,22 @@
+2023-08-11 Bruno Haible <br...@clisp.org>
+
+ readutmp: Refactor boot time determination code.
+ * lib/boot-time-aux.h: New file, extracted from lib/readutmp.c.
+ * lib/readutmp.c: On Linux, include <sys/sysinfo.h> even if
+ !READUTMP_USE_SYSTEMD.
+ Include boot-time-aux.h.
+ (SIZEOF): Remove macro, moved to boot-time-aux.h.
+ (get_linux_uptime): Remove function, moved to boot-time-aux.h.
+ (read_utmp_from_file): Invoke get_linux_boot_time_fallback,
+ get_android_boot_time, get_openbsd_boot_time, get_windows_boot_time.
+ Code moved to boot-time-aux.h.
+ (get_boot_time_uncached: Invoke get_linux_boot_time_final_fallback.
+ Code moved to boot-time-aux.h.
+ * m4/readutmp.m4 (gl_PREREQ_READUTMP_H): New macro, extracted from
+ gl_READUTMP.
+ (gl_READUTMP): Invoke it.
+ * modules/readutmp (Files): Add lib/boot-time-aux.h.
+
2023-08-11 Bruno Haible <br...@clisp.org>
readutmp: Make 'struct utmpx32' usable by other code.
diff --git a/lib/boot-time-aux.h b/lib/boot-time-aux.h
new file mode 100644
index 0000000000..fc84086f3f
--- /dev/null
+++ b/lib/boot-time-aux.h
@@ -0,0 +1,228 @@
+/* Auxiliary functions for determining the time when the machine last booted.
+ Copyright (C) 2023 Free Software Foundation, Inc.
+
+ This file is free software: you can redistribute it and/or modify
+ it under the terms of the GNU General Public License as published
+ by the Free Software Foundation, either version 3 of the License,
+ or (at your option) any later version.
+
+ This file is distributed in the hope that it will be useful,
+ but WITHOUT ANY WARRANTY; without even the implied warranty of
+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ GNU General Public License for more details.
+
+ You should have received a copy of the GNU General Public License
+ along with this program. If not, see <https://www.gnu.org/licenses/>. */
+
+/* Written by Bruno Haible <br...@clisp.org>. */
+
+#define SIZEOF(a) (sizeof(a)/sizeof(a[0]))
+
+#if defined __linux__ || defined __ANDROID__
+
+/* Store the uptime counter, as managed by the Linux kernel, in *P_UPTIME.
+ Return 0 upon success, -1 upon failure. */
+_GL_ATTRIBUTE_MAYBE_UNUSED
+static int
+get_linux_uptime (struct timespec *p_uptime)
+{
+ /* The clock_gettime facility returns the uptime with a resolution of 1 µsec.
+ It is available with glibc >= 2.14. In glibc < 2.17 it required linking
+ with librt. */
+# if (__GLIBC__ + (__GLIBC_MINOR__ >= 17) > 2) || defined __ANDROID__
+ if (clock_gettime (CLOCK_BOOTTIME, p_uptime) >= 0)
+ return 0;
+# endif
+
+ /* /proc/uptime contains the uptime with a resolution of 0.01 sec.
+ But it does not have read permissions on Android. */
+# if !defined __ANDROID__
+ 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)
+ {
+ p_uptime->tv_sec = (time_t) uptime;
+ p_uptime->tv_nsec = (uptime - p_uptime->tv_sec) * 1e9 + 0.5;
+ return 0;
+ }
+ }
+ }
+# endif
+
+ /* The sysinfo call returns the uptime with a resolution of 1 sec only. */
+ struct sysinfo info;
+ if (sysinfo (&info) >= 0)
+ {
+ p_uptime->tv_sec = info.uptime;
+ p_uptime->tv_nsec = 0;
+ return 0;
+ }
+
+ return -1;
+}
+
+#endif
+
+#if defined __linux__ && !defined __ANDROID__
+
+static int
+get_linux_boot_time_fallback (struct timespec *p_boot_time)
+{
+ /* On Alpine Linux, UTMP_FILE is not filled. It is always empty.
+ So, get the time stamp of a file that gets touched only during the
+ boot process. */
+
+ const char * const boot_touched_files[] =
+ {
+ "/var/lib/systemd/random-seed", /* seen on distros with systemd */
+ "/var/run/utmp", /* seen on distros with OpenRC */
+ "/var/lib/random-seed" /* seen on older distros */
+ };
+ for (idx_t i = 0; i < SIZEOF (boot_touched_files); i++)
+ {
+ const char *filename = boot_touched_files[i];
+ struct stat statbuf;
+ if (stat (filename, &statbuf) >= 0)
+ {
+ *p_boot_time = get_stat_mtime (&statbuf);
+ return 0;
+ }
+ }
+ return -1;
+}
+
+# if NEED_BOOT_TIME_FINAL_FALLBACK
+
+/* The following approach is only usable as a fallback, because it is of
+ the form
+ boot_time = (time now) - (kernel's ktime_get_boottime[_ts64] ())
+ and therefore produces wrong values after the date has been bumped in the
+ running system, which happens frequently if the system is running in a
+ virtual machine and this VM has been put into "saved" or "sleep" state
+ and then resumed. */
+static int
+get_linux_boot_time_final_fallback (struct timespec *p_boot_time)
+{
+ struct timespec uptime;
+ if (get_linux_uptime (&uptime) >= 0)
+ {
+ struct timespec result;
+ /* equivalent to:
+ if (clock_gettime (CLOCK_REALTIME, &result) >= 0)
+ */
+ if (timespec_get (&result, TIME_UTC) >= 0)
+ {
+ if (result.tv_nsec < uptime.tv_nsec)
+ {
+ result.tv_nsec += 1000000000;
+ result.tv_sec -= 1;
+ }
+ result.tv_sec -= uptime.tv_sec;
+ result.tv_nsec -= uptime.tv_nsec;
+ *p_boot_time = result;
+ return 0;
+ }
+ }
+ return -1;
+}
+
+# endif
+
+#endif
+
+#if defined __ANDROID__
+
+static int
+get_android_boot_time (struct timespec *p_boot_time)
+{
+ /* On Android, there is no /var, and normal processes don't have access
+ to system files. Therefore use the kernel's uptime counter, although
+ it produces wrong values after the date has been bumped in the running
+ system. */
+ struct timespec uptime;
+ if (get_linux_uptime (&uptime) >= 0)
+ {
+ struct timespec result;
+ if (clock_gettime (CLOCK_REALTIME, &result) >= 0)
+ {
+ if (result.tv_nsec < uptime.tv_nsec)
+ {
+ result.tv_nsec += 1000000000;
+ result.tv_sec -= 1;
+ }
+ result.tv_sec -= uptime.tv_sec;
+ result.tv_nsec -= uptime.tv_nsec;
+ *p_boot_time = result;
+ return 0;
+ }
+ }
+ return -1;
+}
+
+#endif
+
+#if defined __OpenBSD__
+
+static int
+get_openbsd_boot_time (struct timespec *p_boot_time)
+{
+ /* On OpenBSD, UTMP_FILE is not filled. It contains only dummy entries.
+ So, get the time stamp of a file that gets touched only during the
+ boot process. */
+ const char * const boot_touched_files[] =
+ {
+ "/var/db/host.random",
+ "/var/run/utmp"
+ };
+ for (idx_t i = 0; i < SIZEOF (boot_touched_files); i++)
+ {
+ const char *filename = boot_touched_files[i];
+ struct stat statbuf;
+ if (stat (filename, &statbuf) >= 0)
+ {
+ *p_boot_time = get_stat_mtime (&statbuf);
+ return 0;
+ }
+ }
+ return -1;
+}
+
+#endif
+
+# if defined __CYGWIN__ || defined _WIN32
+
+static int
+get_windows_boot_time (struct timespec *p_boot_time)
+{
+ /* On Cygwin, /var/run/utmp is empty.
+ On native Windows, <utmpx.h> and <utmp.h> don't exist.
+ Instead, on Windows, the boot time can be retrieved by looking at the
+ time stamp of a file that (normally) gets touched only during the boot
+ process, namely C:\pagefile.sys. */
+ const char * const boot_touched_file =
+ #if defined __CYGWIN__ && !defined _WIN32
+ "/cygdrive/c/pagefile.sys"
+ #else
+ "C:\\pagefile.sys"
+ #endif
+ ;
+ struct stat statbuf;
+ if (stat (boot_touched_file, &statbuf) >= 0)
+ {
+ *p_boot_time = get_stat_mtime (&statbuf);
+ return 0;
+ }
+ return -1;
+}
+
+# endif
diff --git a/lib/readutmp.c b/lib/readutmp.c
index 00dbbcea48..f2e66899bb 100644
--- a/lib/readutmp.c
+++ b/lib/readutmp.c
@@ -31,7 +31,7 @@
#include <stdlib.h>
#include <stdint.h>
-#if READUTMP_USE_SYSTEMD || defined __ANDROID__
+#if defined __linux__ || defined __ANDROID__
# include <sys/sysinfo.h>
# include <time.h>
#endif
@@ -46,6 +46,10 @@
/* Each of the FILE streams in this file is only used in a single thread. */
#include "unlocked-io.h"
+/* Some helper functions. */
+#define NEED_BOOT_TIME_FINAL_FALLBACK READUTMP_USE_SYSTEMD
+#include "boot-time-aux.h"
+
/* The following macros describe the 'struct UTMP_STRUCT_NAME',
*not* 'struct gl_utmp'. */
#undef UT_USER
@@ -135,8 +139,6 @@
/* Size of the ut->ut_host member. */
#define UT_HOST_SIZE sizeof (((struct UTMP_STRUCT_NAME *) 0)->ut_host)
-#define SIZEOF(a) (sizeof(a)/sizeof(a[0]))
-
#if 8 <= __GNUC__
# pragma GCC diagnostic ignored "-Wsizeof-pointer-memaccess"
#endif
@@ -288,60 +290,6 @@ finish_utmp (struct utmp_alloc a)
return a;
}
-# if READUTMP_USE_SYSTEMD || defined __ANDROID__
-
-/* Store the uptime counter, as managed by the Linux kernel, in *P_UPTIME.
- Return 0 upon success, -1 upon failure. */
-static int
-get_linux_uptime (struct timespec *p_uptime)
-{
- /* The clock_gettime facility returns the uptime with a resolution of 1 µsec.
- It is available with glibc >= 2.14. In glibc < 2.17 it required linking
- with librt. */
-# if (__GLIBC__ + (__GLIBC_MINOR__ >= 17) > 2) || defined __ANDROID__
- if (clock_gettime (CLOCK_BOOTTIME, p_uptime) >= 0)
- return 0;
-# endif
-
- /* /proc/uptime contains the uptime with a resolution of 0.01 sec.
- But it does not have read permissions on Android. */
-# if !defined __ANDROID__
- 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)
- {
- p_uptime->tv_sec = (time_t) uptime;
- p_uptime->tv_nsec = (uptime - p_uptime->tv_sec) * 1e9 + 0.5;
- return 0;
- }
- }
- }
-# endif
-
- /* The sysinfo call returns the uptime with a resolution of 1 sec only. */
- struct sysinfo info;
- if (sysinfo (&info) >= 0)
- {
- p_uptime->tv_sec = info.uptime;
- p_uptime->tv_nsec = 0;
- return 0;
- }
-
- return -1;
-}
-
-# endif
-
# if !HAVE_UTMPX_H && HAVE_UTMP_H && defined UTMP_NAME_FUNCTION && !HAVE_DECL_GETUTENT
struct utmp *getutent (void);
# endif
@@ -472,28 +420,14 @@ read_utmp_from_file (char const *file, idx_t *n_entries, STRUCT_UTMP **utmp_buf,
if (!have_boot_time)
{
/* Workaround for Alpine Linux: */
- const char * const boot_touched_files[] =
- {
- "/var/lib/systemd/random-seed", /* seen on distros with systemd */
- "/var/run/utmp", /* seen on distros with OpenRC */
- "/var/lib/random-seed" /* seen on older distros */
- };
- for (idx_t i = 0; i < SIZEOF (boot_touched_files); i++)
- {
- const char *filename = boot_touched_files[i];
- struct stat statbuf;
- if (stat (filename, &statbuf) >= 0)
- {
- struct timespec boot_time = get_stat_mtime (&statbuf);
- a = add_utmp (a, options,
- "reboot", strlen ("reboot"),
- "", 0,
- "~", strlen ("~"),
- "", 0,
- 0, BOOT_TIME, boot_time, 0, 0, 0);
- break;
- }
- }
+ struct timespec boot_time;
+ if (get_linux_boot_time_fallback (&boot_time) >= 0)
+ a = add_utmp (a, options,
+ "reboot", strlen ("reboot"),
+ "", 0,
+ "~", strlen ("~"),
+ "", 0,
+ 0, BOOT_TIME, boot_time, 0, 0, 0);
}
}
# endif
@@ -518,28 +452,14 @@ read_utmp_from_file (char const *file, idx_t *n_entries, STRUCT_UTMP **utmp_buf,
}
if (!have_boot_time)
{
- struct timespec uptime;
- if (get_linux_uptime (&uptime) >= 0)
- {
- struct timespec result;
- if (clock_gettime (CLOCK_REALTIME, &result) >= 0)
- {
- if (result.tv_nsec < uptime.tv_nsec)
- {
- result.tv_nsec += 1000000000;
- result.tv_sec -= 1;
- }
- result.tv_sec -= uptime.tv_sec;
- result.tv_nsec -= uptime.tv_nsec;
- struct timespec boot_time = result;
- a = add_utmp (a, options,
- "reboot", strlen ("reboot"),
- "", 0,
- "", 0,
- "", 0,
- 0, BOOT_TIME, boot_time, 0, 0, 0);
- }
- }
+ struct timespec boot_time;
+ if (get_android_boot_time (&boot_time) >= 0)
+ a = add_utmp (a, options,
+ "reboot", strlen ("reboot"),
+ "", 0,
+ "", 0,
+ "", 0,
+ 0, BOOT_TIME, boot_time, 0, 0, 0);
}
}
# endif
@@ -629,9 +549,6 @@ read_utmp_from_file (char const *file, idx_t *n_entries, STRUCT_UTMP **utmp_buf,
}
# if defined __OpenBSD__
- /* On OpenBSD, UTMP_FILE is not filled. It contains only dummy entries.
- So, fake a BOOT_TIME entry, by getting the time stamp of a file that
- gets touched only during the boot process. */
if ((options & (READ_UTMP_USER_PROCESS | READ_UTMP_NO_BOOT_TIME)) == 0
&& strcmp (file, UTMP_FILE) == 0)
{
@@ -639,26 +556,16 @@ read_utmp_from_file (char const *file, idx_t *n_entries, STRUCT_UTMP **utmp_buf,
bool have_boot_time = false;
if (!have_boot_time)
{
- const char * const boot_touched_files[] =
- {
- "/var/db/host.random",
- "/var/run/utmp"
- };
- for (idx_t i = 0; i < SIZEOF (boot_touched_files); i++)
+ struct timespec boot_time;
+ if (get_openbsd_boot_time (&boot_time) >= 0)
{
- const char *filename = boot_touched_files[i];
- struct stat statbuf;
- if (stat (filename, &statbuf) >= 0)
- {
- struct timespec boot_time = get_stat_mtime (&statbuf);
- a = add_utmp (a, options,
- "reboot", strlen ("reboot"),
- "", 0,
- "", 0,
- "", 0,
- 0, BOOT_TIME, boot_time, 0, 0, 0);
- break;
- }
+ a = add_utmp (a, options,
+ "reboot", strlen ("reboot"),
+ "", 0,
+ "", 0,
+ "", 0,
+ 0, BOOT_TIME, boot_time, 0, 0, 0);
+ break;
}
}
}
@@ -678,24 +585,14 @@ read_utmp_from_file (char const *file, idx_t *n_entries, STRUCT_UTMP **utmp_buf,
&& strcmp (file, UTMP_FILE) == 0
&& a.filled == 0)
{
- const char * const boot_touched_file =
- #if defined __CYGWIN__ && !defined _WIN32
- "/cygdrive/c/pagefile.sys"
- #else
- "C:\\pagefile.sys"
- #endif
- ;
- struct stat statbuf;
- if (stat (boot_touched_file, &statbuf) >= 0)
- {
- struct timespec boot_time = get_stat_mtime (&statbuf);
- a = add_utmp (a, options,
- "reboot", strlen ("reboot"),
- "", 0,
- "", 0,
- "", 0,
- 0, BOOT_TIME, boot_time, 0, 0, 0);
- }
+ struct timespec boot_time;
+ if (get_windows_boot_time (&boot_time) >= 0)
+ a = add_utmp (a, options,
+ "reboot", strlen ("reboot"),
+ "", 0,
+ "", 0,
+ "", 0,
+ 0, BOOT_TIME, boot_time, 0, 0, 0);
}
# endif
@@ -727,33 +624,10 @@ get_boot_time_uncached (void)
free (utmp);
}
- /* The following approach is only usable as a fallback, because it is of
- the form
- boot_time = (time now) - (kernel's ktime_get_boottime[_ts64] ())
- and therefore produces wrong values after the date has been bumped in the
- running system, which happens frequently if the system is running in a
- virtual machine and this VM has been put into "saved" or "sleep" state
- and then resumed. */
{
- struct timespec uptime;
- if (get_linux_uptime (&uptime) >= 0)
- {
- struct timespec result;
- /* equivalent to:
- if (clock_gettime (CLOCK_REALTIME, &result) >= 0)
- */
- if (timespec_get (&result, TIME_UTC) >= 0)
- {
- if (result.tv_nsec < uptime.tv_nsec)
- {
- result.tv_nsec += 1000000000;
- result.tv_sec -= 1;
- }
- result.tv_sec -= uptime.tv_sec;
- result.tv_nsec -= uptime.tv_nsec;
- return result;
- }
- }
+ struct timespec boot_time;
+ if (get_linux_boot_time_final_fallback (&boot_time) >= 0)
+ return boot_time;
}
/* We shouldn't get here. */
diff --git a/m4/readutmp.m4 b/m4/readutmp.m4
index 6ba5b2e225..07eebcd43d 100644
--- a/m4/readutmp.m4
+++ b/m4/readutmp.m4
@@ -1,4 +1,4 @@
-# readutmp.m4 serial 23
+# readutmp.m4 serial 24
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,
@@ -6,9 +6,6 @@
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
@@ -45,6 +42,15 @@ AC_DEFUN([gl_READUTMP]
fi
AC_SUBST([READUTMP_LIB])
+ gl_PREREQ_READUTMP_H
+])
+
+# Prerequisites of readutmp.h.
+AC_DEFUN_ONCE([gl_PREREQ_READUTMP_H],
+[
+ dnl Persuade utmpx.h to declare utmpxname
+ AC_REQUIRE([AC_USE_SYSTEM_EXTENSIONS])
+
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/modules/readutmp b/modules/readutmp
index 21f6de5777..85bbf74954 100644
--- a/modules/readutmp
+++ b/modules/readutmp
@@ -4,6 +4,7 @@ Read entire utmp file into memory.
Files:
lib/readutmp.h
lib/readutmp.c
+lib/boot-time-aux.h
m4/readutmp.m4
m4/systemd.m4
--
2.34.1
>From bea15dd14f8388a4b78b63ecfa0decad0414ec88 Mon Sep 17 00:00:00 2001
From: Bruno Haible <br...@clisp.org>
Date: Fri, 11 Aug 2023 23:30:01 +0200
Subject: [PATCH 3/4] boot-time: Simplify execution.
* lib/boot-time.c: Include <stdio.h>, <string.h>, <sys/types.h>,
<sys/stat.h>, <sys/sysinfo.h>, <time.h>, stat-time.h, unlocked-io.h,
boot-time-aux.h.
(UT_USER): New macro, from lib/readutmp.c.
(getutent): New declaration.
(get_boot_time_uncached): New function, containing a simplified code
from lib/readutmp.c.
(get_boot_time): Don't invoke read_utmp. Instead, invoke
get_boot_time_uncached and cache the result.
* modules/boot-time (Files): Add lib/boot-time-aux.h, lib/readutmp.h,
m4/readutmp.m4.
(Depends-on): Remove readutmp. Add extensions, fopen-gnu, stat-time,
stdbool, time-h, timespec_get, unlocked-io-internal.
(configure.ac): Invoke gl_PREREQ_READUTMP_H.
(Link): Remove $(READUTMP_LIB). Add $(CLOCK_TIME_LIB).
* modules/boot-time-tests (Makefile.am): Link test-boot-time with
$(CLOCK_TIME_LIB), not with $(READUTMP_LIB).
---
ChangeLog | 21 ++++
lib/boot-time.c | 223 ++++++++++++++++++++++++++++++++++++++--
modules/boot-time | 14 ++-
modules/boot-time-tests | 2 +-
4 files changed, 250 insertions(+), 10 deletions(-)
diff --git a/ChangeLog b/ChangeLog
index 29d5c73907..bfc2954a80 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,24 @@
+2023-08-11 Bruno Haible <br...@clisp.org>
+
+ boot-time: Simplify execution.
+ * lib/boot-time.c: Include <stdio.h>, <string.h>, <sys/types.h>,
+ <sys/stat.h>, <sys/sysinfo.h>, <time.h>, stat-time.h, unlocked-io.h,
+ boot-time-aux.h.
+ (UT_USER): New macro, from lib/readutmp.c.
+ (getutent): New declaration.
+ (get_boot_time_uncached): New function, containing a simplified code
+ from lib/readutmp.c.
+ (get_boot_time): Don't invoke read_utmp. Instead, invoke
+ get_boot_time_uncached and cache the result.
+ * modules/boot-time (Files): Add lib/boot-time-aux.h, lib/readutmp.h,
+ m4/readutmp.m4.
+ (Depends-on): Remove readutmp. Add extensions, fopen-gnu, stat-time,
+ stdbool, time-h, timespec_get, unlocked-io-internal.
+ (configure.ac): Invoke gl_PREREQ_READUTMP_H.
+ (Link): Remove $(READUTMP_LIB). Add $(CLOCK_TIME_LIB).
+ * modules/boot-time-tests (Makefile.am): Link test-boot-time with
+ $(CLOCK_TIME_LIB), not with $(READUTMP_LIB).
+
2023-08-11 Bruno Haible <br...@clisp.org>
readutmp: Refactor boot time determination code.
diff --git a/lib/boot-time.c b/lib/boot-time.c
index fe1e13eccb..932ee22d69 100644
--- a/lib/boot-time.c
+++ b/lib/boot-time.c
@@ -22,22 +22,231 @@
#include "boot-time.h"
#include <stddef.h>
+#include <stdio.h>
+#include <string.h>
+#include <sys/types.h>
+#include <sys/stat.h>
+
+#if defined __linux__ || defined __ANDROID__
+# include <sys/sysinfo.h>
+# include <time.h>
+#endif
#include "idx.h"
#include "readutmp.h"
+#include "stat-time.h"
+
+/* Each of the FILE streams in this file is only used in a single thread. */
+#include "unlocked-io.h"
+
+/* Some helper functions. */
+#define NEED_BOOT_TIME_FINAL_FALLBACK 1
+#include "boot-time-aux.h"
+
+/* The following macros describe the 'struct UTMP_STRUCT_NAME',
+ *not* 'struct gl_utmp'. */
+#undef UT_USER
+
+/* Accessor macro for the member named ut_user or ut_name. */
+#if (HAVE_UTMPX_H ? HAVE_STRUCT_UTMPX_UT_NAME \
+ : HAVE_UTMP_H && HAVE_STRUCT_UTMP_UT_NAME)
+# define UT_USER(UT) ((UT)->ut_name)
+#else
+# define UT_USER(UT) ((UT)->ut_user)
+#endif
+
+#if !HAVE_UTMPX_H && HAVE_UTMP_H && defined UTMP_NAME_FUNCTION && !HAVE_DECL_GETUTENT
+struct utmp *getutent (void);
+#endif
+
+#if defined __linux__ || HAVE_UTMPX_H || HAVE_UTMP_H || defined __CYGWIN__ || defined _WIN32
+
+static int
+get_boot_time_uncached (struct timespec *p_boot_time)
+{
+ struct timespec found_boot_time = {0};
+
+# if !(HAVE_UTMPX_H ? HAVE_STRUCT_UTMPX_UT_TYPE : HAVE_STRUCT_UTMP_UT_TYPE) /* old FreeBSD, OpenBSD, native Windows */
+
+# if defined __OpenBSD__
+ /* Workaround for OpenBSD: */
+ get_openbsd_boot_time (&found_boot_time);
+# endif
+
+# else
+
+ /* Try to find the boot time in the /var/run/utmp file. */
+
+# if defined UTMP_NAME_FUNCTION /* glibc, musl, macOS, FreeBSD, NetBSD, Minix, AIX, IRIX, Solaris, Cygwin, Android */
+
+ /* Ignore the return value for now.
+ Solaris' utmpname returns 1 upon success -- which is contrary
+ to what the GNU libc version does. In addition, older GNU libc
+ versions are actually void. */
+ UTMP_NAME_FUNCTION ((char *) UTMP_FILE);
+
+ SET_UTMP_ENT ();
+
+# if (defined __linux__ && !defined __ANDROID__) || defined __minix
+ /* Timestamp of the "runlevel" entry, if any. */
+ struct timespec runlevel_ts = {0};
+# endif
+
+ void const *entry;
+
+ while ((entry = GET_UTMP_ENT ()) != NULL)
+ {
+ struct UTMP_STRUCT_NAME const *ut = (struct UTMP_STRUCT_NAME const *) entry;
+
+ struct timespec ts =
+ #if (HAVE_UTMPX_H ? 1 : HAVE_STRUCT_UTMP_UT_TV)
+ { .tv_sec = ut->ut_tv.tv_sec, .tv_nsec = ut->ut_tv.tv_usec * 1000 };
+ #else
+ { .tv_sec = ut->ut_time, .tv_nsec = 0 };
+ #endif
+
+ if (ut->ut_type == BOOT_TIME)
+ found_boot_time = ts;
+
+# if defined __linux__ && !defined __ANDROID__
+ if (memcmp (UT_USER (ut), "runlevel", strlen ("runlevel") + 1) == 0
+ && memcmp (ut->ut_line, "~", strlen ("~") + 1) == 0)
+ runlevel_ts = ts;
+# endif
+# if defined __minix
+ if (UT_USER (ut)[0] == '\0'
+ && memcmp (ut->ut_line, "run-level ", strlen ("run-level ")) == 0)
+ runlevel_ts = ts;
+# endif
+ }
+
+ END_UTMP_ENT ();
+
+# if defined __linux__ && !defined __ANDROID__
+ /* On Raspbian, which runs on hardware without a real-time clock, during boot,
+ 1. the clock gets set to 1970-01-01 00:00:00,
+ 2. an entry gets written into /var/run/utmp, with ut_type = BOOT_TIME,
+ ut_user = "reboot", ut_line = "~", time = 1970-01-01 00:00:05 or so,
+ 3. the clock gets set to a correct value through NTP,
+ 4. an entry gets written into /var/run/utmp, with
+ ut_user = "runlevel", ut_line = "~", time = correct value.
+ In this case, get the time from the "runlevel" entry. */
+
+ /* Workaround for Raspbian: */
+ if (found_boot_time.tv_sec <= 60 && runlevel_ts.tv_sec != 0)
+ found_boot_time = runlevel_ts;
+ if (found_boot_time.tv_sec == 0)
+ {
+ /* Workaround for Alpine Linux: */
+ get_linux_boot_time_fallback (&found_boot_time);
+ }
+# endif
+
+# if defined __ANDROID__
+ if (found_boot_time.tv_sec == 0)
+ {
+ /* Workaround for Android: */
+ get_android_boot_time (&found_boot_time);
+ }
+# endif
+
+# if defined __minix
+ /* On Minix, during boot,
+ 1. an entry gets written into /var/run/utmp, with ut_type = BOOT_TIME,
+ ut_user = "", ut_line = "system boot", time = 1970-01-01 00:00:00,
+ 2. an entry gets written into /var/run/utmp, with
+ ut_user = "", ut_line = "run-level m", time = correct value.
+ In this case, copy the time from the "run-level m" entry to the
+ "system boot" entry. */
+ if (found_boot_time.tv_sec <= 60 && runlevel_ts.tv_sec != 0)
+ found_boot_time = runlevel_ts;
+# endif
+
+# else /* HP-UX */
+
+ FILE *f = fopen (UTMP_FILE, "re");
+
+ if (f != NULL)
+ {
+ for (;;)
+ {
+ struct UTMP_STRUCT_NAME ut;
+
+ if (fread (&ut, sizeof ut, 1, f) == 0)
+ break;
+
+ struct timespec ts =
+ #if (HAVE_UTMPX_H ? 1 : HAVE_STRUCT_UTMP_UT_TV)
+ { .tv_sec = ut.ut_tv.tv_sec, .tv_nsec = ut.ut_tv.tv_usec * 1000 };
+ #else
+ { .tv_sec = ut.ut_time, .tv_nsec = 0 };
+ #endif
+
+ if (ut.ut_type == BOOT_TIME)
+ found_boot_time = ts;
+ }
+
+ fclose (f);
+ }
+
+# endif
+
+# if defined __linux__ && !defined __ANDROID__
+ if (found_boot_time.tv_sec == 0)
+ {
+ get_linux_boot_time_final_fallback (&found_boot_time);
+ }
+# endif
+
+# endif
+
+# if defined __CYGWIN__ || defined _WIN32
+ if (found_boot_time.tv_sec == 0)
+ {
+ /* Workaround for Windows: */
+ get_windows_boot_time (&found_boot_time);
+ }
+# endif
+
+ if (found_boot_time.tv_sec != 0)
+ {
+ *p_boot_time = found_boot_time;
+ return 0;
+ }
+ else
+ return -1;
+}
int
get_boot_time (struct timespec *p_boot_time)
{
- idx_t n_entries = 0;
- STRUCT_UTMP *utmp = NULL;
- read_utmp (UTMP_FILE, &n_entries, &utmp, READ_UTMP_BOOT_TIME);
- if (n_entries > 0)
+ /* Cache the result from get_boot_time_uncached. */
+ static int volatile cached_result = -1;
+ static struct timespec volatile cached_boot_time;
+
+ if (cached_result < 0)
+ {
+ struct timespec boot_time;
+ int result = get_boot_time_uncached (&boot_time);
+ cached_boot_time = boot_time;
+ cached_result = result;
+ }
+
+ if (cached_result == 0)
{
- *p_boot_time = utmp[0].ut_ts;
- free (utmp);
+ *p_boot_time = cached_boot_time;
return 0;
}
- free (utmp);
+ else
+ return -1;
+}
+
+#else
+
+int
+get_boot_time (struct timespec *p_boot_time)
+{
return -1;
}
+
+#endif
diff --git a/modules/boot-time b/modules/boot-time
index 99ae5c9fe7..ba8a2b4e6f 100644
--- a/modules/boot-time
+++ b/modules/boot-time
@@ -4,12 +4,22 @@ Determine the time when the machine last booted.
Files:
lib/boot-time.h
lib/boot-time.c
+lib/boot-time-aux.h
+lib/readutmp.h
+m4/readutmp.m4
Depends-on:
+extensions
+fopen-gnu
idx
-readutmp
+stat-time
+stdbool
+time-h
+timespec_get
+unlocked-io-internal
configure.ac:
+gl_PREREQ_READUTMP_H
Makefile.am:
lib_SOURCES += boot-time.c
@@ -18,7 +28,7 @@ Include:
"boot-time.h"
Link:
-$(READUTMP_LIB)
+$(CLOCK_TIME_LIB)
License:
GPL
diff --git a/modules/boot-time-tests b/modules/boot-time-tests
index 0ba9d467ca..bb56ee36e5 100644
--- a/modules/boot-time-tests
+++ b/modules/boot-time-tests
@@ -8,4 +8,4 @@ configure.ac:
Makefile.am:
TESTS += test-boot-time
check_PROGRAMS += test-boot-time
-test_boot_time_LDADD = $(LDADD) $(READUTMP_LIB)
+test_boot_time_LDADD = $(LDADD) $(CLOCK_TIME_LIB)
--
2.34.1
>From 5cd9573bc638b433eae64331dc61188eae6e434e Mon Sep 17 00:00:00 2001
From: Bruno Haible <br...@clisp.org>
Date: Fri, 11 Aug 2023 23:31:37 +0200
Subject: [PATCH 4/4] boot-time: Add comment about multithread-safety.
* lib/boot-time.h (get_boot_time): Add comment, same as in readutmp.h.
---
ChangeLog | 5 +++++
lib/boot-time.h | 8 +++++++-
2 files changed, 12 insertions(+), 1 deletion(-)
diff --git a/ChangeLog b/ChangeLog
index bfc2954a80..472349e5e4 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,8 @@
+2023-08-11 Bruno Haible <br...@clisp.org>
+
+ boot-time: Add comment about multithread-safety.
+ * lib/boot-time.h (get_boot_time): Add comment, same as in readutmp.h.
+
2023-08-11 Bruno Haible <br...@clisp.org>
boot-time: Simplify execution.
diff --git a/lib/boot-time.h b/lib/boot-time.h
index 159a0056f9..401e854adb 100644
--- a/lib/boot-time.h
+++ b/lib/boot-time.h
@@ -27,7 +27,13 @@ extern "C" {
/* Store the approximate time when the machine last booted in *P_BOOT_TIME,
- and return 0. If it cannot be determined, return -1. */
+ and return 0. If it cannot be determined, return -1.
+
+ This function is not multithread-safe, since on many platforms it
+ invokes the functions setutxent, getutxent, endutxent. These
+ functions are needed because they may lock FILE (so that we don't
+ read garbage when a concurrent process writes to FILE), but their
+ drawback is that they have a common global state. */
extern int get_boot_time (struct timespec *p_boot_time);
--
2.34.1
