* [PATCH proxmox-mini-journalreader v2 1/2] add -B parameter to lists boots
2026-08-05 9:45 [PATCH manager/proxmox-mini-journalreader v2 0/2] report: list recent reboot events and their kernel version Maximiliano Sandoval
@ 2026-08-05 9:45 ` Maximiliano Sandoval
2026-08-05 9:45 ` [PATCH manager v2 2/2] report: list recent reboot events and their kernel version Maximiliano Sandoval
1 sibling, 0 replies; 3+ messages in thread
From: Maximiliano Sandoval @ 2026-08-05 9:45 UTC (permalink / raw)
To: pve-devel
The parameter will print all boots, in practice it should be piped into tail.
Sample output:
2026-07-27 08:28 2026-07-27 15:56 3e3813556d53477f9a139a7cb2f3e8f2 7.0.14-6-pve
2026-07-27 15:57 2026-07-27 17:03 5a0324e1ac3f4f24907a21ab81b67384 7.0.14-7-pve
2026-07-28 08:26 2026-07-28 17:07 e62bc71e85274f21a1bfb954be38c071 7.0.14-7-pve
2026-07-29 08:43 2026-07-29 08:48 7f668e4499644ea1b8339d6b8c29d53d 7.0.14-7-pve
2026-07-29 08:49 2026-07-29 17:09 9ff5eb6f0485466383e0b89512f937c9 7.0.14-8-pve
glib is added as a dependency for simplicity of memory management.
As per SD_JOURNAL_QUERY_UNIQUE(3), sd_journal_query_unique ignore matches hence
why we need to iterate twice:
Note that these functions currently are not influenced by matches
set with sd_journal_add_match() but this might change in a later
version of this software.
Signed-off-by: Maximiliano Sandoval <m.sandoval@proxmox.com>
---
Notes:
We usually require the output from `last` or similar in support to query the
previously booted kernel versions. We add this helper to avoid adding a
dependency on either last or wtmpdb on the ISO images.
This seems quick enough for ~400 boots:
time sudo ./proxmox-mini-journalreader -B | wc -l
417
real 0m0,143s
user 0m0,004s
sys 0m0,004s
Open questions:
- Should it list the latest boots first? It amounts to reversing the sign on
boot_info_cmp.
- We assume the first line in the journal is the "Linux version" line. This is
true as of now in practice. One could add a match like:
sd_journal_add_match(j, "_TRANSPORT=kernel", strlen("_TRANSPORT=kernel"));
if this is undesirable.
Differences from v1:
- Replace uint with size_t
- Remove the use of a second journal
- Copy only 32 chars instead of 33. We were copying \0 which is added by
g_strndup anyways and 32 is the actual length of a BOOT_ID
- use strlen("BOOT_ID=") instead of sizeof("BOOT_ID") so it does not work by accident
- Use proper signature for GCompareFunc
- Add a couple of guards for empty messages
debian/control | 2 +-
src/Makefile | 2 +-
src/mini-journalreader.c | 154 ++++++++++++++++++++++++++++++++++++++-
3 files changed, 155 insertions(+), 3 deletions(-)
diff --git a/debian/control b/debian/control
index 8280f6d..d7d8cc0 100644
--- a/debian/control
+++ b/debian/control
@@ -2,7 +2,7 @@ Source: proxmox-mini-journalreader
Section: admin
Priority: optional
Maintainer: Proxmox Support Team <support@proxmox.com>
-Build-Depends: debhelper-compat (= 13), libsystemd-dev, pkg-config, scdoc,
+Build-Depends: debhelper-compat (= 13), libsystemd-dev, pkg-config, scdoc, libglib2.0-dev,
Standards-Version: 4.6.2
Package: proxmox-mini-journalreader
diff --git a/src/Makefile b/src/Makefile
index e64e066..c89e74a 100644
--- a/src/Makefile
+++ b/src/Makefile
@@ -5,7 +5,7 @@ LIBEXEC_DIR ?= $(DESTDIR)/usr/libexec/
MAN1_DIR ?= $(DESTDIR)/usr/share/man/man1
MANPAGE ?= $(PROGRAM).1
-LIBS := libsystemd
+LIBS := libsystemd glib-2.0
CFLAGS += -Wall -Wextra -Wl,-z,relro -g -O2 --std=gnu11
CFLAGS += -fstack-protector-strong -D_FORTIFY_SOURCE=2
CFLAGS += $(shell pkg-config --cflags $(LIBS))
diff --git a/src/mini-journalreader.c b/src/mini-journalreader.c
index fc78f65..7d0d76b 100644
--- a/src/mini-journalreader.c
+++ b/src/mini-journalreader.c
@@ -21,6 +21,7 @@
#include <errno.h>
#include <fnmatch.h>
+#include <glib.h>
#include <stdbool.h>
#include <stdint.h>
#include <stdio.h>
@@ -37,6 +38,148 @@ bool json = false;
bool structured = false;
bool first_line = true;
+typedef struct {
+ char *boot_id;
+ char *version;
+ uint64_t first_timestamp;
+ uint64_t last_timestamp;
+} BootInfo;
+
+static void boot_info_free(BootInfo *info) {
+ g_free(info->boot_id);
+ g_free(info->version);
+ g_free(info);
+}
+
+static int boot_info_cmp(gconstpointer a, gconstpointer b) {
+ const BootInfo *entry1 = a;
+ const BootInfo *entry2 = b;
+
+ if (entry1->first_timestamp < entry2->first_timestamp) return -1;
+ if (entry1->first_timestamp > entry2->first_timestamp) return 1;
+ return 0;
+}
+
+char* get_version_from_journal_entry(const char *message) {
+ g_autoptr(GRegex) regex = NULL;
+ g_autoptr(GMatchInfo) match_info = NULL;
+ g_autoptr(GError) error = NULL;
+ int start_pos = 0, end_pos = 0;
+
+ g_return_val_if_fail(message != NULL, g_strdup("unknown"));
+
+ regex = g_regex_new("Linux version ([a-zA-Z0-9.-]+)", G_REGEX_OPTIMIZE, G_REGEX_MATCH_DEFAULT, &error);
+ if (error) {
+ g_critical("Regex compilation failed: %s", error->message);
+ return g_strdup("unknown");
+ }
+
+ g_return_val_if_fail(regex != NULL, g_strdup("unknown"));
+
+ g_regex_match(regex, message, G_REGEX_MATCH_DEFAULT, &match_info);
+
+ if (!g_match_info_matches(match_info))
+ return g_strdup("unknown");
+
+ g_match_info_fetch_pos(match_info, 1, &start_pos, &end_pos);
+
+ return g_strndup(message + start_pos, end_pos - start_pos);
+}
+
+char* format_timestamp(uint64_t timestamp) {
+ g_autoptr(GDateTime) time = NULL;
+
+ if (timestamp == 0) {
+ return g_strdup ("-");
+ }
+
+ time = g_date_time_new_from_unix_local_usec(timestamp);
+ return g_date_time_format(time, "%Y-%m-%d %H:%M");
+}
+
+static void print_boot(BootInfo *info, gpointer user_data) {
+ g_return_if_fail(info != NULL);
+
+ g_autofree char *start = format_timestamp(info->first_timestamp);
+ g_autofree char *end = format_timestamp(info->last_timestamp);
+ g_print("%s\t%s\t%s\t%s\n", start, end, info->boot_id, info->version);
+}
+
+static int list_boots_and_kernels(sd_journal *j) {
+ const void *data;
+ const size_t prefix_len = strlen("_BOOT_ID=");
+ size_t len;
+ int r;
+ g_autoptr(GPtrArray) boot_ids = NULL;
+ g_autoptr(GPtrArray) boot_array = NULL;
+
+ boot_ids = g_ptr_array_new_with_free_func(g_free);
+
+ r = sd_journal_query_unique(j, "_BOOT_ID");
+ if (r < 0) {
+ g_printerr("Failed to query _BOOT_ID identifier: %s\n", strerror(-r));
+ return 1;
+ }
+ SD_JOURNAL_FOREACH_UNIQUE(j, data, len) {
+ g_ptr_array_add(boot_ids, g_strndup((const char *)data, len));
+ }
+
+ boot_array = g_ptr_array_new_full(boot_ids->len, (GDestroyNotify)boot_info_free);
+
+ sd_journal_flush_matches(j);
+
+ for (size_t i = 0; i < boot_ids->len; i++) {
+ uint64_t first_ts = 0, last_ts = 0;
+ size_t msg_len;
+ const char *message = NULL;
+ const char *match = g_ptr_array_index(boot_ids, i);
+ g_autofree char* version = NULL;
+ g_autofree char *boot_id = NULL;
+
+ // Strip _BOOT_ID= from the message
+ boot_id = g_strndup(match + prefix_len, 32);
+
+ sd_journal_add_match(j, match, strlen(match));
+
+ r = sd_journal_seek_head(j);
+ if (r >= 0) {
+ r = sd_journal_next(j);
+ if (r > 0) {
+ sd_journal_get_realtime_usec(j, &first_ts);
+ }
+ }
+
+ r = sd_journal_get_data(j, "MESSAGE", (const void **)&message, &msg_len);
+ if (r >= 0 && message != NULL && msg_len > 0)
+ version = get_version_from_journal_entry(message);
+ else
+ version = g_strdup("unknown");
+
+ r = sd_journal_seek_tail(j);
+ if (r >= 0) {
+ r = sd_journal_previous(j);
+ if (r > 0) {
+ sd_journal_get_realtime_usec(j, &last_ts);
+ }
+ }
+
+ sd_journal_flush_matches(j);
+
+ BootInfo *boot_info = g_new0 (BootInfo, 1);
+ boot_info->boot_id = g_steal_pointer(&boot_id);
+ boot_info->version = g_steal_pointer(&version);
+ boot_info->first_timestamp = first_ts;
+ boot_info->last_timestamp = last_ts;
+
+ g_ptr_array_add(boot_array, boot_info);
+ }
+
+ g_ptr_array_sort_values(boot_array, (GCompareFunc)boot_info_cmp);
+ g_ptr_array_foreach(boot_array, (GFunc)print_boot, NULL);
+
+ return 0;
+}
+
// helper to print errors on stderr
// if we're in json mode, print closing json body if possible
static void print_error_and_exit(const char *fmt, ...) {
@@ -471,6 +614,7 @@ _Noreturn static void usage(char *error) {
" -J\t\t\tprint as json with one object of separate fields per entry\n"
" -I\t\t\twith -J, also emit a record listing the distinct syslog identifiers\n"
" -U\t\t\twith -J, also emit a record listing the distinct systemd units\n"
+ " -B\t\t\tList boots. The columns are: the date of the first entry in the boot and last entry, the boot id, and the kernel version\n"
" -h\t\t\tthis help\n"
"\n"
"Passing no range option will dump all the available journal\n"
@@ -711,11 +855,12 @@ int main(int argc, char *argv[]) {
bool kernel = false;
bool list_identifiers = false;
bool list_units = false;
+ bool list_boots = false;
int c;
progname = argv[0];
- while ((c = getopt(argc, argv, "b:e:d:n:f:t:p:i:u:jJIUkh")) != -1) {
+ while ((c = getopt(argc, argv, "b:e:d:n:f:t:p:i:u:jJIUkh:B")) != -1) {
switch (c) {
case 'b':
begin = arg_to_timestamp_usec(optarg);
@@ -762,6 +907,9 @@ int main(int argc, char *argv[]) {
case 'U':
list_units = true;
break;
+ case 'B':
+ list_boots = true;
+ break;
case 'h':
usage(NULL);
case '?':
@@ -816,6 +964,10 @@ int main(int argc, char *argv[]) {
return 1;
}
+ if (list_boots) {
+ return list_boots_and_kernels(j);
+ }
+
// restrict the traversal before seeking. Each filter is a separate group, conjoined (AND) with
// the others; within a group matches are OR'd (same field, or an explicit disjunction for the
// unit), so the groups must be split by a conjunction
--
2.47.3
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