analyze: add new "calendar" command

This little new command can parse, validate, normalize calendar events,
and calculate when they will elapse next. This should be useful for
anyone writing calendar events and who'd like to validate the expression
before running them as timer units.

4 files changed, 88 insertions, 1 deletions

diff --git a/man/systemd-analyze.xml b/man/systemd-analyze.xml
index 956790c50c..876f96d559 100644
--- a/man/systemd-analyze.xml
+++ b/man/systemd-analyze.xml
@@ -125,6 +125,12 @@
       <arg choice="plain">verify</arg>
       <arg choice="opt" rep="repeat"><replaceable>FILES</replaceable></arg>
     </cmdsynopsis>
+    <cmdsynopsis>
+      <command>systemd-analyze</command>
+      <arg choice="opt" rep="repeat">OPTIONS</arg>
+      <arg choice="plain">calendar</arg>
+      <arg choice="plain" rep="repeat"><replaceable>SPECS</replaceable></arg>
+    </cmdsynopsis>
   </refsynopsisdiv>
 
   <refsect1>
@@ -220,6 +226,12 @@
     All units files present in the directories containing the command line arguments will
     be used in preference to the other paths.</para>
 
+    <para><command>systemd-analyze calendar</command> will parse and normalize repetitive calendar time events, and
+    will calculate when they will elapse next. This takes the same input as the <varname>OnCalendar=</varname> setting
+    in <citerefentry><refentrytitle>systemd.timer</refentrytitle><manvolnum>5</manvolnum></citerefentry>, following the
+    syntax described in
+    <citerefentry><refentrytitle>systemd.time</refentrytitle><manvolnum>7</manvolnum></citerefentry>.</para>
+
     <para>If no command is passed, <command>systemd-analyze
     time</command> is implied.</para>
 
diff --git a/man/systemd.time.xml b/man/systemd.time.xml
index a2fff2d101..6cb32f13b7 100644
--- a/man/systemd.time.xml
+++ b/man/systemd.time.xml
@@ -302,6 +302,10 @@ Wed..Sat,Tue 12-10-15 1:2:3 → Tue..Sat 2012-10-15 01:02:03
       <citerefentry><refentrytitle>systemd.timer</refentrytitle><manvolnum>5</manvolnum></citerefentry>
       for details.</para>
 
+      <para>Use the <command>calendar</command> command of
+      <citerefentry><refentrytitle>systemd-analyze</refentrytitle><manvolnum>1</manvolnum></citerefentry> to validate
+      and normalize calendar time specifications for testing purposes. The tool also calculates when a specified
+      calendar event would elapse next.</para>
   </refsect1>
 
   <refsect1>
@@ -311,7 +315,8 @@ Wed..Sat,Tue 12-10-15 1:2:3 → Tue..Sat 2012-10-15 01:02:03
         <citerefentry><refentrytitle>journalctl</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
         <citerefentry><refentrytitle>systemd.timer</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
         <citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
-        <citerefentry><refentrytitle>systemd.directives</refentrytitle><manvolnum>7</manvolnum></citerefentry>
+        <citerefentry><refentrytitle>systemd.directives</refentrytitle><manvolnum>7</manvolnum></citerefentry>,
+        <citerefentry><refentrytitle>systemd-analyze</refentrytitle><manvolnum>1</manvolnum></citerefentry>
       </para>
   </refsect1>
 
diff --git a/src/analyze/analyze.c b/src/analyze/analyze.c
index 913aa35016..5229b3a082 100644
--- a/src/analyze/analyze.c
+++ b/src/analyze/analyze.c
@@ -31,6 +31,7 @@
 #include "bus-error.h"
 #include "bus-unit-util.h"
 #include "bus-util.h"
+#include "calendarspec.h"
 #include "glob-util.h"
 #include "hashmap.h"
 #include "locale-util.h"
@@ -1395,6 +1396,70 @@ static int dump_syscall_filters(char** names) {
 }
 #endif
 
+static int test_calendar(char **args) {
+        int ret = 0, r;
+        char **p;
+        usec_t n;
+
+        if (strv_isempty(args)) {
+                log_error("Expected at least one calendar specification string as argument.");
+                return -EINVAL;
+        }
+
+        n = now(CLOCK_REALTIME);
+
+        STRV_FOREACH(p, args) {
+                _cleanup_(calendar_spec_freep) CalendarSpec *spec = NULL;
+                _cleanup_free_ char *t = NULL;
+                usec_t next;
+
+                r = calendar_spec_from_string(*p, &spec);
+                if (r < 0) {
+                        ret = log_error_errno(r, "Failed to parse calendar specification '%s': %m", *p);
+                        continue;
+                }
+
+                r = calendar_spec_normalize(spec);
+                if (r < 0) {
+                        ret = log_error_errno(r, "Failed to normalize calendar specification '%s': %m", *p);
+                        continue;
+                }
+
+                r = calendar_spec_to_string(spec, &t);
+                if (r < 0) {
+                        ret = log_error_errno(r, "Failed to fomat calendar specification '%s': %m", *p);
+                        continue;
+                }
+
+                if (!streq(t, *p))
+                        printf("  Original form: %s\n", *p);
+
+                printf("Normalized form: %s\n", t);
+
+                r = calendar_spec_next_usec(spec, n, &next);
+                if (r == -ENOENT)
+                        printf("    Next elapse: never\n");
+                else if (r < 0) {
+                        ret = log_error_errno(r, "Failed to determine next elapse for '%s': %m", *p);
+                        continue;
+                } else {
+                        char buffer[CONST_MAX(FORMAT_TIMESTAMP_MAX, FORMAT_TIMESTAMP_RELATIVE_MAX)];
+
+                        printf("    Next elapse: %s\n", format_timestamp(buffer, sizeof(buffer), next));
+
+                        if (!in_utc_timezone())
+                                printf("       (in UTC): %s\n", format_timestamp_utc(buffer, sizeof(buffer), next));
+
+                        printf("       From now: %s\n", format_timestamp_relative(buffer, sizeof(buffer), next));
+                }
+
+                if (*(p+1))
+                        putchar('\n');
+        }
+
+        return ret;
+}
+
 static void help(void) {
 
         pager_open(arg_no_pager, false);
@@ -1429,6 +1494,7 @@ static void help(void) {
                "  dump                     Output state serialization of service manager\n"
                "  syscall-filter [NAME...] Print list of syscalls in seccomp filter\n"
                "  verify FILE...           Check unit files for correctness\n"
+               "  calendar SPEC...         Validate repetitive calendar time events\n"
                , program_invocation_short_name);
 
         /* When updating this list, including descriptions, apply
@@ -1618,6 +1684,8 @@ int main(int argc, char *argv[]) {
                         r = get_log_target(bus, argv+optind+1);
                 else if (streq(argv[optind], "syscall-filter"))
                         r = dump_syscall_filters(argv+optind+1);
+                else if (streq(argv[optind], "calendar"))
+                        r = test_calendar(argv+optind+1);
                 else
                         log_error("Unknown operation '%s'.", argv[optind]);
         }
diff --git a/src/basic/calendarspec.h b/src/basic/calendarspec.h
index d2a19dd7dd..124f7f5880 100644
--- a/src/basic/calendarspec.h
+++ b/src/basic/calendarspec.h
@@ -61,3 +61,5 @@ int calendar_spec_to_string(const CalendarSpec *spec, char **p);
 int calendar_spec_from_string(const char *p, CalendarSpec **spec);
 
 int calendar_spec_next_usec(const CalendarSpec *spec, usec_t usec, usec_t *next);
+
+DEFINE_TRIVIAL_CLEANUP_FUNC(CalendarSpec*, calendar_spec_free);