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portablectl: block when stopping a unit on detach (--now)

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If portablectl detach --now is used, there's a possible race condition
where the unit is not stopped in time before the detach is attempted,
which causes it to fail.
Add a DBUS call to block after starting/stopping if --now is passed,
and add a --no-block parameter to skip it optionally when starting,
since it is not necessary in that case for correct functioning.
This commit is contained in:
Luca Boccassi 2020-02-12 17:27:43 +00:00
parent d4ffda3871
commit 31c33315b3
2 changed files with 52 additions and 6 deletions
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13
man/portablectl.xml
View File

@ -135,7 +135,8 @@
the service manager are seen by it.</para>
<para>If <option>--now</option> and/or <option>--enable</option> are passed, the portable service(s) are
immediately started and/or enabled after attaching the image.</para>
immediately started (blocking operation unless <option>--no-block</option> is passed) and/or enabled after
attaching the image.</para>
</listitem>
</varlistentry>
@ -150,8 +151,8 @@
<command>detach</command>.</para></listitem>
<para>If <option>--now</option> and/or <option>--enable</option> are passed, the portable service(s) are
immediately started and/or enabled before detaching the image. Prefix(es) are also accepted, to be used in
case the unit names do not match the image name as described in the <command>attach</command>.</para>
immediately stopped (blocking operation) and/or disabled before detaching the image. Prefix(es) are also accepted,
to be used in case the unit names do not match the image name as described in the <command>attach</command>.</para>
</varlistentry>
<varlistentry>
@ -330,6 +331,12 @@
<listitem><para>Immediately start/stop the portable service after attaching/before detaching.</para></listitem>
</varlistentry>
<varlistentry>
<term><option>--no-block</option></term>
<listitem><para>Don't block waiting for attach --now to complete.</para></listitem>
</varlistentry>
<xi:include href="user-system-options.xml" xpointer="host" />
<xi:include href="user-system-options.xml" xpointer="machine" />

45
src/portable/portablectl.c
View File

@ -9,6 +9,7 @@
#include "bus-error.h"
#include "bus-unit-util.h"
#include "bus-util.h"
#include "bus-wait-for-jobs.h"
#include "def.h"
#include "dirent-util.h"
#include "env-file.h"
@ -42,6 +43,7 @@ static BusTransport arg_transport = BUS_TRANSPORT_LOCAL;
static const char *arg_host = NULL;
static bool arg_enable = false;
static bool arg_now = false;
static bool arg_no_block = false;
static int determine_image(const char *image, bool permit_non_existing, char **ret) {
int r;
@ -445,7 +447,7 @@ static int maybe_enable_disable(sd_bus *bus, const char *path, bool enable) {
return 0;
}
static int maybe_start_stop(sd_bus *bus, const char *path, bool start) {
static int maybe_start_stop(sd_bus *bus, const char *path, bool start, BusWaitForJobs *wait) {
_cleanup_(sd_bus_message_unrefp) sd_bus_message *reply = NULL;
_cleanup_(sd_bus_error_free) sd_bus_error error = SD_BUS_ERROR_NULL;
char *name = (char *)basename(path), *job = NULL;
@ -476,15 +478,29 @@ static int maybe_start_stop(sd_bus *bus, const char *path, bool start) {
if (!arg_quiet)
log_info("Queued %s to %s portable service %s.", job, start ? "start" : "stop", name);
if (wait) {
r = bus_wait_for_jobs_add(wait, job);
if (r < 0)
return log_error_errno(r, "Failed to watch %s job for %s %s: %m",
job, start ? "starting" : "stopping", name);
}
return 0;
}
static int maybe_enable_start(sd_bus *bus, sd_bus_message *reply) {
_cleanup_(bus_wait_for_jobs_freep) BusWaitForJobs *wait = NULL;
int r;
if (!arg_enable && !arg_now)
return 0;
if (!arg_no_block) {
r = bus_wait_for_jobs_new(bus, &wait);
if (r < 0)
return log_error_errno(r, "Could not watch jobs: %m");
}
r = sd_bus_message_rewind(reply, true);
if (r < 0)
return r;
@ -503,7 +519,7 @@ static int maybe_enable_start(sd_bus *bus, sd_bus_message *reply) {
if (STR_IN_SET(type, "symlink", "copy") && ENDSWITH_SET(path, ".service", ".target", ".socket")) {
(void) maybe_enable_disable(bus, path, true);
(void) maybe_start_stop(bus, path, true);
(void) maybe_start_stop(bus, path, true, wait);
}
}
@ -511,10 +527,17 @@ static int maybe_enable_start(sd_bus *bus, sd_bus_message *reply) {
if (r < 0)
return r;
if (!arg_no_block) {
r = bus_wait_for_jobs(wait, arg_quiet, NULL);
if (r < 0)
return r;
}
return 0;
}
static int maybe_stop_disable(sd_bus *bus, char *image, char *argv[]) {
_cleanup_(bus_wait_for_jobs_freep) BusWaitForJobs *wait = NULL;
_cleanup_(sd_bus_message_unrefp) sd_bus_message *m = NULL, *reply = NULL;
_cleanup_(sd_bus_error_free) sd_bus_error error = SD_BUS_ERROR_NULL;
_cleanup_strv_free_ char **matches = NULL;
@ -527,6 +550,10 @@ static int maybe_stop_disable(sd_bus *bus, char *image, char *argv[]) {
if (r < 0)
return r;
r = bus_wait_for_jobs_new(bus, &wait);
if (r < 0)
return log_error_errno(r, "Could not watch jobs: %m");
r = sd_bus_message_new_method_call(
bus,
&m,
@ -578,7 +605,7 @@ static int maybe_stop_disable(sd_bus *bus, char *image, char *argv[]) {
if (r < 0)
return bus_log_parse_error(r);
(void) maybe_start_stop(bus, name, false);
(void) maybe_start_stop(bus, name, false, wait);
(void) maybe_enable_disable(bus, name, false);
}
@ -586,6 +613,11 @@ static int maybe_stop_disable(sd_bus *bus, char *image, char *argv[]) {
if (r < 0)
return bus_log_parse_error(r);
/* Stopping must always block or the detach will fail if the unit is still running */
r = bus_wait_for_jobs(wait, arg_quiet, NULL);
if (r < 0)
return r;
return 0;
}
@ -997,6 +1029,7 @@ static int help(int argc, char *argv[], void *userdata) {
" after attach/detach\n"
" --now Immediately start/stop the portable service after\n"
" attach/before detach\n"
" --no-block Don't block waiting for attach --now to complete\n"
"\nSee the %s for details.\n"
, program_invocation_short_name
, ansi_highlight()
@ -1020,6 +1053,7 @@ static int parse_argv(int argc, char *argv[]) {
ARG_CAT,
ARG_ENABLE,
ARG_NOW,
ARG_NO_BLOCK,
};
static const struct option options[] = {
@ -1038,6 +1072,7 @@ static int parse_argv(int argc, char *argv[]) {
{ "cat", no_argument, NULL, ARG_CAT },
{ "enable", no_argument, NULL, ARG_ENABLE },
{ "now", no_argument, NULL, ARG_NOW },
{ "no-block", no_argument, NULL, ARG_NO_BLOCK },
{}
};
@ -1132,6 +1167,10 @@ static int parse_argv(int argc, char *argv[]) {
arg_now = true;
break;
case ARG_NO_BLOCK:
arg_no_block = true;
break;
case '?':
return -EINVAL;