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initctl: restore 'cond [set|clr] foo' for user-defined conditions

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In 7447192 we dropped support for 'cond set' and 'cond clear' commands
with the motivation they were unsafe and sent the wrong message to the
user.  That was true, but mostly because it was too generic and required
the user to call `initctl reload` to apply the changes.

This patch restores the behavior, albeit in a very reduced and simple
format.  All conditions set with this command are constrained to the
'usr/...' namespace.  No subdirectories are allowed.  The argument to
the 'cond set|clear' command is disallowed if it contains '/' or '.'
but anything else is supported, for example:

    initctl cond set foo:2

creates a static/oneshot condition in /run/finit/cond/usr/foo:2

These conditions are static and are fully handled by the user.  The
initctl command is the recommended, and only supported, way of setting
and clearing usr conditions.

This patch also includes a new plugin, usr.so, which is a very simple
inotify plugin for the /run/finit/cond/usr/ directory.  When files are
created or removed here the plugin tells the Finit condition engine to
update and trigger service changes.

For instance, the following service is not started by default at boot:

    service <usr/foo> myservice -- MyService

However, as soon as `initctl cond set foo` is called, myservice starts.
Consequently, it is stopped when `initctl cond clr foo` is called.

Another major difference from the original is that this implementation
doesn't send IPC commands to create/delete the conditions.  This makes
calling these new commands non-blocking so they can be used very early
in the bootstrap, by plugins, if needed.

Signed-off-by: Joachim Wiberg <troglobit@gmail.com>
This commit is contained in:
Joachim Wiberg
2021-03-11 11:44:23 +01:00
parent e3c8febe3b
commit 8000d361b3
6 changed files with 183 additions and 4 deletions
Download Patch File Download Diff File Expand all files Collapse all files
plugins/Makefile.am
+2 -2
View File
@@ -7,7 +7,7 @@ AM_CPPFLAGS += $(lite_CFLAGS)
if STATIC
noinst_LTLIBRARIES = libplug.la
libplug_la_SOURCES = bootmisc.c modprobe.c rtc.c pidfile.c procps.c tty.c urandom.c
libplug_la_SOURCES = bootmisc.c modprobe.c rtc.c pidfile.c procps.c tty.c urandom.c usr.c
if BUILD_ALSA_UTILS_PLUGIN
libplug_la_SOURCES += alsa-utils.c
@@ -34,7 +34,7 @@ libplug_la_SOURCES += resolvconf.c
endif
else
pkglib_LTLIBRARIES = bootmisc.la modprobe.la rtc.la pidfile.la procps.la tty.la urandom.la
pkglib_LTLIBRARIES = bootmisc.la modprobe.la rtc.la pidfile.la procps.la tty.la urandom.la usr.la
if BUILD_ALSA_UTILS_PLUGIN
pkglib_LTLIBRARIES += alsa-utils.la
plugins/pidfile.c
+1
View File
@@ -242,6 +242,7 @@ static void pidfile_init(void *arg)
*/
path = realpath(_PATH_VARRUN, NULL);
if (!path) {
_d("Failed querying realpath(%s): %s", _PATH_VARRUN, strerror(errno));
path = realpath("/run", NULL);
if (!path) {
_e("System does not have %s or /run, aborting.", _PATH_VARRUN);
plugins/usr.c
+133
View File
@@ -0,0 +1,133 @@
/* User-defined condtion event monitor for the Finit condition engine
*
* Copyright (c) 2021 Joachim Wiberg <troglobit@gmail.com>
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to deal
* in the Software without restriction, including without limitation the rights
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in
* all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
* THE SOFTWARE.
*/
#include <fnmatch.h>
#include <glob.h>
#include <limits.h>
#include <paths.h>
#include "finit.h"
#include "cond.h"
#include "pid.h"
#include "plugin.h"
#include "iwatch.h"
static struct iwatch iw_usr;
static void usr_cond(char *name, uint32_t mask)
{
char cond[MAX_COND_LEN] = COND_USR;
strlcat(cond, name, sizeof(cond));
cond_update(cond);
}
static void usr_callback(void *arg, int fd, int events)
{
static char ev_buf[8 *(sizeof(struct inotify_event) + NAME_MAX + 1) + 1];
struct inotify_event *ev;
ssize_t sz;
size_t off;
sz = read(fd, ev_buf, sizeof(ev_buf) - 1);
if (sz <= 0) {
_pe("invalid inotify event");
return;
}
ev_buf[sz] = 0;
for (off = 0; off < (size_t)sz; off += sizeof(*ev) + ev->len) {
if (off + sizeof(*ev) > (size_t)sz)
break;
ev = (struct inotify_event *)&ev_buf[off];
if (off + sizeof(*ev) + ev->len > (size_t)sz)
break;
_d("name %s, event: 0x%08x", ev->name, ev->mask);
if (!ev->mask)
continue;
if (ev->mask & IN_ISDIR)
continue; /* unsupported */
if (ev->mask & IN_DELETE)
sync(); /* dont ask */
usr_cond(ev->name, ev->mask);
}
}
static void usr_init(void *arg)
{
char usrdir[MAX_ARG_LEN];
char *path;
if (mkpath(pid_runpath(_PATH_CONDUSR, usrdir, sizeof(usrdir)), 0755) && errno != EEXIST) {
_pe("Failed creating %s condition directory, %s", COND_USR, _PATH_CONDUSR);
return;
}
path = realpath(_PATH_CONDUSR, NULL);
if (!path) {
_pe("Cannot figure out real path to %s, aborting", _PATH_CONDUSR);
return;
}
if (iwatch_add(&iw_usr, path, IN_ONLYDIR))
iwatch_exit(&iw_usr);
}
static plugin_t plugin = {
.name = __FILE__,
.hook[HOOK_BASEFS_UP] = { .cb = usr_init },
};
PLUGIN_INIT(plugin_init)
{
int fd;
fd = iwatch_init(&iw_usr);
if (fd < 0)
return;
plugin.io.fd = fd;
plugin.io.cb = usr_callback;
plugin.io.flags = PLUGIN_IO_READ;
plugin_register(&plugin);
}
PLUGIN_EXIT(plugin_exit)
{
iwatch_exit(&iw_usr);
plugin_unregister(&plugin);
}
/**
* Local Variables:
* indent-tabs-mode: t
* c-file-style: "linux"
* End:
*/
src/cond-w.c
+2 -1
View File
@@ -162,7 +162,8 @@ int cond_set_path(const char *path, enum cond_state new)
return new != old;
}
static void cond_update(const char *name)
/* Should only be used by cond_set*(), cond_clear(), and usr plugin! */
void cond_update(const char *name)
{
svc_t *svc, *iter = NULL;
src/cond.h
+1
View File
@@ -26,6 +26,7 @@ enum cond_state cond_get (const char *name);
enum cond_state cond_get_agg (const char *names);
int cond_affects (const char *name, const char *names);
void cond_update (const char *name);
int cond_set_path (const char *path, enum cond_state new);
void cond_set (const char *name);
void cond_set_oneshot (const char *name);
src/initctl.c
+44 -1
View File
@@ -270,6 +270,12 @@ static int dump_one_cond(const char *fpath, const struct stat *sb, int tflag, st
nm = svc_ident(svc, NULL, 0);
pid = svc->pid;
}
} else if (strncmp("usr/", cond, 4) == 0) {
nm = "static";
pid = 0;
} else if (strncmp("hook/", cond, 4) == 0) {
nm = "static";
pid = 1;
}
printf("%-*d %-*s %-6s %s\n", pw, pid, iw, nm, asserted, cond);
@@ -296,6 +302,38 @@ static int do_cond_dump(char *arg)
return 0;
}
static int do_cond_act(char *arg, int creat)
{
char oneshot[256];
size_t off;
if (arg && strncmp(arg, COND_USR, strlen(COND_USR)) == 0)
arg += strlen(COND_USR);
if (!arg || !arg[0])
errx(1, "Invalid condition (empty)");
if (strchr(arg, '/'))
errx(1, "Invalid condition (slashes)");
if (strchr(arg, '.'))
errx(1, "Invalid condition (periods)");
snprintf(oneshot, sizeof(oneshot), _PATH_CONDUSR "%s", arg);
off = strlen(_PATH_COND);
if (creat) {
if (symlink(_PATH_RECONF, oneshot) && errno != EEXIST)
err(1, "Failed asserting condition <%s>", &oneshot[off]);
} else {
if (erase(oneshot))
err(1, "Failed deasserting condition <%s>", &oneshot[off]);
}
return 0;
}
static int do_cond_set(char *arg) { return do_cond_act(arg, 1); }
static int do_cond_clr(char *arg) { return do_cond_act(arg, 0); }
static void show_cond_one(const char *_conds)
{
static char conds[MAX_COND_LEN];
@@ -765,7 +803,9 @@ static int usage(int rc)
fprintf(stderr,
// " reload <NAME>[:ID] Reload (SIGHUP) service by name\n"
"\n"
" cond show Show condition status\n"
" cond set <COND> Set (assert) user-defined condition +usr/COND\n"
" cond clear <COND> Clear (deassert) user-defined condition -usr/COND\n"
" cond status Show condition status, default cond command\n"
" cond dump Dump all conditions and their status\n"
"\n"
" log [NAME] Show ten last Finit, or NAME, messages from syslog\n"
@@ -850,6 +890,9 @@ int main(int argc, char *argv[])
struct cmd cond[] = {
{ "status", NULL, do_cond_show }, /* default cmd */
{ "dump", NULL, do_cond_dump },
{ "set", NULL, do_cond_set },
{ "clr", NULL, do_cond_clr },
{ "clear", NULL, do_cond_clr },
{ NULL, NULL, NULL }
};
struct cmd command[] = {