Fix #109: Support PID files in subdirectories to /var/run

Services, like dbus and teamd for instance, may create their PID files
in a subdirectory of /var/run (today often /run). E.g.,

   - /var/run/teamd/a1.pid    -- For aggregate A1
   - /var/run/dbus/pid
   - /var/run/lxc/foo.pid     -- For container foo

This patch adds support for dynamically adding inotify watchers to any
new subdirectory created in /var/run (discarding too deep directories).

To match services in this directory the run/task/service/sysv stanza
must contain the pid:!/path/to/pidfile.pid syntax.  This pid file name
is also used to create the condition this service asserts using the
following formula:

   svc/ + <dirname of service> + <subdir and file without .pid>

E.g., the case of teamd (above) gives condition 'svc/usr/bin/teamd/a1'

The special case of dbus is interesting, since it may not be a special
case, but rather the norm for services using a subdirectory.  It is
handled as follows; when a new subdirectory is detected, the directory
is scanned for files matching *.pid.  Matching files follow the teamd
case.  The directory is also scanned for 'pid', which then gives us the
condition 'svc/usr/bin/dbus'

One last example, illustrated by lxc-start, where we want to track the
condition for the LXC container foo.  The service stanza:

   service pid:!/run/lxc/foo.pid lxc-start -n foo -F -p /run/lxc/foo.pid -- Container foo

This command has no leading path so the condition is composed entirely
from the PID file location:

   svc/  + '' + lxc/foo => svc/lxc/foo

Signed-off-by: Joachim Nilsson <troglobit@gmail.com>

src/cond.h

@@ -2,6 +2,7 @@
 #define FINIT_COND_H_
 
 #include <paths.h>
+#include <svc.h>
 
 #define COND_DIR      "finit/cond"
 #define COND_PATH     _PATH_VARRUN COND_DIR
@@ -13,7 +14,7 @@ typedef enum cond_state {
 	COND_ON
 } cond_state_t;
 
-char           *mkcond       (char *buf, size_t len, char *nm);
+char           *mkcond       (svc_t *svc, char *buf, size_t len);
 const char     *condstr      (enum cond_state s);
 const char     *cond_path    (const char *name);
 unsigned int    cond_get_gen (const char *path);