init support for cgroups.

This adds the "writepid" option that instructs init to write the child's
pid to the given filenames (such as /dev/cpuctl/bg_non_interactive/cgroup.procs
and/or /dev/cpuset/foreground/cgroup.procs).

Bug: http://b/21163745
Change-Id: I121bb22aa208bc99c4fb334eb552fdd5bcc47c1a
(cherry picked from commit d62f0608d9d67bf647cf15debbd163e84584fe44)

5 files changed, 71 insertions, 40 deletions

diff --git a/init/init.cpp b/init/init.cpp
index 85d7909..93fe944 100644
--- a/init/init.cpp
+++ b/init/init.cpp
@@ -290,6 +290,16 @@ void service_start(struct service *svc, const char *dynamic_args)
         freecon(scon);
         scon = NULL;
 
+        if (svc->writepid_files_) {
+            std::string pid_str = android::base::StringPrintf("%d", pid);
+            for (auto& file : *svc->writepid_files_) {
+                if (!android::base::WriteStringToFile(pid_str, file)) {
+                    ERROR("couldn't write %s to %s: %s\n",
+                          pid_str.c_str(), file.c_str(), strerror(errno));
+                }
+            }
+        }
+
         if (svc->ioprio_class != IoSchedClass_NONE) {
             if (android_set_ioprio(getpid(), svc->ioprio_class, svc->ioprio_pri)) {
                 ERROR("Failed to set pid %d ioprio = %d,%d: %s\n",
diff --git a/init/init.h b/init/init.h
index 1cabb14..c166969 100644
--- a/init/init.h
+++ b/init/init.h
@@ -19,6 +19,9 @@
 
 #include <sys/types.h>
 
+#include <string>
+#include <vector>
+
 #include <cutils/list.h>
 #include <cutils/iosched_policy.h>
 
@@ -116,6 +119,8 @@ struct service {
 
     struct action onrestart;  /* Actions to execute on restart. */
 
+    std::vector<std::string>* writepid_files_;
+
     /* keycodes for triggering this service via /dev/keychord */
     int *keycodes;
     int nkeycodes;
diff --git a/init/init_parser.cpp b/init/init_parser.cpp
index 385b37b..666a86e 100644
--- a/init/init_parser.cpp
+++ b/init/init_parser.cpp
@@ -206,6 +206,7 @@ static int lookup_keyword(const char *s)
         break;
     case 'w':
         if (!strcmp(s, "rite")) return K_write;
+        if (!strcmp(s, "ritepid")) return K_writepid;
         if (!strcmp(s, "ait")) return K_wait;
         break;
     }
@@ -926,6 +927,16 @@ static void parse_line_service(struct parse_state *state, int nargs, char **args
             svc->seclabel = args[1];
         }
         break;
+    case K_writepid:
+        if (nargs < 2) {
+            parse_error(state, "writepid option requires at least one filename\n");
+            break;
+        }
+        svc->writepid_files_ = new std::vector<std::string>;
+        for (int i = 1; i < nargs; ++i) {
+            svc->writepid_files_->push_back(args[i]);
+        }
+        break;
 
     default:
         parse_error(state, "invalid option '%s'\n", args[0]);
diff --git a/init/keywords.h b/init/keywords.h
index 37f01b8..e637d7d 100644
--- a/init/keywords.h
+++ b/init/keywords.h
@@ -43,11 +43,15 @@ int do_wait(int nargs, char **args);
 enum {
     K_UNKNOWN,
 #endif
+    KEYWORD(bootchart_init,        COMMAND, 0, do_bootchart_init)
+    KEYWORD(chmod,       COMMAND, 2, do_chmod)
+    KEYWORD(chown,       COMMAND, 2, do_chown)
     KEYWORD(class,       OPTION,  0, 0)
+    KEYWORD(class_reset, COMMAND, 1, do_class_reset)
     KEYWORD(class_start, COMMAND, 1, do_class_start)
     KEYWORD(class_stop,  COMMAND, 1, do_class_stop)
-    KEYWORD(class_reset, COMMAND, 1, do_class_reset)
     KEYWORD(console,     OPTION,  0, 0)
+    KEYWORD(copy,        COMMAND, 2, do_copy)
     KEYWORD(critical,    OPTION,  0, 0)
     KEYWORD(disabled,    OPTION,  0, 0)
     KEYWORD(domainname,  COMMAND, 1, do_domainname)
@@ -57,16 +61,20 @@ enum {
     KEYWORD(group,       OPTION,  0, 0)
     KEYWORD(hostname,    COMMAND, 1, do_hostname)
     KEYWORD(ifup,        COMMAND, 1, do_ifup)
+    KEYWORD(import,      SECTION, 1, 0)
     KEYWORD(insmod,      COMMAND, 1, do_insmod)
     KEYWORD(installkey,  COMMAND, 1, do_installkey)
-    KEYWORD(import,      SECTION, 1, 0)
+    KEYWORD(ioprio,      OPTION,  0, 0)
     KEYWORD(keycodes,    OPTION,  0, 0)
+    KEYWORD(load_all_props,        COMMAND, 0, do_load_all_props)
+    KEYWORD(load_persist_props,    COMMAND, 0, do_load_persist_props)
+    KEYWORD(loglevel,    COMMAND, 1, do_loglevel)
     KEYWORD(mkdir,       COMMAND, 1, do_mkdir)
     KEYWORD(mount_all,   COMMAND, 1, do_mount_all)
     KEYWORD(mount,       COMMAND, 3, do_mount)
-    KEYWORD(on,          SECTION, 0, 0)
     KEYWORD(oneshot,     OPTION,  0, 0)
     KEYWORD(onrestart,   OPTION,  0, 0)
+    KEYWORD(on,          SECTION, 0, 0)
     KEYWORD(powerctl,    COMMAND, 1, do_powerctl)
     KEYWORD(restart,     COMMAND, 1, do_restart)
     KEYWORD(restorecon,  COMMAND, 1, do_restorecon)
@@ -82,22 +90,15 @@ enum {
     KEYWORD(start,       COMMAND, 1, do_start)
     KEYWORD(stop,        COMMAND, 1, do_stop)
     KEYWORD(swapon_all,  COMMAND, 1, do_swapon_all)
-    KEYWORD(trigger,     COMMAND, 1, do_trigger)
     KEYWORD(symlink,     COMMAND, 1, do_symlink)
     KEYWORD(sysclktz,    COMMAND, 1, do_sysclktz)
+    KEYWORD(trigger,     COMMAND, 1, do_trigger)
     KEYWORD(user,        OPTION,  0, 0)
     KEYWORD(verity_load_state,      COMMAND, 0, do_verity_load_state)
     KEYWORD(verity_update_state,    COMMAND, 0, do_verity_update_state)
     KEYWORD(wait,        COMMAND, 1, do_wait)
     KEYWORD(write,       COMMAND, 2, do_write)
-    KEYWORD(copy,        COMMAND, 2, do_copy)
-    KEYWORD(chown,       COMMAND, 2, do_chown)
-    KEYWORD(chmod,       COMMAND, 2, do_chmod)
-    KEYWORD(loglevel,    COMMAND, 1, do_loglevel)
-    KEYWORD(load_persist_props,    COMMAND, 0, do_load_persist_props)
-    KEYWORD(load_all_props,        COMMAND, 0, do_load_all_props)
-    KEYWORD(ioprio,      OPTION,  0, 0)
-    KEYWORD(bootchart_init,        COMMAND, 0, do_bootchart_init)
+    KEYWORD(writepid,    OPTION,  0, 0)
 #ifdef __MAKE_KEYWORD_ENUM__
     KEYWORD_COUNT,
 };
diff --git a/init/readme.txt b/init/readme.txt
index c213041..9e3394e 100644
--- a/init/readme.txt
+++ b/init/readme.txt
@@ -60,36 +60,36 @@ Options are modifiers to services.  They affect how and when init
 runs the service.
 
 critical
-   This is a device-critical service. If it exits more than four times in
-   four minutes, the device will reboot into recovery mode.
+  This is a device-critical service. If it exits more than four times in
+  four minutes, the device will reboot into recovery mode.
 
 disabled
-   This service will not automatically start with its class.
-   It must be explicitly started by name.
+  This service will not automatically start with its class.
+  It must be explicitly started by name.
 
 setenv <name> <value>
-   Set the environment variable <name> to <value> in the launched process.
+  Set the environment variable <name> to <value> in the launched process.
 
 socket <name> <type> <perm> [ <user> [ <group> [ <seclabel> ] ] ]
-   Create a unix domain socket named /dev/socket/<name> and pass
-   its fd to the launched process.  <type> must be "dgram", "stream" or "seqpacket".
-   User and group default to 0.
-   'seclabel' is the SELinux security context for the socket.
-   It defaults to the service security context, as specified by seclabel or
-   computed based on the service executable file security context.
+  Create a unix domain socket named /dev/socket/<name> and pass
+  its fd to the launched process.  <type> must be "dgram", "stream" or "seqpacket".
+  User and group default to 0.
+  'seclabel' is the SELinux security context for the socket.
+  It defaults to the service security context, as specified by seclabel or
+  computed based on the service executable file security context.
 
 user <username>
-   Change to username before exec'ing this service.
-   Currently defaults to root.  (??? probably should default to nobody)
-   Currently, if your process requires linux capabilities then you cannot use
-   this command. You must instead request the capabilities in-process while
-   still root, and then drop to your desired uid.
+  Change to username before exec'ing this service.
+  Currently defaults to root.  (??? probably should default to nobody)
+  Currently, if your process requires linux capabilities then you cannot use
+  this command. You must instead request the capabilities in-process while
+  still root, and then drop to your desired uid.
 
 group <groupname> [ <groupname> ]*
-   Change to groupname before exec'ing this service.  Additional
-   groupnames beyond the (required) first one are used to set the
-   supplemental groups of the process (via setgroups()).
-   Currently defaults to root.  (??? probably should default to nobody)
+  Change to groupname before exec'ing this service.  Additional
+  groupnames beyond the (required) first one are used to set the
+  supplemental groups of the process (via setgroups()).
+  Currently defaults to root.  (??? probably should default to nobody)
 
 seclabel <seclabel>
   Change to 'seclabel' before exec'ing this service.
@@ -99,22 +99,26 @@ seclabel <seclabel>
   If not specified and no transition is defined in policy, defaults to the init context.
 
 oneshot
-   Do not restart the service when it exits.
+  Do not restart the service when it exits.
 
 class <name>
-   Specify a class name for the service.  All services in a
-   named class may be started or stopped together.  A service
-   is in the class "default" if one is not specified via the
-   class option.
+  Specify a class name for the service.  All services in a
+  named class may be started or stopped together.  A service
+  is in the class "default" if one is not specified via the
+  class option.
 
 onrestart
-    Execute a Command (see below) when service restarts.
+  Execute a Command (see below) when service restarts.
+
+writepid <file...>
+  Write the child's pid to the given files when it forks. Meant for
+  cgroup/cpuset usage.
 
 
 Triggers
 --------
-   Triggers are strings which can be used to match certain kinds
-   of events and used to cause an action to occur.
+Triggers are strings which can be used to match certain kinds
+of events and used to cause an action to occur.
 
 boot
    This is the first trigger that will occur when init starts