init: Add gentle_kill service property

If a service specifies gentle_kill, attempt to stop it will send SIGTERM
instead of SIGKILL. After 200ms, it will issue a SIGKILL.

Bug: 249043036
Test: atest CtsInitTestCases:init#GentleKill
      Added in next patch
Change-Id: Ieb0e4e24d31780aca1cf291f9d21d49cee181cf2

init/README.md

@@ -244,6 +244,10 @@ runs the service.
   "r", "w" or "rw".  For native executables see libcutils
   android\_get\_control\_file().
 
+`gentle_kill`
+> This service will be sent SIGTERM instead of SIGKILL when stopped. After a 200 ms timeout, it will
+  be sent SIGKILL.
+
 `group <groupname> [ <groupname>\* ]`
 > Change to 'groupname' before exec'ing this service.  Additional
   groupnames beyond the (required) first one are used to set the

init/service.cpp

@@ -26,6 +26,7 @@
 #include <sys/time.h>
 #include <termios.h>
 #include <unistd.h>
+#include <thread>
 
 #include <android-base/file.h>
 #include <android-base/logging.h>
@@ -887,6 +888,10 @@ void Service::StopOrReset(int how) {
     }
 
     if (pid_) {
+        if (flags_ & SVC_GENTLE_KILL) {
+            KillProcessGroup(SIGTERM);
+            if (!process_cgroup_empty()) std::this_thread::sleep_for(200ms);
+        }
         KillProcessGroup(SIGKILL);
         NotifyStateChange("stopping");
     } else {

init/service.h

@@ -56,6 +56,8 @@
                                      // should not be killed during shutdown
 #define SVC_TEMPORARY 0x1000  // This service was started by 'exec' and should be removed from the
                               // service list once it is reaped.
+#define SVC_GENTLE_KILL 0x2000  // This service should be stopped with SIGTERM instead of SIGKILL
+                                // Will still be SIGKILLed after timeout period of 200 ms
 
 #define NR_SVC_SUPP_GIDS 12    // twelve supplementary groups
 

init/service_parser.cpp

@@ -151,6 +151,11 @@ Result<void> ServiceParser::ParseEnterNamespace(std::vector<std::string>&& args)
     return {};
 }
 
+Result<void> ServiceParser::ParseGentleKill(std::vector<std::string>&& args) {
+    service_->flags_ |= SVC_GENTLE_KILL;
+    return {};
+}
+
 Result<void> ServiceParser::ParseGroup(std::vector<std::string>&& args) {
     auto gid = DecodeUid(args[1]);
     if (!gid.ok()) {
@@ -584,6 +589,7 @@ const KeywordMap<ServiceParser::OptionParser>& ServiceParser::GetParserMap() con
         {"disabled",                {0,     0,    &ServiceParser::ParseDisabled}},
         {"enter_namespace",         {2,     2,    &ServiceParser::ParseEnterNamespace}},
         {"file",                    {2,     2,    &ServiceParser::ParseFile}},
+        {"gentle_kill",             {0,     0,    &ServiceParser::ParseGentleKill}},
         {"group",                   {1,     NR_SVC_SUPP_GIDS + 1, &ServiceParser::ParseGroup}},
         {"interface",               {2,     2,    &ServiceParser::ParseInterface}},
         {"ioprio",                  {2,     2,    &ServiceParser::ParseIoprio}},

init/service_parser.h

@@ -53,6 +53,7 @@ class ServiceParser : public SectionParser {
     Result<void> ParseDisabled(std::vector<std::string>&& args);
     Result<void> ParseEnterNamespace(std::vector<std::string>&& args);
     Result<void> ParseGroup(std::vector<std::string>&& args);
+    Result<void> ParseGentleKill(std::vector<std::string>&& args);
     Result<void> ParsePriority(std::vector<std::string>&& args);
     Result<void> ParseInterface(std::vector<std::string>&& args);
     Result<void> ParseIoprio(std::vector<std::string>&& args);