adb: fix subprocess exit handling, oom adjust fixes, extra debugging.

* Add support for correctly handling subprocess termination in shell service  (b/3400254 b/3482112 b/2249397)
 - have a waitpid() track the subprocess, then notify the fdevent via a socket
 - force an eof on the pty master in fdevent's new subproc handler.
 - modify fdevent to force-read the pty after an exit.
* Migrate the "shell:blabla" handling to "#if !ADB_HOST" sections, where it
 belongs.
* Fix the race around OOM adjusting.
  - Do it in the child before exec() instead of the in the parent as the
   child could already have started or not (no /proc/pid/... yet).
* Allow for multi-threaded D() invocations to not clobber each other.
  - Allow locks across object files.
  - Add lock within D()
  - Make sure sysdesp init (mutex init also) is called early.
* Add some missing close(fd) calls
  - Match similar existing practices near dup2()
* Add extra D() invocations related to FD handling.
* Warn about using debugging as stderr/stdout is used for protocol.
* Fix some errno handling and make D() correctly handle it.
* Add new adb trace_mask: services.
* Make fdevent_loop's handle BADFDs more gracefully (could occur some subproc closed its pts explicitely).
* Remove obsolete commandline args reported in help. (b/3509092)


Change-Id: I928287fdf4f1a86777e22ce105f9581685f46e35
diff --git a/adb/adb.c b/adb/adb.c
index f5e6e0c..b0a70dc 100644
--- a/adb/adb.c
+++ b/adb/adb.c
@@ -36,6 +36,9 @@
 #include "usb_vendors.h"
 #endif
 
+#if ADB_TRACE
+ADB_MUTEX_DEFINE( D_lock );
+#endif
 
 int HOST = 0;
 
@@ -90,6 +93,7 @@
         { "sysdeps", TRACE_SYSDEPS },
         { "transport", TRACE_TRANSPORT },
         { "jdwp", TRACE_JDWP },
+        { "services", TRACE_SERVICES },
         { NULL, 0 }
     };
 
@@ -591,14 +595,6 @@
     return 0;
 }
 
-#ifdef HAVE_FORKEXEC
-static void sigchld_handler(int n)
-{
-    int status;
-    while(waitpid(-1, &status, WNOHANG) > 0) ;
-}
-#endif
-
 #ifdef HAVE_WIN32_PROC
 static BOOL WINAPI ctrlc_handler(DWORD type)
 {
@@ -641,6 +637,7 @@
 
     fd = unix_open("/dev/null", O_RDONLY);
     dup2(fd, 0);
+    adb_close(fd);
 
     fd = unix_open("/tmp/adb.log", O_WRONLY | O_CREAT | O_APPEND, 0640);
     if(fd < 0) {
@@ -648,6 +645,7 @@
     }
     dup2(fd, 1);
     dup2(fd, 2);
+    adb_close(fd);
     fprintf(stderr,"--- adb starting (pid %d) ---\n", getpid());
 #endif
 }
@@ -807,9 +805,10 @@
         // wait for the "OK\n" message
         adb_close(fd[1]);
         int ret = adb_read(fd[0], temp, 3);
+        int saved_errno = errno;
         adb_close(fd[0]);
         if (ret < 0) {
-            fprintf(stderr, "could not read ok from ADB Server, errno = %d\n", errno);
+            fprintf(stderr, "could not read ok from ADB Server, errno = %d\n", saved_errno);
             return -1;
         }
         if (ret != 3 || temp[0] != 'O' || temp[1] != 'K' || temp[2] != '\n') {
@@ -848,7 +847,7 @@
 #ifdef HAVE_WIN32_PROC
     SetConsoleCtrlHandler( ctrlc_handler, TRUE );
 #elif defined(HAVE_FORKEXEC)
-    signal(SIGCHLD, sigchld_handler);
+    // No SIGCHLD. Let the service subproc handle its children.
     signal(SIGPIPE, SIG_IGN);
 #endif
 
@@ -957,7 +956,9 @@
         // listen on default port
         local_init(DEFAULT_ADB_LOCAL_TRANSPORT_PORT);
     }
+    D("adb_main(): pre init_jdwp()\n");
     init_jdwp();
+    D("adb_main(): post init_jdwp()\n");
 #endif
 
     if (is_daemon)
@@ -971,6 +972,7 @@
 #endif
         start_logging();
     }
+    D("Event loop starting\n");
 
     fdevent_loop();
 
@@ -1269,8 +1271,9 @@
 int main(int argc, char **argv)
 {
 #if ADB_HOST
-    adb_trace_init();
     adb_sysdeps_init();
+    adb_trace_init();
+    D("Handling commandline()\n");
     return adb_commandline(argc - 1, argv + 1);
 #else
     if((argc > 1) && (!strcmp(argv[1],"recovery"))) {
@@ -1279,6 +1282,7 @@
     }
 
     start_device_log();
+    D("Handling main()\n");
     return adb_main(0, DEFAULT_ADB_PORT);
 #endif
 }