From a23fcd7be8e40078a913b1a99222cdd89229e67b Mon Sep 17 00:00:00 2001
From: Narayan Kamath <narayan@google.com>
Date: Fri, 28 Mar 2014 13:39:21 +0000
Subject: [PATCH] Remove ProcessState::mArgc,mArgV,mArgLen

These look like historical oddities, and weren't really being
used for anything useful.

Process:setArgV0 was being called by android.util.Process, but
that functionality can be moved directly into the implementation
of that class.

bug: 13647418

Change-Id: I216c8f8a4c065f0cf3a61f19f9e32decd26f93f6
---
 cmds/app_process/app_main.cpp            | 46 ++++++++++++------------
 core/jni/AndroidRuntime.cpp              | 11 ++++--
 core/jni/android_util_Process.cpp        |  6 ++--
 include/android_runtime/AndroidRuntime.h |  6 +++-
 4 files changed, 41 insertions(+), 28 deletions(-)

diff --git a/cmds/app_process/app_main.cpp b/cmds/app_process/app_main.cpp
index 8d2b739fc3011..bdbb08c949670 100644
--- a/cmds/app_process/app_main.cpp
+++ b/cmds/app_process/app_main.cpp
@@ -30,8 +30,9 @@ void app_usage()
 class AppRuntime : public AndroidRuntime
 {
 public:
-    AppRuntime()
-        : mParentDir(NULL)
+    AppRuntime(char* argBlockStart, const size_t argBlockLength)
+        : AndroidRuntime(argBlockStart, argBlockLength)
+        , mParentDir(NULL)
         , mClassName(NULL)
         , mClass(NULL)
         , mArgC(0)
@@ -125,29 +126,30 @@ public:
 
 using namespace android;
 
-/*
- * sets argv0 to as much of newArgv0 as will fit
- */
-static void setArgv0(const char *argv0, const char *newArgv0)
-{
-    strlcpy(const_cast<char *>(argv0), newArgv0, strlen(argv0));
+static size_t computeArgBlockSize(int argc, char* const argv[]) {
+    // TODO: This assumes that all arguments are allocated in
+    // contiguous memory. There isn't any documented guarantee
+    // that this is the case, but this is how the kernel does it
+    // (see fs/exec.c).
+    //
+    // Also note that this is a constant for "normal" android apps.
+    // Since they're forked from zygote, the size of their command line
+    // is the size of the zygote command line.
+    //
+    // We change the process name of the process by over-writing
+    // the start of the argument block (argv[0]) with the new name of
+    // the process, so we'd mysteriously start getting truncated process
+    // names if the zygote command line decreases in size.
+    uintptr_t start = reinterpret_cast<uintptr_t>(argv[0]);
+    uintptr_t end = reinterpret_cast<uintptr_t>(argv[argc - 1]);
+    end += strlen(argv[argc - 1]);
+
+    return (end - start);
 }
 
 int main(int argc, char* const argv[])
 {
-    // These are global variables in ProcessState.cpp
-    mArgC = argc;
-    mArgV = argv;
-
-    mArgLen = 0;
-    for (int i=0; i<argc; i++) {
-        mArgLen += strlen(argv[i]) + 1;
-    }
-    mArgLen--;
-
-    AppRuntime runtime;
-    const char* argv0 = argv[0];
-
+    AppRuntime runtime(argv[0], computeArgBlockSize(argc, argv));
     // Process command line arguments
     // ignore argv[0]
     argc--;
@@ -184,7 +186,7 @@ int main(int argc, char* const argv[])
     }
 
     if (niceName && *niceName) {
-        setArgv0(argv0, niceName);
+        runtime.setArgv0(niceName);
         set_process_name(niceName);
     }
 
diff --git a/core/jni/AndroidRuntime.cpp b/core/jni/AndroidRuntime.cpp
index 5dc0c52ff5b7e..cce4e0d0a0cef 100644
--- a/core/jni/AndroidRuntime.cpp
+++ b/core/jni/AndroidRuntime.cpp
@@ -228,9 +228,10 @@ int register_com_android_internal_os_RuntimeInit(JNIEnv* env)
 
 /*static*/ JavaVM* AndroidRuntime::mJavaVM = NULL;
 
-
-AndroidRuntime::AndroidRuntime() :
-        mExitWithoutCleanup(false)
+AndroidRuntime::AndroidRuntime(char* argBlockStart, const size_t argBlockLength) :
+        mExitWithoutCleanup(false),
+        mArgBlockStart(argBlockStart),
+        mArgBlockLength(argBlockLength)
 {
     SkGraphics::Init();
     // this sets our preference for 16bit images during decode
@@ -265,6 +266,10 @@ AndroidRuntime::~AndroidRuntime()
     return jniRegisterNativeMethods(env, className, gMethods, numMethods);
 }
 
+void AndroidRuntime::setArgv0(const char* argv0) {
+    strlcpy(mArgBlockStart, argv0, mArgBlockLength);
+}
+
 status_t AndroidRuntime::callMain(const char* className,
     jclass clazz, int argc, const char* const argv[])
 {
diff --git a/core/jni/android_util_Process.cpp b/core/jni/android_util_Process.cpp
index 601975af01b92..9f8eb34c62099 100644
--- a/core/jni/android_util_Process.cpp
+++ b/core/jni/android_util_Process.cpp
@@ -19,8 +19,8 @@
 
 #include <utils/Log.h>
 #include <binder/IPCThreadState.h>
-#include <binder/ProcessState.h>
 #include <binder/IServiceManager.h>
+#include <cutils/process_name.h>
 #include <cutils/sched_policy.h>
 #include <utils/String8.h>
 #include <utils/Vector.h>
@@ -402,7 +402,9 @@ void android_os_Process_setArgV0(JNIEnv* env, jobject clazz, jstring name)
     }
 
     if (name8.size() > 0) {
-        ProcessState::self()->setArgV0(name8.string());
+        const char* procName = name8.string();
+        set_process_name(procName);
+        AndroidRuntime::getRuntime()->setArgv0(procName);
     }
 }
 
diff --git a/include/android_runtime/AndroidRuntime.h b/include/android_runtime/AndroidRuntime.h
index 649f4c344d64c..6f2af908f70d2 100644
--- a/include/android_runtime/AndroidRuntime.h
+++ b/include/android_runtime/AndroidRuntime.h
@@ -34,7 +34,7 @@ namespace android {
 class AndroidRuntime
 {
 public:
-    AndroidRuntime();
+    AndroidRuntime(char* argBlockStart, size_t argBlockSize);
     virtual ~AndroidRuntime();
 
     enum StartMode {
@@ -44,6 +44,8 @@ public:
         Tool,
     };
 
+    void setArgv0(const char* argv0);
+
     /**
      * Register a set of methods in the specified class.
      */
@@ -120,6 +122,8 @@ private:
 
     Vector<JavaVMOption> mOptions;
     bool mExitWithoutCleanup;
+    char* const mArgBlockStart;
+    const size_t mArgBlockLength;
 
     /* JNI JavaVM pointer */
     static JavaVM* mJavaVM;