Allow ProcessState to use another binder dev node.

Since we have different binder domains at different
/dev nodes now, processes using libbinder must be able
to select which /dev node they want to use. This is
achieved with a new ProcessState::initWithDriver() API,
which takes the /dev node to talk to as an argument.

Bug: 36052864
Test: system boots without issues
Change-Id: I5b3b13decf254ca0957665c91abac4b287e448c4

2 files changed, 22 insertions, 7 deletions

diff --git a/include/binder/ProcessState.h b/include/binder/ProcessState.h
index 64cf72e170..05e9d09ee8 100644
--- a/include/binder/ProcessState.h
+++ b/include/binder/ProcessState.h
@@ -35,6 +35,11 @@ class ProcessState : public virtual RefBase
 {
 public:
     static  sp<ProcessState>    self();
+    /* initWithDriver() can be used to configure libbinder to use
+     * a different binder driver dev node. It must be called *before*
+     * any call to ProcessState::self(). /dev/binder remains the default.
+     */
+    static  sp<ProcessState>    initWithDriver(const char *driver);
 
             void                setContextObject(const sp<IBinder>& object);
             sp<IBinder>         getContextObject(const sp<IBinder>& caller);
@@ -67,7 +72,7 @@ public:
 private:
     friend class IPCThreadState;
     
-                                ProcessState();
+                                ProcessState(const char* driver);
                                 ~ProcessState();
 
                                 ProcessState(const ProcessState& o);
diff --git a/libs/binder/ProcessState.cpp b/libs/binder/ProcessState.cpp
index 98107c578d..5c4cfe2156 100644
--- a/libs/binder/ProcessState.cpp
+++ b/libs/binder/ProcessState.cpp
@@ -71,7 +71,17 @@ sp<ProcessState> ProcessState::self()
     if (gProcess != NULL) {
         return gProcess;
     }
-    gProcess = new ProcessState;
+    gProcess = new ProcessState("/dev/binder");
+    return gProcess;
+}
+
+sp<ProcessState> ProcessState::initWithDriver(const char* driver)
+{
+    Mutex::Autolock _l(gProcessMutex);
+    if (gProcess != NULL) {
+        LOG_ALWAYS_FATAL("ProcessState was already initialized.");
+    }
+    gProcess = new ProcessState(driver);
     return gProcess;
 }
 
@@ -307,9 +317,9 @@ void ProcessState::giveThreadPoolName() {
     androidSetThreadName( makeBinderThreadName().string() );
 }
 
-static int open_driver()
+static int open_driver(const char *driver)
 {
-    int fd = open("/dev/binder", O_RDWR | O_CLOEXEC);
+    int fd = open(driver, O_RDWR | O_CLOEXEC);
     if (fd >= 0) {
         int vers = 0;
         status_t result = ioctl(fd, BINDER_VERSION, &vers);
@@ -330,13 +340,13 @@ static int open_driver()
             ALOGE("Binder ioctl to set max threads failed: %s", strerror(errno));
         }
     } else {
-        ALOGW("Opening '/dev/binder' failed: %s\n", strerror(errno));
+        ALOGW("Opening '%s' failed: %s\n", driver, strerror(errno));
     }
     return fd;
 }
 
-ProcessState::ProcessState()
-    : mDriverFD(open_driver())
+ProcessState::ProcessState(const char *driver)
+    : mDriverFD(open_driver(driver))
     , mVMStart(MAP_FAILED)
     , mThreadCountLock(PTHREAD_MUTEX_INITIALIZER)
     , mThreadCountDecrement(PTHREAD_COND_INITIALIZER)