commit 2fd1febdbb8d039fe371295b929910d178172ac9
author Steven Moreland <smoreland@google.com> Sat May 25 00:13:10 2024 +0000
committer Steven Moreland <smoreland@google.com> Sat May 25 00:15:33 2024 +0000
tree 717f2170adadd9f9e1ebda3e3267fc32fa84142a
parent dbecfa8c6e89fe56d323be583f73b620976ee12f

libbinder: report binder error in abort message

This bug has been eluding me for years. It's so rare,
you never see the logcat. I only see the crash stacks.

I'm going to guess it's FD exhaustion causing this?

But we'll see...

Bug: 197637414
Test: boot
Change-Id: I78533a8de7cfb5edb7226cd6cfeac5b8aa6ffdf0

libs/binder/ProcessState.cpp

diff --git a/libs/binder/ProcessState.cpp b/libs/binder/ProcessState.cpp
index fb2781b..8485ecd 100644
--- a/libs/binder/ProcessState.cpp
+++ b/libs/binder/ProcessState.cpp
@@ -516,22 +516,23 @@
     return mDriverName;
 }
 
-static unique_fd open_driver(const char* driver) {
+static unique_fd open_driver(const char* driver, String8* error) {
     auto fd = unique_fd(open(driver, O_RDWR | O_CLOEXEC));
     if (!fd.ok()) {
-        PLOGE("Opening '%s' failed", driver);
+        error->appendFormat("%d (%s) Opening '%s' failed", errno, strerror(errno), driver);
         return {};
     }
     int vers = 0;
     int result = ioctl(fd.get(), BINDER_VERSION, &vers);
     if (result == -1) {
-        PLOGE("Binder ioctl to obtain version failed");
+        error->appendFormat("%d (%s) Binder ioctl to obtain version failed", errno,
+                            strerror(errno));
         return {};
     }
     if (result != 0 || vers != BINDER_CURRENT_PROTOCOL_VERSION) {
-        ALOGE("Binder driver protocol(%d) does not match user space protocol(%d)! "
-              "ioctl() return value: %d",
-              vers, BINDER_CURRENT_PROTOCOL_VERSION, result);
+        error->appendFormat("Binder driver protocol(%d) does not match user space protocol(%d)! "
+                            "ioctl() return value: %d",
+                            vers, BINDER_CURRENT_PROTOCOL_VERSION, result);
         return {};
     }
     size_t maxThreads = DEFAULT_MAX_BINDER_THREADS;
@@ -565,7 +566,8 @@
         mThreadPoolStarted(false),
         mThreadPoolSeq(1),
         mCallRestriction(CallRestriction::NONE) {
-    unique_fd opened = open_driver(driver);
+    String8 error;
+    unique_fd opened = open_driver(driver, &error);
 
     if (opened.ok()) {
         // mmap the binder, providing a chunk of virtual address space to receive transactions.
@@ -580,8 +582,9 @@
     }
 
 #ifdef __ANDROID__
-    LOG_ALWAYS_FATAL_IF(!opened.ok(), "Binder driver '%s' could not be opened. Terminating.",
-                        driver);
+    LOG_ALWAYS_FATAL_IF(!opened.ok(),
+                        "Binder driver '%s' could not be opened. Error: %s. Terminating.",
+                        error.c_str(), driver);
 #endif
 
     if (opened.ok()) {