Android: improve native debuggability

base/debug/debugger_posix.cc

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "base/debug/debugger.h"
 #include "build/build_config.h"
 
 #include <errno.h>
 #include <fcntl.h>
 #include <stdio.h>
@@ skipping 200 matching lines @@
 #define DEBUG_BREAK() abort()
 #elif defined(ARCH_CPU_ARM_FAMILY)
 #if defined(OS_ANDROID)
 // Though Android has a "helpful" process called debuggerd to catch native
 // signals on the general assumption that they are fatal errors. The bkpt
 // instruction appears to cause SIGBUS which is trapped by debuggerd, and
 // we've had great difficulty continuing in a debugger once we stop from
 // SIG triggered by native code.
 //
 // Use GDB to set |go| to 1 to resume execution.
-#define DEBUG_BREAK() do { \
-  if (!BeingDebugged()) { \
-    abort(); \
-  } else { \
-    volatile int go = 0; \
-    while (!go) { \
-      base::PlatformThread::Sleep(base::TimeDelta::FromMilliseconds(100)); \
-    } \
-  } \
-} while (0)
+void DEBUG_BREAK() {

[darin (slow to review), 2013/03/19 22:24:14]

nit: I recommend preserving the DEBUG_BREAK macro (in an effort to reduce
surprises between ports), and instead introduce a function that DEBUG_BREAK
resolves to.

void DebugBreak() {
  ...
}
#define DEBUG_BREAK() DebugBreak()

[mostynb%opera.com, 2013/03/20 05:32:39]

Done.

+  do {
+    if (!BeingDebugged()) {
+      abort();
+    } else {
+      volatile int go = 0;
+      while (!go) {
+        base::PlatformThread::Sleep(base::TimeDelta::FromMilliseconds(100));
+      }
+    }
+  } while (0);
+}
 #else
 // ARM && !ANDROID
 #define DEBUG_BREAK() asm("bkpt 0")
 #endif
 #elif defined(ARCH_CPU_MIPS_FAMILY)
 #define DEBUG_BREAK() asm("break 2")
 #else
 #define DEBUG_BREAK() asm("int3")
 #endif
 
 void BreakDebugger() {
   // NOTE: This code MUST be async-signal safe (it's used by in-process
   // stack dumping signal handler). NO malloc or stdio is allowed here.
 
   DEBUG_BREAK();
 #if defined(OS_ANDROID) && !defined(OFFICIAL_BUILD)
   // For Android development we always build release (debug builds are
   // unmanageably large), so the unofficial build is used for debugging. It is
   // helpful to be able to insert BreakDebugger() statements in the source,
   // attach the debugger, inspect the state of the program and then resume it by
   // setting the 'go' variable above.
 #elif defined(NDEBUG)
   // Terminate the program after signaling the debug break.
   _exit(1);
 #endif
 }
 
 }  // namespace debug
 }  // namespace base