Don't bail if a thread's stack pointer is invalid

Currently, if a thread's stack pointer is not within a valid memory page,
the minidump writing will fail with an error.  This change allows an invalid
stack pointer by simply setting the memory size to zero in the minidump.
The processing code already checks for the size being zero, although it
currently just gives an error (see https://breakpad.appspot.com/413002/).

BUG=google-breakpad:499, chromium-os:34880
TEST=make check, manually ran minidump-2-core and core2md
Review URL: https://breakpad.appspot.com/478002

git-svn-id: http://google-breakpad.googlecode.com/svn/trunk@1065 4c0a9323-5329-0410-9bdc-e9ce6186880e

1 files changed, 80 insertions, 0 deletions

diff --git a/src/client/linux/minidump_writer/minidump_writer_unittest.cc b/src/client/linux/minidump_writer/minidump_writer_unittest.cc
index e0d0fa9c..68bde073 100644
--- a/src/client/linux/minidump_writer/minidump_writer_unittest.cc
+++ b/src/client/linux/minidump_writer/minidump_writer_unittest.cc
@@ -501,3 +501,83 @@ TEST(MinidumpWriterTest, AdditionalMemory) {
   delete[] memory;
   close(fds[1]);
 }
+
+// Test that an invalid thread stack pointer still results in a minidump.
+TEST(MinidumpWriterTest, InvalidStackPointer) {
+  int fds[2];
+  ASSERT_NE(-1, pipe(fds));
+
+  const pid_t child = fork();
+  if (child == 0) {
+    close(fds[1]);
+    char b;
+    HANDLE_EINTR(read(fds[0], &b, sizeof(b)));
+    close(fds[0]);
+    syscall(__NR_exit);
+  }
+  close(fds[0]);
+
+  ExceptionHandler::CrashContext context;
+
+  // This needs a valid context for minidump writing to work, but getting
+  // a useful one from the child is too much work, so just use one from
+  // the parent since the child is just a forked copy anyway.
+  ASSERT_EQ(0, getcontext(&context.context));
+  context.tid = child;
+
+  // Fake the child's stack pointer for its crashing thread.  NOTE: This must
+  // be an invalid memory address for the child process (stack or otherwise).
+#if defined(__i386)
+  // Try 1MB below the current stack.
+  uintptr_t invalid_stack_pointer =
+      reinterpret_cast<uintptr_t>(&context) - 1024*1024;
+  context.context.uc_mcontext.gregs[REG_ESP] = invalid_stack_pointer;
+#elif defined(__x86_64)
+  // Try 1MB below the current stack.
+  uintptr_t invalid_stack_pointer =
+      reinterpret_cast<uintptr_t>(&context) - 1024*1024;
+  context.context.uc_mcontext.gregs[REG_RSP] = invalid_stack_pointer;
+#elif defined(__ARM_EABI__)
+  // Try 1MB below the current stack.
+  uintptr_t invalid_stack_pointer =
+      reinterpret_cast<uintptr_t>(&context) - 1024*1024;
+  context.context.uc_mcontext.arm_sp = invalid_stack_pointer;
+#else
+# error "This code has not been ported to your platform yet."
+#endif
+
+  AutoTempDir temp_dir;
+  string templ = temp_dir.path() + "/minidump-writer-unittest";
+  // NOTE: In previous versions of Breakpad, WriteMinidump() would fail if
+  // presented with an invalid stack pointer.
+  ASSERT_TRUE(WriteMinidump(templ.c_str(), child, &context, sizeof(context)));
+
+  // Read the minidump. Ensure that the memory region is present
+  Minidump minidump(templ.c_str());
+  ASSERT_TRUE(minidump.Read());
+
+  // TODO(ted.mielczarek,mkrebs): Enable this part of the test once
+  // https://breakpad.appspot.com/413002/ is committed.
+#if 0
+  // Make sure there's a thread without a stack.  NOTE: It's okay if
+  // GetThreadList() shows the error: "ERROR: MinidumpThread has a memory
+  // region problem".
+  MinidumpThreadList* dump_thread_list = minidump.GetThreadList();
+  ASSERT_TRUE(dump_thread_list);
+  bool found_empty_stack = false;
+  for (int i = 0; i < dump_thread_list->thread_count(); i++) {
+    MinidumpThread* thread = dump_thread_list->GetThreadAtIndex(i);
+    ASSERT_TRUE(thread->thread() != NULL);
+    // When the stack size is zero bytes, GetMemory() returns NULL.
+    if (thread->GetMemory() == NULL) {
+      found_empty_stack = true;
+      break;
+    }
+  }
+  // NOTE: If you fail this, first make sure that "invalid_stack_pointer"
+  // above is indeed set to an invalid address.
+  ASSERT_TRUE(found_empty_stack);
+#endif
+
+  close(fds[1]);
+}