Allow setting a limit on the number of frames to be recovered by stack scanning.

Patch by Julian Seward <jseward@acm.org> R=ted at https://bugzilla.mozilla.org/show_bug.cgi?id=894264

git-svn-id: http://google-breakpad.googlecode.com/svn/trunk@1206 4c0a9323-5329-0410-9bdc-e9ce6186880e

1 files changed, 59 insertions, 0 deletions

diff --git a/src/processor/stackwalker_arm_unittest.cc b/src/processor/stackwalker_arm_unittest.cc
index b50f4e99..c73322e6 100644
--- a/src/processor/stackwalker_arm_unittest.cc
+++ b/src/processor/stackwalker_arm_unittest.cc
@@ -54,6 +54,7 @@ using google_breakpad::CodeModule;
 using google_breakpad::StackFrameSymbolizer;
 using google_breakpad::StackFrame;
 using google_breakpad::StackFrameARM;
+using google_breakpad::Stackwalker;
 using google_breakpad::StackwalkerARM;
 using google_breakpad::SystemInfo;
 using google_breakpad::WindowsFrameInfo;
@@ -97,6 +98,9 @@ class StackwalkerARMFixture {
     // Avoid GMOCK WARNING "Uninteresting mock function call - returning
     // directly" for FreeSymbolData().
     EXPECT_CALL(supplier, FreeSymbolData(_)).Times(AnyNumber());
+
+    // Reset max_frames_scanned since it's static.
+    Stackwalker::set_max_frames_scanned(1024);
   }
 
   // Set the Breakpad symbol information that supplier should return for
@@ -406,6 +410,61 @@ TEST_F(GetCallerFrame, ScanFirstFrame) {
   EXPECT_EQ(frame1_sp.Value(), frame1->context.iregs[MD_CONTEXT_ARM_REG_SP]);
 }
 
+// Test that set_max_frames_scanned prevents using stack scanning
+// to find caller frames.
+TEST_F(GetCallerFrame, ScanningNotAllowed) {
+  // When the stack walker resorts to scanning the stack,
+  // only addresses located within loaded modules are
+  // considered valid return addresses.
+  stack_section.start() = 0x80000000;
+  uint32_t return_address1 = 0x50000100;
+  uint32_t return_address2 = 0x50000900;
+  Label frame1_sp, frame2_sp;
+  stack_section
+    // frame 0
+    .Append(16, 0)                      // space
+
+    .D32(0x40090000)                    // junk that's not
+    .D32(0x60000000)                    // a return address
+
+    .D32(return_address1)               // actual return address
+    // frame 1
+    .Mark(&frame1_sp)
+    .Append(16, 0)                      // space
+
+    .D32(0xF0000000)                    // more junk
+    .D32(0x0000000D)
+
+    .D32(return_address2)               // actual return address
+    // frame 2
+    .Mark(&frame2_sp)
+    .Append(32, 0);                     // end of stack
+  RegionFromSection();
+
+  raw_context.iregs[MD_CONTEXT_ARM_REG_PC] = 0x40005510;
+  raw_context.iregs[MD_CONTEXT_ARM_REG_SP] = stack_section.start().Value();
+
+  StackFrameSymbolizer frame_symbolizer(&supplier, &resolver);
+  StackwalkerARM walker(&system_info, &raw_context, -1, &stack_region, &modules,
+                        &frame_symbolizer);
+  Stackwalker::set_max_frames_scanned(0);
+
+  vector<const CodeModule*> modules_without_symbols;
+  vector<const CodeModule*> modules_with_corrupt_symbols;
+  ASSERT_TRUE(walker.Walk(&call_stack, &modules_without_symbols,
+                          &modules_with_corrupt_symbols));
+  ASSERT_EQ(1U, modules_without_symbols.size());
+  ASSERT_EQ("module1", modules_without_symbols[0]->debug_file());
+  ASSERT_EQ(0U, modules_with_corrupt_symbols.size());
+  frames = call_stack.frames();
+  ASSERT_EQ(1U, frames->size());
+
+  StackFrameARM *frame0 = static_cast<StackFrameARM *>(frames->at(0));
+  EXPECT_EQ(StackFrame::FRAME_TRUST_CONTEXT, frame0->trust);
+  ASSERT_EQ(StackFrameARM::CONTEXT_VALID_ALL, frame0->context_validity);
+  EXPECT_EQ(0, memcmp(&raw_context, &frame0->context, sizeof(raw_context)));
+}
+
 struct CFIFixture: public StackwalkerARMFixture {
   CFIFixture() {
     // Provide a bunch of STACK CFI records; we'll walk to the caller