Add error propagation into Unwinder/Elf objects.

The backtrace offline code uses these error codes to diagnose errors.
In addtion, I've had cases where seeing these errors would help diagnose
failures.

This also allows us to add a few features to indicate why an unwind
terminated (such as max frames exceeded).

Bug: 65682279

Test: Updated unit tests pass.
Change-Id: If82b5092698e8a194016d670efff1320f9b44d50
diff --git a/libunwindstack/tests/ElfTest.cpp b/libunwindstack/tests/ElfTest.cpp
index 7e6a62a..eb85033 100644
--- a/libunwindstack/tests/ElfTest.cpp
+++ b/libunwindstack/tests/ElfTest.cpp
@@ -581,4 +581,30 @@
   EXPECT_TRUE(elf.IsValidPc(0x1500));
 }
 
+TEST_F(ElfTest, error_code_not_valid) {
+  ElfFake elf(memory_);
+  elf.FakeSetValid(false);
+
+  ErrorData error{ERROR_MEMORY_INVALID, 0x100};
+  elf.GetLastError(&error);
+  EXPECT_EQ(ERROR_MEMORY_INVALID, error.code);
+  EXPECT_EQ(0x100U, error.address);
+}
+
+TEST_F(ElfTest, error_code_valid) {
+  ElfFake elf(memory_);
+  elf.FakeSetValid(true);
+  ElfInterfaceFake* interface = new ElfInterfaceFake(memory_);
+  elf.FakeSetInterface(interface);
+  interface->FakeSetErrorCode(ERROR_MEMORY_INVALID);
+  interface->FakeSetErrorAddress(0x1000);
+
+  ErrorData error{ERROR_NONE, 0};
+  elf.GetLastError(&error);
+  EXPECT_EQ(ERROR_MEMORY_INVALID, error.code);
+  EXPECT_EQ(0x1000U, error.address);
+  EXPECT_EQ(ERROR_MEMORY_INVALID, elf.GetLastErrorCode());
+  EXPECT_EQ(0x1000U, elf.GetLastErrorAddress());
+}
+
 }  // namespace unwindstack