commit 2fcf4cf13e9aefa8c312084af12ca2d712a6ead3
author Christopher Ferris <cferris@google.com> Tue Jan 23 17:52:23 2018 -0800
committer Christopher Ferris <cferris@google.com> Wed Jan 24 17:50:46 2018 -0800
tree b5221be7ee35e1b7e2cfed8f931a704cc5f40da4
parent 335675c2fd8ff39e5af635eb375edc766147cbb9

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

libunwindstack/DwarfEhFrameWithHdr.cpp

diff --git a/libunwindstack/DwarfEhFrameWithHdr.cpp b/libunwindstack/DwarfEhFrameWithHdr.cpp
index e0f1eed..a131abe 100644
--- a/libunwindstack/DwarfEhFrameWithHdr.cpp
+++ b/libunwindstack/DwarfEhFrameWithHdr.cpp
@@ -16,12 +16,12 @@
 
 #include <stdint.h>
 
+#include <unwindstack/DwarfError.h>
 #include <unwindstack/DwarfStructs.h>
 #include <unwindstack/Memory.h>
 
 #include "Check.h"
 #include "DwarfEhFrameWithHdr.h"
-#include "DwarfError.h"
 
 namespace unwindstack {
 
@@ -36,14 +36,15 @@
 
   // Read the first four bytes all at once.
   if (!memory_.ReadBytes(data, 4)) {
-    last_error_ = DWARF_ERROR_MEMORY_INVALID;
+    last_error_.code = DWARF_ERROR_MEMORY_INVALID;
+    last_error_.address = memory_.cur_offset();
     return false;
   }
 
   version_ = data[0];
   if (version_ != 1) {
     // Unknown version.
-    last_error_ = DWARF_ERROR_UNSUPPORTED_VERSION;
+    last_error_.code = DWARF_ERROR_UNSUPPORTED_VERSION;
     return false;
   }
 
@@ -54,18 +55,20 @@
 
   memory_.set_pc_offset(memory_.cur_offset());
   if (!memory_.template ReadEncodedValue<AddressType>(ptr_encoding_, &ptr_offset_)) {
-    last_error_ = DWARF_ERROR_MEMORY_INVALID;
+    last_error_.code = DWARF_ERROR_MEMORY_INVALID;
+    last_error_.address = memory_.cur_offset();
     return false;
   }
 
   memory_.set_pc_offset(memory_.cur_offset());
   if (!memory_.template ReadEncodedValue<AddressType>(fde_count_encoding, &fde_count_)) {
-    last_error_ = DWARF_ERROR_MEMORY_INVALID;
+    last_error_.code = DWARF_ERROR_MEMORY_INVALID;
+    last_error_.address = memory_.cur_offset();
     return false;
   }
 
   if (fde_count_ == 0) {
-    last_error_ = DWARF_ERROR_NO_FDES;
+    last_error_.code = DWARF_ERROR_NO_FDES;
     return false;
   }
 
@@ -101,7 +104,8 @@
   uint64_t value;
   if (!memory_.template ReadEncodedValue<AddressType>(table_encoding_, &value) ||
       !memory_.template ReadEncodedValue<AddressType>(table_encoding_, &info->offset)) {
-    last_error_ = DWARF_ERROR_MEMORY_INVALID;
+    last_error_.code = DWARF_ERROR_MEMORY_INVALID;
+    last_error_.address = memory_.cur_offset();
     fde_info_.erase(index);
     return nullptr;
   }
@@ -147,7 +151,9 @@
 template <typename AddressType>
 bool DwarfEhFrameWithHdr<AddressType>::GetFdeOffsetSequential(uint64_t pc, uint64_t* fde_offset) {
   CHECK(fde_count_ != 0);
-  last_error_ = DWARF_ERROR_NONE;
+  last_error_.code = DWARF_ERROR_NONE;
+  last_error_.address = 0;
+
   // We can do a binary search if the pc is in the range of the elements
   // that have already been cached.
   if (!fde_info_.empty()) {
@@ -176,14 +182,16 @@
     memory_.set_pc_offset(memory_.cur_offset());
     uint64_t value;
     if (!memory_.template ReadEncodedValue<AddressType>(table_encoding_, &value)) {
-      last_error_ = DWARF_ERROR_MEMORY_INVALID;
+      last_error_.code = DWARF_ERROR_MEMORY_INVALID;
+      last_error_.address = memory_.cur_offset();
       return false;
     }
 
     FdeInfo* info = &fde_info_[current];
     if (!memory_.template ReadEncodedValue<AddressType>(table_encoding_, &info->offset)) {
       fde_info_.erase(current);
-      last_error_ = DWARF_ERROR_MEMORY_INVALID;
+      last_error_.code = DWARF_ERROR_MEMORY_INVALID;
+      last_error_.address = memory_.cur_offset();
       return false;
     }
     info->pc = value + 4;