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/DwarfCfa.cpp

diff --git a/libunwindstack/DwarfCfa.cpp b/libunwindstack/DwarfCfa.cpp
index b1d55ba..4fc95c7 100644
--- a/libunwindstack/DwarfCfa.cpp
+++ b/libunwindstack/DwarfCfa.cpp
@@ -23,12 +23,12 @@
 
 #include <android-base/stringprintf.h>
 
+#include <unwindstack/DwarfError.h>
 #include <unwindstack/DwarfLocation.h>
 #include <unwindstack/Log.h>
 
 #include "DwarfCfa.h"
 #include "DwarfEncoding.h"
-#include "DwarfError.h"
 #include "DwarfOp.h"
 
 namespace unwindstack {
@@ -44,7 +44,8 @@
       (*loc_regs)[entry.first] = entry.second;
     }
   }
-  last_error_ = DWARF_ERROR_NONE;
+  last_error_.code = DWARF_ERROR_NONE;
+  last_error_.address = 0;
 
   memory_->set_cur_offset(start_offset);
   uint64_t cfa_offset;
@@ -54,7 +55,8 @@
     // Read the cfa information.
     uint8_t cfa_value;
     if (!memory_->ReadBytes(&cfa_value, 1)) {
-      last_error_ = DWARF_ERROR_MEMORY_INVALID;
+      last_error_.code = DWARF_ERROR_MEMORY_INVALID;
+      last_error_.address = memory_->cur_offset();
       return false;
     }
     uint8_t cfa_low = cfa_value & 0x3f;
@@ -66,7 +68,8 @@
       case 2: {
         uint64_t offset;
         if (!memory_->ReadULEB128(&offset)) {
-          last_error_ = DWARF_ERROR_MEMORY_INVALID;
+          last_error_.code = DWARF_ERROR_MEMORY_INVALID;
+          last_error_.address = memory_->cur_offset();
           return false;
         }
         SignedType signed_offset =
@@ -78,7 +81,7 @@
       case 3: {
         if (cie_loc_regs_ == nullptr) {
           log(0, "restore while processing cie");
-          last_error_ = DWARF_ERROR_ILLEGAL_STATE;
+          last_error_.code = DWARF_ERROR_ILLEGAL_STATE;
           return false;
         }
 
@@ -93,7 +96,7 @@
       case 0: {
         const auto handle_func = DwarfCfa<AddressType>::kCallbackTable[cfa_low];
         if (handle_func == nullptr) {
-          last_error_ = DWARF_ERROR_ILLEGAL_VALUE;
+          last_error_.code = DWARF_ERROR_ILLEGAL_VALUE;
           return false;
         }
 
@@ -102,7 +105,8 @@
           if (cfa->operands[i] == DW_EH_PE_block) {
             uint64_t block_length;
             if (!memory_->ReadULEB128(&block_length)) {
-              last_error_ = DWARF_ERROR_MEMORY_INVALID;
+              last_error_.code = DWARF_ERROR_MEMORY_INVALID;
+              last_error_.address = memory_->cur_offset();
               return false;
             }
             operands_.push_back(block_length);
@@ -111,7 +115,8 @@
           }
           uint64_t value;
           if (!memory_->ReadEncodedValue<AddressType>(cfa->operands[i], &value)) {
-            last_error_ = DWARF_ERROR_MEMORY_INVALID;
+            last_error_.code = DWARF_ERROR_MEMORY_INVALID;
+            last_error_.address = memory_->cur_offset();
             return false;
           }
           operands_.push_back(value);
@@ -334,7 +339,7 @@
   AddressType reg = operands_[0];
   if (cie_loc_regs_ == nullptr) {
     log(0, "restore while processing cie");
-    last_error_ = DWARF_ERROR_ILLEGAL_STATE;
+    last_error_.code = DWARF_ERROR_ILLEGAL_STATE;
     return false;
   }
   auto reg_entry = cie_loc_regs_->find(reg);
@@ -396,7 +401,7 @@
   auto cfa_location = loc_regs->find(CFA_REG);
   if (cfa_location == loc_regs->end() || cfa_location->second.type != DWARF_LOCATION_REGISTER) {
     log(0, "Attempt to set new register, but cfa is not already set to a register.");
-    last_error_ = DWARF_ERROR_ILLEGAL_STATE;
+    last_error_.code = DWARF_ERROR_ILLEGAL_STATE;
     return false;
   }
 
@@ -410,7 +415,7 @@
   auto cfa_location = loc_regs->find(CFA_REG);
   if (cfa_location == loc_regs->end() || cfa_location->second.type != DWARF_LOCATION_REGISTER) {
     log(0, "Attempt to set offset, but cfa is not set to a register.");
-    last_error_ = DWARF_ERROR_ILLEGAL_STATE;
+    last_error_.code = DWARF_ERROR_ILLEGAL_STATE;
     return false;
   }
   cfa_location->second.values[1] = operands_[0];
@@ -454,7 +459,7 @@
   auto cfa_location = loc_regs->find(CFA_REG);
   if (cfa_location == loc_regs->end() || cfa_location->second.type != DWARF_LOCATION_REGISTER) {
     log(0, "Attempt to set offset, but cfa is not set to a register.");
-    last_error_ = DWARF_ERROR_ILLEGAL_STATE;
+    last_error_.code = DWARF_ERROR_ILLEGAL_STATE;
     return false;
   }
   SignedType offset = static_cast<SignedType>(operands_[0]) * fde_->cie->data_alignment_factor;