1 files changed, 223 insertions, 0 deletions
diff --git a/libunwindstack/DwarfEhFrameWithHdr.cpp b/libunwindstack/DwarfEhFrameWithHdr.cpp
new file mode 100644
index 000000000..0337dbaac
--- /dev/null
+++ b/libunwindstack/DwarfEhFrameWithHdr.cpp
@@ -0,0 +1,223 @@
+/*
+ * Copyright (C) 2017 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include <stdint.h>
+
+#include <unwindstack/DwarfStructs.h>
+#include <unwindstack/Memory.h>
+
+#include "Check.h"
+#include "DwarfEhFrameWithHdr.h"
+#include "DwarfError.h"
+
+namespace unwindstack {
+
+template <typename AddressType>
+bool DwarfEhFrameWithHdr<AddressType>::Init(uint64_t offset, uint64_t size) {
+  uint8_t data[4];
+
+  memory_.clear_func_offset();
+  memory_.clear_text_offset();
+  memory_.set_data_offset(offset);
+  memory_.set_cur_offset(offset);
+
+  // Read the first four bytes all at once.
+  if (!memory_.ReadBytes(data, 4)) {
+    last_error_ = DWARF_ERROR_MEMORY_INVALID;
+    return false;
+  }
+
+  version_ = data[0];
+  if (version_ != 1) {
+    // Unknown version.
+    last_error_ = DWARF_ERROR_UNSUPPORTED_VERSION;
+    return false;
+  }
+
+  ptr_encoding_ = data[1];
+  uint8_t fde_count_encoding = data[2];
+  table_encoding_ = data[3];
+  table_entry_size_ = memory_.template GetEncodedSize<AddressType>(table_encoding_);
+
+  memory_.set_pc_offset(memory_.cur_offset());
+  if (!memory_.template ReadEncodedValue<AddressType>(ptr_encoding_, &ptr_offset_)) {
+    last_error_ = DWARF_ERROR_MEMORY_INVALID;
+    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;
+    return false;
+  }
+
+  entries_offset_ = memory_.cur_offset();
+  entries_end_ = offset + size;
+  entries_data_offset_ = offset;
+  cur_entries_offset_ = entries_offset_;
+
+  return true;
+}
+
+template <typename AddressType>
+const DwarfFde* DwarfEhFrameWithHdr<AddressType>::GetFdeFromIndex(size_t index) {
+  const FdeInfo* info = GetFdeInfoFromIndex(index);
+  if (info == nullptr) {
+    return nullptr;
+  }
+  return this->GetFdeFromOffset(info->offset);
+}
+
+template <typename AddressType>
+const typename DwarfEhFrameWithHdr<AddressType>::FdeInfo*
+DwarfEhFrameWithHdr<AddressType>::GetFdeInfoFromIndex(size_t index) {
+  auto entry = fde_info_.find(index);
+  if (entry != fde_info_.end()) {
+    return &fde_info_[index];
+  }
+  FdeInfo* info = &fde_info_[index];
+
+  memory_.set_data_offset(entries_data_offset_);
+  memory_.set_cur_offset(entries_offset_ + 2 * index * table_entry_size_);
+  memory_.set_pc_offset(memory_.cur_offset());
+  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;
+    fde_info_.erase(index);
+    return nullptr;
+  }
+  info->pc = value + 4;
+  return info;
+}
+
+template <typename AddressType>
+bool DwarfEhFrameWithHdr<AddressType>::GetFdeOffsetBinary(uint64_t pc, uint64_t* fde_offset,
+                                                          uint64_t total_entries) {
+  CHECK(fde_count_ > 0);
+  CHECK(total_entries <= fde_count_);
+
+  size_t first = 0;
+  size_t last = total_entries;
+  while (first < last) {
+    size_t current = (first + last) / 2;
+    const FdeInfo* info = GetFdeInfoFromIndex(current);
+    if (info == nullptr) {
+      return false;
+    }
+    if (pc == info->pc) {
+      *fde_offset = info->offset;
+      return true;
+    }
+    if (pc < info->pc) {
+      last = current;
+    } else {
+      first = current + 1;
+    }
+  }
+  if (last != 0) {
+    const FdeInfo* info = GetFdeInfoFromIndex(last - 1);
+    if (info == nullptr) {
+      return false;
+    }
+    *fde_offset = info->offset;
+    return true;
+  }
+  return false;
+}
+
+template <typename AddressType>
+bool DwarfEhFrameWithHdr<AddressType>::GetFdeOffsetSequential(uint64_t pc, uint64_t* fde_offset) {
+  CHECK(fde_count_ != 0);
+  last_error_ = DWARF_ERROR_NONE;
+  // 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()) {
+    const FdeInfo* info = &fde_info_[fde_info_.size() - 1];
+    if (pc >= info->pc) {
+      *fde_offset = info->offset;
+      return true;
+    }
+    if (pc < info->pc) {
+      return GetFdeOffsetBinary(pc, fde_offset, fde_info_.size());
+    }
+  }
+
+  if (cur_entries_offset_ == 0) {
+    // All entries read, or error encountered.
+    return false;
+  }
+
+  memory_.set_data_offset(entries_data_offset_);
+  memory_.set_cur_offset(cur_entries_offset_);
+  cur_entries_offset_ = 0;
+
+  FdeInfo* prev_info = nullptr;
+  for (size_t current = fde_info_.size();
+       current < fde_count_ && memory_.cur_offset() < entries_end_; current++) {
+    memory_.set_pc_offset(memory_.cur_offset());
+    uint64_t value;
+    if (!memory_.template ReadEncodedValue<AddressType>(table_encoding_, &value)) {
+      last_error_ = DWARF_ERROR_MEMORY_INVALID;
+      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;
+      return false;
+    }
+    info->pc = value + 4;
+
+    if (pc < info->pc) {
+      if (prev_info == nullptr) {
+        return false;
+      }
+      cur_entries_offset_ = memory_.cur_offset();
+      *fde_offset = prev_info->offset;
+      return true;
+    }
+    prev_info = info;
+  }
+
+  if (fde_count_ == fde_info_.size() && pc >= prev_info->pc) {
+    *fde_offset = prev_info->offset;
+    return true;
+  }
+  return false;
+}
+
+template <typename AddressType>
+bool DwarfEhFrameWithHdr<AddressType>::GetFdeOffsetFromPc(uint64_t pc, uint64_t* fde_offset) {
+  if (fde_count_ == 0) {
+    return false;
+  }
+
+  if (table_entry_size_ > 0) {
+    // Do a binary search since the size of each table entry is fixed.
+    return GetFdeOffsetBinary(pc, fde_offset, fde_count_);
+  } else {
+    // Do a sequential search since each table entry size is variable.
+    return GetFdeOffsetSequential(pc, fde_offset);
+  }
+}
+
+// Explicitly instantiate DwarfEhFrameWithHdr
+template class DwarfEhFrameWithHdr<uint32_t>;
+template class DwarfEhFrameWithHdr<uint64_t>;
+
+}  // namespace unwindstack