Add MachOImageSegmentReader

util/mac/mach_o_image_segment_reader.cc

Index: util/mac/mach_o_image_segment_reader.cc
diff --git a/util/mac/mach_o_image_segment_reader.cc b/util/mac/mach_o_image_segment_reader.cc
new file mode 100644
index 0000000000000000000000000000000000000000..7469497fe4ff681dbb6c977d8e172762a5a36ef4
--- /dev/null
+++ b/util/mac/mach_o_image_segment_reader.cc
@@ -0,0 +1,230 @@
+// Copyright 2014 The Crashpad Authors. All rights reserved.
+//
+// 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 "util/mac/mach_o_image_segment_reader.h"
+
+#include <mach-o/loader.h>
+
+#include "base/logging.h"
+#include "base/strings/stringprintf.h"
+#include "util/mac/checked_mach_address_range.h"
+#include "util/mac/process_reader.h"
+#include "util/stdlib/strnlen.h"
+
+namespace crashpad {
+
+namespace {
+
+std::string SizeLimitedCString(const char* c_string, size_t max_length) {
+  return std::string(c_string, strnlen(c_string, max_length));
+}
+
+}  // namespace
+
+MachOImageSegmentReader::MachOImageSegmentReader()
+    : segment_command_(), sections_(), section_map_(), initialized_() {
+}
+
+MachOImageSegmentReader::~MachOImageSegmentReader() {
+}
+
+bool MachOImageSegmentReader::Initialize(ProcessReader* process_reader,
+                                         mach_vm_address_t load_command_address,
+                                         const std::string& load_command_info) {
+  INITIALIZATION_STATE_SET_INITIALIZING(initialized_);
+
+  if (!segment_command_.Read(process_reader, load_command_address)) {
+    LOG(WARNING) << "could not read segment_command" << load_command_info;
+    return false;
+  }
+
+  const uint32_t kExpectedSegmentCommand =
+      process_reader->Is64Bit() ? LC_SEGMENT_64 : LC_SEGMENT;
+  DCHECK_EQ(segment_command_.cmd, kExpectedSegmentCommand);
+  DCHECK_GE(segment_command_.cmdsize, segment_command_.Size());
+  const size_t kSectionStructSize =
+      process_types::section::ExpectedSize(process_reader);
+  const size_t kRequiredSize =
+      segment_command_.Size() + segment_command_.nsects * kSectionStructSize;
+  if (segment_command_.cmdsize < kRequiredSize) {
+    LOG(WARNING) << base::StringPrintf(
+                        "segment command cmdsize 0x%x insufficient for %u "
+                        "section%s (0x%zx)",
+                        segment_command_.cmdsize,
+                        segment_command_.nsects,
+                        segment_command_.nsects == 1 ? "" : "s",
+                        kRequiredSize) << load_command_info;
+    return false;
+  }
+
+  std::string segment_name = NameInternal();
+  std::string segment_info = base::StringPrintf(
+      ", segment %s%s", segment_name.c_str(), load_command_info.c_str());
+
+  // This checks the unslid segment range. The slid range (as loaded into
+  // memory) will be checked later by MachOImageReader.
+  CheckedMachAddressRange segment_range(
+      process_reader, segment_command_.vmaddr, segment_command_.vmsize);
+  if (!segment_range.IsValid()) {
+    LOG(WARNING) << base::StringPrintf("invalid segment range 0x%llx + 0x%llx",
+                                       segment_command_.vmaddr,
+                                       segment_command_.vmsize) << segment_info;
+    return false;
+  }
+
+  sections_.resize(segment_command_.nsects);
+  if (!process_types::section::ReadArrayInto(
+          process_reader,
+          load_command_address + segment_command_.Size(),
+          segment_command_.nsects,
+          &sections_[0])) {
+    LOG(WARNING) << "could not read sections" << segment_info;
+    return false;
+  }
+
+  for (size_t section_index = 0;
+       section_index < sections_.size();
+       ++section_index) {
+    const process_types::section& section = sections_[section_index];
+    std::string section_segment_name = SegmentNameString(section.segname);
+    std::string section_name = SectionNameString(section.sectname);
+    std::string section_full_name =
+        SegmentAndSectionNameString(section.segname, section.sectname);
+
+    std::string section_info = base::StringPrintf(", section %s %zu/%zu%s",
+                                                  section_full_name.c_str(),
+                                                  section_index,
+                                                  sections_.size(),
+                                                  load_command_info.c_str());
+
+    if (section_segment_name != segment_name) {
+      LOG(WARNING) << "section.segname incorrect in segment " << segment_name
+                   << section_info;
+      return false;
+    }
+
+    CheckedMachAddressRange section_range(
+        process_reader, section.addr, section.size);
+    if (!section_range.IsValid()) {
+      LOG(WARNING) << base::StringPrintf(
+                          "invalid section range 0x%llx + 0x%llx",
+                          section.addr,
+                          section.size) << section_info;
+      return false;
+    }
+
+    if (!segment_range.ContainsRange(section_range)) {
+      LOG(WARNING) << base::StringPrintf(
+                          "section at 0x%llx + 0x%llx outside of segment at "
+                          "0x%llx + 0x%llx",
+                          section.addr,
+                          section.size,
+                          segment_command_.vmaddr,
+                          segment_command_.vmsize) << section_info;
+      return false;
+    }
+
+    uint32_t section_type = (section.flags & SECTION_TYPE);
+    bool zero_fill = section_type == S_ZEROFILL ||
+                     section_type == S_GB_ZEROFILL ||
+                     section_type == S_THREAD_LOCAL_ZEROFILL;
+
+    // Zero-fill section types aren’t mapped from the file, so their |offset|
+    // fields are irrelevant and are typically 0.
+    if (!zero_fill &&
+        section.offset - segment_command_.fileoff !=
+            section.addr - segment_command_.vmaddr) {
+      LOG(WARNING) << base::StringPrintf(
+                          "section type 0x%x at 0x%llx has unexpected offset "
+                          "0x%x in segment at 0x%llx with offset 0x%llx",
+                          section_type,
+                          section.addr,
+                          section.offset,
+                          segment_command_.vmaddr,
+                          segment_command_.fileoff) << section_info;
+      return false;
+    }
+
+    const auto& iterator = section_map_.find(section_name);
+    if (iterator != section_map_.end()) {
+      LOG(WARNING) << base::StringPrintf("duplicate section name at %zu",
+                                         iterator->second) << section_info;
+      return false;
+    }
+
+    section_map_[section_name] = section_index;
+  }
+
+  INITIALIZATION_STATE_SET_VALID(initialized_);
+  return true;
+}
+
+std::string MachOImageSegmentReader::Name() const {
+  INITIALIZATION_STATE_DCHECK_VALID(initialized_);
+  return NameInternal();
+}
+
+const process_types::section* MachOImageSegmentReader::GetSectionByName(
+    const std::string& section_name) const {
+  INITIALIZATION_STATE_DCHECK_VALID(initialized_);
+
+  const auto& iterator = section_map_.find(section_name);
+  if (iterator == section_map_.end()) {
+    return NULL;
+  }
+
+  return &sections_[iterator->second];
+}
+
+const process_types::section* MachOImageSegmentReader::GetSectionAtIndex(
+    size_t index) const {
+  INITIALIZATION_STATE_DCHECK_VALID(initialized_);
+  CHECK_LT(index, sections_.size());
+  return &sections_[index];
+}
+
+// static
+std::string MachOImageSegmentReader::SegmentNameString(
+    const char* segment_name_c) {
+  // This is used to interpret the segname field of both the segment_command and
+  // section structures, so be sure that they’re identical.
+  COMPILE_ASSERT(sizeof(process_types::segment_command::segname) ==
+                     sizeof(process_types::section::segname),
+                 sizes_must_be_equal);
+
+  return SizeLimitedCString(segment_name_c,
+                            sizeof(process_types::segment_command::segname));
+}
+
+// static
+std::string MachOImageSegmentReader::SectionNameString(
+    const char* section_name_c) {
+  return SizeLimitedCString(section_name_c,
+                            sizeof(process_types::section::sectname));
+}
+
+// static
+std::string MachOImageSegmentReader::SegmentAndSectionNameString(
+    const char* segment_name_c,
+    const char* section_name_c) {
+  return base::StringPrintf("%s,%s",
+                            SegmentNameString(segment_name_c).c_str(),
+                            SectionNameString(section_name_c).c_str());
+}
+
+std::string MachOImageSegmentReader::NameInternal() const {
+  return SegmentNameString(segment_command_.segname);
+}
+
+}  // namespace crashpad