Add MachOImageReader and its test

util/mac/mach_o_image_reader.cc

+// 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_reader.h"
+
+#include <mach-o/loader.h>
+#include <mach-o/nlist.h>
+#include <string.h>
+
+#include <limits>
+#include <vector>
+
+#include "base/logging.h"
+#include "base/strings/stringprintf.h"
+#include "util/mac/checked_mach_address_range.h"
+#include "util/mac/mach_o_image_segment_reader.h"
+#include "util/mac/process_reader.h"
+
+namespace {
+
+const uint32_t kInvalidSegmentIndex = std::numeric_limits<uint32_t>::max();
+
+}  // namespace
+
+namespace crashpad {
+
+MachOImageReader::MachOImageReader()
+    : segments_(),
+      segment_map_(),
+      module_info_(),
+      dylinker_name_(),
+      uuid_(),
+      address_(0),
+      size_(0),
+      slide_(0),
+      source_version_(0),
+      symtab_command_(),
+      dysymtab_command_(),
+      id_dylib_command_(),
+      process_reader_(NULL),
+      file_type_(0),
+      initialized_() {
+}
+
+MachOImageReader::~MachOImageReader() {
+}
+
+bool MachOImageReader::Initialize(ProcessReader* process_reader,
+                                  mach_vm_address_t address,
+                                  const std::string& name) {
+  INITIALIZATION_STATE_SET_INITIALIZING(initialized_);
+
+  process_reader_ = process_reader;
+  address_ = address;
+
+  module_info_ =
+      base::StringPrintf(", module %s, address 0x%llx", name.c_str(), address);
+
+  process_types::mach_header mach_header;
+  if (!mach_header.Read(process_reader, address)) {
+    LOG(WARNING) << "could not read mach_header" << module_info_;
+    return false;
+  }
+
+  const bool is_64_bit = process_reader->Is64Bit();
+  const uint32_t kExpectedMagic = is_64_bit ? MH_MAGIC_64 : MH_MAGIC;
+  if (mach_header.magic != kExpectedMagic) {
+    LOG(WARNING) << base::StringPrintf("unexpected mach_header::magic 0x%08x",
+                                       mach_header.magic) << module_info_;
+    return false;
+  }
+
+  file_type_ = mach_header.filetype;
+
+  const uint32_t kExpectedSegmentCommand =
+      is_64_bit ? LC_SEGMENT_64 : LC_SEGMENT;
+  const uint32_t kUnexpectedSegmentCommand =
+      is_64_bit ? LC_SEGMENT : LC_SEGMENT_64;
+
+  const struct {
+    // Which method to call when encountering a load command matching |command|.
+    bool (MachOImageReader::*function)(mach_vm_address_t, const std::string&);
+
+    // The minimum size that may be allotted to store the load command.
+    size_t size;
+
+    // The load command to match.
+    uint32_t command;
+
+    // True if the load command must not appear more than one time.
+    bool singleton;
+  } kLoadCommandReaders[] = {
+    {
+      &MachOImageReader::ReadSegmentCommand,
+      process_types::segment_command::ExpectedSize(process_reader),
+      kExpectedSegmentCommand,
+      false,
+    },
+    {
+      &MachOImageReader::ReadSymTabCommand,
+      process_types::symtab_command::ExpectedSize(process_reader),
+      LC_SYMTAB,
+      true,
+    },
+    {
+      &MachOImageReader::ReadDySymTabCommand,
+      process_types::symtab_command::ExpectedSize(process_reader),
+      LC_DYSYMTAB,
+      true,
+    },
+    {
+      &MachOImageReader::ReadIdDylibCommand,
+      process_types::dylib_command::ExpectedSize(process_reader),
+      LC_ID_DYLIB,
+      true,
+    },
+    {
+      &MachOImageReader::ReadDylinkerCommand,
+      process_types::dylinker_command::ExpectedSize(process_reader),
+      LC_LOAD_DYLINKER,
+      true,
+    },
+    {
+      &MachOImageReader::ReadDylinkerCommand,
+      process_types::dylinker_command::ExpectedSize(process_reader),
+      LC_ID_DYLINKER,
+      true,
+    },
+    {
+      &MachOImageReader::ReadUUIDCommand,
+      process_types::uuid_command::ExpectedSize(process_reader),
+      LC_UUID,
+      true,
+    },
+    {
+      &MachOImageReader::ReadSourceVersionCommand,
+      process_types::source_version_command::ExpectedSize(process_reader),
+      LC_SOURCE_VERSION,
+      true,
+    },
+
+    // When reading a 64-bit process, no 32-bit segment commands should be
+    // present, and vice-versa.
+    {
+      &MachOImageReader::ReadUnexpectedCommand,
+      process_types::load_command::ExpectedSize(process_reader),
+      kUnexpectedSegmentCommand,
+      false,
+    },
+  };
+
+  // This vector is parallel to the kLoadCommandReaders array, and tracks
+  // whether a singleton load command matching the |command| field has been
+  // found yet.
+  std::vector<uint32_t> singleton_indices(arraysize(kLoadCommandReaders),
+                                          kInvalidSegmentIndex);
+
+  size_t offset = mach_header.Size();
+  const mach_vm_address_t kLoadCommandAddressLimit =
+      address + offset + mach_header.sizeofcmds;
+
+  for (uint32_t load_command_index = 0;
+       load_command_index < mach_header.ncmds;
+       ++load_command_index) {
+    mach_vm_address_t load_command_address = address + offset;
+    std::string load_command_info = base::StringPrintf(", load command %u/%u%s",
+                                                       load_command_index,
+                                                       mach_header.ncmds,
+                                                       module_info_.c_str());
+
+    process_types::load_command load_command;
+
+    // Make sure that the basic load command structure doesn’t overflow the
+    // space allotted for load commands.
+    if (load_command_address + load_command.ExpectedSize(process_reader) >
+        kLoadCommandAddressLimit) {

[Robert Sesek, 2014/09/04 13:18:41]

nit: indent +4

+      LOG(WARNING) << base::StringPrintf(
+                          "load_command at 0x%llx exceeds sizeofcmds 0x%x",
+                          load_command_address,
+                          mach_header.sizeofcmds) << load_command_info;
+      return false;
+    }
+
+    if (!load_command.Read(process_reader, load_command_address)) {
+      LOG(WARNING) << "could not read load_command" << load_command_info;
+      return false;
+    }
+
+    load_command_info = base::StringPrintf(", load command 0x%x %u/%u%s",
+                                           load_command.cmd,
+                                           load_command_index,
+                                           mach_header.ncmds,
+                                           module_info_.c_str());
+
+    // Now that the load command’s stated size is known, make sure that it
+    // doesn’t overflow the space allotted for load commands.
+    if (load_command_address + load_command.cmdsize >
+        kLoadCommandAddressLimit) {

[Robert Sesek, 2014/09/04 13:18:41]

+4

+      LOG(WARNING)
+          << base::StringPrintf(
+                 "load_command at 0x%llx cmdsize 0x%x exceeds sizeofcmds 0x%x",
+                 load_command_address,
+                 load_command.cmdsize,
+                 mach_header.sizeofcmds) << load_command_info;
+      return false;
+    }
+
+    for (size_t reader_index = 0;
+         reader_index < arraysize(kLoadCommandReaders);
+         ++reader_index) {
+      if (load_command.cmd == kLoadCommandReaders[reader_index].command) {

[Robert Sesek, 2014/09/04 13:18:41]

Flip this to a != and continue instead? Would reduce some nesting.

+        if (load_command.cmdsize < kLoadCommandReaders[reader_index].size) {
+          LOG(WARNING)
+              << base::StringPrintf(
+                     "load command cmdsize 0x%x insufficient for 0x%zx",
+                     load_command.cmdsize,
+                     kLoadCommandReaders[reader_index].size)
+              << load_command_info;
+          return false;
+        }
+
+        if (kLoadCommandReaders[reader_index].singleton) {
+          if (singleton_indices[reader_index] != kInvalidSegmentIndex) {
+            LOG(WARNING) << "duplicate load command at "
+                         << singleton_indices[reader_index]
+                         << load_command_info;
+            return false;
+          }
+
+          singleton_indices[reader_index] = load_command_index;
+        }
+
+        if (!((this)->*(kLoadCommandReaders[reader_index].function))(
+                load_command_address, load_command_info)) {
+          return false;
+        }
+
+        break;
+      }
+    }
+
+    offset += load_command.cmdsize;
+  }
+
+  // This was already checked for the unslid values while the segments were
+  // read, but now that the slide is known, check the slid values too. The
+  // individual sections don’t need to be checked because they were verified to
+  // be contained within their respective segments when the segments were read.
+  for (const MachOImageSegmentReader* segment : segments_) {
+    mach_vm_address_t slid_segment_address = segment->vmaddr();
+    mach_vm_size_t slid_segment_size = segment->vmsize();
+    if (segment->SegmentSlides()) {
+      slid_segment_address += slide_;
+    } else {
+      // The non-sliding __PAGEZERO segment extends instead of slides.
+      slid_segment_size += slide_;
+    }
+    CheckedMachAddressRange slid_segment_range(
+        process_reader_, slid_segment_address, slid_segment_size);
+    if (!slid_segment_range.IsValid()) {
+      LOG(WARNING) << base::StringPrintf(
+                          "invalid slid segment range 0x%llx + 0x%llx, "
+                          "segment ",
+                          slid_segment_address,
+                          slid_segment_size) << segment->Name() << module_info_;
+      return false;
+    }
+  }
+
+  if (!segment_map_.count(SEG_TEXT)) {
+    // The __TEXT segment is required. Even a module with no executable code
+    // will have a __TEXT segment encompassing the Mach-O header and load
+    // commands. Without a __TEXT segment, |size_| will not have been computed.
+    LOG(WARNING) << "no " SEG_TEXT " segment" << module_info_;
+    return false;
+  }
+
+  if (mach_header.filetype == MH_DYLIB && !id_dylib_command_) {
+    // This doesn’t render a module unusable, it’s just weird and worth noting.
+    LOG(INFO) << "no LC_ID_DYLIB" << module_info_;
+  }
+
+  INITIALIZATION_STATE_SET_VALID(initialized_);
+  return true;
+}
+
+const MachOImageSegmentReader* MachOImageReader::GetSegmentByName(
+    const std::string& segment_name,
+    mach_vm_address_t* address,
+    mach_vm_size_t* size) const {
+  INITIALIZATION_STATE_DCHECK_VALID(initialized_);
+
+  const auto& iterator = segment_map_.find(segment_name);
+  if (iterator == segment_map_.end()) {
+    return NULL;
+  }
+
+  const MachOImageSegmentReader* segment = segments_[iterator->second];
+  if (address) {
+    *address = segment->vmaddr() + (segment->SegmentSlides() ? slide_ : 0);
+  }
+  if (size) {
+    *size = segment->vmsize() + (segment->SegmentSlides() ? 0 : slide_);

[Robert Sesek, 2014/09/04 13:18:41]

This is because if the segment doesn't slide, it grows, right? Is vmsize always
zero in this case?

Recommend leaving a comment here, since this condition took a while to vet.

+  }
+
+  return segment;
+}
+
+const process_types::section* MachOImageReader::GetSectionByName(
+    const std::string& segment_name,
+    const std::string& section_name,
+    mach_vm_address_t* address) const {
+  INITIALIZATION_STATE_DCHECK_VALID(initialized_);
+
+  const MachOImageSegmentReader* segment =
+      GetSegmentByName(segment_name, NULL, NULL);
+  if (!segment) {
+    return NULL;
+  }
+
+  const process_types::section* section =
+      segment->GetSectionByName(section_name);
+  if (!section) {
+    return NULL;
+  }
+
+  if (address) {
+    *address = section->addr + (segment->SegmentSlides() ? slide_ : 0);
+  }
+
+  return section;
+}
+
+const process_types::section* MachOImageReader::GetSectionAtIndex(
+    size_t index,
+    mach_vm_address_t* address) const {
+  INITIALIZATION_STATE_DCHECK_VALID(initialized_);
+
+  COMPILE_ASSERT(NO_SECT == 0, no_sect_must_be_zero);
+  if (index == NO_SECT) {
+    LOG(WARNING) << "section index " << index << " out of range";
+    return NULL;
+  }
+
+  // Switch to a more comfortable 0-based index.
+  size_t local_index = index - 1;
+
+  for (const MachOImageSegmentReader* segment : segments_) {
+    size_t nsects = segment->nsects();
+    if (local_index < nsects) {
+      const process_types::section* section =
+          segment->GetSectionAtIndex(local_index);
+
+      if (address) {
+        *address = section->addr + (segment->SegmentSlides() ? slide_ : 0);
+      }
+
+      return section;
+    }
+
+    local_index -= nsects;
+  }
+
+  LOG(WARNING) << "section index " << index << " out of range";
+  return NULL;
+}
+
+uint32_t MachOImageReader::DylibVersion() const {
+  INITIALIZATION_STATE_DCHECK_VALID(initialized_);
+  DCHECK_EQ(FileType(), static_cast<uint32_t>(MH_DYLIB));
+
+  if (id_dylib_command_) {
+    return id_dylib_command_->dylib_current_version;
+  }
+
+  // In case this was a weird dylib without an LC_ID_DYLIB command.
+  return 0;
+}
+
+void MachOImageReader::UUID(struct UUID* uuid) const {
+  INITIALIZATION_STATE_DCHECK_VALID(initialized_);
+  memcpy(uuid, &uuid_, sizeof(uuid_));
+}
+
+template <typename T>
+bool MachOImageReader::ReadLoadCommand(mach_vm_address_t load_command_address,
+                                       const std::string& load_command_info,
+                                       uint32_t expected_load_command_id,
+                                       T* load_command) {
+  if (!load_command->Read(process_reader_, load_command_address)) {
+    LOG(WARNING) << "could not read load command" << load_command_info;
+    return false;
+  }
+
+  DCHECK_GE(load_command->cmdsize, load_command->Size());
+  DCHECK_EQ(load_command->cmd, expected_load_command_id);
+  return true;
+}
+
+bool MachOImageReader::ReadSegmentCommand(
+    mach_vm_address_t load_command_address,
+    const std::string& load_command_info) {
+  MachOImageSegmentReader* segment = new MachOImageSegmentReader();
+  size_t segment_index = segments_.size();
+  segments_.push_back(segment);

[Robert Sesek, 2014/09/04 13:18:41]

"// Takes ownership."

+
+  if (!segment->Initialize(
+          process_reader_, load_command_address, load_command_info)) {
+    segments_.pop_back();
+    return false;
+  }
+
+  const std::string segment_name = segment->Name();
+  const auto& iterator = segment_map_.find(segment_name);
+  if (iterator != segment_map_.end()) {
+    LOG(WARNING) << base::StringPrintf("duplicate %s segment at %zu and %zu",
+                                       segment_name.c_str(),
+                                       iterator->second,
+                                       segment_index) << load_command_info;
+    return false;

[Robert Sesek, 2014/09/04 13:18:41]

But keep it in segments_?

+  }
+  segment_map_[segment_name] = segment_index;
+
+  mach_vm_size_t vmsize = segment->vmsize();
+
+  if (segment_name == SEG_TEXT) {
+    if (vmsize == 0) {
+      LOG(WARNING) << "zero-sized " SEG_TEXT " segment" << load_command_info;
+      return false;
+    }
+
+    mach_vm_size_t fileoff = segment->fileoff();
+    if (fileoff != 0) {
+      LOG(WARNING) << base::StringPrintf(
+                          SEG_TEXT " segment has unexpected fileoff 0x%llx",
+                          fileoff) << load_command_info;
+      return false;
+    }
+
+    size_ = vmsize;
+
+    // The slide is computed as the difference between the __TEXT segment’s
+    // preferred and actual load addresses. This is the same way that dyld
+    // computes slide. See 10.9.2 dyld-239.4/src/dyldInitialization.cpp
+    // slideOfMainExecutable().
+    slide_ = address_ - segment->vmaddr();
+  }
+
+  return true;
+}
+
+bool MachOImageReader::ReadSymTabCommand(mach_vm_address_t load_command_address,
+                                         const std::string& load_command_info) {
+  symtab_command_.reset(new process_types::symtab_command());
+  return ReadLoadCommand(load_command_address,
+                         load_command_info,
+                         LC_SYMTAB,
+                         symtab_command_.get());
+}
+
+bool MachOImageReader::ReadDySymTabCommand(
+    mach_vm_address_t load_command_address,
+    const std::string& load_command_info) {
+  dysymtab_command_.reset(new process_types::dysymtab_command());
+  return ReadLoadCommand(load_command_address,
+                         load_command_info,
+                         LC_DYSYMTAB,
+                         dysymtab_command_.get());
+}
+
+bool MachOImageReader::ReadIdDylibCommand(
+    mach_vm_address_t load_command_address,
+    const std::string& load_command_info) {
+  if (file_type_ != MH_DYLIB) {
+    LOG(WARNING) << base::StringPrintf(
+                        "LC_ID_DYLIB inappropriate in non-dylib file type 0x%x",
+                        file_type_) << load_command_info;
+    return false;
+  }
+
+  DCHECK(!id_dylib_command_);
+  id_dylib_command_.reset(new process_types::dylib_command());
+  return ReadLoadCommand(load_command_address,
+                         load_command_info,
+                         LC_ID_DYLIB,
+                         id_dylib_command_.get());
+}
+
+bool MachOImageReader::ReadDylinkerCommand(
+    mach_vm_address_t load_command_address,
+    const std::string& load_command_info) {
+  if (file_type_ != MH_EXECUTE && file_type_ != MH_DYLINKER) {
+    LOG(WARNING) << base::StringPrintf(
+                        "LC_LOAD_DYLINKER/LC_ID_DYLINKER inappropriate in file "
+                        "type 0x%x",
+                        file_type_) << load_command_info;
+    return false;
+  }
+
+  const uint32_t kExpectedCommand =
+      file_type_ == MH_DYLINKER ? LC_ID_DYLINKER : LC_LOAD_DYLINKER;
+  process_types::dylinker_command dylinker_command;
+  if (!ReadLoadCommand(load_command_address,
+                       load_command_info,
+                       kExpectedCommand,
+                       &dylinker_command)) {
+    return false;
+  }
+
+  if (!process_reader_->Memory()->ReadCStringSizeLimited(
+          load_command_address + dylinker_command.name,
+          dylinker_command.cmdsize - dylinker_command.name,
+          &dylinker_name_)) {
+    LOG(WARNING) << "could not read dylinker_command name" << load_command_info;
+    return false;
+  }
+
+  return true;
+}
+
+bool MachOImageReader::ReadUUIDCommand(mach_vm_address_t load_command_address,
+                                       const std::string& load_command_info) {
+  process_types::uuid_command uuid_command;
+  if (!ReadLoadCommand(
+          load_command_address, load_command_info, LC_UUID, &uuid_command)) {
+    return false;
+  }
+
+  uuid_.InitializeFromBytes(uuid_command.uuid);
+  return true;
+}
+
+bool MachOImageReader::ReadSourceVersionCommand(
+    mach_vm_address_t load_command_address,
+    const std::string& load_command_info) {
+  process_types::source_version_command source_version_command;
+  if (!ReadLoadCommand(load_command_address,
+                       load_command_info,
+                       LC_SOURCE_VERSION,
+                       &source_version_command)) {
+    return false;
+  }
+
+  source_version_ = source_version_command.version;
+  return true;
+}
+
+bool MachOImageReader::ReadUnexpectedCommand(
+    mach_vm_address_t load_command_address,
+    const std::string& load_command_info) {
+  LOG(WARNING) << "unexpected load command" << load_command_info;
+  return false;
+}
+
+}  // namespace crashpad