Add new Mach-O reader class

src/common/mac/macho_reader.h

Index: src/common/mac/macho_reader.h
===================================================================
new file mode 100644
--- src/common/mac/macho_reader.h	(revision 0)
+++ src/common/mac/macho_reader.h	(working copy)
@@ -0,0 +1,458 @@
+// -*- mode: C++ -*-
+
+// Copyright (c) 2010, Google Inc.
+// All rights reserved.
+//
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//     * Redistributions of source code must retain the above copyright
+// notice, this list of conditions and the following disclaimer.
+//     * Redistributions in binary form must reproduce the above
+// copyright notice, this list of conditions and the following disclaimer
+// in the documentation and/or other materials provided with the
+// distribution.
+//     * Neither the name of Google Inc. nor the names of its
+// contributors may be used to endorse or promote products derived from
+// this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+// Original author: Jim Blandy <jimb@mozilla.com> <jimb@red-bean.com>
+
+// macho_reader.h: A class for parsing Mach-O files.
+
+#ifndef BREAKPAD_COMMON_MAC_MACHO_READER_H_
+#define BREAKPAD_COMMON_MAC_MACHO_READER_H_
+
+#include <mach-o/loader.h>
+#include <mach-o/fat.h>
+#include <stdint.h>
+#include <stdlib.h>
+#include <unistd.h>
+
+#include <map>
+#include <string>
+
+#include "common/byte_cursor.h"
+
+namespace google_breakpad {
+namespace mach_o {
+
+using std::map;
+using std::string;
+
+// The Mac headers don't specify particular types for these groups of
+// constants, but defining them here provides some documentation
+// value.  We also give them the same width as the fields in which
+// they appear, which makes them a bit easier to use with ByteCursors.
+typedef uint32_t Magic;
+typedef uint32_t FileType;
+typedef uint32_t FileFlags;
+typedef uint32_t LoadCommandType;
+typedef uint32_t SegmentFlags;
+typedef uint32_t SectionFlags;
+
+// A parser for fat binary files, used to store universal binaries.
+// When applied to a (non-fat) Mach-O file, this behaves as if the
+// file were a fat file containing a single object file.
+class FatReader {
+ public:
+
+  // A class for reporting errors found while parsing fat binary files. The
+  // default definitions of these methods print messages to stderr.
+  class Reporter {
+   public:
+    // Create a reporter that attributes problems to |filename|.
+    explicit Reporter(const string &filename) : filename_(filename) { }
+
+    virtual ~Reporter() { }
+
+    // The data does not begin with a fat binary or Mach-O magic number.
+    // This is a fatal error.
+    virtual void BadHeader();
+
+    // The Mach-O fat binary file ends abruptly, without enough space
+    // to contain an object file it claims is present.
+    virtual void MisplacedObjectFile();
+
+    // The file ends abruptly: either it is not large enough to hold a
+    // complete header, or the header implies that contents are present
+    // beyond the actual end of the file.
+    virtual void TooShort();
+  
+   private:
+    // The filename to which the reader should attribute problems.
+    string filename_;
+  };
+
+  // Create a fat binary file reader that uses |reporter| to report problems.
+  explicit FatReader(Reporter *reporter)
+      : reporter_(reporter), object_files_(), object_files_count_(0) { }
+  ~FatReader();
+  
+  // Read the |size| bytes at |buffer| as a fat binary file. On success,
+  // return true; on failure, report the problem to reporter_ and return
+  // false.
+  //
+  // If the data is a plain Mach-O file, rather than a fat binary file,
+  // then the reader behaves as if it had found a fat binary file whose
+  // single object file is the Mach-O file.
+  bool Read(const uint8_t *buffer, size_t size);
+
+  // Return an array of 'struct fat_arch' structures describing the
+  // object files present in this fat binary file. Set |size| to the
+  // number of elements in the array.
+  //
+  // Assuming Read returned true, the entries are validated: it is
+  // safe to assume that the offsets and sizes in each 'struct
+  // fat_arch' refer to subranges of the bytes passed to Read.
+  //
+  // The array is owned by this FatReader instance; it will be freed when
+  // this FatReader is destroyed.
+  //
+  // This function returns a C-style array instead of a vector to make it
+  // possible to use the result with OS X functions like NXFindBestFatArch,
+  // so that the symbol dumper will behave consistently with other OS X
+  // utilities that work with fat binaries.
+  struct fat_arch *object_files(size_t *count) const { 
+    *count = object_files_count_;
+    return object_files_;
+  }
+
+ private:
+  // We use this to report problems parsing the file's contents. (WEAK)
+  Reporter *reporter_;
+
+  // The contents of the fat binary or Mach-O file we're parsing. We do not
+  // own the storage it refers to.
+  ByteBuffer buffer_;
+
+  // The magic number of this binary, in host byte order.
+  Magic magic_;
+
+  // The list of object files in this binary.  It would be nice to use
+  // vector here, but our clients want to be able to use
+  // NXFindBestFatArch, so it's really best to just do things old-school.
+  struct fat_arch *object_files_;

[Mark Mentovai, 2010/06/16 16:57:41]

If object_files_ is a std::vector<struct fat_arch>, then &object_files_[0]
should still return a struct fat_arch* suitable for use with NXFindBestFatArch.

(Assuming, as always with std::vector, that you are careful to not use &v[0]
notation when v.size() == 0.)

If that works for you, it seems better than doing things old-school and doing
that malloc with the ugly cast. It would also let you get rid of the destructor,
and you wouldn’t need to track object_files_count_ separately.

+
+  // The number of array entries object_files_ refers to.
+  size_t object_files_count_;  // fat_header.nfat_arch
+};
+
+// A segment in a Mach-O file. All these fields have been byte-swapped as
+// appropriate for use by the executing architecture.
+struct Segment {
+  // The ByteBuffers below point into the bytes passed to the Reader that
+  // created this Segment.
+
+  ByteBuffer section_list;    // This segment's section list.
+  ByteBuffer contents;        // This segment's contents.
+
+  // This segment's name.
+  string name;
+
+  // The address at which this segment should be loaded in memory. If
+  // bits_64 is false, only the bottom 32 bits of this value are valid.
+  uint64_t vmaddr;
+
+  // The size of this segment when loaded into memory. This may be larger
+  // than contents.Size(), in which case the extra area will be
+  // initialized with zeros. If bits_64 is false, only the bottom 32 bits
+  // of this value are valid.
+  uint64_t vmsize;
+
+  // The maximum and initial VM protection of this segment's contents.
+  uint32_t maxprot;
+  uint32_t initprot;
+  
+  // The number of sections in section_list.
+  uint32_t nsects;
+
+  // Flags describing this segment, from SegmentFlags.
+  uint32_t flags;
+
+  // True if this is a 64-bit section; false if it is a 32-bit section.
+  bool bits_64;
+};
+
+// A section in a Mach-O file. All these fields have been byte-swapped as
+// appropriate for use by the executing architecture.
+struct Section {
+  // This section's contents. This points into the bytes passed to the
+  // Reader that created this Section.
+  ByteBuffer contents;
+
+  // This section's name.
+  string section_name;  // section[_64].sectname
+  // The name of the segment this section belongs to.
+  string segment_name;  // section[_64].segname
+
+  // The address at which this section's contents should be loaded in
+  // memory. If bits_64 is false, only the bottom 32 bits of this value
+  // are valid.
+  uint64_t address;
+
+  // The contents of this section should be loaded into memory at an
+  // address which is a multiple of (two raised to this power).
+  uint32_t align;
+
+  // Flags from SectionFlags describing the section's contents.
+  uint32_t flags;
+
+  // We don't support reading relocations yet.
+
+  // True if this is a 64-bit section; false if it is a 32-bit section.
+  bool bits_64;
+};
+
+// A map from section names to Sections.
+typedef map<string, Section> SectionMap;
+
+// A reader for a Mach-O file.
+//
+// This does not handle fat binaries; see FatReader above. FatReader
+// provides a friendly interface for parsing data that could be either a
+// fat binary or a Mach-O file.
+class Reader {
+ public:
+
+  // A class for reporting errors found while parsing Mach-O files. The
+  // default definitions of these member functions print messages to
+  // stderr.
+  class Reporter {
+   public:
+    // Create a reporter that attributes problems to |filename|.
+    explicit Reporter(const string &filename) : filename_(filename) { }
+    virtual ~Reporter() { }
+
+    // Reporter functions for fatal errors return void; the reader will
+    // definitely return an error to its caller after calling them
+
+    // The data does not begin with a Mach-O magic number, or the magic
+    // number does not match the expected value for the cpu architecture.
+    // This is a fatal error.
+    virtual void BadHeader();
+
+    // The data contained in a Mach-O fat binary (|cpu_type|, |cpu_subtype|)
+    // does not match the expected CPU architecture
+    // (|expected_cpu_type|, |expected_cpu_subtype|).
+    virtual void CPUTypeMismatch(cpu_type_t cpu_type,
+                                 cpu_subtype_t cpu_subtype,
+                                 cpu_type_t expected_cpu_type,
+                                 cpu_subtype_t expected_cpu_subtype);
+
+    // The file ends abruptly: either it is not large enough to hold a
+    // complete header, or the header implies that contents are present
+    // beyond the actual end of the file.
+    virtual void HeaderTruncated();
+
+    // The file's load command region, as given in the Mach-O header, is
+    // too large for the file.
+    virtual void LoadCommandRegionTruncated();
+
+    // The file's Mach-O header claims the file contains |claimed| load
+    // commands, but the I'th load command, of type |type|, extends beyond
+    // the end of the load command region, as given by the Mach-O header.
+    // If |type| is zero, the command's type was unreadable.
+    virtual void LoadCommandsOverrun(size_t claimed, size_t i,
+                                     LoadCommandType type);
+
+    // The contents of the |i|'th load command, of type |type|, extend beyond
+    // the size given in the load command's header.
+    virtual void LoadCommandTooShort(size_t i, LoadCommandType type);
+
+    // The LC_SEGMENT or LC_SEGMENT_64 load command for the segment named
+    // |name| is too short to hold the sections that its header says it does.
+    // (This more specific than LoadCommandTooShort.)
+    virtual void SectionsMissing(const string &name);
+
+    // The segment named |name| claims that its contents lie beyond the end
+    // of the file.
+    virtual void MisplacedSegmentData(const string &name);
+
+    // The section named |section| in the segment named |segment| claims that
+    // its contents do not lie entirely within the segment.
+    virtual void MisplacedSectionData(const string &section,
+                                      const string &segment);
+
+    // The LC_SYMTAB command claims that symbol table contents are located
+    // beyond the end of the file.
+    virtual void MisplacedSymbolTable();
+
+    // An attempt was made to read a Mach-O file of the unsupported
+    // CPU architecture |cpu_type|.
+    virtual void UnsupportedCPUType(cpu_type_t cpu_type);
+
+   private:
+    string filename_;
+  };
+
+  // A handler for sections parsed from a segment. The WalkSegmentSections
+  // member function accepts an instance of this class, and applies it to
+  // each section defined in a given segment.
+  class SectionHandler {
+   public:
+    virtual ~SectionHandler() { }
+
+    // Called to report that the segment's section list contains |section|.
+    // This should return true if the iteration should continue, or false
+    // if it should stop.
+    virtual bool HandleSection(const Section &section) = 0;
+  };
+
+  // A handler for the load commands in a Mach-O file.
+  class LoadCommandHandler {
+   public:
+    LoadCommandHandler() { }
+    virtual ~LoadCommandHandler() { }
+
+    // When called from WalkLoadCommands, the following handler functions
+    // should return true if they wish to continue iterating over the load
+    // command list, or false if they wish to stop iterating.
+    //
+    // When called from LoadCommandIterator::Handle or Reader::Handle,
+    // these functions' return values are simply passed through to Handle's
+    // caller.
+    //
+    // The definitions provided by this base class simply return true; the
+    // default is to silently ignore sections whose member functions the
+    // subclass doesn't override.
+
+    // COMMAND is load command we don't recognize. We provide only the
+    // command type and a ByteBuffer enclosing the command's data (If we
+    // cannot parse the command type or its size, we call
+    // reporter_->IncompleteLoadCommand instead.)
+    virtual bool UnknownCommand(LoadCommandType type,
+                                const ByteBuffer &contents) {
+      return true;
+    }
+
+    // The load command is LC_SEGMENT or LC_SEGMENT_64, defining a segment
+    // with the properties given in |segment|.
+    virtual bool SegmentCommand(const Segment &segment) {
+      return true;
+    }
+
+    // The load command is LC_SYMTAB. |entries| holds the array of nlist
+    // entries, and |names| holds the strings the entries refer to.
+    virtual bool SymtabCommand(const ByteBuffer &entries,
+                               const ByteBuffer &names) {
+      return true;
+    }
+
+    // Add handler functions for more load commands here as needed.
+  };
+
+  // Create a Mach-O file reader that reports problems to |reporter|.
+  explicit Reader(Reporter *reporter)
+      : reporter_(reporter) { }
+
+  // Read the given data as a Mach-O file. The reader retains pointers
+  // into the data passed, so the data should live as long as the reader
+  // does. On success, return true; on failure, return false.
+  //
+  // At most one of these functions should be invoked once on each Reader
+  // instance.
+  bool Read(const uint8_t *buffer,
+            size_t size,
+            cpu_type_t expected_cpu_type,
+            cpu_subtype_t expected_cpu_subtype);
+  bool Read(const ByteBuffer &buffer,
+            cpu_type_t expected_cpu_type,
+            cpu_subtype_t expected_cpu_subtype) {
+    return Read(buffer.start,
+                buffer.Size(),
+                expected_cpu_type,
+                expected_cpu_subtype); 
+  }
+
+  // Return this file's characteristics, as found in the Mach-O header.
+  cpu_type_t    cpu_type()    const { return cpu_type_; }
+  cpu_subtype_t cpu_subtype() const { return cpu_subtype_; }
+  FileType      file_type()   const { return file_type_; }
+  FileFlags     flags()       const { return flags_; }
+
+  // Return true if this is a 64-bit Mach-O file, false if it is a 32-bit
+  // Mach-O file.
+  bool bits_64() const { return bits_64_; }
+
+  // Return true if this is a big-endian Mach-O file, false if it is
+  // little-endian.
+  bool big_endian() const { return big_endian_; }
+
+  // Apply |handler| to each load command in this Mach-O file, stopping when
+  // a handler function returns false. If we encounter a malformed load
+  // command, report it via reporter_ and return false. Return true if all
+  // load commands were parseable and all handlers returned true.
+  bool WalkLoadCommands(LoadCommandHandler *handler) const;
+
+  // Set |segment| to describe the segment named |name|, if present. If
+  // found, |segment|'s byte buffers refer to a subregion of the bytes
+  // passed to Read. If we find the section, return true; otherwise,
+  // return false.
+  bool FindSegment(const string &name, Segment *segment) const;
+
+  // Apply |handler| to each section defined in |segment|. If |handler| returns
+  // false, stop iterating and return false. If all calls to |handler| return
+  // true and we reach the end of the section list, return true.
+  bool WalkSegmentSections(const Segment &segment, SectionHandler *handler)
+    const;
+
+  // Clear |section_map| and then populate it with a map of the sections
+  // in |segment|, from section names to Section structures.
+  // Each Section's contents refer to bytes in |segment|'s contents.
+  // On success, return true; if a problem occurs, report it and return false.
+  bool MapSegmentSections(const Segment &segment, SectionMap *section_map)
+    const;
+
+ private:
+  // Used internally.
+  class SegmentFinder;
+  class SectionMapper;
+
+  // We use this to report problems parsing the file's contents. (WEAK)
+  Reporter *reporter_;
+
+  // The contents of the Mach-O file we're parsing. We do not own the
+  // storage it refers to.
+  ByteBuffer buffer_;
+
+  // True if this file is big-endian.
+  bool big_endian_;
+
+  // True if this file is a 64-bit Mach-O file.
+  bool bits_64_;
+
+  // This file's cpu type and subtype.
+  cpu_type_t cpu_type_;       // mach_header[_64].cputype
+  cpu_subtype_t cpu_subtype_; // mach_header[_64].cpusubtype

[Mark Mentovai, 2010/06/16 16:57:41]

Two spaces between the ; and //. Also on 449. Also on the other comments here if
you intend to keep them lined up.

+
+  // This file's type.
+  FileType file_type_;        // mach_header[_64].filetype
+
+  // The region of buffer_ occupied by load commands.
+  ByteBuffer load_commands_;
+
+  // The number of load commands in load_commands_.
+  size_t load_command_count_; // mach_header[_64].ncmds
+
+  // This file's header flags.
+  FileFlags flags_;
+};
+
+}  // namespace mach_o
+}  // namespace google_breakpad
+
+#endif  // BREAKPAD_COMMON_MAC_MACHO_READER_H_