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// Copyright (c) 2010, Google Inc.
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// All rights reserved.
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// Redistribution and use in source and binary forms, with or without
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// modification, are permitted provided that the following conditions are
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// * Redistributions of source code must retain the above copyright
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// notice, this list of conditions and the following disclaimer.
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// * Redistributions in binary form must reproduce the above
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// copyright notice, this list of conditions and the following disclaimer
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// in the documentation and/or other materials provided with the
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// * Neither the name of Google Inc. nor the names of its
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// contributors may be used to endorse or promote products derived from
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// this software without specific prior written permission.
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// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
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// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
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// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
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// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
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// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
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// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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// Original author: Jim Blandy <jimb@mozilla.com> <jimb@red-bean.com>
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// macho_reader.h: A class for parsing Mach-O files.
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#ifndef BREAKPAD_COMMON_MAC_MACHO_READER_H_
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#define BREAKPAD_COMMON_MAC_MACHO_READER_H_
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#include <mach-o/loader.h>
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#include <mach-o/fat.h>
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#include "common/byte_cursor.h"
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namespace google_breakpad {
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// The Mac headers don't specify particular types for these groups of
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// constants, but defining them here provides some documentation
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// value. We also give them the same width as the fields in which
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// they appear, which makes them a bit easier to use with ByteCursors.
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typedef uint32_t Magic;
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typedef uint32_t FileType;
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typedef uint32_t FileFlags;
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typedef uint32_t LoadCommandType;
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typedef uint32_t SegmentFlags;
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typedef uint32_t SectionFlags;
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// A parser for fat binary files, used to store universal binaries.
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// When applied to a (non-fat) Mach-O file, this behaves as if the
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// file were a fat file containing a single object file.
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// A class for reporting errors found while parsing fat binary files. The
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// default definitions of these methods print messages to stderr.
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// Create a reporter that attributes problems to |filename|.
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explicit Reporter(const string &filename) : filename_(filename) { }
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virtual ~Reporter() { }
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// The data does not begin with a fat binary or Mach-O magic number.
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// This is a fatal error.
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virtual void BadHeader();
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// The Mach-O fat binary file ends abruptly, without enough space
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// to contain an object file it claims is present.
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virtual void MisplacedObjectFile();
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// The file ends abruptly: either it is not large enough to hold a
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// complete header, or the header implies that contents are present
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// beyond the actual end of the file.
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virtual void TooShort();
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// The filename to which the reader should attribute problems.
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// Create a fat binary file reader that uses |reporter| to report problems.
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explicit FatReader(Reporter *reporter) : reporter_(reporter) { }
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// Read the |size| bytes at |buffer| as a fat binary file. On success,
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// return true; on failure, report the problem to reporter_ and return
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// If the data is a plain Mach-O file, rather than a fat binary file,
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// then the reader behaves as if it had found a fat binary file whose
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// single object file is the Mach-O file.
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bool Read(const uint8_t *buffer, size_t size);
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// Return an array of 'struct fat_arch' structures describing the
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// object files present in this fat binary file. Set |size| to the
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// number of elements in the array.
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// Assuming Read returned true, the entries are validated: it is
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// safe to assume that the offsets and sizes in each 'struct
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// fat_arch' refer to subranges of the bytes passed to Read.
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// If there are no object files in this fat binary, then this
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// function can return NULL.
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// The array is owned by this FatReader instance; it will be freed when
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// this FatReader is destroyed.
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// This function returns a C-style array instead of a vector to make it
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// possible to use the result with OS X functions like NXFindBestFatArch,
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// so that the symbol dumper will behave consistently with other OS X
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// utilities that work with fat binaries.
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const struct fat_arch *object_files(size_t *count) const {
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*count = object_files_.size();
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if (object_files_.size() > 0)
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return &object_files_[0];
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// We use this to report problems parsing the file's contents. (WEAK)
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// The contents of the fat binary or Mach-O file we're parsing. We do not
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// own the storage it refers to.
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// The magic number of this binary, in host byte order.
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// The list of object files in this binary.
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// object_files_.size() == fat_header.nfat_arch
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vector<struct fat_arch> object_files_;
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// A segment in a Mach-O file. All these fields have been byte-swapped as
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// appropriate for use by the executing architecture.
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// The ByteBuffers below point into the bytes passed to the Reader that
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// created this Segment.
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ByteBuffer section_list; // This segment's section list.
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ByteBuffer contents; // This segment's contents.
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// This segment's name.
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// The address at which this segment should be loaded in memory. If
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// bits_64 is false, only the bottom 32 bits of this value are valid.
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// The size of this segment when loaded into memory. This may be larger
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// than contents.Size(), in which case the extra area will be
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// initialized with zeros. If bits_64 is false, only the bottom 32 bits
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// of this value are valid.
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// The maximum and initial VM protection of this segment's contents.
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// The number of sections in section_list.
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// Flags describing this segment, from SegmentFlags.
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// True if this is a 64-bit section; false if it is a 32-bit section.
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// A section in a Mach-O file. All these fields have been byte-swapped as
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// appropriate for use by the executing architecture.
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// This section's contents. This points into the bytes passed to the
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// Reader that created this Section.
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// This section's name.
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string section_name; // section[_64].sectname
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// The name of the segment this section belongs to.
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string segment_name; // section[_64].segname
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// The address at which this section's contents should be loaded in
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// memory. If bits_64 is false, only the bottom 32 bits of this value
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// The contents of this section should be loaded into memory at an
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// address which is a multiple of (two raised to this power).
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// Flags from SectionFlags describing the section's contents.
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// We don't support reading relocations yet.
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// True if this is a 64-bit section; false if it is a 32-bit section.
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// A map from section names to Sections.
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typedef map<string, Section> SectionMap;
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// A reader for a Mach-O file.
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// This does not handle fat binaries; see FatReader above. FatReader
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// provides a friendly interface for parsing data that could be either a
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// fat binary or a Mach-O file.
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// A class for reporting errors found while parsing Mach-O files. The
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// default definitions of these member functions print messages to
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// Create a reporter that attributes problems to |filename|.
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explicit Reporter(const string &filename) : filename_(filename) { }
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virtual ~Reporter() { }
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// Reporter functions for fatal errors return void; the reader will
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// definitely return an error to its caller after calling them
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// The data does not begin with a Mach-O magic number, or the magic
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// number does not match the expected value for the cpu architecture.
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// This is a fatal error.
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virtual void BadHeader();
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// The data contained in a Mach-O fat binary (|cpu_type|, |cpu_subtype|)
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// does not match the expected CPU architecture
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// (|expected_cpu_type|, |expected_cpu_subtype|).
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virtual void CPUTypeMismatch(cpu_type_t cpu_type,
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cpu_subtype_t cpu_subtype,
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cpu_type_t expected_cpu_type,
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cpu_subtype_t expected_cpu_subtype);
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// The file ends abruptly: either it is not large enough to hold a
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// complete header, or the header implies that contents are present
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// beyond the actual end of the file.
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virtual void HeaderTruncated();
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// The file's load command region, as given in the Mach-O header, is
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// too large for the file.
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virtual void LoadCommandRegionTruncated();
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// The file's Mach-O header claims the file contains |claimed| load
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// commands, but the I'th load command, of type |type|, extends beyond
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// the end of the load command region, as given by the Mach-O header.
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// If |type| is zero, the command's type was unreadable.
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virtual void LoadCommandsOverrun(size_t claimed, size_t i,
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LoadCommandType type);
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// The contents of the |i|'th load command, of type |type|, extend beyond
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// the size given in the load command's header.
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virtual void LoadCommandTooShort(size_t i, LoadCommandType type);
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// The LC_SEGMENT or LC_SEGMENT_64 load command for the segment named
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// |name| is too short to hold the sections that its header says it does.
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// (This more specific than LoadCommandTooShort.)
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virtual void SectionsMissing(const string &name);
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// The segment named |name| claims that its contents lie beyond the end
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virtual void MisplacedSegmentData(const string &name);
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// The section named |section| in the segment named |segment| claims that
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// its contents do not lie entirely within the segment.
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virtual void MisplacedSectionData(const string §ion,
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const string &segment);
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// The LC_SYMTAB command claims that symbol table contents are located
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// beyond the end of the file.
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virtual void MisplacedSymbolTable();
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// An attempt was made to read a Mach-O file of the unsupported
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// CPU architecture |cpu_type|.
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virtual void UnsupportedCPUType(cpu_type_t cpu_type);
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// A handler for sections parsed from a segment. The WalkSegmentSections
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// member function accepts an instance of this class, and applies it to
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// each section defined in a given segment.
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class SectionHandler {
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virtual ~SectionHandler() { }
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// Called to report that the segment's section list contains |section|.
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// This should return true if the iteration should continue, or false
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// if it should stop.
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virtual bool HandleSection(const Section §ion) = 0;
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// A handler for the load commands in a Mach-O file.
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class LoadCommandHandler {
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LoadCommandHandler() { }
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virtual ~LoadCommandHandler() { }
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// When called from WalkLoadCommands, the following handler functions
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// should return true if they wish to continue iterating over the load
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// command list, or false if they wish to stop iterating.
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// When called from LoadCommandIterator::Handle or Reader::Handle,
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// these functions' return values are simply passed through to Handle's
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// The definitions provided by this base class simply return true; the
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// default is to silently ignore sections whose member functions the
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// subclass doesn't override.
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// COMMAND is load command we don't recognize. We provide only the
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// command type and a ByteBuffer enclosing the command's data (If we
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// cannot parse the command type or its size, we call
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// reporter_->IncompleteLoadCommand instead.)
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virtual bool UnknownCommand(LoadCommandType type,
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const ByteBuffer &contents) {
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// The load command is LC_SEGMENT or LC_SEGMENT_64, defining a segment
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// with the properties given in |segment|.
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virtual bool SegmentCommand(const Segment &segment) {
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// The load command is LC_SYMTAB. |entries| holds the array of nlist
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// entries, and |names| holds the strings the entries refer to.
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virtual bool SymtabCommand(const ByteBuffer &entries,
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const ByteBuffer &names) {
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// Add handler functions for more load commands here as needed.
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// Create a Mach-O file reader that reports problems to |reporter|.
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explicit Reader(Reporter *reporter)
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: reporter_(reporter) { }
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// Read the given data as a Mach-O file. The reader retains pointers
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// into the data passed, so the data should live as long as the reader
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// does. On success, return true; on failure, return false.
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// At most one of these functions should be invoked once on each Reader
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bool Read(const uint8_t *buffer,
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cpu_type_t expected_cpu_type,
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cpu_subtype_t expected_cpu_subtype);
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bool Read(const ByteBuffer &buffer,
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cpu_type_t expected_cpu_type,
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cpu_subtype_t expected_cpu_subtype) {
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return Read(buffer.start,
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expected_cpu_subtype);
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// Return this file's characteristics, as found in the Mach-O header.
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cpu_type_t cpu_type() const { return cpu_type_; }
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cpu_subtype_t cpu_subtype() const { return cpu_subtype_; }
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FileType file_type() const { return file_type_; }
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FileFlags flags() const { return flags_; }
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// Return true if this is a 64-bit Mach-O file, false if it is a 32-bit
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bool bits_64() const { return bits_64_; }
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// Return true if this is a big-endian Mach-O file, false if it is
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bool big_endian() const { return big_endian_; }
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// Apply |handler| to each load command in this Mach-O file, stopping when
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// a handler function returns false. If we encounter a malformed load
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// command, report it via reporter_ and return false. Return true if all
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// load commands were parseable and all handlers returned true.
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bool WalkLoadCommands(LoadCommandHandler *handler) const;
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// Set |segment| to describe the segment named |name|, if present. If
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// found, |segment|'s byte buffers refer to a subregion of the bytes
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// passed to Read. If we find the section, return true; otherwise,
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bool FindSegment(const string &name, Segment *segment) const;
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// Apply |handler| to each section defined in |segment|. If |handler| returns
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// false, stop iterating and return false. If all calls to |handler| return
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// true and we reach the end of the section list, return true.
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bool WalkSegmentSections(const Segment &segment, SectionHandler *handler)
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// Clear |section_map| and then populate it with a map of the sections
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// in |segment|, from section names to Section structures.
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// Each Section's contents refer to bytes in |segment|'s contents.
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// On success, return true; if a problem occurs, report it and return false.
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bool MapSegmentSections(const Segment &segment, SectionMap *section_map)
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// We use this to report problems parsing the file's contents. (WEAK)
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// The contents of the Mach-O file we're parsing. We do not own the
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// storage it refers to.
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// True if this file is big-endian.
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// True if this file is a 64-bit Mach-O file.
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// This file's cpu type and subtype.
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cpu_type_t cpu_type_; // mach_header[_64].cputype
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cpu_subtype_t cpu_subtype_; // mach_header[_64].cpusubtype
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FileType file_type_; // mach_header[_64].filetype
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// The region of buffer_ occupied by load commands.
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ByteBuffer load_commands_;
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// The number of load commands in load_commands_.
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uint32_t load_command_count_; // mach_header[_64].ncmds
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// This file's header flags.
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} // namespace mach_o
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} // namespace google_breakpad
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#endif // BREAKPAD_COMMON_MAC_MACHO_READER_H_
added
removed
thirdparty/breakpad/common/mac/macho_reader.h
