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+// -*- 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>
+
+// stabs_reader.h: Define StabsReader, a parser for STABS debugging
+// information. A description of the STABS debugging format can be
+// found at:
+//
+// http://sourceware.org/gdb/current/onlinedocs/stabs_toc.html
+//
+// The comments here assume you understand the format.
+//
+// This parser can handle big-endian and little-endian data, and the symbol
+// values may be either 32 or 64 bits long. It handles both STABS in
+// sections (as used on Linux) and STABS appearing directly in an
+// a.out-like symbol table (as used in Darwin OS X Mach-O files).
+
+#ifndef COMMON_STABS_READER_H__
+#define COMMON_STABS_READER_H__
+
+#include <stddef.h>
+#include <stdint.h>
+
+#ifdef HAVE_CONFIG_H
+#include <config.h>
+#endif
+
+#ifdef HAVE_MACH_O_NLIST_H
+#include <mach-o/nlist.h>
+#elif defined(HAVE_A_OUT_H)
+#include <a.out.h>
+#endif
+
+#include <string>
+#include <vector>
+
+#include "common/byte_cursor.h"
+#include "common/using_std_string.h"
+
+namespace google_breakpad {
+
+class StabsHandler;
+
+class StabsReader {
+ public:
+ // Create a reader for the STABS debug information whose .stab section is
+ // being traversed by ITERATOR, and whose .stabstr section is referred to
+ // by STRINGS. The reader will call the member functions of HANDLER to
+ // report the information it finds, when the reader's 'Process' member
+ // function is called.
+ //
+ // BIG_ENDIAN should be true if the entries in the .stab section are in
+ // big-endian form, or false if they are in little-endian form.
+ //
+ // VALUE_SIZE should be either 4 or 8, indicating the size of the 'value'
+ // field in each entry in bytes.
+ //
+ // UNITIZED should be true if the STABS data is stored in units with
+ // N_UNDF headers. This is usually the case for STABS stored in sections,
+ // like .stab/.stabstr, and usually not the case for STABS stored in the
+ // actual symbol table; UNITIZED should be true when parsing Linux stabs,
+ // false when parsing Mac OS X STABS. For details, see:
+ // http://sourceware.org/gdb/current/onlinedocs/stabs/Stab-Section-Basics.html
+ //
+ // Note that, in ELF, the .stabstr section should be found using the
+ // 'sh_link' field of the .stab section header, not by name.
+ StabsReader(const uint8_t *stab, size_t stab_size,
+ const uint8_t *stabstr, size_t stabstr_size,
+ bool big_endian, size_t value_size, bool unitized,
+ StabsHandler *handler);
+
+ // Process the STABS data, calling the handler's member functions to
+ // report what we find. While the handler functions return true,
+ // continue to process until we reach the end of the section. If we
+ // processed the entire section and all handlers returned true,
+ // return true. If any handler returned false, return false.
+ //
+ // This is only meant to be called once per StabsReader instance;
+ // resuming a prior processing pass that stopped abruptly isn't supported.
+ bool Process();
+
+ private:
+
+ // An class for walking arrays of STABS entries. This isolates the main
+ // STABS reader from the exact format (size; endianness) of the entries
+ // themselves.
+ class EntryIterator {
+ public:
+ // The contents of a STABS entry, adjusted for the host's endianness,
+ // word size, 'struct nlist' layout, and so on.
+ struct Entry {
+ // True if this iterator has reached the end of the entry array. When
+ // this is set, the other members of this structure are not valid.
+ bool at_end;
+
+ // The number of this entry within the list.
+ size_t index;
+
+ // The current entry's name offset. This is the offset within the
+ // current compilation unit's strings, as establish by the N_UNDF entries.
+ size_t name_offset;
+
+ // The current entry's type, 'other' field, descriptor, and value.
+ unsigned char type;
+ unsigned char other;
+ short descriptor;
+ uint64_t value;
+ };
+
+ // Create a EntryIterator walking the entries in BUFFER. Treat the
+ // entries as big-endian if BIG_ENDIAN is true, as little-endian
+ // otherwise. Assume each entry has a 'value' field whose size is
+ // VALUE_SIZE.
+ //
+ // This would not be terribly clean to extend to other format variations,
+ // but it's enough to handle Linux and Mac, and we'd like STABS to die
+ // anyway.
+ //
+ // For the record: on Linux, STABS entry values are always 32 bits,
+ // regardless of the architecture address size (don't ask me why); on
+ // Mac, they are 32 or 64 bits long. Oddly, the section header's entry
+ // size for a Linux ELF .stab section varies according to the ELF class
+ // from 12 to 20 even as the actual entries remain unchanged.
+ EntryIterator(const ByteBuffer *buffer, bool big_endian, size_t value_size);
+
+ // Move to the next entry. This function's behavior is undefined if
+ // at_end() is true when it is called.
+ EntryIterator &operator++() { Fetch(); entry_.index++; return *this; }
+
+ // Dereferencing this iterator produces a reference to an Entry structure
+ // that holds the current entry's values. The entry is owned by this
+ // EntryIterator, and will be invalidated at the next call to operator++.
+ const Entry &operator*() const { return entry_; }
+ const Entry *operator->() const { return &entry_; }
+
+ private:
+ // Read the STABS entry at cursor_, and set entry_ appropriately.
+ void Fetch();
+
+ // The size of entries' value field, in bytes.
+ size_t value_size_;
+
+ // A byte cursor traversing buffer_.
+ ByteCursor cursor_;
+
+ // Values for the entry this iterator refers to.
+ Entry entry_;
+ };
+
+ // A source line, saved to be reported later.
+ struct Line {
+ uint64_t address;
+ const char *filename;
+ int number;
+ };
+
+ // Return the name of the current symbol.
+ const char *SymbolString();
+
+ // Process a compilation unit starting at symbol_. Return true
+ // to continue processing, or false to abort.
+ bool ProcessCompilationUnit();
+
+ // Process a function in current_source_file_ starting at symbol_.
+ // Return true to continue processing, or false to abort.
+ bool ProcessFunction();
+
+ // Process an exported function symbol.
+ // Return true to continue processing, or false to abort.
+ bool ProcessExtern();
+
+ // The STABS entries being parsed.
+ ByteBuffer entries_;
+
+ // The string section to which the entries refer.
+ ByteBuffer strings_;
+
+ // The iterator walking the STABS entries.
+ EntryIterator iterator_;
+
+ // True if the data is "unitized"; see the explanation in the comment for
+ // StabsReader::StabsReader.
+ bool unitized_;
+
+ StabsHandler *handler_;
+
+ // The offset of the current compilation unit's strings within stabstr_.
+ size_t string_offset_;
+
+ // The value string_offset_ should have for the next compilation unit,
+ // as established by N_UNDF entries.
+ size_t next_cu_string_offset_;
+
+ // The current source file name.
+ const char *current_source_file_;
+
+ // Mac OS X STABS place SLINE records before functions; we accumulate a
+ // vector of these until we see the FUN record, and then report them
+ // after the StartFunction call.
+ std::vector<Line> queued_lines_;
+};
+
+// Consumer-provided callback structure for the STABS reader. Clients
+// of the STABS reader provide an instance of this structure. The
+// reader then invokes the member functions of that instance to report
+// the information it finds.
+//
+// The default definitions of the member functions do nothing, and return
+// true so processing will continue.
+class StabsHandler {
+ public:
+ StabsHandler() { }
+ virtual ~StabsHandler() { }
+
+ // Some general notes about the handler callback functions:
+
+ // Processing proceeds until the end of the .stabs section, or until
+ // one of these functions returns false.
+
+ // The addresses given are as reported in the STABS info, without
+ // regard for whether the module may be loaded at different
+ // addresses at different times (a shared library, say). When
+ // processing STABS from an ELF shared library, the addresses given
+ // all assume the library is loaded at its nominal load address.
+ // They are *not* offsets from the nominal load address. If you
+ // want offsets, you must subtract off the library's nominal load
+ // address.
+
+ // The arguments to these functions named FILENAME are all
+ // references to strings stored in the .stabstr section. Because
+ // both the Linux and Solaris linkers factor out duplicate strings
+ // from the .stabstr section, the consumer can assume that if two
+ // FILENAME values are different addresses, they represent different
+ // file names.
+ //
+ // Thus, it's safe to use (say) std::map<char *, ...>, which does
+ // string address comparisons, not string content comparisons.
+ // Since all the strings are in same array of characters --- the
+ // .stabstr section --- comparing their addresses produces
+ // predictable, if not lexicographically meaningful, results.
+
+ // Begin processing a compilation unit whose main source file is
+ // named FILENAME, and whose base address is ADDRESS. If
+ // BUILD_DIRECTORY is non-NULL, it is the name of the build
+ // directory in which the compilation occurred.
+ virtual bool StartCompilationUnit(const char *filename, uint64_t address,
+ const char *build_directory) {
+ return true;
+ }
+
+ // Finish processing the compilation unit. If ADDRESS is non-zero,
+ // it is the ending address of the compilation unit. If ADDRESS is
+ // zero, then the compilation unit's ending address is not
+ // available, and the consumer must infer it by other means.
+ virtual bool EndCompilationUnit(uint64_t address) { return true; }
+
+ // Begin processing a function named NAME, whose starting address is
+ // ADDRESS. This function belongs to the compilation unit that was
+ // most recently started but not ended.
+ //
+ // Note that, unlike filenames, NAME is not a pointer into the
+ // .stabstr section; this is because the name as it appears in the
+ // STABS data is followed by type information. The value passed to
+ // StartFunction is the function name alone.
+ //
+ // In languages that use name mangling, like C++, NAME is mangled.
+ virtual bool StartFunction(const string &name, uint64_t address) {
+ return true;
+ }
+
+ // Finish processing the function. If ADDRESS is non-zero, it is
+ // the ending address for the function. If ADDRESS is zero, then
+ // the function's ending address is not available, and the consumer
+ // must infer it by other means.
+ virtual bool EndFunction(uint64_t address) { return true; }
+
+ // Report that the code at ADDRESS is attributable to line NUMBER of
+ // the source file named FILENAME. The caller must infer the ending
+ // address of the line.
+ virtual bool Line(uint64_t address, const char *filename, int number) {
+ return true;
+ }
+
+ // Report that an exported function NAME is present at ADDRESS.
+ // The size of the function is unknown.
+ virtual bool Extern(const string &name, uint64_t address) {
+ return true;
+ }
+
+ // Report a warning. FORMAT is a printf-like format string,
+ // specifying how to format the subsequent arguments.
+ virtual void Warning(const char *format, ...) = 0;
+};
+
+} // namespace google_breakpad
+
+#endif // COMMON_STABS_READER_H__