windows/converter/ms_symbol_server_converter.h

// Copyright (c) 2007, Google Inc.
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// ms_symbol_server_converter.h: Obtain symbol files from a Microsoft
// symbol server, and convert them to Breakpad's dumped format.
//
// At runtime, MSSymbolServerConverter and code that it calls depend on being
// able to locate suitable versions of dbghelp.dll and symsrv.dll.  For best
// results, place these files in the same directory as the executable.
// dbghelp.dll and symsrv.dll as supplied with Debugging Tools for Windows are
// both redistributable, as indicated by the package's redist.txt file.
//
// When connecting to Microsoft's symbol server at
// http://msdl.microsoft.com/download/symbols/, which provides access to
// symbols for the operating system itself, symsrv.dll requires agreement to
// Microsoft's "Terms of Use for Microsoft Symbols and Binaries."  Because this
// library places the symbol engine into a promptless mode, the dialog with the
// terms will not appear, and use of Microsoft's symbol server will not be
// possible.  To indicate agreement to the terms, create a file called
// symsrv.yes in the same directory as symsrv.dll.  (Note that symsrv.dll will
// also recognize a symsrv.no file as indicating that you do not accept the
// terms; the .yes file takes priority over the .no file.)  The terms of use
// are contained within symsrv.dll; they were formerly available online at
// http://www.microsoft.com/whdc/devtools/debugging/symsrvTOU2.mspx , but
// do not appear to be available online any longer as of January, 2007.  It is
// possible to view the terms from within WinDbg (Debugging Tools for Windows)
// by removing any symsrv.yes and symsrv.no files from WinDbg's directory,
// setting the symbol path to include Microsoft's symbol server (.sympath), and
// attempting to load symbols from their server (.reload).
//
// This code has been tested with dbghelp.dll 6.5.3.7 and symsrv.dll 6.5.3.8,
// included with Microsoft Visual Studio 8 in Common7/IDE.  This has also
// been tested with dbghelp.dll and symsrv.dll 6.6.7.5, included with that
// version of Debugging Tools for Windows, available at
// http://www.microsoft.com/whdc/devtools/debugging/ .
//
// Author: Mark Mentovai


#ifndef MS_SYMBOL_SERVER_CONVERTER_H__
#define MS_SYMBOL_SERVER_CONVERTER_H__

#include <Windows.h>

#include <string>
#include <vector>

namespace google_breakpad {

using std::string;
using std::vector;

// MissingSymbolInfo contains the subset of the information in the processor's
// CodeModule structure relevant to obtaining a missing symbol file.  Only
// debug_file and debug_identifier are relevant in actually obtaining the
// missing file; the other fields are for convenience.
struct MissingSymbolInfo {
  string code_file;
  string code_identifier;
  string debug_file;
  string debug_identifier;
  string version;
};

class GUIDOrSignatureIdentifier {
 public:
  enum GUIDOrSignatureType {
    TYPE_NONE = 0,
    TYPE_GUID,
    TYPE_SIGNATURE
  };

  GUIDOrSignatureIdentifier() : type_(TYPE_NONE) {}

  // Converts |identifier|, a debug_identifier-formatted string, into its
  // component fields: either a GUID and age, or signature and age.  If
  // successful, sets the relevant fields in the object, including the type
  // field, and returns true.  On error, returns false.
  bool InitializeFromString(const string &identifier);

  GUIDOrSignatureType type() const { return type_; }
  GUID guid() const { return guid_; }
  DWORD signature() const { return signature_; }
  int age() const { return age_; }
  const void *guid_or_signature_pointer() const { return &guid_; }

 private:
  GUIDOrSignatureType type_;

  // An identifier contains either a 128-bit uuid or a 32-bit signature.
  union {
    GUID guid_;
    DWORD signature_;
  };

  // All identifiers used here have age fields, which indicate a specific
  // revision given a uuid or signature.
  int age_;
};

class MSSymbolServerConverter {
 public:
  enum LocateResult {
    LOCATE_FAILURE = 0,
    LOCATE_NOT_FOUND,    // Authoritative: the file is not present.
    LOCATE_RETRY,        // Transient (network?) error, try again later.
    LOCATE_SUCCESS
  };

  // Create a new object.  local_cache is the location (pathname) of a local
  // symbol store used to hold downloaded and converted symbol files.  This
  // directory will be created by LocateSymbolFile when it successfully
  // retrieves a symbol file. symbol_servers contains a list of locations (URLs
  // or pathnames) of the upstream symbol server stores, given in order of
  // preference, with the first string in the vector identifying the first
  // store to try.  The vector must contain at least one string.  None of the
  // strings passed to this constructor may contain asterisk ('*') or semicolon
  // (';') characters, as the symbol engine uses these characters as separators.
  MSSymbolServerConverter(const string &local_cache,
                          const vector<string> &symbol_servers);

  // Locates the symbol file specified by the identifying information in
  // |missing|, by checking the symbol stores identified when the object
  // was created.  When returning LOCATE_SUCCESS, symbol_file is set to
  // the pathname of the decompressed symbol file as it is stored in the
  // local cache.
  LocateResult LocateSymbolFile(const MissingSymbolInfo &missing,
                                string *symbol_file);

  // Calls LocateSymbolFile and converts the returned symbol file to the
  // dumped-symbol format, storing it adjacent to the symbol file.  The
  // only conversion supported is from pdb files.  Returns the return
  // value of LocateSymbolFile, or if LocateSymbolFile succeeds but
  // conversion fails, returns LOCATE_FAILURE.  The pathname to the
  // pdb file and to the converted symbol file are returned in
  // converted_symbol_file and symbol_file.  symbol_file is optional and
  // may be NULL.  If only the converted symbol file is desired, set
  // keep_symbol_file to false to indicate that the original symbol file
  // (pdb) should be deleted after conversion.
  LocateResult LocateAndConvertSymbolFile(const MissingSymbolInfo &missing,
                                          bool keep_symbol_file,
                                          string *converted_symbol_file,
                                          string *symbol_file);

 private:
  // Called by various SymSrv functions to report status as progress is made
  // and to allow the callback to influence processing.  Messages sent to this
  // callback can be used to distinguish between the various failure modes
  // that SymFindFileInPath might encounter.
  static BOOL CALLBACK SymCallback(HANDLE process, ULONG action, ULONG64 data,
                                   ULONG64 context);

  // Called by SymFindFileInPath (in LocateSymbolFile) after a candidate
  // symbol file is located, when it's present in the local cache.
  // SymFindFileInPath actually seems to accept NULL for a callback function
  // and behave properly for our needs in that case, but the documentation
  // doesn't mention it, so this little callback is provided.
  static BOOL CALLBACK SymFindFileInPathCallback(char *filename,
                                                 void *context);

  // The search path used by SymSrv, built based on the arguments to the
  // constructor.
  string symbol_path_;

  // SymCallback will set at least one of these failure variables if
  // SymFindFileInPath fails for an expected reason.
  bool fail_dns_;        // DNS failures (fail_not_found_ will also be set).
  bool fail_timeout_;    // Timeouts (fail_not_found_ will also be set).
  bool fail_not_found_;  // The file could not be found.  If this is the only
                         // fail_* member set, then it is authoritative.
};

}  // namespace google_breakpad

#endif  // MS_SYMBOL_SERVER_CONVERTER_H__