extract_source.rb

# rubocop:disable all

# You need to call this with the PostgreSQL source directory as the first commandline agument, and the output dir as the second
# ./scripts/extract_source.rb ./tmp/postgres ./src/postgres

require 'ffi/clang'
require 'json'

module FFI::Clang::Lib
  enum :storage_class, [
    :invalid, 0,
    :none, 1,
    :extern, 2,
    :static, 3,
    :private_extern, 4,
    :opencl_workgroup_local, 5,
    :auto, 6,
    :register, 7,
  ]

  attach_function :get_storage_class, :clang_Cursor_getStorageClass, [FFI::Clang::Lib::CXCursor.by_value], :storage_class
end

module FFI::Clang
  class Cursor
    def storage_class
      Lib.get_storage_class(@cursor)
    end

    # Copy of clang::VarDecl::hasExternalStorage http://clang.llvm.org/doxygen/Decl_8h_source.html#l00982
    def has_external_storage
      storage_class == :extern || storage_class == :private_extern
    end
  end
end

class Runner
  attr_reader :unresolved
  attr_reader :code_for_resolve

  def initialize
    @file_analysis = {}
    @global_method_to_base_filename = {}
    @file_to_method_and_pos = {}

    @resolved_static_by_base_filename = {}
    @resolved_global = []

    @symbols_to_output = {}
    @include_files_to_output = []
    @unresolved = []

    @blacklist = []
    @mock = {}

    @basepath = File.absolute_path(ARGV[0]) + '/'
    @out_path = File.absolute_path(ARGV[1]) + '/'
  end

  def blacklist(symbol)
    @blacklist << symbol
  end

  def mock(symbol, code)
    @mock[symbol] = code
  end

  def run
    files = Dir.glob(@basepath + 'src/backend/**/*.c') +
    Dir.glob(@basepath + 'src/common/**/*.c') +
    Dir.glob(@basepath + 'src/port/**/*.c') +
    Dir.glob(@basepath + 'src/timezone/**/*.c') +
    Dir.glob(@basepath + 'src/pl/plpgsql/src/*.c') +
    Dir.glob(@basepath + 'contrib/pgcrypto/*.c') -
    [ # Blacklist
      @basepath + 'src/backend/libpq/be-secure-openssl.c', # OpenSSL include error
      @basepath + 'src/backend/utils/adt/levenshtein.c', # Built through varlena.c
      @basepath + 'src/backend/utils/adt/like_match.c', # Built through like.c
      @basepath + 'src/backend/utils/misc/guc-file.c', # Built through guc.c
      @basepath + 'src/backend/utils/sort/qsort_tuple.c', # Built through tuplesort.c
      @basepath + 'src/backend/parser/scan.c', # Built through gram.c
      @basepath + 'src/backend/bootstrap/bootscanner.c', # Built through bootparse.c
      @basepath + 'src/backend/regex/regc_color.c', # Built through regcomp.c
      @basepath + 'src/backend/regex/regc_cvec.c', # Built through regcomp.c
      @basepath + 'src/backend/regex/regc_lex.c', # Built through regcomp.c
      @basepath + 'src/backend/regex/regc_pg_locale.c', # Built through regcomp.c
      @basepath + 'src/backend/regex/regc_locale.c', # Built through regcomp.c
      @basepath + 'src/backend/regex/regc_nfa.c', # Built through regcomp.c
      @basepath + 'src/backend/regex/rege_dfa.c', # Built through regexec.c
      @basepath + 'src/backend/replication/repl_scanner.c', # Built through repl_gram.c
      @basepath + 'src/backend/port/posix_sema.c', # Linux only
      @basepath + 'src/common/fe_memutils.c', # This file is not expected to be compiled for backend code
      @basepath + 'src/common/restricted_token.c', # This file is not expected to be compiled for backend code
      @basepath + 'src/port/dirent.c', # Win32 only
      @basepath + 'src/port/getaddrinfo.c', # Win32 only
      @basepath + 'src/port/getrusage.c', # Win32 only
      @basepath + 'src/port/gettimeofday.c', # Win32 only
      @basepath + 'src/port/strerror.c', # Win32 only
      @basepath + 'src/port/strerror.c', # Win32 only
      @basepath + 'src/port/strlcat.c', # Win32 only
      @basepath + 'src/port/strlcpy.c', # Win32 only
      @basepath + 'src/port/unsetenv.c', # Win32 only
      @basepath + 'src/port/win32error.c', # Win32 only
    ] -
    Dir.glob(@basepath + 'src/backend/port/dynloader/*.c') -
    Dir.glob(@basepath + 'src/backend/port/win32/*.c') -
    Dir.glob(@basepath + 'src/backend/port/win32_*.c') -
    Dir.glob(@basepath + 'src/backend/snowball/**/*.c')

    #files = [@basepath + 'src/backend/commands/analyze.c']

    files.each do |file|
      if files == [file]
        puts format('Analysing single file: %s', file)
        analysis = analyze_file(file)
        analysis_file = analysis.save
        puts format('Result: %s', analysis_file)
        exit 1
      end

      print '.'
      analysis = FileAnalysis.restore(file, @basepath) || analyze_file(file)
      analysis.save

      @file_analysis[file] = analysis

      analysis.symbol_to_file.each do |symbol, _|
        next if analysis.static_symbols.include?(symbol)
        if @global_method_to_base_filename[symbol] && !['main', 'Pg_magic_func', 'pg_open_tzfile', '_PG_init'].include?(symbol) && !@global_method_to_base_filename[symbol].end_with?('c')
          puts format('Error processing %s, symbol %s already defined by %s', file, symbol, @global_method_to_base_filename[symbol])
        end
        @global_method_to_base_filename[symbol] = file
      end

      analysis.file_to_symbol_positions.each do |file, method_and_pos|
        @file_to_method_and_pos[file] = method_and_pos
      end
    end

    #puts @caller_to_static_callees['/Users/lfittl/Code/libpg_query/postgres/src/backend/regex/regc_locale.c']['cclass'].inspect

    puts "\nFinished parsing"
  end

  class FileAnalysis
    attr_accessor :references, :static_symbols, :symbol_to_file, :file_to_symbol_positions, :included_files

    def initialize(filename, basepath, references = {}, static_symbols = [],
      symbol_to_file = {}, file_to_symbol_positions = {}, included_files = [])
      @filename = filename
      @basepath = basepath
      @references = references
      @static_symbols = static_symbols
      @symbol_to_file = symbol_to_file
      @file_to_symbol_positions = file_to_symbol_positions
      @included_files = included_files
    end

    def save
      json = JSON.pretty_generate({
        references: @references,
        static_symbols: @static_symbols,
        symbol_to_file: @symbol_to_file,
        file_to_symbol_positions: @file_to_symbol_positions,
        included_files: @included_files,
      })

      file = self.class.analysis_filename(@filename, @basepath)
      FileUtils.mkdir_p(File.dirname(file))
      File.write(file, json)
      file
    end

    def self.restore(filename, basepath)
      json = File.read(analysis_filename(filename, basepath))
      hsh = JSON.parse(json)
      new(filename, basepath, hsh['references'], hsh['static_symbols'],
      hsh['symbol_to_file'], hsh['file_to_symbol_positions'], hsh['included_files'])
    rescue Errno::ENOENT
      nil
    end

    private

    def self.analysis_filename(filename, basepath)
      File.absolute_path('./tmp/analysis') + '/' + filename.gsub(%r{^#{basepath}}, '').gsub(/.c$/, '.json')
    end
  end

  def analyze_file(file)
    index = FFI::Clang::Index.new(true, true)
    translation_unit = index.parse_translation_unit(file, ['-I', @basepath + 'src/include', '-DDLSUFFIX=".bundle"', '-msse4.2', '-g'])
    cursor = translation_unit.cursor

    func_cursor = nil
    analysis = FileAnalysis.new(file, @basepath)

    included_files = []
    translation_unit.inclusions do |included_file, _inclusions|
      next if !included_file.start_with?(@basepath) || included_file == file

      included_files << included_file
    end
    analysis.included_files = included_files.uniq.sort

    cursor.visit_children do |cursor, parent|
      if cursor.location.file && (File.dirname(file) == File.dirname(cursor.location.file) || cursor.location.file.end_with?('_impl.h'))
        if parent.kind == :cursor_translation_unit
          if (cursor.kind == :cursor_function && cursor.definition?) || (cursor.kind == :cursor_variable && !cursor.has_external_storage)
            analysis.symbol_to_file[cursor.spelling] = cursor.location.file

            if cursor.linkage == :external
              # Nothing special
            elsif cursor.linkage == :internal
              (analysis.static_symbols << cursor.spelling).uniq!
            else
              fail format('Unknown linkage: %s', cursor.linkage.inspect)
            end

            start_offset = cursor.extent.start.offset
            end_offset = cursor.extent.end.offset
            end_offset += 1 if cursor.kind == :cursor_variable # The ";" isn't counted correctly by clang

            analysis.file_to_symbol_positions[cursor.location.file] ||= {}
            analysis.file_to_symbol_positions[cursor.location.file][cursor.spelling] = [start_offset, end_offset]

            cursor.visit_children do |child_cursor, parent|
              # Ignore variable definitions from the local scope
              next :recurse if child_cursor.definition.semantic_parent == cursor

              if child_cursor.kind == :cursor_decl_ref_expr || child_cursor.kind == :cursor_call_expr
                analysis.references[cursor.spelling] ||= []
                (analysis.references[cursor.spelling] << child_cursor.spelling).uniq!
              end

              :recurse
            end
          end
        end
      end

      next :recurse
    end

    analysis
  end

  RESOLVE_MAX_DEPTH = 100

  def deep_resolve(method_name, depth: 0, trail: [], global_resolved_by_parent: [], static_resolved_by_parent: [], static_base_filename: nil)
    if @blacklist.include?(method_name)
      puts 'ERROR: Hit blacklist entry ' + method_name
      puts 'Trail: ' + trail.inspect
      exit 1
    end

    if depth > RESOLVE_MAX_DEPTH
      puts 'ERROR: Exceeded max depth'
      puts method_name.inspect
      puts trail.inspect
      exit 1
    end

    base_filename = static_base_filename || @global_method_to_base_filename[method_name]
    if !base_filename
      (@unresolved << method_name).uniq!
      return
    end

    analysis = @file_analysis[base_filename]
    fail "could not find analysis data for #{base_filename}" if analysis.nil?

    # We need to determine if we can lookup the place where the method lives
    implementation_filename = analysis.symbol_to_file[method_name]
    if !implementation_filename
      (@unresolved << method_name).uniq!
      return
    end

    @symbols_to_output[implementation_filename] ||= []
    @symbols_to_output[implementation_filename] << method_name

    (@include_files_to_output += analysis.included_files).uniq!

    if @mock.key?(method_name)
      # Code will be overwritten at output time, no need to investigate dependents
      return
    end

    # Now we need to resolve all symbols called by this one
    dependents = (analysis.references[method_name] || [])
    global_dependents = dependents.select { |c| !analysis.static_symbols.include?(c) } - global_resolved_by_parent
    static_dependents = dependents.select { |c| analysis.static_symbols.include?(c) } - static_resolved_by_parent

    # First, make sure we exclude all that have been visited before
    @resolved_static_by_base_filename[base_filename] ||= []
    global_dependents.delete_if { |s| @resolved_global.include?(s) }
    static_dependents.delete_if { |s| @resolved_static_by_base_filename[base_filename].include?(s) }

    # Second, make sure we never visit any of the dependents again
    global_dependents.each { |s| @resolved_global << s }
    static_dependents.each { |s| @resolved_static_by_base_filename[base_filename] << s }

    # Third, actually traverse into the remaining, non-visited, dependents
    global_dependents.each do |symbol|
      deep_resolve(
        symbol, depth: depth + 1, trail: trail + [method_name],
        global_resolved_by_parent: global_resolved_by_parent + global_dependents
      )
    end

    static_dependents.each do |symbol|
      deep_resolve(
        symbol, depth: depth + 1, trail: trail + [method_name],
        global_resolved_by_parent: global_resolved_by_parent + global_dependents,
        static_resolved_by_parent: static_resolved_by_parent + static_dependents,
        static_base_filename: base_filename
      )
    end
  end

  def special_include_file?(filename)
    filename[/\/(reg(c|e)_[\w_]+|scan|guc-file|qsort_tuple|repl_scanner|levenshtein|bootscanner|like_match)\.c$/] || filename[/\/[\w_]+_impl.h$/]
  end

  def write_out
    @symbols_to_output.each do |filename, symbols|
      dead_positions = (@file_to_method_and_pos[filename] || {}).dup

      symbols.each do |method|
        next if @mock.key?(method)

        alive_pos = dead_positions[method]

        # In some cases there are other symbols at the same location (macros), so delete by position instead of name
        dead_positions.delete_if { |_,pos| pos == alive_pos }
      end

      full_code = File.read(filename)

      str = "/*--------------------------------------------------------------------\n"
      str += " * Symbols referenced in this file:\n"
      symbols.each do |symbol|
        str += format(" * - %s\n", symbol)
      end
      str += " *--------------------------------------------------------------------\n"
      str += " */\n\n"

      next_start_pos = 0
      dead_positions.each do |method, pos|
        fail format("Position overrun for %s in %s, next_start_pos (%d) > file length (%d)", method, filename, next_start_pos, full_code.size) if next_start_pos > full_code.size
        fail format("Position overrun for %s in %s, dead position pos[0]-1 (%d) > file length (%d)", method, filename, pos[0]-1, full_code.size) if pos[0]-1 > full_code.size

        str += full_code[next_start_pos...(pos[0]-1)]

        if @mock.key?(method)
          str += "\n" + @mock[method] + "\n"
        end

        # In the off chance that part of a macro is before a method (e.g. ifdef),
        # but the closing part is inside (e.g. endif) we need to output all macros inside skipped parts
        skipped_code = full_code[(pos[0]-1)...pos[1]]
        str += "\n" + skipped_code.scan(/^(#\s*(?:include|define|undef|if|ifdef|ifndef|else|endif))((?:[^\n]*\\\s*\n)*)([^\n]*)$/m).map { |m| m.compact.join }.join("\n")

        next_start_pos = pos[1]
      end
      str += full_code[next_start_pos..-1]

      if special_include_file?(filename)
        out_name = File.basename(filename)
      else
        out_name = filename.gsub(%r{^#{@basepath}}, '').gsub('/', '_')
      end

      File.write(@out_path + out_name, str)
    end

    @include_files_to_output.each do |include_file|
      next if special_include_file?(include_file)

      if include_file.start_with?(@basepath + 'src/include')
        out_file = @out_path + include_file.gsub(%r{^#{@basepath}src/}, '')
      else
        out_file = @out_path + 'include/' + File.basename(include_file)
      end

      FileUtils.mkdir_p File.dirname(out_file)
      FileUtils.cp include_file, out_file
    end
  end
end

runner = Runner.new
runner.run

runner.blacklist('SearchSysCache')
runner.blacklist('heap_open')
runner.blacklist('relation_open')
runner.blacklist('RelnameGetRelid')
runner.blacklist('ProcessClientWriteInterrupt')
runner.blacklist('typeStringToTypeName')
runner.blacklist('LWLockAcquire')
runner.blacklist('SPI_freeplan')
runner.blacklist('get_ps_display')
runner.blacklist('pq_beginmessage')

# Mocks REQUIRED for basic operations (error handling, memory management)
runner.mock('ProcessInterrupts', 'void ProcessInterrupts(void) {}') # Required by errfinish
runner.mock('PqCommMethods', 'PQcommMethods *PqCommMethods = NULL;') # Required by errfinish
runner.mock('proc_exit', 'void proc_exit(int code) { printf("Terminating process due to FATAL error\n"); exit(1); }') # Required by errfinish (we use PG_TRY/PG_CATCH, so this should never be reached in practice)
runner.mock('send_message_to_server_log', 'static void send_message_to_server_log(ErrorData *edata) {}')
runner.mock('send_message_to_frontend', 'static void send_message_to_frontend(ErrorData *edata) {}')

# Mocks REQUIRED for PL/pgSQL parsing
runner.mock('format_type_be', 'char * format_type_be(Oid type_oid) { return pstrdup("-"); }')
runner.mock('build_row_from_class', 'static PLpgSQL_row *build_row_from_class(Oid classOid) { return NULL; }')
runner.mock('plpgsql_build_datatype', 'PLpgSQL_type * plpgsql_build_datatype(Oid typeOid, int32 typmod, Oid collation) { PLpgSQL_type *typ; typ = (PLpgSQL_type *) palloc0(sizeof(PLpgSQL_type)); typ->typname = pstrdup("UNKNOWN"); typ->ttype = PLPGSQL_TTYPE_SCALAR; return typ; }')
runner.mock('parse_datatype', 'static PLpgSQL_type * parse_datatype(const char *string, int location) { PLpgSQL_type *typ; typ = (PLpgSQL_type *) palloc0(sizeof(PLpgSQL_type)); typ->typname = pstrdup(string); typ->ttype = PLPGSQL_TTYPE_SCALAR; return typ; }')
runner.mock('get_collation_oid', 'Oid get_collation_oid(List *name, bool missing_ok) { return -1; }')
runner.mock('plpgsql_parse_wordtype', 'PLpgSQL_type * plpgsql_parse_wordtype(char *ident) { return NULL; }')
runner.mock('plpgsql_parse_wordrowtype', 'PLpgSQL_type * plpgsql_parse_wordrowtype(char *ident) { return NULL; }')
runner.mock('plpgsql_parse_cwordtype', 'PLpgSQL_type * plpgsql_parse_cwordtype(List *idents) { return NULL; }')
runner.mock('plpgsql_parse_cwordrowtype', 'PLpgSQL_type * plpgsql_parse_cwordrowtype(List *idents) { return NULL; }')
runner.mock('function_parse_error_transpose', 'bool function_parse_error_transpose(const char *prosrc) { return false; }')
runner.mock('free_expr', "static void free_expr(PLpgSQL_expr *expr) {}") # This would free a cached plan, which does not apply to us
runner.mock('make_return_stmt', %(
static PLpgSQL_stmt *
make_return_stmt(int location)
{
	PLpgSQL_stmt_return *new;

  Assert(plpgsql_curr_compile->fn_rettype == VOIDOID);

	new = palloc0(sizeof(PLpgSQL_stmt_return));
	new->cmd_type = PLPGSQL_STMT_RETURN;
	new->lineno   = plpgsql_location_to_lineno(location);
	new->expr	  = NULL;
	new->retvarno = -1;

  int tok = yylex();

  if (tok != ';')
	{
		plpgsql_push_back_token(tok);
		new->expr = read_sql_expression(';', ";");
	}

	return (PLpgSQL_stmt *) new;
}
)) # We're always working with fn_rettype = VOIDOID, due to our use of plpgsql_compile_inline

## ---

# SQL Parsing
runner.deep_resolve('raw_parser')

# PL/pgSQL Parsing
runner.deep_resolve('plpgsql_compile_inline')
runner.deep_resolve('plpgsql_free_function_memory')

# Basic Postgres needed to call parser
runner.deep_resolve('SetDatabaseEncoding')

# Memory management needed to call parser
runner.deep_resolve('MemoryContextInit')
runner.deep_resolve('AllocSetContextCreate')
runner.deep_resolve('MemoryContextSwitchTo')
runner.deep_resolve('CurrentMemoryContext')
runner.deep_resolve('MemoryContextDelete')
runner.deep_resolve('palloc0')

# Error handling needed to call parser
runner.deep_resolve('CopyErrorData')
runner.deep_resolve('FlushErrorState')

# Needed for output funcs
runner.deep_resolve('bms_first_member')
runner.deep_resolve('bms_free')

# Needed for normalize
runner.deep_resolve('pg_qsort')
runner.deep_resolve('raw_expression_tree_walker')

# SHA1 needed for fingerprinting
runner.deep_resolve('sha1_result')
runner.deep_resolve('sha1_init')
runner.deep_resolve('sha1_loop')

runner.write_out

#puts runner.unresolved.inspect

# Debugging:
# clang -Xclang -ast-dump -fsyntax-only -I src/include/ src/backend/utils/init/globals.c