git_ls.rb in git_ls-0.4.0

- old
+ new

@@ -1,11 +1,11 @@
 # frozen_string_literal: true
 
 # Usage:
 #   GitLS.files -> Array of strings as files.
 #   This will be identical output to git ls-files
-module GitLS
+module GitLS # rubocop:disable Metrics/ModuleLength
   class Error < StandardError; end
 
   class << self
     def files(path = ::Dir.pwd)
       read(path, false)
@@ -13,49 +13,136 @@
 
     def headers(path = ::Dir.pwd)
       read(path, true)
     end
 
-  private
+    private
 
-    def read(path, return_headers_only)
+    def read(path, return_headers_only) # rubocop:disable Metrics/MethodLength, Metrics/AbcSize
       path = ::File.join(path, '.git/index') if ::File.directory?(path)
       file = ::File.new(path)
+      buf = ::String.new
       # 4-byte signature:
       # The signature is { 'D', 'I', 'R', 'C' } (stands for "dircache")
       # 4-byte version number:
       # The current supported versions are 2, 3 and 4.
       # 32-bit number of index entries.
-      sig, git_index_version, length = file.read(12).unpack('A4NN')
-      raise ::GitLS::Error, 'not a git dir or .git/index file' unless sig == 'DIRC'
+      sig, git_index_version, length = file.read(12, buf).unpack('a4NN')
+      raise ::GitLS::Error, ".git/index file not found at #{path}" unless sig == 'DIRC'
 
       return { git_index_version: git_index_version, length: length } if return_headers_only
 
-      files = Array.new(length)
+      files = ::Array.new(length)
       case git_index_version
       when 2 then files_2(files, file)
       when 3 then files_3(files, file)
       when 4 then files_4(files, file)
       else raise ::GitLS::Error, 'Unrecognized git index version'
       end
+
+      extensions(files, file, buf)
       files
-    rescue Errno::ENOENT => e
-      raise GitLS::Error, "Not a git directory: #{e.message}"
+    rescue ::Errno::ENOENT => e
+      raise ::GitLS::Error, "Not a git directory: #{e.message}"
     ensure
       # :nocov:
       # coverage tracking for branches in ensure blocks is weird
       file&.close
       # :nocov:
       files
     end
 
-    private
+    def extensions(files, file, buf)
+      case file.read(4, buf)
+      when 'link' then link_extension(files, file, buf)
+      when /[A-Z]{4}/ then ignored_extension(files, file, buf)
+      else
+        return if (file.pos += 16) && file.eof?
 
-    def files_2(files, file)
+        raise ::GitLS::Error, "Unrecognized .git/index extension #{buf.inspect}"
+      end
+    end
+
+    def ignored_extension(files, file, buf)
+      size = file.read(4, buf).unpack1('N')
+      file.pos += size
+      extensions(files, file, buf)
+    end
+
+    def link_extension(files, file, buf) # rubocop:disable Metrics/MethodLength, Metrics/AbcSize
+      file.pos += 4 # size = file.read(4, buf).unpack1('N')
+
+      sha = file.read(20, buf)
+
+      new_files = files.dup
+
+      files.replace files("#{::File.dirname(file.path)}/sharedindex.#{sha.unpack1('H*')}")
+
+      ewah_each_value(file, buf) do |pos|
+        files[pos] = nil
+      end
+
+      ewah_each_value(file, buf) do |pos|
+        replacement_file = new_files.shift
+        # the documentation *implies* that this *may* get a new filename
+        # i can't get it to happen though
+        # :nocov:
+        files[pos] = replacement_file unless replacement_file.empty?
+        # :nocov:
+      end
+
+      files.compact!
+      files.concat(new_files)
+      files.sort!
+
+      extensions(files, file, buf)
+    end
+
+    # format is defined here:
+    # https://git-scm.com/docs/bitmap-format#_appendix_a_serialization_format_for_an_ewah_bitmap
+    def ewah_each_value(file, buf) # rubocop:disable Metrics/MethodLength, Metrics/AbcSize
+      uncompressed_pos = 0
+      file.pos += 4 # uncompressed_bits_count = file.read(4, buf).unpack1('N')
+      compressed_bytes = file.read(4, buf).unpack1('N') * 8
+
+      final_file_pos = file.pos + compressed_bytes
+
+      until file.pos == final_file_pos
+        run_length_word = file.read(8, buf).unpack1('Q>')
+        # 1st bit
+        run_bit = run_length_word & 1
+        # the next 32 bits, masked, multiplied by 64 (which is shifted by 6 places)
+        run_length = ((run_length_word >> 1) & 0xFFFF_FFFF) << 6
+        # the next 31 bits
+        literal_length = (run_length_word >> 33)
+
+        if run_bit == 1
+          run_length.times do
+            yield uncompressed_pos
+            uncompressed_pos += 1
+          end
+        else
+          uncompressed_pos += run_length
+        end
+
+        literal_length.times do
+          word = file.read(8, buf).unpack1('B*').reverse
+          word.each_char do |char|
+            yield(uncompressed_pos) if char == '1'
+
+            uncompressed_pos += 1
+          end
+        end
+      end
+
+      file.pos += 4 # bitmap metadata for adding to bitmaps
+    end
+
+    def files_2(files, file) # rubocop:disable Metrics/MethodLength
       files.map! do
         file.pos += 60 # skip 60 bytes (40 bytes of stat, 20 bytes of sha)
-        length = (file.getbyte & 0b0000_1111) * 256 + file.getbyte # find the 12 byte length
+        length = ((file.getbyte & 0b0000_1111) << 8) + file.getbyte # find the 12 byte length
         if length < 0xFFF
           path = file.read(length)
           # :nocov:
         else
           # i can't test this i just get ENAMETOOLONG a lot
@@ -66,11 +153,11 @@
         file.pos += 8 - ((length - 2) % 8) # 1-8 bytes padding of nuls
         path
       end
     end
 
-    def files_3(files, file)
+    def files_3(files, file) # rubocop:disable Metrics/MethodLength, Metrics/AbcSize
       files.map! do
         file.pos += 60 # skip 60 bytes (40 bytes of stat, 20 bytes of sha)
 
         flags = file.getbyte * 256 + file.getbyte
         extended_flag = (flags & 0b0100_0000_0000_0000).positive?
@@ -90,11 +177,11 @@
         file.pos += 8 - ((path.bytesize - (extended_flag ? 0 : 2)) % 8) # 1-8 bytes padding of nuls
         path
       end
     end
 
-    def files_4(files, file)
-      prev_entry_path = ""
+    def files_4(files, file) # rubocop:disable Metrics/MethodLength, Metrics/AbcSize
+      prev_entry_path = ''
       files.map! do
         file.pos += 60 # skip 60 bytes (40 bytes of stat, 20 bytes of sha)
         flags = file.getbyte * 256 + file.getbyte
         file.pos += 2 if (flags & 0b0100_0000_0000_0000).positive?
 