fun ReadFatHeader()

in jvm/src/main/kotlin/com/jetbrains/util/filetype/FileTypeDetector.kt [224:294]
55 lines of code
19 McCabe index (conditional complexity)

      fun ReadFatHeader(magic: Long): Pair<EnumSet<FileProperties>, List<ProcessorArchitecture>>? {
        // Note: See https://opensource.apple.com/source/xnu/xnu-344/EXTERNAL_HEADERS/mach-o/fat.h

        val isLe32 = magic == 0xCAFEBABE // FAT_MAGIC
        val isLe64 = magic == 0xCAFEBABF // FAT_MAGIC_64
        val isBe32 = magic == 0xBEBAFECA // FAT_CIGAM
        val isBe64 = magic == 0xBFBAFECA // FAT_CIGAM_64

        if (isLe32 || isLe64 || isBe32 || isBe64) {
          var nFatArch = reader.ReadUInt32Le(isBe32 || isBe64).toInt() // fat_header ::nfat_arch
          val offsets = mutableListOf<ULong>()

          if (isBe64 || isLe64)
            while (nFatArch-- > 0) {
              stream.Seek(8, SeekOrigin.Current)
              offsets.add(reader.ReadUInt64Le(isBe64)) // fat_arch_64::offset
              stream.Seek(16, SeekOrigin.Current)
            }
          else
            while (nFatArch-- > 0) {
              stream.Seek(8, SeekOrigin.Current)
              offsets.add(reader.ReadUInt32Le(isBe32).toULong()) // fat_arch::offset
              stream.Seek(8, SeekOrigin.Current)
            }

          val fileArchitecturesList = mutableListOf<ProcessorArchitecture>()

          val filePropertiesList = offsets.map { offset ->
            stream.Seek(offset.toLong(), SeekOrigin.Begin)
            val fileProperties = ReadHeader(reader.ReadUInt32().toLong()) // mach_header::magic / mach_header64::magic
            if (fileProperties != null)
              fileArchitecturesList.add(fileProperties.second[0])
            fileProperties?.first
          }

          if (filePropertiesList.isEmpty())
            return enumSetOf(FileProperties.UnknownType) to listOf()

          // One of headers is invalid
          if (filePropertiesList.any { x -> x == null })
            return null

          val signed = filePropertiesList.all {
            it != null && it.contains(FileProperties.Signed)
          }
          if (filePropertiesList.asSequence().filterNotNull().map {
              if (signed) it else {
                // One binary in MultiArch file is not signed
                it - FileProperties.Signed
              }
            }.distinct().count() > 1
          ) {
            // Headers are incompatible
            return null
          }

          val totalFileProperty = filePropertiesList[0]

          if (filePropertiesList.count() > 1)
            if (totalFileProperty != null) {
              totalFileProperty += FileProperties.MultiArch
              if (!signed) {
                totalFileProperty -= FileProperties.Signed
              }
            }

          return totalFileProperty!! to fileArchitecturesList
        }

        return null
      }