256 static FILE *in_stream;  variable
906           in_stream = stdin;  in open_next_file()
912           in_stream = fopen (input_filename, (O_BINARY ? "rb" : "r"));  in open_next_file()
913           if (in_stream == nullptr)  in open_next_file()
920   while (in_stream == nullptr);  in open_next_file()
923     setvbuf (in_stream, nullptr, _IONBF, 0);  in open_next_file()
940   if (in_stream != nullptr)  in check_and_close()
942       if (!ferror (in_stream))  in check_and_close()
945         clearerr (in_stream);  in check_and_close()
946       else if (fclose (in_stream) != 0 && !in_errno)  in check_and_close()
954       in_stream = nullptr;  in check_and_close()
1009   while (in_stream != nullptr)	/* EOF.  */  in skip()
1023       if (fstat (fileno (in_stream), &file_stats) == 0)  in skip()
1040                   if (fseeko (in_stream, n_skip, SEEK_CUR) != 0)  in skip()
1049           else if (!usable_size && fseeko (in_stream, n_skip, SEEK_CUR) == 0)  in skip()
1065                   n_bytes_read = fread (buf, 1, n_bytes_to_read, in_stream);  in skip()
1069                       if (ferror (in_stream))  in skip()
1076                       if (feof (in_stream))  in skip()
1247   while (in_stream != nullptr)	/* EOF.  */  in read_char()
1249       *c = fgetc (in_stream);  in read_char()
1285   while (in_stream != nullptr)	/* EOF.  */  in read_block()
1291       n_read = fread (block + *n_bytes_in_buffer, 1, n_needed, in_stream);  in read_block()
1911   if (in_stream == nullptr)  in main()
1916   if (in_stream == nullptr)  in main()