# Changes in TIFF v4.0.5

References
Current Version | v4.0.5 (tag Release-v4-0-5)
Previous Version | v4.0.4
Master Download Site | https://download.osgeo.org/libtiff/
Master HTTP Site | https://download.osgeo.org/libtiff/

This document describes the changes made to the software between the previous and current versions (see above). If you don’t find something listed here, then it was not done in this timeframe, or it was not considered important enough to be mentioned. The following information is located here:

## Major changes

- Support for configure/build using CMake.

- Support for large (> 2GB) files under Microsoft Windows.

## Software configuration changes

- `CMakeLists.txt` / CMake

  - Configuration and building using CMake is now supported under Microsoft Windows and on Unix-type systems.

- `configure.ac` / configure

  - Test for and use `fseeko()` if it is available. This allows supporting large files on Unix-type systems with a 32-bit long type and a 64-bit `off_t` type.

## Library changes

- `tiffiop.h`:

  - Macros added to use 64-bit equivalents for all standard I/O and POSIX APIs used by libtiff and its tools which are limited to 2GB in Windows builds. Note that these 64-bit equivalents were introduced by the CRT provided with Visual Studio 2005 and if the necessary CRT is not installed on the target computer, the program will not run. The wrapper macros will not be activated unless the definition `_MSC_VER` is at least 1400 or :c:macro:`__MSVCRT_VERSION__` is at least `0x800`.

- `tif_unix.c`:

  - Updated to support large files under Microsoft Windows. This makes `tif_unix.c` a completely viable candidate for use under Windows (in spite of its name) if the CRT is modern enough. Please note that `tif_win32.c` already supported large files, but only tiffinfo and tiffdump made any provision to support large files under Windows.

  - `_tiffReadProc()` and `_tiffWriteProc()` are modified to chunk I/O to a maximum size of 2GB for extremely large I/O requests. This surmounts limitations in the Microsoft Windows `read()` and `write()` APIs (which are limited to the range of a 32-bit int), and may avoid poor behavior with extremely large I/O requests on other systems.

## Tools changes

- All tools

  - Updated to use I/O wrapper macros from `tiffiop.h` in order to support large files under Microsoft Windows.

## Contributed software changes

None