Utilities/cmexpat/README.md - external/github.com/Kitware/CMake - Git at Google

 [![Run Linux CI tasks](https://github.com/libexpat/libexpat/actions/workflows/linux.yml/badge.svg)](https://github.com/libexpat/libexpat/actions/workflows/linux.yml)
 [![Packaging status](https://repology.org/badge/tiny-repos/expat.svg)](https://repology.org/metapackage/expat/versions)
 [![Downloads SourceForge](https://img.shields.io/sourceforge/dt/expat?label=Downloads%20SourceForge)](https://sourceforge.net/projects/expat/files/)
 [![Downloads GitHub](https://img.shields.io/github/downloads/libexpat/libexpat/total?label=Downloads%20GitHub)](https://github.com/libexpat/libexpat/releases)
 [![OpenSSF Best Practices](https://www.bestpractices.dev/projects/10205/badge)](https://www.bestpractices.dev/projects/10205)

 > [!CAUTION]
 >
 > Expat is **understaffed** and without funding.
 > There is a [call for help with details](https://github.com/libexpat/libexpat/blob/master/expat/Changes)
 > at the top of the `Changes` file.


 # Expat, Release 2.7.3

 This is Expat, a C99 library for parsing
 [XML 1.0 Fourth Edition](https://www.w3.org/TR/2006/REC-xml-20060816/), started by
 [James Clark](https://en.wikipedia.org/wiki/James_Clark_%28programmer%29) in 1997.
 Expat is a stream-oriented XML parser.  This means that you register
 handlers with the parser before starting the parse.  These handlers
 are called when the parser discovers the associated structures in the
 document being parsed.  A start tag is an example of the kind of
 structures for which you may register handlers.

 Expat supports the following C99 compilers:

 - GNU GCC >=4.5 (for use from C) or GNU GCC >=4.8.1 (for use from C++)
 - LLVM Clang >=3.5
 - Microsoft Visual Studio >=17.0/2022
   (the oldest version supported by the [official GitHub Actions Windows images](https://github.com/actions/runner-images))

 Windows users can use the
 [`expat-win32bin-*.*.*.{exe,zip}` download](https://github.com/libexpat/libexpat/releases),
 which includes both pre-compiled libraries and executables, and source code for
 developers.

 Expat is [free software](https://www.gnu.org/philosophy/free-sw.en.html).
 You may copy, distribute, and modify it under the terms of the License
 contained in the file
 [`COPYING`](https://github.com/libexpat/libexpat/blob/master/expat/COPYING)
 distributed with this package.
 This license is the same as the MIT/X Consortium license.


 ## Using libexpat in your CMake-Based Project

 There are three documented ways of using libexpat with CMake:

 ### a) `find_package` with Module Mode

 This approach leverages CMake's own [module `FindEXPAT`](https://cmake.org/cmake/help/latest/module/FindEXPAT.html).

 Notice the *uppercase* `EXPAT` in the following example:

 ```cmake
 cmake_minimum_required(VERSION 3.10)

 project(hello VERSION 1.0.0)

 find_package(EXPAT 2.2.8 MODULE REQUIRED)

 add_executable(hello
     hello.c
 )

 target_link_libraries(hello PUBLIC EXPAT::EXPAT)
 ```

 ### b) `find_package` with Config Mode

 This approach requires files from…

 - libexpat >=2.2.8 where packaging uses the CMake build system
 or
 - libexpat >=2.3.0 where packaging uses the GNU Autotools build system
   on Linux
 or
 - libexpat >=2.4.0 where packaging uses the GNU Autotools build system
   on macOS or MinGW.

 Notice the *lowercase* `expat` in the following example:

 ```cmake
 cmake_minimum_required(VERSION 3.10)

 project(hello VERSION 1.0.0)

 find_package(expat 2.2.8 CONFIG REQUIRED char dtd ns)

 add_executable(hello
     hello.c
 )

 target_link_libraries(hello PUBLIC expat::expat)
 ```

 ### c) The `FetchContent` module

 This approach — as demonstrated below — requires CMake >=3.18 for both the
 [`FetchContent` module](https://cmake.org/cmake/help/latest/module/FetchContent.html)
 and its support for the `SOURCE_SUBDIR` option to be available.

 Please note that:
 - Use of the `FetchContent` module with *non-release* SHA1s or `master`
   of libexpat is neither advised nor considered officially supported.
 - Pinning to a specific commit is great for robust CI.
 - Pinning to a specific commit needs updating every time there is a new
   release of libexpat — either manually or through automation —,
   to not miss out on libexpat security updates.

 For an example that pulls in libexpat via Git:

 ```cmake
 cmake_minimum_required(VERSION 3.18)

 include(FetchContent)

 project(hello VERSION 1.0.0)

 FetchContent_Declare(
     expat
     GIT_REPOSITORY https://github.com/libexpat/libexpat/
     GIT_TAG        000000000_GIT_COMMIT_SHA1_HERE_000000000  # i.e. Git tag R_X_Y_Z
     SOURCE_SUBDIR  expat/
 )

 FetchContent_MakeAvailable(expat)

 add_executable(hello
     hello.c
 )

 target_link_libraries(hello PUBLIC expat)
 ```


 ## Building from a Git Clone

 If you are building Expat from a check-out from the
 [Git repository](https://github.com/libexpat/libexpat/),
 you need to run a script that generates the configure script using the
 GNU autoconf and libtool tools.  To do this, you need to have
 autoconf 2.58 or newer. Run the script like this:

 ```console
 ./buildconf.sh
 ```

 Once this has been done, follow the same instructions as for building
 from a source distribution.


 ## Building from a Source Distribution

 ### a) Building with the configure script (i.e. GNU Autotools)

 To build Expat from a source distribution, you first run the
 configuration shell script in the top level distribution directory:

 ```console
 ./configure
 ```

 There are many options which you may provide to configure (which you
 can discover by running configure with the `--help` option).  But the
 one of most interest is the one that sets the installation directory.
 By default, the configure script will set things up to install
 libexpat into `/usr/local/lib`, `expat.h` into `/usr/local/include`, and
 `xmlwf` into `/usr/local/bin`.  If, for example, you'd prefer to install
 into `/home/me/mystuff/lib`, `/home/me/mystuff/include`, and
 `/home/me/mystuff/bin`, you can tell `configure` about that with:

 ```console
 ./configure --prefix=/home/me/mystuff
 ```

 Another interesting option is to enable 64-bit integer support for
 line and column numbers and the over-all byte index:

 ```console
 ./configure CPPFLAGS=-DXML_LARGE_SIZE
 ```

 However, such a modification would be a breaking change to the ABI
 and is therefore not recommended for general use &mdash; e.g. as part of
 a Linux distribution &mdash; but rather for builds with special requirements.

 After running the configure script, the `make` command will build
 things and `make install` will install things into their proper
 location.  Have a look at the `Makefile` to learn about additional
 `make` options.  Note that you need to have write permission into
 the directories into which things will be installed.

 If you are interested in building Expat to provide document
 information in UTF-16 encoding rather than the default UTF-8, follow
 these instructions (after having run `make distclean`).
 Please note that we configure with `--without-xmlwf` as xmlwf does not
 support this mode of compilation (yet):

 1. Mass-patch `Makefile.am` files to use `libexpatw.la` for a library name:
    <br/>
    `find . -name Makefile.am -exec sed
        -e 's,libexpat\.la,libexpatw.la,'
        -e 's,libexpat_la,libexpatw_la,'
        -i.bak {} +`

 1. Run `automake` to re-write `Makefile.in` files:<br/>
    `automake`

 1. For UTF-16 output as unsigned short (and version/error strings as char),
    run:<br/>
    `./configure CPPFLAGS=-DXML_UNICODE --without-xmlwf`<br/>
    For UTF-16 output as `wchar_t` (incl. version/error strings), run:<br/>
    `./configure CFLAGS="-g -O2 -fshort-wchar" CPPFLAGS=-DXML_UNICODE_WCHAR_T
        --without-xmlwf`
    <br/>Note: The latter requires libc compiled with `-fshort-wchar`, as well.

 1. Run `make` (which excludes xmlwf).

 1. Run `make install` (again, excludes xmlwf).

 Using `DESTDIR` is supported.  It works as follows:

 ```console
 make install DESTDIR=/path/to/image
 ```

 overrides the in-makefile set `DESTDIR`, because variable-setting priority is

 1. commandline
 1. in-makefile
 1. environment

 Note: This only applies to the Expat library itself, building UTF-16 versions
 of xmlwf and the tests is currently not supported.

 When using Expat with a project using autoconf for configuration, you
 can use the probing macro in `conftools/expat.m4` to determine how to
 include Expat.  See the comments at the top of that file for more
 information.

 A reference manual is available in the file `doc/reference.html` in this
 distribution.


 ### b) Building with CMake

 The CMake build system is still *experimental* and may replace the primary
 build system based on GNU Autotools at some point when it is ready.


 #### Available Options

 For an idea of the available (non-advanced) options for building with CMake:

 ```console
 # rm -f CMakeCache.txt ; cmake -D_EXPAT_HELP=ON -LH . | grep -B1 ':.*=' | sed 's,^--$,,'
 // Choose the type of build, options are: None Debug Release RelWithDebInfo MinSizeRel ...
 CMAKE_BUILD_TYPE:STRING=

 // Install path prefix, prepended onto install directories.
 CMAKE_INSTALL_PREFIX:PATH=/usr/local

 // Path to a program.
 DOCBOOK_TO_MAN:FILEPATH=/usr/bin/docbook2x-man

 // Build man page for xmlwf
 EXPAT_BUILD_DOCS:BOOL=ON

 // Build the examples for expat library
 EXPAT_BUILD_EXAMPLES:BOOL=ON

 // Build fuzzers for the expat library
 EXPAT_BUILD_FUZZERS:BOOL=OFF

 // Build pkg-config file
 EXPAT_BUILD_PKGCONFIG:BOOL=ON

 // Build the tests for expat library
 EXPAT_BUILD_TESTS:BOOL=ON

 // Build the xmlwf tool for expat library
 EXPAT_BUILD_TOOLS:BOOL=ON

 // Character type to use (char|ushort|wchar_t) [default=char]
 EXPAT_CHAR_TYPE:STRING=char

 // Install expat files in cmake install target
 EXPAT_ENABLE_INSTALL:BOOL=ON

 // Use /MT flag (static CRT) when compiling in MSVC
 EXPAT_MSVC_STATIC_CRT:BOOL=OFF

 // Build fuzzers via OSS-Fuzz for the expat library
 EXPAT_OSSFUZZ_BUILD:BOOL=OFF

 // Build a shared expat library
 EXPAT_SHARED_LIBS:BOOL=ON

 // Treat all compiler warnings as errors
 EXPAT_WARNINGS_AS_ERRORS:BOOL=OFF

 // Make use of getrandom function (ON|OFF|AUTO) [default=AUTO]
 EXPAT_WITH_GETRANDOM:STRING=AUTO

 // Utilize libbsd (for arc4random_buf)
 EXPAT_WITH_LIBBSD:BOOL=OFF

 // Make use of syscall SYS_getrandom (ON|OFF|AUTO) [default=AUTO]
 EXPAT_WITH_SYS_GETRANDOM:STRING=AUTO
 ```
	[![Run Linux CI tasks](https://github.com/libexpat/libexpat/actions/workflows/linux.yml/badge.svg)](https://github.com/libexpat/libexpat/actions/workflows/linux.yml)
	[![Packaging status](https://repology.org/badge/tiny-repos/expat.svg)](https://repology.org/metapackage/expat/versions)
	[![Downloads SourceForge](https://img.shields.io/sourceforge/dt/expat?label=Downloads%20SourceForge)](https://sourceforge.net/projects/expat/files/)
	[![Downloads GitHub](https://img.shields.io/github/downloads/libexpat/libexpat/total?label=Downloads%20GitHub)](https://github.com/libexpat/libexpat/releases)
	[![OpenSSF Best Practices](https://www.bestpractices.dev/projects/10205/badge)](https://www.bestpractices.dev/projects/10205)

	> [!CAUTION]
	>
	> Expat is understaffed and without funding.
	> There is a [call for help with details](https://github.com/libexpat/libexpat/blob/master/expat/Changes)
	> at the top of the `Changes` file.


	# Expat, Release 2.7.3

	This is Expat, a C99 library for parsing
	[XML 1.0 Fourth Edition](https://www.w3.org/TR/2006/REC-xml-20060816/), started by
	[James Clark](https://en.wikipedia.org/wiki/James_Clark_%28programmer%29) in 1997.
	Expat is a stream-oriented XML parser. This means that you register
	handlers with the parser before starting the parse. These handlers
	are called when the parser discovers the associated structures in the
	document being parsed. A start tag is an example of the kind of
	structures for which you may register handlers.

	Expat supports the following C99 compilers:

	- GNU GCC >=4.5 (for use from C) or GNU GCC >=4.8.1 (for use from C++)
	- LLVM Clang >=3.5
	- Microsoft Visual Studio >=17.0/2022
	(the oldest version supported by the [official GitHub Actions Windows images](https://github.com/actions/runner-images))

	Windows users can use the
	[`expat-win32bin-..*.{exe,zip}` download](https://github.com/libexpat/libexpat/releases),
	which includes both pre-compiled libraries and executables, and source code for
	developers.

	Expat is [free software](https://www.gnu.org/philosophy/free-sw.en.html).
	You may copy, distribute, and modify it under the terms of the License
	contained in the file
	[`COPYING`](https://github.com/libexpat/libexpat/blob/master/expat/COPYING)
	distributed with this package.
	This license is the same as the MIT/X Consortium license.


	## Using libexpat in your CMake-Based Project

	There are three documented ways of using libexpat with CMake:

	### a) `find_package` with Module Mode

	This approach leverages CMake's own [module `FindEXPAT`](https://cmake.org/cmake/help/latest/module/FindEXPAT.html).

	Notice the uppercase `EXPAT` in the following example:

	```cmake
	cmake_minimum_required(VERSION 3.10)

	project(hello VERSION 1.0.0)

	find_package(EXPAT 2.2.8 MODULE REQUIRED)

	add_executable(hello
	hello.c
	)

	target_link_libraries(hello PUBLIC EXPAT::EXPAT)
	```

	### b) `find_package` with Config Mode

	This approach requires files from…

	- libexpat >=2.2.8 where packaging uses the CMake build system
	or
	- libexpat >=2.3.0 where packaging uses the GNU Autotools build system
	on Linux
	or
	- libexpat >=2.4.0 where packaging uses the GNU Autotools build system
	on macOS or MinGW.

	Notice the lowercase `expat` in the following example:

	```cmake
	cmake_minimum_required(VERSION 3.10)

	project(hello VERSION 1.0.0)

	find_package(expat 2.2.8 CONFIG REQUIRED char dtd ns)

	add_executable(hello
	hello.c
	)

	target_link_libraries(hello PUBLIC expat::expat)
	```

	### c) The `FetchContent` module

	This approach — as demonstrated below — requires CMake >=3.18 for both the
	[`FetchContent` module](https://cmake.org/cmake/help/latest/module/FetchContent.html)
	and its support for the `SOURCE_SUBDIR` option to be available.

	Please note that:
	- Use of the `FetchContent` module with non-release SHA1s or `master`
	of libexpat is neither advised nor considered officially supported.
	- Pinning to a specific commit is great for robust CI.
	- Pinning to a specific commit needs updating every time there is a new
	release of libexpat — either manually or through automation —,
	to not miss out on libexpat security updates.

	For an example that pulls in libexpat via Git:

	```cmake
	cmake_minimum_required(VERSION 3.18)

	include(FetchContent)

	project(hello VERSION 1.0.0)

	FetchContent_Declare(
	expat
	GIT_REPOSITORY https://github.com/libexpat/libexpat/
	GIT_TAG 000000000_GIT_COMMIT_SHA1_HERE_000000000 # i.e. Git tag R_X_Y_Z
	SOURCE_SUBDIR expat/
	)

	FetchContent_MakeAvailable(expat)

	add_executable(hello
	hello.c
	)

	target_link_libraries(hello PUBLIC expat)
	```


	## Building from a Git Clone

	If you are building Expat from a check-out from the
	[Git repository](https://github.com/libexpat/libexpat/),
	you need to run a script that generates the configure script using the
	GNU autoconf and libtool tools. To do this, you need to have
	autoconf 2.58 or newer. Run the script like this:

	```console
	./buildconf.sh
	```

	Once this has been done, follow the same instructions as for building
	from a source distribution.


	## Building from a Source Distribution

	### a) Building with the configure script (i.e. GNU Autotools)

	To build Expat from a source distribution, you first run the
	configuration shell script in the top level distribution directory:

	```console
	./configure
	```

	There are many options which you may provide to configure (which you
	can discover by running configure with the `--help` option). But the
	one of most interest is the one that sets the installation directory.
	By default, the configure script will set things up to install
	libexpat into `/usr/local/lib`, `expat.h` into `/usr/local/include`, and
	`xmlwf` into `/usr/local/bin`. If, for example, you'd prefer to install
	into `/home/me/mystuff/lib`, `/home/me/mystuff/include`, and
	`/home/me/mystuff/bin`, you can tell `configure` about that with:

	```console
	./configure --prefix=/home/me/mystuff
	```

	Another interesting option is to enable 64-bit integer support for
	line and column numbers and the over-all byte index:

	```console
	./configure CPPFLAGS=-DXML_LARGE_SIZE
	```

	However, such a modification would be a breaking change to the ABI
	and is therefore not recommended for general use — e.g. as part of
	a Linux distribution — but rather for builds with special requirements.

	After running the configure script, the `make` command will build
	things and `make install` will install things into their proper
	location. Have a look at the `Makefile` to learn about additional
	`make` options. Note that you need to have write permission into
	the directories into which things will be installed.

	If you are interested in building Expat to provide document
	information in UTF-16 encoding rather than the default UTF-8, follow
	these instructions (after having run `make distclean`).
	Please note that we configure with `--without-xmlwf` as xmlwf does not
	support this mode of compilation (yet):

	1. Mass-patch `Makefile.am` files to use `libexpatw.la` for a library name:
	<br/>
	`find . -name Makefile.am -exec sed
	-e 's,libexpat\.la,libexpatw.la,'
	-e 's,libexpat_la,libexpatw_la,'
	-i.bak {} +`

	1. Run `automake` to re-write `Makefile.in` files:<br/>
	`automake`

	1. For UTF-16 output as unsigned short (and version/error strings as char),
	run:<br/>
	`./configure CPPFLAGS=-DXML_UNICODE --without-xmlwf`<br/>
	For UTF-16 output as `wchar_t` (incl. version/error strings), run:<br/>
	`./configure CFLAGS="-g -O2 -fshort-wchar" CPPFLAGS=-DXML_UNICODE_WCHAR_T
	--without-xmlwf`
	<br/>Note: The latter requires libc compiled with `-fshort-wchar`, as well.

	1. Run `make` (which excludes xmlwf).

	1. Run `make install` (again, excludes xmlwf).

	Using `DESTDIR` is supported. It works as follows:

	```console
	make install DESTDIR=/path/to/image
	```

	overrides the in-makefile set `DESTDIR`, because variable-setting priority is

	1. commandline
	1. in-makefile
	1. environment

	Note: This only applies to the Expat library itself, building UTF-16 versions
	of xmlwf and the tests is currently not supported.

	When using Expat with a project using autoconf for configuration, you
	can use the probing macro in `conftools/expat.m4` to determine how to
	include Expat. See the comments at the top of that file for more
	information.

	A reference manual is available in the file `doc/reference.html` in this
	distribution.


	### b) Building with CMake

	The CMake build system is still experimental and may replace the primary
	build system based on GNU Autotools at some point when it is ready.


	#### Available Options

	For an idea of the available (non-advanced) options for building with CMake:

	```console
	# rm -f CMakeCache.txt ; cmake -D_EXPAT_HELP=ON -LH . \| grep -B1 ':.*=' \| sed 's,^--$,,'
	// Choose the type of build, options are: None Debug Release RelWithDebInfo MinSizeRel ...
	CMAKE_BUILD_TYPE:STRING=

	// Install path prefix, prepended onto install directories.
	CMAKE_INSTALL_PREFIX:PATH=/usr/local

	// Path to a program.
	DOCBOOK_TO_MAN:FILEPATH=/usr/bin/docbook2x-man

	// Build man page for xmlwf
	EXPAT_BUILD_DOCS:BOOL=ON

	// Build the examples for expat library
	EXPAT_BUILD_EXAMPLES:BOOL=ON

	// Build fuzzers for the expat library
	EXPAT_BUILD_FUZZERS:BOOL=OFF

	// Build pkg-config file
	EXPAT_BUILD_PKGCONFIG:BOOL=ON

	// Build the tests for expat library
	EXPAT_BUILD_TESTS:BOOL=ON

	// Build the xmlwf tool for expat library
	EXPAT_BUILD_TOOLS:BOOL=ON

	// Character type to use (char\|ushort\|wchar_t) [default=char]
	EXPAT_CHAR_TYPE:STRING=char

	// Install expat files in cmake install target
	EXPAT_ENABLE_INSTALL:BOOL=ON

	// Use /MT flag (static CRT) when compiling in MSVC
	EXPAT_MSVC_STATIC_CRT:BOOL=OFF

	// Build fuzzers via OSS-Fuzz for the expat library
	EXPAT_OSSFUZZ_BUILD:BOOL=OFF

	// Build a shared expat library
	EXPAT_SHARED_LIBS:BOOL=ON

	// Treat all compiler warnings as errors
	EXPAT_WARNINGS_AS_ERRORS:BOOL=OFF

	// Make use of getrandom function (ON\|OFF\|AUTO) [default=AUTO]
	EXPAT_WITH_GETRANDOM:STRING=AUTO

	// Utilize libbsd (for arc4random_buf)
	EXPAT_WITH_LIBBSD:BOOL=OFF

	// Make use of syscall SYS_getrandom (ON\|OFF\|AUTO) [default=AUTO]
	EXPAT_WITH_SYS_GETRANDOM:STRING=AUTO
	```