## Compiling the GLib package

Compiling the GLib Package — How to compile GLib itself

## Building the Library on UNIX

On UNIX, GLib uses the standard GNU build system, using autoconf for package configuration and resolving portability issues, automake for building makefiles that comply with the GNU Coding Standards, and libtool for building shared libraries on multiple platforms. The normal sequence for compiling and installing the GLib library is thus:

`./configure`
`make`
`make install`

The standard options provided by GNU autoconf may be passed to the configure script. Please see the autoconf documentation or run ./configure --help for information about the standard options.

The GTK+ documentation contains further details about the build process and ways to influence it.

## Dependencies

Before you can compile the GLib library, you need to have various other tools and libraries installed on your system. The two tools needed during the build process (as differentiated from the tools used in when creating GLib mentioned above such as autoconf) are pkg-config and GNU make.

- pkg-config is a tool for tracking the compilation flags needed for libraries that are used by the GLib library. (For each library, a small `.pc` text file is installed in a standard location that contains the compilation flags needed for that library along with version number information.) The version of pkg-config needed to build GLib is mirrored in the `dependencies` directory on the GTK+ FTP site.

- The GTK+ makefiles will mostly work with different versions of make, however, there tends to be a few incompatibilities, so the GTK+ team recommends installing GNU make if you don't already have it on your system and using it. (It may be called gmake rather than make.)

GLib depends on a number of other libraries.

- The GNU libiconv library is needed to build GLib if your system doesn't have the `iconv()` function for doing conversion between character encodings. Most modern systems should have `iconv()`, however many older systems lack an `iconv()` implementation. On such systems, you must install the libiconv library. This can be found at: http://www.gnu.org/software/libiconv.

  If your system has an `iconv()` implementation but you want to use libiconv instead, you can pass the --with-libiconv option to configure. This forces libiconv to be used.

  Note that if you have libiconv installed in your default include search path (for instance, in `/usr/local/`), but don't enable it, you will get an error while compiling GLib because the `iconv.h` that libiconv installs hides the system iconv.

  If you are using the native iconv implementation on Solaris instead of libiconv, you'll need to make sure that you have the converters between locale encodings and UTF-8 installed. At a minimum you'll need the SUNWuiu8 package. You probably should also install the SUNWciu8, SUNWhiu8, SUNWjiu8, and SUNWkiu8 packages.

  The native iconv on Compaq Tru64 doesn't contain support for UTF-8, so you'll need to use GNU libiconv instead. (When using GNU libiconv for GLib, you'll need to use GNU libiconv for GNU gettext as well.) This probably applies to related operating systems as well.

- The libintl library from the GNU gettext package is needed if your system doesn't have the `gettext()` functionality for handling message translation databases.

- A thread implementation is needed. The thread support in GLib can be based upon POSIX threads or win32 threads.

- GRegex uses the PCRE library for regular expression matching. The default is to use the internal version of PCRE that is patched to use GLib for memory management and Unicode handling. If you prefer to use the system-supplied PCRE library you can pass the `--with-pcre=system` option to, but it is not recommended.

- The optional extended attribute support in GIO requires the getxattr() family of functions that may be provided by glibc or by the standalone libattr library. To build GLib without extended attribute support, use the `--disable-xattr` option.

- The optional SELinux support in GIO requires libselinux. To build GLib without SELinux support, use the `--disable-selinux` option.

- The optional support for DTrace requires the `sys/sdt.h` header, which is provided by SystemTap on Linux. To build GLib without DTrace, use the `--disable-dtrace` configure option.

- The optional support for SystemTap can be disabled with the `--disable-systemtap` configure option.

## Extra Configuration Options

In addition to the normal options, the configure script in the GLib library supports these additional arguments:

`--enable-debug`. Turns on various amounts of debugging support. Setting this to 'no' disables g_assert(), g_return_if_fail(), g_return_val_if_fail() and all cast checks between different object types. Setting it to 'minimum' disables only cast checks. Setting it to 'yes' enables runtime debugging. The default is 'minimum'. Note that 'no' is fast, but dangerous as it tends to destabilize even mostly bug-free software by changing the effect of many bugs from simple warnings into fatal crashes. Thus `--enable-debug=no` should not be used for stable releases of GLib.

`--disable-gc-friendly` and `--enable-gc-friendly`. By default, and with `--disable-gc-friendly` as well, Glib does not clear the memory for certain objects before they are freed. For example, Glib may decide to recycle GList nodes by putting them in a free list. However, memory profiling and debugging tools like Valgrind work better if an application does not keep dangling pointers to freed memory (even though these pointers are no longer dereferenced), or invalid pointers inside uninitialized memory. The `--enable-gc-friendly` option makes Glib clear memory in these situations:

- When shrinking a GArray, Glib will clear the memory no longer available in the array: shrink an array from 10 bytes to 7, and the last 3 bytes will be cleared. This includes removals of single and multiple elements.

- When growing a GArray, Glib will clear the new chunk of memory. Grow an array from 7 bytes to 10 bytes, and the last 3 bytes will be cleared.

- The above applies to GPtrArray as well.

- When freeing a node from a GHashTable, Glib will first clear the node, which used to have pointers to the key and the value stored at that node.

- When destroying or removing a GTree node, Glib will clear the node, which used to have pointers to the node's value, and the left and right subnodes.

Since clearing the memory has a cost, `--disable-gc-friendly` is the default.

`--disable-mem-pools` and `--enable-mem-pools`. Many small chunks of memory are often allocated via collective pools in GLib and are cached after release to speed up reallocations. For sparse memory systems this behaviour is often inferior, so memory pools can be disabled to avoid excessive caching and force atomic maintenance of chunks through the `g_malloc()` and `g_free()` functions. Code currently affected by this:

- GMemChunks become basically non-effective

- GSignal disables all caching (potentially very slow)

- GType doesn't honour the GTypeInfo `n_preallocs` field anymore

- the GBSearchArray flag `G_BSEARCH_ALIGN_POWER2` becomes non-functional

`--with-threads`. Specify a thread implementation to use. Available options are 'posix' or 'win32'. Normally, configure should be able to work out the system threads API on its own.

`--disable-regex` and `--enable-regex`. Do not compile GLib with regular expression support. GLib will be smaller because it will not need the PCRE library. This is however not recommended, as programs may need GRegex.

`--with-pcre`. Specify whether to use the internal or the system-supplied PCRE library.

- 'internal' means that GRegex will be compiled to use the internal PCRE library.

- 'system' means that GRegex will be compiled to use the system-supplied PCRE library.

Using the internal PCRE is the preferred solution:

- System-supplied PCRE has a separated copy of the big tables used for Unicode handling.

- Some systems have PCRE libraries compiled without some needed features, such as UTF-8 and Unicode support.

- PCRE uses some global variables for memory management and other features. In the rare case of a program using both GRegex and PCRE (maybe indirectly through a library), this variables could lead to problems when they are modified.

`--disable-included-printf` and `--enable-included-printf`. By default the configure script will try to auto-detect whether the C library provides a suitable set of printf() functions. In detail, configure checks that the semantics of snprintf() are as specified by C99 and that positional parameters as specified in the Single Unix Specification are supported. If this not the case, GLib will include an implementation of the printf() family. These options can be used to explicitly control whether an implementation fo the printf() family should be included or not.

`--disable-Bsymbolic` and `--enable-Bsymbolic`. By default, GLib uses the -Bsymbolic-functions linker flag to avoid intra-library PLT jumps. A side-effect of this is that it is no longer possible to override internal uses of GLib functions with `LD_PRELOAD`. Therefore, it may make sense to turn this feature off in some situations. The `--disable-Bsymbolic` option allows to do that.

`--disable-gtk-doc` and `--enable-gtk-doc`. By default the configure script will try to auto-detect whether the gtk-doc package is installed. If it is, then it will use it to extract and build the documentation for the GLib library. These options can be used to explicitly control whether gtk-doc should be used or not. If it is not used, the distributed, pre-generated HTML files will be installed instead of building them on your machine.

`--disable-man` and `--enable-man`. By default the configure script will try to auto-detect whether xsltproc and the necessary Docbook stylesheets are installed. If they are, then it will use them to rebuild the included man pages from the XML sources. These options can be used to explicitly control whether man pages should be rebuilt used or not. The distribution includes pre-generated man pages.

`--disable-xattr` and `--enable-xattr`. By default the configure script will try to auto-detect whether the getxattr() family of functions is available. If it is, then extended attribute support will be included in GIO. These options can be used to explicitly control whether extended attribute support should be included or not. getxattr() and friends can be provided by glibc or by the standalone libattr library.

`--disable-selinux` and `--enable-selinux`. By default the configure script will auto-detect if libselinux is available and include SELinux support in GIO if it is. These options can be used to explicitly control whether SELinux support should be included.

`--disable-dtrace` and `--enable-dtrace`. By default the configure script will detect if DTrace support is available, and use it.

`--disable-systemtap` and `--enable-systemtap`. This option requires DTrace support. If it is available, then the configure script will also check for the presence of SystemTap.

`--enable-gcov` and `--disable-gcov`. Enable the generation of coverage reports for the GLib tests. This requires the lcov frontend to gcov from the Linux Test Project. To generate a coverage report, use the lcov make target. The report is placed in the `glib-lcov` directory.

`--with-runtime-libdir=RELPATH`. Allows specifying a relative path to where to install the runtime libraries (meaning library files used for running, not developing, GLib applications). This can be used in operating system setups where programs using GLib needs to run before e.g. `/usr` is mounted. For example, if LIBDIR is `/usr/lib` and `../../lib` is passed to `--with-runtime-libdir` then the runtime libraries are installed into `/lib` rather than `/usr/lib`.

`--with-python`. Allows specifying the Python interpreter to use, either as an absolute path, or as a program name. GLib can be built with Python 2 (at least version 2.5) or Python 3.