Apache Portable Runtime Library (APR)

The Apache Portable Runtime Library provides a predictable and consistent interface to underlying platform-specific implementations, with an API to which software developers may code and be assured of predictable if not identical behavior regardless of the platform on which their software is built, relieving them of the need to code special-case conditions to work around or take advantage of platform-specific deficiencies or features.

APR and its companion libraries are implemented entirely in C and provide a common programming interface across a wide variety of operating system platforms without sacrificing performance. Currently supported platforms include:

 UNIX variants
 Windows
 Mac OS X
 OS/2

To give a brief overview, the primary core subsystems of APR 1.3 include the following:

 Atomic operations
 Dynamic Shared Object loading
 File I/O
 Locks (mutexes, condition variables, etc)
 Memory management (high performance allocators)
 Memory-mapped files
 Multicast Sockets
 Network I/O
 Shared memory
 Thread and Process management
 Various data structures (tables, hashes, priority queues, etc)

APR 2.0 also provides a number of utility functions and library compatibility interfaces. These were formerly part of APR-util, a seperate utility library in version 1 releases. These include;

 Hashing and UUID services
 Multiple SQL DBD client interfaces
 Multiple flat-database DBM client interfaces
 Typesafe function Hooks abstraction
 MemCache interface
 Date parsing rourtines
 Resource Lists
 Thread Pools
 Queues
 Relocatable Memory Management functions
 String filename-style pattern matching
 URI Parsing
 Charset translation (iconv based)
 XML parsing (expat based)

For a more complete list, please refer to the following URLs:

 http://apr.apache.org/docs/apr/modules.html

Users of APR 0.9 should be aware that migrating to the APR 1.x programming interfaces may require some adjustments; APR 1.x is neither source nor binary compatible with earlier APR 0.9 releases. Users of APR 1.x can expect consistent interfaces and binary backwards compatibility throughout the entire APR 1.x release cycle, as defined in our versioning rules:

 http://apr.apache.org/versioning.html

APR is already used extensively by the Apache HTTP Server version 2 and the Subversion revision control system, to name but a few. We list all known projects using APR at http://apr.apache.org/projects.html – so please let us know if you find our libraries useful in your own projects!

Database Providers

Interfaces for copy-left licensed MySQL and gdbm DBD drivers, and Berkeley DB DBM all ship as part of the distribution. To avoid licensing incompatibilities, these are not built by default. To enable support, the corresponding use the –with-{provider} option, but be aware that these licenses may introduce licensing implications for your compiled code. Similarly, the bindings for propritary drivers such as Oracle must also be explicitly enabled.

Whenever distributing apr-util in combination with database client drivers, always review the license requirements of all components.

Using a Subversion Checkout on Unix

If you are building APR from SVN, you need to perform a prerequisite step. You must have autoconf, libtool and python installed for this to work. The prerequisite is simply;

./buildconf

If you are building APR from a distribution tarball, buildconf is already run for you, and you do not need autoconf, libtool or python installed or to run buildconf unless you have patched APR’s buildconf inputs (such as configure.in, build.conf, virtually any file within the build/ tree, or you add or remove source files).

Remember when updating from svn that you must rerun ./buildconf again to effect any changes made to the build schema in your fresh update.

Configuring and Building APR on Unix

Simply;

./configure –prefix=/desired/path/of/apr make make test make install

Configure has additional options, ./configure –help will offer you those choices. You may also add CC=compiler CFLAGS=”compiler flags” etc. prior to the ./configure statement (on the same line). Please be warned, some flags must be passed as part of the CC command, itself, in order for autoconf to make the right determinations. Eg.;

CC=”gcc -m64” ./configure –prefix=/desired/path/of/apr

will inform APR that you are compiling to a 64 bit CPU, and autoconf must consider that when setting up all of APR’s internal and external type declarations.

For more verbose output from testall, you may wish to invoke testall with the flag;

cd test ./testall -v

Building APR RPM files on Linux

Run the following to create SRPMs:

rpmbuild -ts apr-.tar.bz2 rpmbuild -ts apr-util-.tar.bz2

Run the following to create RPMs (or build from the SRPMs):

rpmbuild -tb apr-.tar.bz2 rpmbuild -tb apr-util-.tar.bz2

Resolve dependencies as appropriate.

Configuring and Building APR on Windows

APR uses CMake to build on Windows.

Using command line: cmake -B out/build -G Ninja -DCMAKE_INSTALL_PREFIX=out/install cmake –build out/build cmake –install out/build

Using Visual Studio:

1. Make sure that “C++ CMake tools for Windows” component is installed.
2. Use Visual Studio Open Folder command to open APR source code directory.
3. Use Build command to build APR

Please refer to README.cmake for more information about CMake options.

Generating Test Coverage information with gcc

If you want to generate test coverage data, use the following steps:

./buildconf CFLAGS=”–coverage -fprofile-abs-path” LDFLAGS=”–coverage” ./configure make cd test make ./testall cd .. make gcov

Cryptographic Software Notice

This distribution includes cryptographic software. The country in which you currently reside may have restrictions on the import, possession, use, and/or re-export to another country, of encryption software. BEFORE using any encryption software, please check your country’s laws, regulations and policies concerning the import, possession, or use, and re-export of encryption software, to see if this is permitted. See http://www.wassenaar.org/ for more information.

The U.S. Government Department of Commerce, Bureau of Industry and Security (BIS), has classified this software as Export Commodity Control Number (ECCN) 5D002.C.1, which includes information security software using or performing cryptographic functions with asymmetric algorithms. The form and manner of this Apache Software Foundation distribution makes it eligible for export under the License Exception ENC Technology Software Unrestricted (TSU) exception (see the BIS Export Administration Regulations, Section 740.13) for both object code and source code.

The following provides more details on the included cryptographic software:

APR provides an abstract interface for symmetrical cryptographic functions that make use of a general-purpose encryption library, such as OpenSSL, NSS, or the operating system’s platform-specific facilities. This interface is known as the apr_crypto interface, with implementation beneath the /crypto directory.