Getting started¶

Pre-built Linux packages are distributed from the libcbor website.

OS X users can use Homebrew:

brew tap pjk/libcbor
brew install libcbor

For other platforms, you will need to compile it from source.

Building & installing libcbor¶

Prerequisites:

C99 compiler
CMake 2.8 or newer (might also be called cmakesetup, cmake-gui or ccmake depending on the installed version and system)
C build system CMake can target (make, Apple Xcode, MinGW, …)

Note

As of May 2015, not even the 2015 release candidate of Visual Studio supports C99. While CMake will be happy to generate a VS solution that you can play with, libcbor currently cannot be compiled using the MSVC toolchain. ICC, GCC under Cygwin, and MinGW’s GCC will all work. The MinGW build process is described below.

Configuration options

A handful of configuration flags can be passed to cmake. The following table lists libcbor compile-time directives and several important generic flags.

Option	Meaning	Default	Possible values
`CMAKE_C_COMPILER`	C compiler to use	`cc`	`gcc`, `clang`, `clang-3.5`, …
`CMAKE_INSTALL_PREFIX`	Installation prefix	System-dependent	`/usr/local/lib`, …
`HUGE_FUZZ`	Fuzz test with 8GB of data	`OFF`	`ON`, `OFF`
`SANE_MALLOC`	Assume `malloc` will refuse unreasonable allocations	`OFF`	`ON`, `OFF`
`COVERAGE`	Generate test coverage instrumentation	`OFF`	`ON`, `OFF`
`WITH_TESTS`	Build unit tests (see Development)	`OFF`	`ON`, `OFF`

The following configuration options will also be defined as macros[#]_ in <cbor/common.h> and can therefore be used in client code:

Option	Meaning	Default	Possible values
`CBOR_CUSTOM_ALLOC`	Enable custom allocator support	`OFF`	`ON`, `OFF`
`CBOR_PRETTY_PRINTER`	Include a pretty-printing routine	`ON`	`ON`, `OFF`
`CBOR_BUFFER_GROWTH`	Factor for buffer growth & shrinking	`2`	Decimals > 1

1: ON & OFF will be translated to 1 and 0 using cmakedefine.

If you want to pass other custom configuration options, please refer to http://www.cmake.org/Wiki/CMake_Useful_Variables.

Building using make

CMake will generate a Makefile and other configuration files for the build. As a rule of thumb, you should configure the build outside of the source tree in order to keep different configurations isolated. If you are unsure where to execute the build, just use a temporary directory:

cd $(mktemp -d /tmp/cbor_build.XXXX)

Now, assuming you are in the directory where you want to build, execute the following to configure the build and run make

cmake -DCMAKE_BUILD_TYPE=Release path_to_libcbor_dir
make cbor cbor_shared

Both the shared (libcbor.so) and the static (libcbor.a) libraries should now be in the src subdirectory.

In order to install the libcbor headers and libraries, the usual

make install

is what your’re looking for. Root permissions are required on most systems when using the default installation prefix.

Portability

libcbor is highly portable and works on both little- and big-endian systems regardless of the operating system. After building on an exotic platform, you might wish to verify the result by running the test suite. If you encounter any problems, please report them to the issue tracker.

libcbor is known to successfully work on ARM Android devices. Cross-compilation is possible with arm-linux-gnueabi-gcc.

Linking with libcbor¶

If you include and linker paths include the directories to which libcbor has been installed, compiling programs that uses libcbor requires no extra considerations.

You can verify that everything has been set up properly by creating a file with the following contents

#include <cbor.h>
#include <stdio.h>

int main(int argc, char * argv[])
{
    printf("Hello from libcbor %s\n", CBOR_VERSION);
}

and compiling it

cc hello_cbor.c -lcbor -o hello_cbor

libcbor also comes with pkg-config support. If you install libcbor with a custom prefix, you can use pkg-config to resolve the headers and objects:

cc $(pkg-config --cflags libcbor) hello_cbor.c $(pkg-config --libs libcbor) -o hello_cbor

A note on linkage

libcbor is primarily intended to be linked statically. The shared library versioning scheme generally follows SemVer, but is irregular for the 0.X.Y development branch for historical reasons. The following version identifiers are used as a part of the SONAME (Linux) or the dylib “Compatibility version” (OS X):

0.Y for the 0.Y.Z branch. Patches are backwards compatible, minor releases are generally not and require re-compilation of any dependent code.

X for the X.Y.Z stable versions starting 1.X.Y. All minor release of the major version are backwards compatible.

Warning

Please note that releases up to and including v0.6.0 may export misleading .so/.dylib version number.

MinGW build instructions¶

Prerequisites:

MinGW
CMake GUI

First of all, create a folder that will be used for the output. For this demonstration, we will use cbor_out. Start CMake and select the source path and the destination folder.

Then hit the ‘Configure’ button. You will be prompted to select the build system:

Choose MinGW and confirm.

Note

If you select Visual Studio at this point, a MSVC project will be generated for you. This is useful if you just want to browse through the source code.

You can then adjust the build options. The defaults will work just fine. Hit ‘Generate’ when you are done.

You can then adjust the build options. The defaults will work just fine. Hit ‘Generate’ when you are done.

Open the shell, navigate to the output directory, and run mingw32-make cbor cbor_shared.

libcbor will be built and your .dll should be ready at this point

Feel free to also try building and running some of the examples, e.g. mingw32-make sort

Troubleshooting¶

cbor.h not found: The headers directory is probably not in your include path. First, verify the installation location by checking the installation log. If you used make, it will look something like

...
-- Installing: /usr/local/include/cbor
-- Installing: /usr/local/include/cbor/callbacks.h
-- Installing: /usr/local/include/cbor/encoding.h
...

Make sure that CMAKE_INSTALL_PREFIX (if you provided it) was correct. Including the path path during compilation should suffice, e.g.:

cc -I/usr/local/include hello_cbor.c -lcbor -o hello_cbor

cannot find -lcbor during linking: Most likely the same problem as before. Include the installation directory in the linker shared path using -R, e.g.:

cc -Wl,-rpath,/usr/local/lib -lcbor -o hello_cbor

shared library missing during execution: Verify the linkage using ldd, otool, or similar and adjust the compilation directives accordingly:

⇒  ldd hello_cbor
    linux-vdso.so.1 =>  (0x00007ffe85585000)
    libcbor.so => /usr/local/lib/libcbor.so (0x00007f9af69da000)
    libc.so.6 => /lib/x86_64-linux-gnu/libc.so.6 (0x00007f9af65eb000)
    /lib64/ld-linux-x86-64.so.2 (0x00007f9af6be9000)

compilation failed: If your compiler supports C99 yet the compilation has failed, please report the issue to the issue tracker.