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Compiling librsvg

Librsvg uses a mostly normal autotools setup, but it has some peculiarities due to librsvg's use of a Rust sub-library. The details of how librsvg integrates Cargo and Rust into its autotools setup are described in this blog post, although hopefully you will not need to refer to it.

It is perfectly fine to ask the maintainer if you have questions about the Autotools setup; it's a tricky bit of machinery, and we are glad to help.

There are generic compilation/installation instructions in the INSTALL file, which comes from Autotools. The following explains librsvg's peculiarities.

Installing dependencies for building

To compile librsvg, you need the following packages installed. The minimum version is listed here; you may use a newer version instead.

Compilers:

  • a C compiler and make tool; we recommend GNU make.
  • rust 1.36 or later
  • cargo

Mandatory dependencies:

  • Cairo 1.16.0 with PNG support
  • Freetype2 2.8.0
  • Gdk-pixbuf 2.20.0
  • GIO 2.24.0
  • GObject-Introspection 0.10.8
  • Libxml2 2.9.0
  • Pango 1.38.0

The following sections describe how to install these dependencies on several systems.

Debian based systems

As of 2018/Feb/22, librsvg cannot be built in debian stable and ubuntu 18.04, as they have packages that are too old.

Build dependencies on Debian Testing or Ubuntu 18.10:

apt-get install -y gcc make rustc cargo \
automake autoconf libtool gettext itstool \
libgdk-pixbuf2.0-dev libgirepository1.0-dev \
gtk-doc-tools git \
libxml2-dev libcairo2-dev libpango1.0-dev

Additionally, as of September 2018 you need to add gdk-pixbuf utilities to your path, see #331 for more.

PATH="$PATH:/usr/lib/x86_64-linux-gnu/gdk-pixbuf-2.0"

Fedora based systems

dnf install -y gcc rust rust-std-static cargo make \
automake autoconf libtool gettext itstool \
gdk-pixbuf2-devel gobject-introspection-devel \
gtk-doc git redhat-rpm-config gettext-devel \
libxml2-devel cairo-devel pango-devel

openSUSE based systems

zypper install -y gcc rust rust-std cargo make \
automake autoconf libtool gettext itstool git \
gtk-doc gobject-introspection-devel \
libxml2-devel cairo-devel \
pango-devel gdk-pixbuf-devel

macOS systems

Dependencies may be installed using Homebrew or another package manager.

brew install cairo gdk-pixbuf glib pango \
gobject-introspection rust

export PKG_CONFIG_PATH="`brew --prefix`/lib/pkgconfig:\
`brew --prefix libffi`/lib/pkgconfig:\
/usr/lib/pkgconfig"
export ARCHFLAGS="-arch x86_64"

Note that PKG_CONFIG_PATH must be manually set to include Homebrew's libffi, as the system libffi is too old but Homebrew does not install it in a public location by default.

Currently, cairo 1.15.4 or later must also be installed manually, as the Homebrew package is for the older stable release. This may require adding it to PKG_CONFIG_PATH as well if you do not install it in /usr/local.

Setting ARCHFLAGS is required if gobject-introspection is using the system Python provided by Apple, as on Homebrew.

Basic compilation instructions

If you are compiling a tarball:

./configure
make
make install

See the INSTALL file for details on options you can pass to the configure script to select where to install the compiled library.

If you are compiling from a git checkout:

./autogen.sh
make
make install

Verbosity

By default the compilation process is quiet, and it just tells you which files it is compiling.

If you wish to see the full compilation command lines, use "make V=1" instead of plain "make".

Debug or release builds

Librsvg has code both in C and Rust, and each language has a different way of specifying compilation options to select compiler optimizations, or whether debug information should be included.

You should set the CFLAGS environment variable with compiler flags that you want to pass to the C compiler.

Controlling debug or release mode for Rust

  • With a configure option: --enable-debug or --disable-debug
  • With an environment variable: LIBRSVG_DEBUG=yes or LIBRSVG_DEBUG=no

For the Rust part of librsvg, we have a flag that you can pass at configure time. When enabled, the Rust sub-library will have debugging information and no compiler optimizations. This flag is off by default: if the flag is not specified, the Rust sub-library will be built in release mode (no debug information, full compiler optimizations).

The rationale is that people who already had scripts in place to build binary packages for librsvg, generally from release tarballs, are already using conventional machinery to specify C compiler options, such as that in RPM specfiles or Debian source packages. However, they may not contemplate Rust sub-libraries and they will certainly not want to modify their existing packaging scripts too much.

So, by default, the Rust library builds in release mode, to make life easier to binary distributions. Librsvg's build scripts will add --release to the Cargo command line by default.

Developers can request a debug build of the Rust sub-library by passing --enable-debug to the configure script, or by setting the LIBRSVG_DEBUG=yes environment variable before calling configure. This will omit the --release option from Cargo, so that it will build the Rust sub-library in debug mode.

In case both the environment variable and the command-line option are specified, the command-line option overrides the env var.

Selecting a Rust toolchain

By default, the configure/make steps will use the cargo binary that is found in your $PATH. If you have a system installation of Rust and one in your home directory, or for special build systems, you may need to override the locations of cargo and/or rustc. In this case, you can set any of these environment variables before running configure or autogen.sh:

  • RUSTC - path to the rustc compiler
  • CARGO - path to cargo

Note that $RUSTC only gets used in the configure script to ensure that there is a Rust compiler installed with an appropriate version. The actual compilation process just uses $CARGO, and assumes that that cargo binary will use the same Rust compiler as the other variable.

Cross-compilation

If you need to cross-compile librsvg, specify the --host=TRIPLE to the configure script as usual with Autotools. This will cause librsvg's build scripts to automatically pass --target=TRIPLE to cargo.

Note, however, that Rust may support different targets than the C compiler on your system. Rust's supported targets can be found in the rust/src/librustc_back/target in the Rust compiler's source code.

You can check Jorge Aparicio's guide on cross-compilation for Rust for more details.

Overriding the Rust target name

If you need cargo --target=FOO to obtain a different value from the one you specified for --host=TRIPLE, you can use the RUST_TARGET variable, and this will be passed to cargo. For example,

RUST_TARGET=aarch64-unknown-linux-gnu ./configure --host=aarch64-buildroot-linux-gnu
# will run "cargo --target=aarch64-unknown-linux-gnu" for the Rust part

Cross-compiling to a target not supported by Rust out of the box

When building with a target that is not supported out of the box by Rust, you have to do this:

  1. Create a target JSON definition file.

  2. Set the environment variable RUST_TARGET_PATH to its directory for the make command.

Example:

cd /my/target/definition
echo "JSON goes here" > MYMACHINE-VENDOR-OS.json
cd /source/tree/for/librsvg
./configure --host=MYMACHINE-VENDOR-OS
make RUST_TARGET_PATH=/my/target/definition

Cross-compiling for win32 target

You can also cross-compile to win32 (Microsoft Windows) target by using MinGW-w64. You need to specify the appropriate target in the same way as usual:

  • Set an appropriate target via the --host configure option:
    • i686-w64-mingw32 for 32-bit target
    • x86_64-w64-mingw32 for 64-bit target
  • Set an appropriate RUST_TARGET:
    • i686-pc-windows-gnu for 32-bit target
    • x86_64-pc-windows-gnu for 64-bit target

In addition you may need to link with some win32 specific libraries like LIBS="-lws2_32 -luserenv".

Example:

./configure \
  --host=x86_64-w64-mingw32 \
  RUST_TARGET=x86_64-pc-windows-gnu \
  LIBS="-lws2_32 -luserenv"
make

The most painful aspect of this way of building is preparing a win32 build for each of librsvg's dependencies. MXE may help you on this work.

Building with no network access

Automated build systems generally avoid network access so that they can compile from known-good sources, instead of pulling random updates from the net every time. However, normally Cargo likes to download dependencies when it first compiles a Rust project.

We use cargo vendor to ship librsvg release tarballs with the source code for Rust dependencies embedded within the tarball. If you unpack a librsvg tarball, these sources will appear in the rust/vendor subdirectory. If you build librsvg from a tarball, instead of git, it should not need to access the network to download extra sources at all.

Build systems can use Cargo's source replacement mechanism to override the location of the source code for the Rust dependencies, for example, in order to patch one of the Rust crates that librsvg uses internally.

The source replacement information is in rust/.cargo/config in the unpacked tarball. Your build system can patch this file as needed.

Running make distcheck

The make distcheck command will built a release tarball, extract it, compile it and test it. However, part of the make install process within that command will try to install the gdk-pixbuf loader in your system location, and it will fail.

Please run make distcheck like this:

$ make distcheck DESTDIR=/tmp/foo

That DESTDIR will keep the gdk-pixbuf loader installation from trying to modify your system locations.