Build Instructions ------------------ * Requirements ------------ - A POSIX-compliant C development environment - GNU make version 3.81 or later - skalibs version 2.14.3.0 or later: https://skarnet.org/software/skalibs/ - Optional (but recommended): execline version 2.9.6.1 or later: https://skarnet.org/software/execline/ - s6 version 2.13.1.0 or later: https://skarnet.org/software/s6/ - s6-dns version 2.4.0.0 or later: https://skarnet.org/software/s6-dns/ - Depending on whether you build the SSL tools, bearssl version 0.6 or later: https://bearssl.org/ or libressl version 3.9.2 or later: https://libressl.org/ or openssl version 3.3.1 or later: https://openssl.org/ *in addition to* libretls version 3.8.1 or later: https://git.causal.agency/libretls/about/ This software will run on any operating system that implements POSIX.1-2008, available at: https://pubs.opengroup.org/onlinepubs/9699919799/ * Standard usage -------------- ./configure && make && sudo make install will work for most users. It will install the binaries in /bin and the static libraries in /usr/lib. You can strip the binaries and libraries of their extra symbols via "make strip" before the "make install" phase. It will shave a few bytes off them. * Customization ------------- You can customize paths via flags given to configure. See ./configure --help for a list of all available configure options. * Environment variables --------------------- Controlling a build process via environment variables is a big and dangerous hammer. You should try and pass flags to configure instead; nevertheless, a few standard environment variables are recognized. If the CC environment variable is set, its value will override compiler detection by configure. The --host=HOST option will still add a HOST- prefix to the value of CC. The values of CFLAGS, CPPFLAGS and LDFLAGS will be appended to flags auto-detected by configure. To entirely override the flags set by configure instead, use make variables. * Make variables -------------- You can invoke make with a few variables for more configuration. CC, CFLAGS, CPPFLAGS, LDFLAGS, LDLIBS, AR, RANLIB, STRIP, INSTALL and CROSS_COMPILE can all be overridden on the make command line. This is an even bigger hammer than running ./configure with environment variables, so it is advised to only do this when it is the only way of obtaining the behaviour you want. DESTDIR can be given on the "make install" command line in order to install to a staging directory. * Shared libraries ---------------- Software from skarnet.org is small enough that shared libraries are generally not worth using. Static linking is simpler and incurs less runtime overhead and less points of failure: so by default, shared libraries are not built and binaries are linked against the static versions of the skarnet.org libraries. Nevertheless, you can: * build shared libraries: --enable-shared * link binaries against shared libraries: --disable-allstatic * Static binaries --------------- By default, binaries are linked against static versions of all the libraries they depend on, except for the libc. You can enforce linking against the static libc with --enable-static-libc. (If you are using a GNU/Linux system, be aware that the GNU libc behaves badly with static linking and produces huge executables, which is why it is not the default. Other libcs are better suited to static linking, for instance musl: https://musl-libc.org/) * Cross-compilation ----------------- skarnet.org packages centralize all the difficulty of cross-compilation in one place: skalibs. Once you have cross-compiled skalibs, the rest is easy. * Use the --host=HOST option to configure, HOST being the triplet for your target. * Make sure your cross-toolchain binaries (i.e. prefixed with HOST-) are accessible via your PATH environment variable. * Make sure to use the correct version of skalibs for your target, and the correct sysdeps directory, making use of the --with-include, --with-lib, --with-dynlib and --with-sysdeps options as necessary. * The slashpackage convention --------------------------- The slashpackage convention (http://cr.yp.to/slashpackage.html) is a package installation scheme that provides a few guarantees over other conventions such as the FHS, for instance fixed absolute pathnames. skarnet.org packages support it: use the --enable-slashpackage option to configure, or --enable-slashpackage=DIR for a prefixed DIR/package tree. This option will activate slashpackage support during the build and set slashpackage-compatible installation directories. If $package_home is the home of the package, defined as DIR/package/$category/$package-$version with the variables read from the package/info file, then: --dynlibdir is set to $package_home/library.so --bindir is set to $package_home/command --sbindir is also set to $package_home/command (slashpackage differentiates root-only binaries by their Unix rights, not their location in the filesystem) --libexecdir is also set to $package_home/command (slashpackage does not need a specific directory for internal binaries) --libdir is set to $package_home/library --includedir is set to $package_home/include --prefix is pretty much ignored when you use --enable-slashpackage. You should probably not use both --enable-slashpackage and --prefix. When using slashpackage, two additional Makefile targets are available after "make install": - "make update" changes the default version of the software to the freshly installed one. (This is useful when you have several installed versions of the same software, which slashpackage supports.) - "make -L global-links" adds links from /command and /library.so to the default version of the binaries and shared libraries. The "-L" option to make is necessary because targets are symbolic links, and the default make behaviour is to check the pointed file's timestamp and not the symlink's timestamp. * Absolute pathnames ------------------ You may want to use fixed absolute pathnames even if you're not following the slashpackage convention: for instance, the Nix packaging system prefers calling binaries with immutable paths rather than rely on PATH resolution. If you are in that case, use the --enable-absolute-paths option to configure. This will ensure that programs calling binaries from this package will call them with their full installation path (in bindir) without relying on a PATH search. * Out-of-tree builds ------------------ skarnet.org packages do not support out-of-tree builds. They are small, so it does not cost much to duplicate the entire source tree if parallel builds are needed. * SSL support ----------- s6-networking implements UCSPI tools for SSL/TLS connections: see the doc/tls-overview.html page for a listing of these tools and what they do. The TLS tools are built if you give the --enable-ssl= flag to configure. There are two supported values for : bearssl and libtls. You should install the relevant header and library files for your chosen implementation before building a SSL-enabled s6-networking. "bearssl" uses the BearSSL API, of which there's only one implementation, from bearssl.org. "libtls" uses the libtls API, which has two possible implementations: - The original one, from libressl.org, bundled with LibreSSL - An alternative one, from causal.agency, that is used on top of OpenSSL. For compatibility, "libressl" is accepted as and is an alias to libtls. If your SSL headers and library files are not installed in /usr/include and /usr/lib, you can use the --with-ssl-path=DIR configure option: headers will be searched in DIR/include and libraries will be searched in DIR/lib. For more complex setups, use the generic --with-include and --with-dir configure options. If you choose --enable-ssl=bearssl, then s6-networking will build a "libsbearssl" support library, which s6-tlsc-io and s6-tlsd-io will be linked against. This support library depends on libbearssl interfaces. If you choose --enable-ssl=libtls, then s6-networking will build a "libstls" support library, which s6-tlsc-io and s6-tlsd-io will be linked against. This support library depends on libtls interfaces, but not on libssl or libcrypto interfaces, so it is possible to use other alternative implementations of the libtls API. There is one such implementation: libtls-bearssl, implementing libtls on top of bearssl, but using it with s6-networking is a waste since s6-networking supports bearssl natively. If your SSL implementation library needs nonstandard -l options to link against it, you can override the CRYPTO_LIB make variable. By default, CRYPTO_LIB is "-lbearssl" when building against bearssl, and "-ltls -lssl -lcrypto" when building against libtls. As of 2020-11-30, please note that BearSSL is considered beta quality by its author, so use with caution. Nevertheless, it's an incredibly good beta, with high-quality interfaces and implementation, and no known serious bugs. When statically linked against BearSSL, the s6-tlsc-io and s6-tlsd-io binaries are 1/10th the size of what they are when statically linked against libressl/openssl, with a much smaller RAM footprint too.