gri3-wm/m4/ax_sanitizers.m4

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Switch to autotools (GNU build system) This commit probably comes as a surprise to some, given that one of i3’s explicitly stated goals used to be “Do not use programs such as autoconf/automake for configuration and creating unreadable/broken makefiles”. I phrased this goal over 7 years ago, based largely on a grudge that I inherited, which — as I’ve realized in the meantime — was largely held against FOSS in general, and not actually nuanced criticism of autotools. In the meantime, I have come to realize that the knee-jerk reaction of “I could do this better!” (i.e. writing our own build system in this particular case) is usually misguided, and nowadays I strongly suggest trying hard to fix the existing system for the benefit of all existing and future users. Further, I recently got to experience the other side of the coin, as I packaged a new version of FreeRADIUS for Debian, which at the time of writing used autoconf in combination with boilermake, a custom make-based build system that only FreeRADIUS uses. Understanding the build system enough to fix issues and enable parallel compilation took me an entire day. That time is time which potentially every downstream maintainer needs to invest, and the resulting knowledge cannot be applied to any other project. Hence, I believe it’s a good idea switch i3 to autotools. Yes, it might be that particular features were easier to implement/understand in our custom Makefiles, and there might be individuals who have an easier time reading through our custom Makefiles than learning autotools. All of these considerations are outweighed by the benefits we get from using the same build system as literally thousands of other FOSS software packages. Aside from these somewhat philosophical considerations, there’s also practical improvements which this change brings us. See the “changes” section below. ┌──────────────────────────────────────────────────────────────────────────────┐ │ new workflow │ └──────────────────────────────────────────────────────────────────────────────┘ You can now build i3 like you build any other software package which uses autotools. Here’s a memory refresher: autoreconf -fi mkdir -p build && cd build ../configure make -j8 (The autoreconf -fi step is unnecessary if you are building from a release tarball, but shouldn’t hurt either.) ┌──────────────────────────────────────────────────────────────────────────────┐ │ recommended reading │ └──────────────────────────────────────────────────────────────────────────────┘ I very much recommend reading “A Practitioner's Guide to GNU Autoconf, Automake, and Libtool” by John Calcote (https://www.nostarch.com/autotools.htm). That book is from 2010 and, AFAICT, is the most up to date comprehensive description of autotools. Do not read older documentation. In particular, if a document you’re reading mentions configure.in (deprecated filename) or recursive make (now considered harmful), it’s likely outdated. ┌──────────────────────────────────────────────────────────────────────────────┐ │ changes │ └──────────────────────────────────────────────────────────────────────────────┘ This commit implements the following new functionality/changes in behavior: • We use the AX_ENABLE_BUILDDIR macro to enforce builds happening in a separate directory. This is a prerequisite for the AX_EXTEND_SRCDIR macro and building in a separate directory is common practice anyway. In case this causes any trouble when packaging i3 for your distribution, please let me know. • “make check” runs the i3 testsuite. You can still use ./testcases/complete-run.pl to get the interactive progress output. • “make distcheck” (runs testsuite on “make dist” result, tiny bit quicker feedback cycle than waiting for the travis build to catch the issue). • “make uninstall” (occasionally requested by users who compile from source) • “make” will build manpages/docs by default if the tools are installed. Conversely, manpages/docs are not tried to be built for users who don’t want to install all these dependencies to get started hacking on i3. • non-release builds will enable address sanitizer by default. Use the --disable-sanitizers configure option to turn off all sanitizers, and see --help for available sanitizers. • Support for pre-compiled headers (PCH) has been dropped for now in the interest of simplicitly. Maybe we can re-add it later. • coverage reports are now generated using “make check-code-coverage”, which requires specifying --enable-code-coverage when calling configure. ┌──────────────────────────────────────────────────────────────────────────────┐ │ build system feature parity/testing │ └──────────────────────────────────────────────────────────────────────────────┘ In addition to what’s described above, I tested the following features: • “make install” installs the same files (plus documentation and manpages) cd i3-old && make install PREFIX=/tmp/inst/old cd i3-new && ./configure --prefix=/tmp/inst/new cd /tmp/inst (cd old && for f in $(find); do [ -e "../new/$f" ] || echo "$f missing"; done) • make dist generates a tarball which includes the same files cd i3-old && make dist cd i3-new/x86_64-pc-linux-gnu && make dist colordiff -u <(tar tf i3-old/i3-4.12.tar.bz2 | sort) \ <(tar tf i3-new/x86_64-pc-linux-gnu/i3-4.12.tar.gz | sort) There are some expected differences: • Some files have been renamed (e.g. the new etc/ and share/ subdirectories) • Some files will now be generated at build-time, so only their corresponding .in file is shipped (e.g. testcases/complete-run.pl) • The generated parser files are shipped in the dist tarball (they only depend on the parser-specs/* files, not on the target system) • autotools infrastructure is shipped (e.g. “configure”, “missing”, etc.) • DLOG and ELOG statements still produce the same file name in logfiles • Listing source code in gdb still works. • gdb backtraces contain the i3-<version> path component • release.sh still works • version embedding 1. git checkout shows “4.12-136-gf720023 (2016-10-10, branch "autotools")” 2. tarball of a git version shows “4.12-non-git” 3. release tarball shows 4.13 • debug mode is enabled by default for non-release builds • enabling verbose builds via V=1 ┌──────────────────────────────────────────────────────────────────────────────┐ │ speed │ └──────────────────────────────────────────────────────────────────────────────┘ There is no noticeable difference in compilation speed itself (of binaries, documentation and manpages): i3-old $ time make all docs mans -j8 make all docs mans -j8 28.92s user 2.15s system 640% cpu 4.852 total i3-new $ time make -j8 make -j8 27.08s user 1.92s system 620% cpu 4.669 total In terms of one-time costs: configuring the build system (../configure) takes about 2.7s on my machine, generating the build system (autoreconf -fi) takes about 3.1s on my machine. ┌──────────────────────────────────────────────────────────────────────────────┐ │ m4 macros │ └──────────────────────────────────────────────────────────────────────────────┘ All files in m4/ have been copied from the autoconf-archive package in version b6aeb1988f4b6c78bf39d97b6c4f6e1d594d59b9 and should be updated whenever they change. This commit has been tested with autoconf 2.69 and automake 1.15.
2016-10-07 13:48:26 +02:00
# ===========================================================================
# http://www.gnu.org/software/autoconf-archive/ax_sanitizers.html
# ===========================================================================
#
# SYNOPSIS
#
# AX_SANITIZERS([SANITIZERS], [ENABLED-BY-DEFAULT], [ACTION-SUCCESS])
#
# DESCRIPTION
#
# Offers users to enable one or more sanitizers (see
# https://github.com/google/sanitizers) with the corresponding
# --enable-<sanitizer>-sanitizer option.
#
# SANITIZERS is a whitespace-separated list of sanitizers to offer via
# --enable-<sanitizer>-sanitizer options, e.g. "address memory" for the
# address sanitizer and the memory sanitizer. If SANITIZERS is not specified,
# all known sanitizers to AX_SANITIZERS will be offered, which at the time of
# writing are "address memory undefined".
# NOTE that SANITIZERS is expanded at autoconf time, not at configure time,
# i.e. you cannot use shell variables in SANITIZERS.
#
# ENABLED-BY-DEFAULT is a whitespace-separated list of sanitizers which
# should be enabled by default, e.g. "memory undefined". Note that not all
# sanitizers can be combined, e.g. memory sanitizer cannot be enabled when
# address sanitizer is already enabled.
# Set ENABLED-BY-DEFAULT to a single whitespace in order to disable all
# sanitizers by default.
# ENABLED-BY-DEFAULT is expanded at configure time, so you can use shell
# variables.
#
# ACTION-SUCCESS allows to specify shell commands to execute on success, i.e.
# when one of the sanitizers was successfully enabled. This is a good place
# to call AC_DEFINE for any precompiler constants you might need to make your
# code play nice with sanitizers.
#
# The variable ax_enabled_sanitizers contains a whitespace-separated list of
# all enabled sanitizers, so that you can print them at the end of configure,
# if you wish.
#
# The additional --enable-sanitizers option allows users to enable/disable
# all sanitizers, effectively overriding ENABLED-BY-DEFAULT.
#
# EXAMPLES
#
# AX_SANITIZERS([address])
# dnl offer users to enable address sanitizer via --enable-address-sanitizer
#
# is_debug_build=…
# if test "x$is_debug_build" = "xyes"; then
# default_sanitizers="address memory"
# else
# default_sanitizers=
# fi
# AX_SANITIZERS([address memory], [$default_sanitizers])
# dnl enable address sanitizer and memory sanitizer by default for debug
# dnl builds, e.g. when building from git instead of a dist tarball.
#
# AX_SANITIZERS(, , [
# AC_DEFINE([SANITIZERS_ENABLED],
# [],
# [At least one sanitizer was enabled])])
# dnl enable all sanitizers known to AX_SANITIZERS by default and set the
# dnl SANITIZERS_ENABLED precompiler constant.
#
# AX_SANITIZERS(, [ ])
# dnl provide all sanitizers, but enable none by default.
#
# LICENSE
#
# Copyright (c) 2016 Michael Stapelberg <michael@i3wm.org>
#
# Copying and distribution of this file, with or without modification,
# are permitted in any medium without royalty provided the copyright
# notice and this notice are preserved. This file is offered as-is,
# without any warranty.
AC_DEFUN([AX_SANITIZERS],
[AX_REQUIRE_DEFINED([AX_CHECK_COMPILE_FLAG])
AX_REQUIRE_DEFINED([AX_CHECK_LINK_FLAG])
AX_REQUIRE_DEFINED([AX_APPEND_FLAG])
AC_ARG_ENABLE(sanitizers,
AS_HELP_STRING(
[--enable-sanitizers],
[enable all known sanitizers]),
[ax_sanitizers_default=$enableval],
[ax_sanitizers_default=])
ax_enabled_sanitizers=
m4_foreach_w([mysan], m4_default($1, [address memory undefined]), [
dnl If ax_sanitizers_default is unset, i.e. the user neither explicitly
dnl enabled nor explicitly disabled all sanitizers, we get the default value
dnl for this sanitizer based on whether it is listed in ENABLED-BY-DEFAULT.
AS_IF([test "x$ax_sanitizers_default" = "x"], [dnl
ax_sanitizer_default=
for mycheck in m4_default([$2], [address memory undefined]); do
AS_IF([test "x$mycheck" = "x[]mysan"], [ax_sanitizer_default=yes])
done
AS_IF([test "x$ax_sanitizer_default" = "x"], [ax_sanitizer_default=no])
],
[ax_sanitizer_default=$ax_sanitizers_default])
AC_ARG_ENABLE(mysan[]-sanitizer,
AS_HELP_STRING(
[--enable-[]mysan[]-sanitizer],
[enable -fsanitize=mysan]),
[ax_sanitizer_enabled=$enableval],
[ax_sanitizer_enabled=$ax_sanitizer_default])
AS_IF([test "x$ax_sanitizer_enabled" = "xyes"], [
dnl Not using AX_APPEND_COMPILE_FLAGS and AX_APPEND_LINK_FLAGS because they
dnl lack the ability to specify ACTION-SUCCESS.
AX_CHECK_COMPILE_FLAG([-fsanitize=[]mysan], [
AX_CHECK_LINK_FLAG([-fsanitize=[]mysan], [
AX_APPEND_FLAG([-fsanitize=[]mysan], [])
dnl If and only if libtool is being used, LDFLAGS needs to contain -Wc,-fsanitize=….
dnl See e.g. https://sources.debian.net/src/systemd/231-7/configure.ac/?hl=128#L135
dnl TODO: how can recognize that situation and add -Wc,?
AX_APPEND_FLAG([-fsanitize=[]mysan], [LDFLAGS])
dnl TODO: add -fPIE -pie for memory
# -fno-omit-frame-pointer results in nicer stack traces in error
# messages, see http://clang.llvm.org/docs/AddressSanitizer.html#usage
AX_CHECK_COMPILE_FLAG([-fno-omit-frame-pointer], [
AX_APPEND_FLAG([-fno-omit-frame-pointer], [])])
dnl TODO: at least for clang, we should specify exactly -O1, not -O2 or -O0, so that performance is reasonable but stacktraces are not tampered with (due to inlining), see http://clang.llvm.org/docs/AddressSanitizer.html#usage
m4_default([$3], :)
ax_enabled_sanitizers="[]mysan $ax_enabled_sanitizers"
])
])
])
])dnl
])dnl AX_SANITIZERS