scripts/buildconf.py is a command line utility (but also can be used as a Python module) that introspects the build configuration.
It uses the generated host level config-host.mak to obtain the general build configuration, and optionally, also target specific config-target.mak and config-devices.mak. It does not attempt to implement a Makefile parser, but instead relies on "make" itself to parse those files and output the queried variable. It requires a build tree that has been both configured and built. By default, for convenience, it will selected a default target, which can be displayed and overriden. A few examples follow. To get the TLS priority (a host level configuration), one would run: $ ./scripts/buildconf.py CONFIG_TLS_PRIORITY NORMAL To get a configuration from the default target devices: $ ./scripts/buildconf.py CONFIG_PARALLEL y If one is not interested in the actual value, but whether a given feature is enabled, the '-c|--check' option can be used: $ ./scripts/buildconf.py -c CONFIG_PARALLEL; echo $? 0 And for checking a target different than the default one: $ ./scripts/buildconf.py -c CONFIG_PARALLEL arm-softmmu; echo $? 255 Signed-off-by: Cleber Rosa <cr...@redhat.com> --- scripts/buildconf.py | 278 +++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 278 insertions(+) create mode 100755 scripts/buildconf.py diff --git a/scripts/buildconf.py b/scripts/buildconf.py new file mode 100755 index 0000000..0eee6d7 --- /dev/null +++ b/scripts/buildconf.py @@ -0,0 +1,278 @@ +#!/usr/bin/env python +# +# QEMU build configuration introspection utilty +# +# Copyright (C) 2017 Red Hat Inc. +# +# This library is free software; you can redistribute it and/or +# modify it under the terms of the GNU Lesser General Public +# License as published by the Free Software Foundation; either +# version 2 of the License, or (at your option) any later version. +# +# This library is distributed in the hope that it will be useful, +# but WITHOUT ANY WARRANTY; without even the implied warranty of +# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU +# Lesser General Public License for more details. +# +# You should have received a copy of the GNU Lesser General Public +# License along with this library; if not, see <http://www.gnu.org/licenses/>. +# +# Authors: +# Cleber Rosa <cr...@redhat.com> + +""" +QEMU's build configuration is recorded in both config-host.mak and +config-host.h, as is specific target configuration expressed in +<target>/config-{target,devices}.{mak,h}. + +This module relies on the .mak files, as they contain a bit more +information than the .h files. + +While it would be possible to write a simple Makefile parser capable to +handle the variable assignments, this would impose limitations on this +script and introduce breakages if the build scripts start using +functionality not expected here. + +The approach chosen was one that is definitely slower at runtime but +is more reliable. Temporary Makefiles that include config-host.mak, +and optionally the target specific config-target.mak and +config-devices.mak files, and print the desired configuration to +stdout. As long as the basic premises of a global config-host.mak, +and target specific config-target.mak and config-devices.mak is kept, +this tool should be able to keep up with any style or feature chances. +""" + +from __future__ import print_function + +import optparse +import os +import subprocess +import sys +import tempfile + + +TEMPLATE = """ +include {build_prefix}/config-host.mak +{target_specific} + +all: + @echo $({conf}) +""" + +TARGET_TEMPLATE = """ +include {build_prefix}/{target}/config-target.mak +include {build_prefix}/{target}/config-devices.mak +""" + + +class InvalidTarget(Exception): + """ + Target chosen is not present in the current build tree configuration + """ + + +def get_build_root(): + """ + Returns the absolute location of the root of the build tree + + This has been tested from build(only) trees, and works fine when + it's executed as a command line tool. + + If this is used as a Python module, it will really depend on how + the module is imported. If the build tree "scripts" directory is + added to the import path, this will work properly. If the current + working directory is the "scripts" directory itself, and no + explicit import path is added, it will only work when building + from the source tree, and will *not* work when the build tree is + different from the source tree. + + A longer explanation on this caveat: the Python import + implementation will look for a matching module in the current + working directory. Python's current working directory, + os.getcwd(), is really like getcwd(3), and not like + os.getenv("PWD"). Because the scripts directory is linked to the + source tree, os.getcwd() returns the source tree location instead. + """ + return os.path.dirname(os.path.dirname(os.path.abspath(__file__))) + + +def is_build_root_configured(): + """ + Checks if the build root has been configured + + In theory, this only makes sense for in-tree builds, because the + out-of-tree build directory, including the link to the scripts + directory containing this script, will only exist after a + successful "./configure" execution. + + Either way, the check is still valid for the main source of + build configuration, that is, the existence of 'config-host.mak' + """ + return os.path.isfile(os.path.join(get_build_root(), 'config-host.mak')) + + +def get_default_target(): + """ + Returns the default target on the current build tree + + The approach used here is to look for a "-softmmu" target that + matches "ARCH". If found, that is the best choice for a default + target. + + If not found, the first "-softmmu" target found is considered the + next best choice for a default target. + + As a fallback if no "-softmmu" target exists, the first entry on + the target list is returned. + + :returns: a target name or None if no target is configured + """ + targets = get_targets() + if not targets: + return None + arch = get_build_conf("ARCH", None) + first_choice = "%s-softmmu" % arch + if first_choice in targets: + return first_choice + else: + softmmu_targets = [t for t in targets if t.endswith("-softmmu")] + if softmmu_targets: + return softmmu_targets[0] + else: + return targets[0] + + +def get_build_conf(conf, target=None): + """ + Returns the value of a given Makefile variable + + :param conf: the configuration name, which really must be a + Makefile variable in either the host or target .mak + files + :param target: the name of a valid target in the current build tree. + it must match the name of a target dir, such as + 'x86_64-softmmu' or 'i386-linux-user'. + :returns: the raw output or None + :rtype: str or None + """ + build_prefix = get_build_root() + + if target is None: + target_specific = '' + else: + if target not in get_targets(): + raise InvalidTarget + target_specific = TARGET_TEMPLATE.format(build_prefix=build_prefix, + target=target) + + mak_fd, mak_path = tempfile.mkstemp() + os.write(mak_fd, TEMPLATE.format(build_prefix=build_prefix, + target_specific=target_specific, + conf=conf)) + proc = subprocess.Popen(['make', '-f', mak_path], + stdout=subprocess.PIPE, + stderr=subprocess.PIPE) + ret = proc.wait() + os.unlink(mak_path) + if (ret == 0): + return proc.stdout.read().strip() + + +def is_enabled(conf, target=None): + """ + Checks wether a given feature is enabled in the build configuration + + The Makefile variables default to using 'y' when they are enabled, + and are just missing (instead of set no 'n') when they're not enabled. + Even if a given variable is set, for instance in the case of TARGET_DIRS, + it will not be considered enabled by this function unless its content is + 'y'. For variables that are known to not contain 'y', please resort to + using get_build_conf() and parsing its output for meaningful value. + + :param conf: the configuration name, which really must be a + Makefile variable in either the host or target .mak + files + :param target: the name of a valid target in the current build tree. + it must match the name of a target dir, such as + 'x86_64-softmmu' or 'i386-linux-user'. + :returns: the raw output or None + :rtype: str or None + """ + build_conf = get_build_conf(conf, target=target) + if build_conf == 'y': + return True + return False + + +def get_targets(): + """ + Returns the list of targets currently configured + + :rtype: list + """ + targets = get_build_conf('TARGET_DIRS', None) + if targets is not None: + return targets.split() + + +if __name__ == '__main__': + class Parser(optparse.OptionParser): + + def __init__(self): + optparse.OptionParser.__init__( + self, + usage=('%prog [options] CONFIG [TARGET]\n\n' + 'CONFIG is the build configuration variable name\n' + 'TARGET is auto selected if not explicitly set')) + self.add_option('-c', '--check', action='store_true', + help=('Checks if the build configuration option is ' + 'set to "y". This causes this tool to be silent ' + 'and return only a status code of either 0 (if ' + 'configuration is set) or non-zero otherwise.')) + self.add_option('-n', '--no-default-target', action='store_true', + help=('Do not attempt to use a default target if one ' + 'was not explicitly given in the command line')) + self.add_option('--print-target', action='store_true', + help=('Also prints the selected target')) + + + class App(object): + + def __init__(self): + self.target = None + self.parser = Parser() + self._parse() + + def _parse(self): + self.opts, self.args = self.parser.parse_args() + args_len = len(self.args) + if (args_len < 1 or args_len > 2): + self.parser.print_help() + sys.exit(0) + elif args_len == 2: + self.target = self.args[1] + else: + if not self.opts.no_default_target: + self.target = get_default_target() + + def run(self): + if self.opts.print_target: + print("TARGET:", self.target) + config = self.args[0] + if self.opts.check: + result = is_enabled(config, self.target) + if result: + sys.exit(0) + else: + sys.exit(-1) + else: + conf = get_build_conf(config, self.target) + if conf: + print(conf) + sys.exit(0) + else: + sys.exit(-1) + + + app = App() + app.run() -- 2.9.4
