Add new env2cross command.env2cross

3 files changed, 192 insertions, 1 deletions

diff --git a/docs/markdown/snippets/env2cross.md b/docs/markdown/snippets/env2cross.md
new file mode 100644
index 0000000..6ebbc15
--- /dev/null
+++ b/docs/markdown/snippets/env2cross.md
@@ -0,0 +1,7 @@
+## Command to convert environments to cross files
+
+Add proper documentation here once the API has been finalized
+
+    meson env2cross --debarch armhf -o debarmhf.cross
+
+Also update the main cross compilation markdown files.
diff --git a/mesonbuild/mesonmain.py b/mesonbuild/mesonmain.py
index 7a4e421..b069e03 100644
--- a/mesonbuild/mesonmain.py
+++ b/mesonbuild/mesonmain.py
@@ -30,7 +30,7 @@ from . import mconf, mdist, minit, minstall, mintro, msetup, mtest, rewriter, ms
 from .mesonlib import MesonException, MesonBugException
 from .environment import detect_msys2_arch
 from .wrap import wraptool
-
+from .scripts import env2cross
 
 # Note: when adding arguments, please also add them to the completion
 # scripts in $MESONSRC/data/shell-completions/
@@ -70,6 +70,8 @@ class CommandLineParser:
                          help_msg='Build the project')
         self.add_command('devenv', mdevenv.add_arguments, mdevenv.run,
                          help_msg='Run commands in developer environment')
+        self.add_command('env2cross', env2cross.add_arguments, env2cross.run,
+                         help_msg='Convert current environment to a cross file')
 
         # Hidden commands
         self.add_command('runpython', self.add_runpython_arguments, self.run_runpython_command,
diff --git a/mesonbuild/scripts/env2cross.py b/mesonbuild/scripts/env2cross.py
new file mode 100755
index 0000000..570549e
--- /dev/null
+++ b/mesonbuild/scripts/env2cross.py
@@ -0,0 +1,182 @@
+#!/usr/bin/env python3
+
+# Copyright 2017 Jussi Pakkanen
+
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+
+#     http://www.apache.org/licenses/LICENSE-2.0
+
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+import sys, os, subprocess, shutil
+
+import argparse
+
+def add_arguments(parser: 'argparse.ArgumentParser') -> None:
+    parser.add_argument('--debarch', default=None,
+                        help='The dpkg architecture to generate.')
+    parser.add_argument('--gccsuffix', default="",
+                        help='A particular gcc version suffix if necessary.')
+    parser.add_argument('-o', required=True, dest='outfile',
+                        help='The output file.')
+
+#parser = argparse.ArgumentParser(description='''Generate cross compilation definition file for the Meson build system.
+#
+#If you do not specify the --arch argument, Meson assumes that running
+#plain 'dpkg-architecture' will return correct information for the
+#host system.
+#
+#This script must be run in an environment where CPPFLAGS et al are set to the
+#same values used in the actual compilation.
+#'''
+#)
+
+def locate_path(program):
+    if os.path.isabs(program):
+        return program
+    for d in os.get_exec_path():
+        f = os.path.join(d, program)
+        if os.access(f, os.X_OK):
+            return f
+    raise ValueError("%s not found on $PATH" % program)
+
+def write_args_line(ofile, name, args):
+    if len(args) == 0:
+        return
+    ostr = name + ' = ['
+    ostr += ', '.join("'" + i + "'" for i in args)
+    ostr += ']\n'
+    ofile.write(ostr)
+
+def write_args_from_envvars(ofile):
+    import shlex
+    cppflags = shlex.split(os.environ.get('CPPFLAGS', ''))
+    cflags = shlex.split(os.environ.get('CFLAGS', ''))
+    cxxflags = shlex.split(os.environ.get('CXXFLAGS', ''))
+    ldflags = shlex.split(os.environ.get('LDFLAGS', ''))
+
+    c_args = cppflags + cflags
+    cpp_args = cppflags + cxxflags
+    c_link_args = cflags + ldflags
+    cpp_link_args = cxxflags + ldflags
+
+    write_args_line(ofile, 'c_args', c_args)
+    write_args_line(ofile, 'cpp_args', cpp_args)
+    write_args_line(ofile, 'c_link_args', c_link_args)
+    write_args_line(ofile, 'cpp_link_args', cpp_link_args)
+
+cpu_family_map = dict(mips64el="mips64",
+                      i686='x86')
+cpu_map = dict(armhf="arm7hlf",
+               mips64el="mips64",)
+
+class CrossInfo:
+    def __init__(self):
+        self.compilers = {}
+        self.binaries = {}
+        self.properties = {}
+        
+        self.system = None
+        self.cpu = None
+        self.cpu_family = None
+        self.endian = None
+
+def deb_compiler_lookup(infos, compilerstems, host_arch, gccsuffix):
+    for langname, stem in compilerstems:
+        compilername = f'{host_arch}-{stem}{gccsuffix}'
+        try:
+            p = locate_path(compilername)
+            infos.compilers[langname] = p
+        except ValueError:
+            pass
+
+def detect_debianlike(options):
+    if options.debarch is None:
+        cmd = ['dpkg-architecture']
+    else:
+        cmd = ['dpkg-architecture', '-a' + options.debarch]
+    output = subprocess.check_output(cmd, universal_newlines=True,
+                                     stderr=subprocess.DEVNULL)
+    data = {}
+    for line in output.split('\n'):
+        line = line.strip()
+        if line == '':
+            continue
+        k, v = line.split('=', 1)
+        data[k] = v
+    host_arch = data['DEB_HOST_GNU_TYPE']
+    host_os = data['DEB_HOST_ARCH_OS']
+    host_cpu_family = cpu_family_map.get(data['DEB_HOST_GNU_CPU'],
+                                         data['DEB_HOST_GNU_CPU'])
+    host_cpu = cpu_map.get(data['DEB_HOST_ARCH'],
+                           data['DEB_HOST_ARCH'])
+    host_endian = data['DEB_HOST_ARCH_ENDIAN']
+    
+    compilerstems = [('c', 'gcc'),
+                     ('cpp', 'h++'),
+                     ('objc', 'gobjc'),
+                     ('objcpp', 'gobjc++')]
+    infos = CrossInfo()
+    deb_compiler_lookup(infos, compilerstems, host_arch, options.gccsuffix)
+    if len(infos.compilers) == 0:
+        print('Warning: no compilers were detected.')
+    infos.binaries['ar'] = locate_path("%s-ar" % host_arch)
+    infos.binaries['strip'] = locate_path("%s-strip" % host_arch)
+    infos.binaries['objcopy'] = locate_path("%s-objcopy" % host_arch)
+    infos.binaries['ld'] = locate_path("%s-ld" % host_arch)
+    try:
+        infos.binaries['pkgconfig'] =  locate_path("%s-pkg-config" % host_arch)
+    except ValueError:
+        pass # pkg-config is optional
+    try:
+        infos.binaries['cups-config'] = locate_path("cups-config")
+    except ValueError:
+        pass
+    infos.system = host_os
+    infos.cpu_family = host_cpu_family
+    infos.cpu = host_cpu
+    infos.endian = host_endian
+
+    return infos
+
+def write_crossfile(infos, ofilename):
+    tmpfilename = ofilename + '~'
+    with open(tmpfilename, 'w') as ofile:
+        ofile.write('[binaries]\n')
+        ofile.write('# Compilers\n')
+        for langname in sorted(infos.compilers.keys()):
+            compiler = infos.compilers[langname]
+            ofile.write(f"{langname} = '{compiler}'\n")
+        ofile.write('\n')
+
+        ofile.write('# Other binaries\n')
+        for exename in sorted(infos.binaries.keys()):
+            exe = infos.binaries[exename]
+            ofile.write(f"{exename} = '{exe}'\n")
+        ofile.write('\n')
+        
+        ofile.write('[host_machine]\n')
+        ofile.write(f"cpu = '{infos.cpu}'\n")
+        ofile.write(f"cpu_family = '{infos.cpu_family}'\n")
+        ofile.write(f"endian = '{infos.endian}'\n")
+        ofile.write(f"system = '{infos.system}'\n")
+    os.replace(tmpfilename, ofilename)
+
+def run(options):
+    if options.debarch:
+        print('Detecting cross environment via dpkg-reconfigure.')
+        infos = detect_debianlike(options)
+    else:
+        #print('Detecting cross environment via environment variables')
+        sys.exit('Can currently only detect debianlike. Patches welcome.')
+    write_crossfile(infos, options.outfile)
+
+if __name__ == '__main__':
+    options = parser.parse_args()
+    run(options)