Factor out pkg-config functionality to a separate module.

Functional changes:

* Consistently check that return code from pkg-config is zero.
* Use shell word splitting rules to process pkg-config output to match
  behaviour obtained by running `cc program.cc $(pkg-config --cflags ...)`.
  Fixes issue #171 .
* Use user preferred encoding to process output from pkg-config on
  Python 3. Python 2 behaviour defaults to using ascii encoding as before.

edit creiter: still ignore pkg-config errors by default for now as we
depend on it when glib is a subproject.

4 files changed, 73 insertions, 33 deletions

diff --git a/giscanner/dumper.py b/giscanner/dumper.py
index bb97bc81..494c7ff7 100644
--- a/giscanner/dumper.py
+++ b/giscanner/dumper.py
@@ -32,7 +32,7 @@ import tempfile
 from distutils.errors import LinkError
 
 from .gdumpparser import IntrospectionBinary
-from . import utils
+from . import pkgconfig, utils
 from .ccompiler import CCompiler
 
 # bugzilla.gnome.org/558436
@@ -94,9 +94,8 @@ class DumpCompiler(object):
         # Acquire the compiler (and linker) commands via the CCompiler class in ccompiler.py
         self._compiler = CCompiler()
 
-        self._pkgconfig_cmd = os.environ.get('PKG_CONFIG', 'pkg-config')
         self._uninst_srcdir = os.environ.get('UNINSTALLED_INTROSPECTION_SRCDIR')
-        self._packages = ['gio-2.0 gmodule-2.0']
+        self._packages = ['gio-2.0', 'gmodule-2.0']
         self._packages.extend(options.packages)
         if self._compiler.check_is_msvc():
             self._linker_cmd = ['link.exe']
@@ -189,21 +188,9 @@ class DumpCompiler(object):
                             self._options.namespace_version, suffix)
         return os.path.join(tmpdir, tmpl)
 
-    def _run_pkgconfig(self, flag):
-        # Enable the --msvc-syntax pkg-config flag when
-        # the Microsoft compiler is used
-        if self._compiler.check_is_msvc():
-            cmd = [self._pkgconfig_cmd, '--msvc-syntax', flag]
-        else:
-            cmd = [self._pkgconfig_cmd, flag]
-        proc = subprocess.Popen(
-            cmd + self._packages,
-            stdout=subprocess.PIPE)
-        out, err = proc.communicate()
-        return out.decode('ascii').split()
-
     def _compile(self, *sources):
-        cflags = self._run_pkgconfig('--cflags')
+        cflags = pkgconfig.cflags(self._packages,
+                                  msvc_syntax=self._compiler.check_is_msvc())
         cflags.extend(self._options.cflags)
         return self._compiler.compile(cflags,
                                       self._options.cpp_includes,
@@ -255,7 +242,8 @@ class DumpCompiler(object):
 
         args.extend(sources)
 
-        pkg_config_libs = self._run_pkgconfig('--libs')
+        pkg_config_libs = pkgconfig.libs(self._packages,
+                                         msvc_syntax=self._compiler.check_is_msvc())
 
         if not self._options.external_library:
             self._compiler.get_internal_link_flags(args,
diff --git a/giscanner/meson.build b/giscanner/meson.build
index b4ec3796..7b4b0d9d 100644
--- a/giscanner/meson.build
+++ b/giscanner/meson.build
@@ -17,6 +17,7 @@ giscanner_files = [
   'maintransformer.py',
   'message.py',
   'msvccompiler.py',
+  'pkgconfig.py',
   'shlibs.py',
   'scannermain.py',
   'sectionparser.py',
diff --git a/giscanner/pkgconfig.py b/giscanner/pkgconfig.py
new file mode 100644
index 00000000..6f0b2d57
--- /dev/null
+++ b/giscanner/pkgconfig.py
@@ -0,0 +1,58 @@
+# GObject-Introspection - a framework for introspecting GObject libraries
+#
+# 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, write to the
+# Free Software Foundation, Inc., 59 Temple Place - Suite 330,
+# Boston, MA 02111-1307, USA.
+#
+
+import os
+import shlex
+import subprocess
+
+
+class PkgConfigError(Exception):
+    pass
+
+
+def check_output(flags, ignore_errors, command=None):
+    if command is None:
+        command = [os.environ.get('PKG_CONFIG', 'pkg-config')]
+    argv = command[:]
+    argv.extend(flags)
+    try:
+        return subprocess.check_output(argv, universal_newlines=True, stderr=subprocess.STDOUT)
+    except subprocess.CalledProcessError as e:
+        output = e.output or ''
+        if ignore_errors:
+            print(output)
+            return ''
+        raise PkgConfigError('pkg-config: %s\n%s' % (e, output))
+    except OSError as e:
+        raise PkgConfigError('pkg-config: error executing command %s: %s' % (argv, e))
+
+
+def cflags(packages, msvc_syntax=False, ignore_errors=True, command=None):
+    flags = ['--msvc-syntax'] if msvc_syntax else []
+    flags.append('--cflags')
+    flags.extend(packages)
+    out = check_output(flags, ignore_errors, command)
+    return shlex.split(out)
+
+
+def libs(packages, msvc_syntax=False, ignore_errors=True, command=None):
+    flags = ['--msvc-syntax'] if msvc_syntax else []
+    flags.append('--libs')
+    flags.extend(packages)
+    out = check_output(flags, ignore_errors, command)
+    return shlex.split(out)
diff --git a/giscanner/scannermain.py b/giscanner/scannermain.py
index 2f1d9095..e0af993a 100755..100644
--- a/giscanner/scannermain.py
+++ b/giscanner/scannermain.py
@@ -37,7 +37,7 @@ import platform
 import shlex
 
 import giscanner
-from giscanner import message
+from giscanner import message, pkgconfig
 from giscanner.annotationparser import GtkDocCommentBlockParser
 from giscanner.ast import Include, Namespace
 from giscanner.dumper import compile_introspection_binary
@@ -288,7 +288,7 @@ def test_codegen(optstring,
 
 
 def process_options(output, allowed_flags):
-    for option in output.split():
+    for option in output:
         for flag in allowed_flags:
             if not option.startswith(flag):
                 continue
@@ -297,19 +297,11 @@ def process_options(output, allowed_flags):
 
 
 def process_packages(options, packages):
-    args = [os.environ.get('PKG_CONFIG', 'pkg-config'), '--cflags']
-    args.extend(packages)
-    output = subprocess.Popen(args,
-                              stdout=subprocess.PIPE).communicate()[0]
-    if output is None:
-        # the error output should have already appeared on our stderr,
-        # so we just exit
-        return 1
-    output = output.decode('ascii')
+    flags = pkgconfig.cflags(packages)
     # Some pkg-config files on Windows have options we don't understand,
     # so we explicitly filter to only the ones we need.
     options_whitelist = ['-I', '-D', '-U', '-l', '-L']
-    filtered_output = list(process_options(output, options_whitelist))
+    filtered_output = list(process_options(flags, options_whitelist))
     parser = _get_option_parser()
     pkg_options, unused = parser.parse_args(filtered_output)
     options.cpp_includes.extend([os.path.realpath(f) for f in pkg_options.cpp_includes])
@@ -539,9 +531,10 @@ def scanner_main(args):
     packages = set(options.packages)
     packages.update(transformer.get_pkgconfig_packages())
     if packages:
-        exit_code = process_packages(options, packages)
-        if exit_code:
-            return exit_code
+        try:
+            process_packages(options, packages)
+        except pkgconfig.PkgConfigError as e:
+            _error(str(e))
 
     ss = create_source_scanner(options, args)