Use PKG_CONFIG_LIBDIR to force pkg-config to use sysroot only

Previously we were using PKG_CONFIG_PATH to tell pkg-config
to search the sysroot directories.  However the default
libpath is always added to this path, so pkg-config would
fall back to looking in the system directories.
Using PKG_CONFIG_LIBDIR instead overrides the default
libdir which makes the build more hermetic and forces the
sysroot to provide all the required .pc files.

Review URL: https://codereview.chromium.org/1580643002

Cr-Commit-Position: refs/heads/master@{#369224}

3 files changed, 38 insertions, 36 deletions

diff --git a/build/config/linux/pkg-config.py b/build/config/linux/pkg-config.py
index d707c5f..d63b2d6 100755
--- a/build/config/linux/pkg-config.py
+++ b/build/config/linux/pkg-config.py
@@ -42,9 +42,11 @@ from optparse import OptionParser
 
 
 def SetConfigPath(options):
-  """Set the PKG_CONFIG_PATH environment variable.
+  """Set the PKG_CONFIG_LIBDIR environment variable.
+
   This takes into account any sysroot and architecture specification from the
-  options on the given command line."""
+  options on the given command line.
+  """
 
   sysroot = options.sysroot
   assert sysroot
@@ -55,19 +57,18 @@ def SetConfigPath(options):
     print "You must specify an architecture via -a if using a sysroot."
     sys.exit(1)
 
-  # Add the sysroot path to the environment's PKG_CONFIG_PATH
-  config_path = sysroot + '/usr/' + options.system_libdir + '/pkgconfig'
-  config_path += ':' + sysroot + '/usr/share/pkgconfig'
-  if 'PKG_CONFIG_PATH' in os.environ:
-    os.environ['PKG_CONFIG_PATH'] += ':' + config_path
-  else:
-    os.environ['PKG_CONFIG_PATH'] = config_path
+  libdir = sysroot + '/usr/' + options.system_libdir + '/pkgconfig'
+  libdir += ':' + sysroot + '/usr/share/pkgconfig'
+  os.environ['PKG_CONFIG_LIBDIR'] = libdir
+  return libdir
 
 
 def GetPkgConfigPrefixToStrip(args):
   """Returns the prefix from pkg-config where packages are installed.
+
   This returned prefix is the one that should be stripped from the beginning of
-  directory names to take into account sysroots."""
+  directory names to take into account sysroots.
+  """
   # Some sysroots, like the Chromium OS ones, may generate paths that are not
   # relative to the sysroot. For example,
   # /path/to/chroot/build/x86-generic/usr/lib/pkgconfig/pkg.pc may have all
@@ -131,9 +132,9 @@ def main():
       strip_out.append(re.compile(regexp))
 
   if options.sysroot:
-    SetConfigPath(options)
+    libdir = SetConfigPath(options)
     if options.debug:
-      sys.stderr.write('PKG_CONFIG_PATH=%s\n' % os.environ['PKG_CONFIG_PATH'])
+      sys.stderr.write('PKG_CONFIG_LIBDIR=%s\n' % libdir)
     prefix = GetPkgConfigPrefixToStrip(args)
   else:
     prefix = ''
@@ -150,28 +151,32 @@ def main():
     return 0
 
   if options.libdir:
+    cmd = [options.pkg_config, "--variable=libdir"] + args
+    if options.debug:
+      sys.stderr.write('Running: %s\n' % cmd)
     try:
-      libdir = subprocess.check_output([options.pkg_config,
-                                        "--variable=libdir"] +
-                                       args)
+      libdir = subprocess.check_output(cmd)
     except:
       print "Error from pkg-config."
       return 1
     sys.stdout.write(libdir.strip())
     return 0
 
+  cmd = [options.pkg_config, "--cflags", "--libs"] + args
+  if options.debug:
+    sys.stderr.write('Running: %s\n' % ' '.join(cmd))
+
   try:
-    flag_string = subprocess.check_output(
-        [ options.pkg_config, "--cflags", "--libs" ] +
-        args)
-    # For now just split on spaces to get the args out. This will break if
-    # pkgconfig returns quoted things with spaces in them, but that doesn't seem
-    # to happen in practice.
-    all_flags = flag_string.strip().split(' ')
+    flag_string = subprocess.check_output(cmd)
   except:
-    print "Could not run pkg-config."
+    sys.stderr.write('Could not run pkg-config.\n')
     return 1
 
+  # For now just split on spaces to get the args out. This will break if
+  # pkgconfig returns quoted things with spaces in them, but that doesn't seem
+  # to happen in practice.
+  all_flags = flag_string.strip().split(' ')
+
 
   sysroot = options.sysroot
   if not sysroot:
diff --git a/build/linux/pkg-config-wrapper b/build/linux/pkg-config-wrapper
index 2afb22b..2512b38 100755
--- a/build/linux/pkg-config-wrapper
+++ b/build/linux/pkg-config-wrapper
@@ -15,6 +15,9 @@
 # the PKG_CONFIG_PATH environment variable- these will be prepended to the
 # generated paths.
 
+set -o nounset
+set -o errexit
+
 root="$1"
 shift
 target_arch="$1"
@@ -31,13 +34,7 @@ fi
 rewrite=`dirname $0`/rewrite_dirs.py
 package=${!#}
 
-config_path=$root/usr/$libpath/pkgconfig:$root/usr/share/pkgconfig
-
-# prepend any paths specified by the environment
-if [ -n "$PKG_CONFIG_PATH" ]
-then
-  config_path="$PKG_CONFIG_PATH:$config_path"
-fi
+libdir=$root/usr/$libpath/pkgconfig:$root/usr/share/pkgconfig
 
 set -e
 # Some sysroots, like the Chromium OS ones, may generate paths that are not
@@ -47,6 +44,6 @@ set -e
 # relative to /path/to/chroot/build/x86-generic (i.e prefix=/usr).
 # To support this correctly, it's necessary to extract the prefix to strip from
 # pkg-config's |prefix| variable.
-prefix=`PKG_CONFIG_PATH=$config_path pkg-config --variable=prefix "$package" | sed -e 's|/usr$||'`
-result=`PKG_CONFIG_PATH=$config_path pkg-config "$@"`
+prefix=`PKG_CONFIG_LIBDIR=$libdir pkg-config --variable=prefix "$package" | sed -e 's|/usr$||'`
+result=`PKG_CONFIG_LIBDIR=$libdir pkg-config "$@"`
 echo "$result"| $rewrite --sysroot "$root" --strip-prefix "$prefix"
diff --git a/build/linux/sysroot_scripts/sysroot-creator.sh b/build/linux/sysroot_scripts/sysroot-creator.sh
index 39c787f..e05cf25 100644
--- a/build/linux/sysroot_scripts/sysroot-creator.sh
+++ b/build/linux/sysroot_scripts/sysroot-creator.sh
@@ -261,7 +261,7 @@ HacksAndPatchesAmd64() {
   sed -i -e 's|/lib/x86_64-linux-gnu/||g' ${lscripts}
 
   # This is for chrome's ./build/linux/pkg-config-wrapper
-  # which overwrites PKG_CONFIG_PATH internally
+  # which overwrites PKG_CONFIG_LIBDIR internally
   SubBanner "Move pkgconfig scripts"
   mv ${INSTALL_ROOT}/usr/lib/x86_64-linux-gnu/pkgconfig ${INSTALL_ROOT}/usr/lib/
 
@@ -284,7 +284,7 @@ HacksAndPatchesI386() {
   sed -i -e 's|/lib/i386-linux-gnu/||g' ${lscripts}
 
   # This is for chrome's ./build/linux/pkg-config-wrapper
-  # which overwrites PKG_CONFIG_PATH internally
+  # which overwrites PKG_CONFIG_LIBDIR internally
   SubBanner "Move pkgconfig scripts"
   mv ${INSTALL_ROOT}/usr/lib/i386-linux-gnu/pkgconfig ${INSTALL_ROOT}/usr/lib/
 
@@ -307,7 +307,7 @@ HacksAndPatchesARM() {
   sed -i -e 's|/lib/arm-linux-gnueabihf/||g' ${lscripts}
 
   # This is for chrome's ./build/linux/pkg-config-wrapper
-  # which overwrites PKG_CONFIG_PATH internally
+  # which overwrites PKG_CONFIG_LIBDIR internally
   SubBanner "Move pkgconfig files"
   mv ${INSTALL_ROOT}/usr/lib/arm-linux-gnueabihf/pkgconfig \
       ${INSTALL_ROOT}/usr/lib/
@@ -326,7 +326,7 @@ HacksAndPatchesMips() {
   sed -i -e 's|/lib/mipsel-linux-gnu/||g' ${lscripts}
 
   # This is for chrome's ./build/linux/pkg-config-wrapper
-  # which overwrites PKG_CONFIG_PATH internally
+  # which overwrites PKG_CONFIG_LIBDIR internally
   SubBanner "Move pkgconfig files"
   mv ${INSTALL_ROOT}/usr/lib/mipsel-linux-gnu/pkgconfig \
       ${INSTALL_ROOT}/usr/lib/