1 files changed, 94 insertions, 0 deletions
diff --git a/python/mozbuild/mozbuild/configure/libstdcxx.py b/python/mozbuild/mozbuild/configure/libstdcxx.py
new file mode 100755
index 0000000000..b84edb401f
--- /dev/null
+++ b/python/mozbuild/mozbuild/configure/libstdcxx.py
@@ -0,0 +1,94 @@
+#!/usr/bin/python
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+
+# This script find the version of libstdc++ and prints it as single number
+# with 8 bits per element. For example, GLIBCXX_3.4.10 becomes
+# 3 << 16 | 4 << 8 | 10 = 197642. This format is easy to use
+# in the C preprocessor.
+
+# We find out both the host and target versions. Since the output
+# will be used from shell, we just print the two assignments and evaluate
+# them from shell.
+
+from __future__ import absolute_import, print_function
+
+import os
+import subprocess
+import re
+import six
+
+re_for_ld = re.compile(".*\((.*)\).*")
+
+
+def parse_readelf_line(x):
+    """Return the version from a readelf line that looks like:
+    0x00ec: Rev: 1  Flags: none  Index: 8  Cnt: 2  Name: GLIBCXX_3.4.6
+    """
+    return x.split(":")[-1].split("_")[-1].strip()
+
+
+def parse_ld_line(x):
+    """Parse a line from the output of ld -t. The output of gold is just
+    the full path, gnu ld prints "-lstdc++ (path)".
+    """
+    t = re_for_ld.match(x)
+    if t:
+        return t.groups()[0].strip()
+    return x.strip()
+
+
+def split_ver(v):
+    """Covert the string '1.2.3' into the list [1,2,3]"""
+    return [int(x) for x in v.split(".")]
+
+
+def encode_ver(v):
+    """Encode the version as a single number."""
+    t = split_ver(v)
+    return t[0] << 16 | t[1] << 8 | t[2]
+
+
+def find_version(args):
+    """Given a base command line for a compiler, find the version of the
+    libstdc++ it uses.
+    """
+    args += ["-shared", "-Wl,-t"]
+    p = subprocess.Popen(args, stderr=subprocess.STDOUT, stdout=subprocess.PIPE)
+    candidates = [six.ensure_text(x, encoding="ascii") for x in p.stdout]
+    candidates = [x for x in candidates if "libstdc++.so" in x]
+    candidates = [x for x in candidates if "skipping incompatible" not in x]
+    if not candidates:
+        raise Exception(
+            """Couldn't find libstdc++ candidates!
+command line: %s"""
+            % args
+        )
+    if len(candidates) != 1:
+        raise Exception(
+            """Too many libstdc++ candidates!
+command line: %s
+candidates:
+%s"""
+            % (args, "\n".join(candidates))
+        )
+
+    libstdcxx = parse_ld_line(candidates[-1])
+
+    p = subprocess.Popen(["readelf", "-V", libstdcxx], stdout=subprocess.PIPE)
+    lines = [six.ensure_text(x, encoding="ascii") for x in p.stdout]
+    versions = [parse_readelf_line(x) for x in lines if "Name: GLIBCXX" in x]
+    last_version = sorted(versions, key=split_ver)[-1]
+    return (last_version, encode_ver(last_version))
+
+
+if __name__ == "__main__":
+    """Given the value of environment variable CXX or HOST_CXX, find the
+    version of the libstdc++ it uses.
+    """
+    cxx_env = os.environ["CXX"]
+    print("MOZ_LIBSTDCXX_TARGET_VERSION=%s" % find_version(cxx_env.split())[1])
+    host_cxx_env = os.environ.get("HOST_CXX", cxx_env)
+    print("MOZ_LIBSTDCXX_HOST_VERSION=%s" % find_version(host_cxx_env.split())[1])