1 files changed, 54 insertions, 4 deletions
diff --git a/src/facter.py b/src/facter.py
index 8786aa3..c90306d 100644
--- a/src/facter.py
+++ b/src/facter.py
@@ -1,7 +1,7 @@
+import ctypes
 import multiprocessing
 import os
 import platform
-import sys
 
 import src.globalvars as gv
 
@@ -19,6 +19,56 @@ def collect_facts():
     with open(os.path.join(gv.builddir, "ccinfo"), "r") as ccinfo:
         gv.facts["cc"] = ccinfo.readlines()[-1][:-1]
 
-def get_libc_version(bin=None):
-    bin = bin or sys.executable
-    platform.libc_ver(executable=bin)
+
+
+# Copied from pip.
+# https://github.com/pypa/pip/blob/master/src/pip/_internal/utils/glibc.py
+# Licensed under MIT.
+def glibc_version_string(bin=None):
+    "Returns glibc version string, or None if not using glibc."
+
+    # ctypes.CDLL(None) internally calls dlopen(NULL), and as the dlopen
+    # manpage says, "If filename is NULL, then the returned handle is for the
+    # main program". This way we can let the linker do the work to figure out
+    # which libc our process is actually using.
+    process_namespace = ctypes.CDLL(bin)
+    try:
+        gnu_get_libc_version = process_namespace.gnu_get_libc_version
+    except AttributeError:
+        # Symbol doesn't exist -> therefore, we are not linked to
+        # glibc.
+        return None
+
+    # Call gnu_get_libc_version, which returns a string like "2.5"
+    gnu_get_libc_version.restype = ctypes.c_char_p
+    version_str = gnu_get_libc_version()
+    # py2 / py3 compatibility:
+    if not isinstance(version_str, str):
+        version_str = version_str.decode("ascii")
+
+    return version_str
+
+# platform.libc_ver regularly returns completely nonsensical glibc
+# versions. E.g. on my computer, platform says:
+#
+#   ~$ python2.7 -c 'import platform; print(platform.libc_ver())'
+#   ('glibc', '2.7')
+#   ~$ python3.5 -c 'import platform; print(platform.libc_ver())'
+#   ('glibc', '2.9')
+#
+# But the truth is:
+#
+#   ~$ ldd --version
+#   ldd (Debian GLIBC 2.22-11) 2.22
+#
+# This is unfortunate, because it means that the linehaul data on libc
+# versions that was generated by pip 8.1.2 and earlier is useless and
+# misleading. Solution: instead of using platform, use our code that actually
+# works.
+def libc_ver(bin=None):
+    glibc_version = glibc_version_string(bin)
+    if glibc_version is None:
+        # For non-glibc platforms, fall back on platform.libc_ver
+        return platform.libc_ver()
+    else:
+        return ("glibc", glibc_version)