fileutil.which implementation

1 files changed, 73 insertions, 0 deletions

diff --git a/src/leap/util/fileutil.py b/src/leap/util/fileutil.py
new file mode 100644
index 00000000..86a44a89
--- /dev/null
+++ b/src/leap/util/fileutil.py
@@ -0,0 +1,73 @@
+from itertools import chain
+import os
+import platform
+import stat
+
+
+def is_user_executable(fpath):
+    st = os.stat(fpath)
+    return bool(st.st_mode & stat.S_IXUSR)
+
+
+def extend_path():
+    ourplatform = platform.system()
+    if ourplatform == "Linux":
+        return "/usr/local/sbin:/usr/sbin"
+    # XXX add mac / win extended search paths?
+
+
+def which(program):
+    """
+    an implementation of which
+    that extends the path with
+    other locations, like sbin
+    (f.i., openvpn binary is likely to be there)
+    @param program: a string representing the binary we're looking for.
+    """
+    def is_exe(fpath):
+        """
+        check that path exists,
+        it's a file,
+        and is executable by the owner
+        """
+        # we would check for access,
+        # but it's likely that we're
+        # using uid 0 + polkitd
+
+        return os.path.isfile(fpath)\
+            and is_user_executable(fpath)
+
+    def ext_candidates(fpath):
+        yield fpath
+        for ext in os.environ.get("PATHEXT", "").split(os.pathsep):
+            yield fpath + ext
+
+    def iter_path(pathset):
+        """
+        returns iterator with
+        full path for a given path list
+        and the current target bin.
+        """
+        for path in pathset.split(os.pathsep):
+            exe_file = os.path.join(path, program)
+            #print 'file=%s' % exe_file
+            for candidate in ext_candidates(exe_file):
+                if is_exe(candidate):
+                    yield candidate
+
+    fpath, fname = os.path.split(program)
+    if fpath:
+        if is_exe(program):
+            return program
+    else:
+        # extended iterator
+        # with extra path
+        extended_path = chain(
+            iter_path(os.environ["PATH"]),
+            iter_path(extend_path()))
+        for candidate in extended_path:
+            if candidate is not None:
+                return candidate
+
+    # sorry bro.
+    return None