upip: Drop _libc, add ffilib.

upip/Makefile

@@ -2,7 +2,7 @@ all:
 
 # This target prepares snapshot of all dependency modules, for
 # self-contained install
-deps: upip__libc.py upip_os.py upip_os_path.py upip_errno.py upip_gzip.py upip_stat.py upip_utarfile.py
+deps: upip_ffilib.py upip_os.py upip_os_path.py upip_errno.py upip_gzip.py upip_stat.py upip_utarfile.py
 
 upip_ffilib.py: ../ffilib/ffilib.py
 	cp $^ $@

upip/upip__libc.py

@@ -1,34 +0,0 @@
-import ffi
-import sys
-
-
-_h = None
-
-names = ('libc.so', 'libc.so.0', 'libc.so.6', 'libc.dylib')
-
-def get():
-    global _h
-    if _h:
-        return _h
-    err = None
-    for n in names:
-        try:
-            _h = ffi.open(n)
-            return _h
-        except OSError as e:
-            err = e
-    raise err
-
-
-def set_names(n):
-    global names
-    names = n
-
-# Find out bitness of the platform, even if long ints are not supported
-# TODO: All bitness differences should be removed from micropython-lib, and
-# this snippet too.
-bitness = 1
-v = sys.maxsize
-while v:
-    bitness += 1
-    v >>= 1

upip/upip_ffilib.py

@@ -0,0 +1,41 @@
+import sys
+import ffi
+
+_cache = {}
+
+def open(name, maxver=10, extra=()):
+    try:
+        return _cache[name]
+    except KeyError:
+        pass
+    def libs():
+        if sys.platform == "linux":
+            yield '%s.so' % name
+            for i in range(maxver, -1, -1):
+                yield '%s.so.%u' % (name, i)
+        else:
+            for ext in ('dylib', 'dll'):
+                yield '%s.%s' % (name, ext)
+        for n in extra:
+            yield n
+    err = None
+    for n in libs():
+        try:
+            l = ffi.open(n)
+            _cache[name] = l
+            return l
+        except OSError as e:
+            err = e
+    raise err
+
+def libc():
+    return open("libc", 6)
+
+# Find out bitness of the platform, even if long ints are not supported
+# TODO: All bitness differences should be removed from micropython-lib, and
+# this snippet too.
+bitness = 1
+v = sys.maxsize
+while v:
+    bitness += 1
+    v >>= 1