Add util.find_binary() to find binaries

This factors the logic out from find_busybox()

Signed-off-by: Andy Lutomirski <luto@kernel.org>

2 files changed, 36 insertions, 19 deletions

diff --git a/virtme/mkinitramfs.py b/virtme/mkinitramfs.py
index 98c7528..1a21c9b 100644
--- a/virtme/mkinitramfs.py
+++ b/virtme/mkinitramfs.py
@@ -13,6 +13,7 @@ import os.path
 import shlex
 import itertools
 from . import cpiowriter
+from . import util
 
 def make_base_layout(cw):
     for dir in (b'lib', b'bin', b'var', b'etc', b'newroot', b'dev', b'proc',
@@ -167,22 +168,5 @@ def mkinitramfs(out, config) -> None:
     cw.write_trailer()
 
 def find_busybox(root, is_native) -> Optional[str]:
-    names = ['busybox-static', 'busybox.static', 'busybox']
-    dirs = [os.path.join(*i) for i in itertools.product(
-        ['usr/local', 'usr', ''],
-        ['bin', 'sbin'])]
-
-    for n in names:
-        if is_native:
-            # Search PATH first
-            path = shutil.which(n)
-            if path is not None:
-                return path
-
-        for d in dirs:
-            path = os.path.join(root, d, n)
-            if os.path.isfile(path):
-                return path
-
-    # We give up.
-    return None
+    return util.find_binary(['busybox-static', 'busybox.static', 'busybox'],
+                            root=root, use_path=is_native)
diff --git a/virtme/util.py b/virtme/util.py
new file mode 100644
index 0000000..16b7ef7
--- /dev/null
+++ b/virtme/util.py
@@ -0,0 +1,33 @@
+# -*- mode: python -*-
+# util.py: Misc helpers
+# Copyright © 2014-2019 Andy Lutomirski
+# Licensed under the GPLv2, which is available in the virtme distribution
+# as a file called LICENSE with SHA-256 hash:
+# 8177f97513213526df2cf6184d8ff986c675afb514d4e68a404010521b880643
+
+from typing import Optional, Sequence
+
+import os
+import shutil
+import itertools
+
+def find_binary(names: Sequence[str], root: str = '/',
+                use_path: bool = True) -> Optional[str]:
+    dirs = [os.path.join(*i) for i in itertools.product(
+        ['usr/local', 'usr', ''],
+        ['bin', 'sbin'])]
+
+    for n in names:
+        if use_path:
+            # Search PATH first
+            path = shutil.which(n)
+            if path is not None:
+                return path
+
+        for d in dirs:
+            path = os.path.join(root, d, n)
+            if os.path.isfile(path):
+                return path
+
+    # We give up.
+    return None