Read and list AR archive.

tools/lsar.py

@@ -0,0 +1,12 @@
+#!/usr/bin/env python2.7 -B
+
+import sys
+from objtools import ar
+
+
+if __name__ == '__main__':
+  for path in sys.argv[1:]:
+    print '%s:' % path
+    for num, entry in enumerate(ar.ReadFile(path), start=1):
+      print '%5d:' % num, entry.name, '(length: %d)' % len(entry.data)
+    print ''

tools/objtools/ar.py

@@ -0,0 +1,48 @@
+import os
+import struct
+
+from collections import namedtuple
+
+
+class ArEntry(namedtuple('ArEntry',
+                         'name modtime owner group mode data')):
+  @classmethod
+  def decode(cls, ar):
+    name, modtime, owner, group, mode, length, magic = \
+        struct.unpack('16s12s6s6s8s10s2s', ar.read(60))
+
+    length = int(length.strip())
+    modtime = int(modtime.strip())
+    owner = int(owner.strip() or '0')
+    group = int(group.strip() or '0')
+    mode = mode.strip() or '100644'
+
+    if name.startswith('#1/'):
+      name_length = int(name[3:])
+      name = ar.read(name_length).strip('\0')
+    else:
+      name_length = 0
+      name = name.strip()
+
+    data = ar.read(length - name_length)
+
+    # next block starts at even boundary
+    if length & 1:
+      ar.seek(1, os.SEEK_CUR)
+
+    return cls(name, modtime, owner, group, mode, data)
+
+
+def ReadFile(path):
+  entries = []
+
+  with open(path) as ar:
+    if ar.read(8) != '!<arch>\n':
+      raise RuntimeError('%s is not an ar archive', path)
+
+    ar_size = os.stat(path).st_size
+
+    while ar.tell() < ar_size:
+      entries.append(ArEntry.decode(ar))
+
+  return entries