1 files changed, 44 insertions, 0 deletions

diff --git a/meta/lib/rootfspostcommands.py b/meta/lib/rootfspostcommands.py
new file mode 100644
index 0000000000..6a9b8b47b7
--- /dev/null
+++ b/meta/lib/rootfspostcommands.py
@@ -0,0 +1,44 @@
+import os
+
+def sort_file(filename, mapping):
+    """
+    Sorts a passwd or group file based on the numeric ID in the third column.
+    If a mapping is given, the name from the first column is mapped via that
+    dictionary instead (necessary for /etc/shadow and /etc/gshadow). If not,
+    a new mapping is created on the fly and returned.
+    """
+    new_mapping = {}
+    with open(filename, 'rb+') as f:
+        lines = f.readlines()
+        # No explicit error checking for the sake of simplicity. /etc
+        # files are assumed to be well-formed, causing exceptions if
+        # not.
+        for line in lines:
+            entries = line.split(b':')
+            name = entries[0]
+            if mapping is None:
+                id = int(entries[2])
+            else:
+                id = mapping[name]
+            new_mapping[name] = id
+        # Sort by numeric id first, with entire line as secondary key
+        # (just in case that there is more than one entry for the same id).
+        lines.sort(key=lambda line: (new_mapping[line.split(b':')[0]], line))
+        # We overwrite the entire file, i.e. no truncate() necessary.
+        f.seek(0)
+        f.write(b''.join(lines))
+    return new_mapping
+
+def sort_passwd(sysconfdir):
+    """
+    Sorts passwd and group files in a rootfs /etc directory by ID.
+    """
+    for suffix in '', '-':
+        for main, shadow in (('passwd', 'shadow'),
+                             ('group', 'gshadow')):
+            filename = os.path.join(sysconfdir, main + suffix)
+            if os.path.exists(filename):
+                mapping = sort_file(filename, None)
+                filename = os.path.join(sysconfdir, shadow + suffix)
+                if os.path.exists(filename):
+                    sort_file(filename, mapping)