add stuff

root/scripts/host/patch_dropbear_sftp.py

@@ -0,0 +1,35 @@
+#!/usr/bin/env python3
+"""Create a Dropbear copy whose SFTP subsystem points at /3rd_rw/sshd/sftp-server.
+
+Dropbear does not ship an sftp-server; it execs the compile-time
+SFTPSERVER_PATH (default /usr/libexec/sftp-server). The target rootfs is
+read-only, so this copy uses the writable /3rd_rw/sshd path instead.
+The replacement has exactly the same length, so no ELF offsets change.
+"""
+import hashlib
+import pathlib
+import sys
+
+ROOT = pathlib.Path(__file__).resolve().parents[2]  # .../root
+SRC = ROOT / "tools" / "pub" / "dropbear"
+DST = ROOT / "tools" / "pub" / "dropbear-sftp"
+OLD = b"/usr/libexec/sftp-server"
+NEW = b"/3rd_rw/sshd/sftp-server"
+
+def main() -> int:
+    data = SRC.read_bytes()
+    if len(OLD) != len(NEW):
+        sys.exit(f"length mismatch: {len(OLD)} != {len(NEW)}")
+    n = data.count(OLD)
+    if n != 1:
+        sys.exit(f"expected exactly 1 occurrence of {OLD!r}, found {n}")
+    DST.write_bytes(data.replace(OLD, NEW))
+    DST.chmod(0o755)
+    h = hashlib.sha256(DST.read_bytes()).hexdigest()
+    print(f"wrote {DST}")
+    print(f"sha256 {h}")
+    print(f"size {DST.stat().st_size}")
+    return 0
+
+if __name__ == "__main__":
+    raise SystemExit(main())