Init

tools/lofi_patch_string.py

@@ -0,0 +1,55 @@
+#!/usr/bin/env python3
+"""Same-length UI string swap. Keeps every address stable (Level-0 mod).
+
+Example: lofi_patch_string.py "Lofi-12 XT.bin" out.bin Threshold ThresholX
+"""
+import argparse, struct, sys, os
+sys.path.insert(0, os.path.dirname(__file__))
+from lofi_image import parse_image, build_image, find_sect_by_role
+
+def main():
+    ap = argparse.ArgumentParser()
+    ap.add_argument('image')
+    ap.add_argument('output')
+    ap.add_argument('old')
+    ap.add_argument('new')
+    ap.add_argument('--sect', type=int, default=None)
+    ap.add_argument('--first-only', action='store_true')
+    a = ap.parse_args()
+    old_b, new_b = a.old.encode(), a.new.encode()
+    assert len(old_b) == len(new_b), \
+        f"lengths differ ({len(old_b)} vs {len(new_b)}); use equal length to keep addresses stable"
+    d = open(a.image, 'rb').read()
+    info = parse_image(d)
+    tgt = None
+    if a.sect is not None:
+        tgt = info['sects'][a.sect]
+    else:
+        tgt = find_sect_by_role(info, 'rodata')
+    hits = []
+    p = tgt['payload']
+    start = 0
+    while True:
+        i = p.find(old_b, start)
+        if i < 0:
+            break
+        hits.append(i)
+        start = i + 1
+    if not hits:
+        sys.exit(f"'{a.old}' not found in sect{tgt['index']} (addr {tgt['addr']:08X})")
+    print(f"found {len(hits)} hit(s) in sect{tgt['index']} at offsets: "
+          + ', '.join(f"+{h:#x} (file {tgt['off']+12+h:#x})" for h in hits))
+    if a.first_only:
+        hits = hits[:1]
+    np = bytearray(p)
+    for h in hits:
+        np[h:h+len(old_b)] = new_b
+    payloads = [(s['addr'], bytes(np) if s['index'] == tgt['index'] else s['payload'])
+                for s in info['sects']]
+    out = build_image(info, payloads)  # recomputes valid checksum
+    open(a.output, 'wb').write(out)
+    print(f"wrote {a.output} with fresh checksum "
+          f"{struct.unpack('<I', out[8:12])[0]:08X} — verify on device.")
+
+if __name__ == '__main__':
+    main()