qapi/commands: Optionally generate trace for QMP commands

[mirror_qemu.git] / scripts / signrom.py

diff --git a/scripts/signrom.py b/scripts/signrom.py
old mode 100644 (file)
new mode 100755 (executable)
index f9c35cc..43693db
--- a/scripts/signrom.py
+++ b/scripts/signrom.py
@@ -1,3 +1,5 @@
+#!/usr/bin/env python3
+
 #
 # Option ROM signing utility
 #
@@ -17,23 +19,34 @@ if len(sys.argv) < 3:
 fin = open(sys.argv[1], 'rb')
 fout = open(sys.argv[2], 'wb')
 
-fin.seek(2)
-size = ord(fin.read(1)) * 512 - 1
+magic = fin.read(2)
+if magic != b'\x55\xaa':
+    sys.exit("%s: option ROM does not begin with magic 55 aa" % sys.argv[1])
 
+size_byte = ord(fin.read(1))
 fin.seek(0)
-data = fin.read(size)
+data = fin.read()
+
+size = size_byte * 512
+if len(data) > size:
+    sys.stderr.write('error: ROM is too large (%d > %d)\n' % (len(data), size))
+    sys.exit(1)
+elif len(data) < size:
+    # Add padding if necessary, rounding the whole input to a multiple of
+    # 512 bytes according to the third byte of the input.
+    # size-1 because a final byte is added below to store the checksum.
+    data = data.ljust(size-1, b'\0')
+else:
+    if ord(data[-1:]) != 0:
+        sys.stderr.write('WARNING: ROM includes nonzero checksum\n')
+    data = data[:size-1]
+
 fout.write(data)
 
 checksum = 0
 for b in data:
-    # catch Python 2 vs. 3 differences
-    if isinstance(b, int):
-        checksum += b
-    else:
-        checksum += ord(b)
-checksum = (256 - checksum) % 256
-
-# Python 3 no longer allows chr(checksum)
+    checksum = (checksum - b) & 255
+
 fout.write(struct.pack('B', checksum))
 
 fin.close()