Mac Archive Type Sniffing

chrome/test/data/safe_browsing/dmg/generate_test_data.sh

 #!/bin/sh
 
 # Copyright 2015 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 set -eu
 
 THIS_DIR=$(dirname "$0")
 
@@ skipping 66 matching lines @@
   touch "${FAKE_APP}/../Info.plist"
 
   mkdir "${DMG_SOURCE}/.hidden"
   cp "${THIS_DIR}/../mach_o/lib64.dylib" "${DMG_SOURCE}/.hidden/"
 
   hdiutil create -srcfolder "${DMG_SOURCE}" \
     -format UDZO -layout SPUD -volname "Mach-O in DMG" -ov \
     "${OUT_DIR}/mach_o_in_dmg"
 
   rm -rf "${DMG_SOURCE}"
+
+  # Copy of Mach-O DMG with 'koly' signature overwritten #######################
+  cp "${OUT_DIR}/mach_o_in_dmg.dmg" \
+  "${OUT_DIR}/mach_o_in_dmg_no_koly_signature.dmg"

[Robert Sesek, 2017/06/12 16:38:39]

nit: indent continuation lines by 4 spaces so it's  clear that this is not a new
command

[mortonm, 2017/06/12 18:31:16]

Done.

+  # Gets size of Mach-O DMG copy.
+  SIZE=`stat -f%z "${OUT_DIR}/mach_o_in_dmg_no_koly_signature.dmg"`
+  # Overwrites 'koly' with '????'.
+  printf '\xa1\xa1\xa1\xa1' | dd conv=notrunc \
+  of="${OUT_DIR}/mach_o_in_dmg_no_koly_signature.dmg" bs=1 seek=$(($SIZE - 512))
+
+  # Copy of Mach-O DMG with extension changed to .txt.
+  cp "${OUT_DIR}/mach_o_in_dmg.dmg" "${OUT_DIR}/mach_o_in_dmg.txt"
+
+  # Copy of Mach-O DMG with extension changed to .txt and no 'koly' signature ##
+  cp "${OUT_DIR}/mach_o_in_dmg_no_koly_signature.dmg" \
+  "${OUT_DIR}/mach_o_in_dmg_no_koly_signature.txt"
+

[Robert Sesek, 2017/06/12 16:38:39]

nit: extra blank line

[mortonm, 2017/06/12 18:31:16]

Done.

 }
 
 # Silence any stdout, but keep stderr.
 generate_test_data > /dev/null