Lion x86 compatibility for mach_override

third_party/mach_override/README.chromium

 Name: mach_override
 Short Name: Part of the mach_star project
 Version: Unknown
 URL: https://github.com/rentzsch/mach_star
 Date: 04/18/2011
 Revision: 32c4560eb09848073f69
 License: MIT
-Security Critical: Yes.
+Security Critical: Yes
 
 
 Description:
-This is the mach_override part of the lastest (as of 04/11/2011) revision of
-mach_star, namely:
+This is the mach_override part of mach_star, namely:
 
   https://github.com/rentzsch/mach_star/tree/aeb1720815c7255070da0f548267ccfdf7bd50b7
 
 This package is used to replace framework functions with different
 implementations at run time.
 
 
 Local Modifications:
 
-None; all local changes have been upstreamed.
+Enabled makeIslandExecutable for 32-bit i386. Main executables linked and run
+on Mac OS X 10.7 ("Lion") have non-executable heap pages by default. See
+http://crbug.com/79642.
+
+Changed the logic surrounding calls to makeIslandExecutable so that
+mach_override_ptr can return successfully when originalFunctionReentryIsland,
+an optional argument, is NULL. Failure in makeIslandExecutable will now
+trigger cleanup of allocated memory.
+
+Changed allocateBranchIsland to use a more appropriate address range per
+http://developer.apple.com/library/mac/#documentation/Performance/Conceptual/LaunchTime/Articles/Prebinding.html.
+The range for x86 (32-bit) with kAllocateHigh set is now [0xffc00000,
+0xffe00000). In this configuration, the loop is now guaranteed to terminate
+instead of exceeding its permitted range. Previously, this function would
+begin looking for a page at 0xfefff000 and would not stop, even after wrapping
+around to low memory. The URL above states 0xfefff000 is within a range marked
+"Reserved for use by the pasteboard and other system services. Do not use this
+address range."