On 15 Jun 2010, at 01:02, Riccardo Mottola wrote: > mprotect() wants a page-aligned address on Solaris. > - valloc instead of malloc, valloc just one page > - mprotect exactly that page, not size > - before freeing, make the page writable again.
I went through this code with Riccardo last night. On other platforms, it's likely that this was the cause of some subtle bugs. Due to limitations of the hardware, mprotect() only works at the page granularity. Solaris, helpfully, tells you that you're doing something wrong if you try to protect memory allocations smaller than a page. Other operating systems don't; the mprotect() call will silently protect the entire page. Other bits of this page may have been allocated to other variables with malloc, or they may subsequently be allocated (because malloc on most platforms expects to be able to write to memory that it has requested from the kernel but not given to the user, marking a page read-only when not all of it is allocated may cause malloc() to crash for no apparent reason). I think that we use mmap() to get exactly one page on other platforms. This fix now gets exactly one page on platforms where mmap() is not available. David -- Sent from my Apple II _______________________________________________ Gnustep-dev mailing list Gnustep-dev@gnu.org http://lists.gnu.org/mailman/listinfo/gnustep-dev
