petdance/scratch — Issue #1235: Assumption made about buffer header alignment
Author: petdance
Created: 2011-11-01 05:39:41+00:00
State: open
Labels: bug, core, Pri-normal, Sev-low

Various memory management routines (e.g., `gc_ms_allocate_buffer_storage`) assume that the size of a buffer header is equal to the size of a pointer. This is probably true throughout the system as it stands, but those same routines take pains not to make that assumption in other places.
Here is a line from the above routine:
{{{
Buffer_buflen(buffer) = new_size - sizeof (void *);
}}}
If the size of a pointer is less than the buffer header size, the value stored in `buflen` will be too big. `new_size` includes the entire size of the buffer header, which may include alignment padding in addition to the pointer.

Originally http://trac.parrot.org/parrot/ticket/1731