Change Details

In Seventh Edition UNIX, the last pointer passed to free() was guaranteed to not actually have been freed allowing memory to be "compacted" via the following patter: free(foo); foo = realloc(foo, newsize); Further, Andrew Koenig reports in "C Traps and Pitfalls" that the original realloc() implementation required this pattern. The C standard is clear that this is Undefined Behavior. Modern allocators don't support it and no portable code could rely on it so remove this support. Note: the removed implementation contains an off-by-one error and if an item isn't found on the freelist, then twice as much memory as the largest possible allocation will be copied.

In Seventh Edition UNIX, the last pointer passed to free() was guaranteed to not actually have been freed allowing memory to be "compacted" via the following pattern: free(foo); foo = realloc(foo, newsize); Further, Andrew Koenig reports in "C Traps and Pitfalls" that the original realloc() implementation required this pattern. The C standard is clear that this is Undefined Behavior. Modern allocators don't support it and no portable code could rely on it so remove this support. Note: the removed implementation contains an off-by-one error and if an item isn't found on the freelist, then twice as much memory as the largest possible allocation will be copied.

In Seventh Edition UNIX, the last pointer passed to free() was guaranteed to not actually have been freed allowing memory to be "compacted" via the following pattern: free(foo); foo = realloc(foo, newsize); Further, Andrew Koenig reports in "C Traps and Pitfalls" that the original realloc() implementation required this pattern. The C standard is clear that this is Undefined Behavior. Modern allocators don't support it and no portable code could rely on it so remove this support. Note: the removed implementation contains an off-by-one error and if an item isn't found on the freelist, then twice as much memory as the largest possible allocation will be copied.