The zero size allocations had no consistent behaviour in RTEMS. For
example, malloc( 0 ) returned NULL and posix_memalign( &p, align, 0 )
returned in p a unique pointer (or NULL if no memory is available). In
POSIX, zero size memory allocations are implementation-defined
behaviour. The implementation has two options:
https://pubs.opengroup.org/onlinepubs/9699919799/functions/malloc.htmlhttps://pubs.opengroup.org/onlinepubs/9699919799/functions/posix_memalign.html
Linux and FreeBSD return a unique pointer for zero size memory
allocations. Use this approach for RTEMS as well throughout the memory
allocation directives
Close#4390.
Move rtems_calloc() since it only depends on rtems_malloc(). This may
make it easier to customize the heap allocator.
Change licence to BSD-2-Clause according to file history.
Update #3053.
Only include the deferred free support if free() is actually used by the
application.
The free() implementation in RTEMS supports that allocated memory is
freed in interrupt context. Since the heap is protected by a mutex, the
frees issued in interrupt context cannot immediately be freed to the
heap, instead they are placed on a deferred free list. This list is
emptied by the core allocation function
rtems_heap_allocate_aligned_with_boundary(). This adds a dependency to
free() in rtems_heap_allocate_aligned_with_boundary(). In order to
better support applications which only allocate memory and never free
it, this dependency should be avoided. Provide a weak default
implementation of _Malloc_Process_deferred_frees() for
rtems_heap_allocate_aligned_with_boundary(). In the free() module
provide the strong implementation.
Close#4032.
Replace malloc_is_system_state_OK() with _Malloc_System_state() to allow
early allocations, e.g. in bsp_start(). Here the _Thread_Executing is
NULL, thus an _API_Mutex_Lock() would lead to a NULL pointer access.
Move malloc() support code to general case
rtems_heap_allocate_aligned_with_boundary(). Use
rtems_heap_allocate_aligned_with_boundary() to avoid duplicated code.
Script does what is expected and tries to do it as
smartly as possible.
+ remove occurrences of two blank comment lines
next to each other after Id string line removed.
+ remove entire comment blocks which only exited to
contain CVS Ids
+ If the processing left a blank line at the top of
a file, it was removed.
* libcsupport/Makefile.am, libcsupport/include/rtems/malloc.h,
libcsupport/src/free.c, libcsupport/src/malloc.c,
libcsupport/src/malloc_deferred.c,
libcsupport/src/malloc_initialize.c, libcsupport/src/malloc_p.h,
libcsupport/src/malloc_sbrk_helpers.c,
libcsupport/src/posix_memalign.c: Place all deferred free code and
place it in subroutines. Add plugin for dirtying allocated memory to
assist in debugging. Clean up comments and spacing as needed.
* libcsupport/src/malloc_dirtier.c: New file.
