[PATCH] libelf: Fix some issues with ELF_C_RDWR_MMAP.

[Mark Wielaard]

On Wed, 2018-09-12 at 15:02 +0200, Mark Wielaard wrote:
> When ELF_C_RDWR_MMAP is used libelf might have to write overlapping memory
> when moving the section data or headers. Make sure to use memmove, not
> memcpy. Also the size of the underlying file might have to change. That
> means we will have to also extend the mmap region with mremap. Since we
> are using direct pointers into the mmapped area we cannot move the mmap,
> only extend it. This might still fail if there is not enough free memory
> available to extend the mmap region.
> 
> Two new test programs have been added. elfcopy which copies a whole elf
> file (using either ELF_C_WRITE or ELF_C_WRITE_MMAP). And addsections which
> adds new sections to an existing ELF file (using either ELF_C_RDWR or
> ELF_C_RDWR_MMAP). The newly added test will fail under valgrind without
> the fixes.

Pushed to master.