The open_temp_exec_file_dir function can create a temporary file without
file system accessible link. If the O_TMPFILE flag is not defined (old
Linux kernel or libc) the behavior is unchanged.
The open_temp_exec_file_name function now need a new argument "flags"
(like O_CLOEXEC) used for temporary file creation.
The O_TMPFILE flag allow temporary file creation without race condition.
This feature/fix prevent another process to access the (future)
executable file from the file system.
The O_CLOEXEC flag automatically close the temporary file for any
execve. This avoid transmitting (executable) file descriptor to a child
process.
This provides working closure support on iOS/ARM devices where
PROT_WRITE|PROT_EXEC is not permitted. The code passes basic
smoke tests, but requires further review.
This implements support for re-mapping a shared table of executable
trampolines directly in front of a writable configuration page, working
around PROT_WRITE restrictions for sandboxed applications on Apple's
iOS.
This implementation is for testing purposes; a proper allocator is still
necessary, and ARM-specific code needs to be moved out of
src/closures.c.
