cctools/ld/cctools_map_fd.c

   1 /* Iain Sandoe, Oct 2015. */
   2
   3 #include "cctools_map_fd.h"
   4 #include <sys/mman.h>
   5
   6 /* The interface is originally defined in libc.h   */
   7
   8 /* The actual code for the map_fd syscall is in kern_mman.c in xnu.
   9    - replace it with a call to mmap.  */
  10
  11 kern_return_t
  12 map_fd(int fd, vm_offset_t offset, vm_offset_t *addr,
  13        boolean_t find_space, vm_size_t numbytes)
  14 {
  15   void *ret_addr = (void *)0; /* default, let the system pick the adddress.  */
  16   int prot = PROT_READ | PROT_WRITE;
  17   int flags = MAP_FILE | MAP_PRIVATE;
  18
  19   if (! find_space) {
  20     /* Use the address specified.
  21        At present, this is not used by cctools - and presumably the code will
  22        be updated on some future drop to remove it.  */
  23     ret_addr = (void *) *addr;
  24     flags |= MAP_FIXED;
  25   }
  26
  27   ret_addr = mmap(ret_addr, numbytes, prot, flags, fd, offset);
  28
  29   /* mmp either returns MAP_FAILED, or the result.  */
  30   if (ret_addr == MAP_FAILED)
  31     return KERN_FAILURE;
  32
  33   *addr = (vm_offset_t)ret_addr;
  34   return KERN_SUCCESS;
  35 }