mmap.c raw

   1  #include <unistd.h>
   2  #include <sys/mman.h>
   3  #include <errno.h>
   4  #include <stdint.h>
   5  #include <limits.h>
   6  #include "syscall.h"
   7  
   8  static void dummy(void) { }
   9  weak_alias(dummy, __vm_wait);
  10  
  11  #define UNIT SYSCALL_MMAP2_UNIT
  12  #define OFF_MASK ((-0x2000ULL << (8*sizeof(syscall_arg_t)-1)) | (UNIT-1))
  13  
  14  void *__mmap(void *start, size_t len, int prot, int flags, int fd, off_t off)
  15  {
  16  	long ret;
  17  	if (off & OFF_MASK) {
  18  		errno = EINVAL;
  19  		return MAP_FAILED;
  20  	}
  21  	if (len >= PTRDIFF_MAX) {
  22  		errno = ENOMEM;
  23  		return MAP_FAILED;
  24  	}
  25  	if (flags & MAP_FIXED) {
  26  		__vm_wait();
  27  	}
  28  #ifdef SYS_mmap2
  29  	ret = __syscall(SYS_mmap2, start, len, prot, flags, fd, off/UNIT);
  30  #else
  31  	ret = __syscall(SYS_mmap, start, len, prot, flags, fd, off);
  32  #endif
  33  	/* Fixup incorrect EPERM from kernel. */
  34  	if (ret == -EPERM && !start && (flags&MAP_ANON) && !(flags&MAP_FIXED))
  35  		ret = -ENOMEM;
  36  	return (void *)__syscall_ret(ret);
  37  }
  38  
  39  weak_alias(__mmap, mmap);
  40  
  41  weak_alias(mmap, mmap64);
  42