clib/mmap.c

   1 #include "config.h"
   2
   3 #include <sys/types.h>
   4
   5 #include <stdlib.h>
   6 #include <unistd.h>
   7
   8 /*
   9  * This function fakes mmap() by reading `len' bytes from the file descriptor
  10  * `fd' and returning a pointer to that memory.  The "mapped" region can later
  11  * be deallocated with munmap().
  12  *
  13  * Note: ONLY reading is supported and only reading of the exact size of the
  14  * file will work.
  15  *
  16  * PUBLIC: #ifndef HAVE_MMAP
  17  * PUBLIC: char *mmap __P((char *, size_t, int, int, int, off_t));
  18  * PUBLIC: #endif
  19  */
  20 char *
  21 mmap(addr, len, prot, flags, fd, off)
  22         char *addr;
  23         size_t len;
  24         int prot, flags, fd;
  25         off_t off;
  26 {
  27         char *ptr;
  28
  29         if ((ptr = (char *)malloc(len)) == 0)
  30                 return ((char *)-1);
  31         if (read(fd, ptr, len) < 0) {
  32                 free(ptr);
  33                 return ((char *)-1);
  34         }
  35         return (ptr);
  36 }
  37
  38 /*
  39  * PUBLIC: #ifndef HAVE_MMAP
  40  * PUBLIC: int munmap __P((char *, size_t));
  41  * PUBLIC: #endif
  42  */
  43 int
  44 munmap(addr, len)
  45         char *addr;
  46         size_t len;
  47 {
  48         free(addr);
  49         return (0);
  50 }