compat/mmap.c

   1 #include "../git-compat-util.h"
   2
   3 void *git_mmap(void *start, size_t length, int prot, int flags, int fd, off_t offset)
   4 {
   5         size_t n = 0;
   6
   7         if (start != NULL || flags != MAP_PRIVATE || prot != PROT_READ)
   8                 die("Invalid usage of mmap when built with NO_MMAP");
   9
  10         start = xmalloc(length);
  11         if (start == NULL) {
  12                 errno = ENOMEM;
  13                 return MAP_FAILED;
  14         }
  15
  16         while (n < length) {
  17                 ssize_t count = xpread(fd, (char *)start + n, length - n, offset + n);
  18
  19                 if (count == 0) {
  20                         memset((char *)start+n, 0, length-n);
  21                         break;
  22                 }
  23
  24                 if (count < 0) {
  25                         free(start);
  26                         errno = EACCES;
  27                         return MAP_FAILED;
  28                 }
  29
  30                 n += count;
  31         }
  32
  33         return start;
  34 }
  35
  36 int git_munmap(void *start, size_t length)
  37 {
  38         free(start);
  39         return 0;
  40 }