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         if (length == 0) {
  11                 errno = EINVAL;
  12                 return MAP_FAILED;
  13         }
  14
  15         start = malloc(length);
  16         if (!start) {
  17                 errno = ENOMEM;
  18                 return MAP_FAILED;
  19         }
  20
  21         while (n < length) {
  22                 ssize_t count = xpread(fd, (char *)start + n, length - n, offset + n);
  23
  24                 if (count == 0) {
  25                         memset((char *)start+n, 0, length-n);
  26                         break;
  27                 }
  28
  29                 if (count < 0) {
  30                         free(start);
  31                         errno = EACCES;
  32                         return MAP_FAILED;
  33                 }
  34
  35                 n += count;
  36         }
  37
  38         return start;
  39 }
  40
  41 int git_munmap(void *start, size_t length)
  42 {
  43         free(start);
  44         return 0;
  45 }