src/mman/shm_open.c

   1 #include <sys/mman.h>
   2 #include <errno.h>
   3 #include <fcntl.h>
   4 #include <unistd.h>
   5 #include <string.h>
   6 #include <limits.h>
   7 #include <pthread.h>
   8
   9 char *__shm_mapname(const char *name, char *buf)
  10 {
  11         char *p;
  12         while (*name == '/') name++;
  13         if (*(p = __strchrnul(name, '/')) || p==name ||
  14             (p-name <= 2 && name[0]=='.' && p[-1]=='.')) {
  15                 errno = EINVAL;
  16                 return 0;
  17         }
  18         if (p-name > NAME_MAX) {
  19                 errno = ENAMETOOLONG;
  20                 return 0;
  21         }
  22         memcpy(buf, "/dev/shm/", 9);
  23         memcpy(buf+9, name, p-name+1);
  24         return buf;
  25 }
  26
  27 int shm_open(const char *name, int flag, mode_t mode)
  28 {
  29         int cs;
  30         char buf[NAME_MAX+10];
  31         if (!(name = __shm_mapname(name, buf))) return -1;
  32         pthread_setcancelstate(PTHREAD_CANCEL_DISABLE, &cs);
  33         int fd = open(name, flag|O_NOFOLLOW|O_CLOEXEC|O_NONBLOCK, mode);
  34         pthread_setcancelstate(cs, 0);
  35         return fd;
  36 }
  37
  38 int shm_unlink(const char *name)
  39 {
  40         char buf[NAME_MAX+10];
  41         if (!(name = __shm_mapname(name, buf))) return -1;
  42         return unlink(name);
  43 }