nsz Git - musl/blob - src/misc/lockf.c

   1 #include <unistd.h>
   2 #include <fcntl.h>
   3 #include <errno.h>
   4 #include "libc.h"
   5
   6 int lockf(int fd, int op, off_t size)
   7 {
   8         struct flock l = {
   9                 .l_type = F_WRLCK,
  10                 .l_whence = SEEK_CUR,
  11                 .l_len = size,
  12         };
  13         switch (op) {
  14         case F_TEST:
  15                 l.l_type = F_RDLCK;
  16                 if (fcntl(fd, F_GETLK, &l) < 0)
  17                         return -1;
  18                 if (l.l_type == F_UNLCK || l.l_pid == getpid())
  19                         return 0;
  20                 errno = EACCES;
  21                 return -1;
  22         case F_ULOCK:
  23                 l.l_type = F_UNLCK;
  24         case F_TLOCK:
  25                 return fcntl(fd, F_SETLK, &l);
  26         case F_LOCK:
  27                 return fcntl(fd, F_SETLKW, &l);
  28         }
  29         errno = EINVAL;
  30         return -1;
  31 }
  32
  33 LFS64(lockf);