skalibs

Mirror/fork of https://skarnet.org/software/skalibs/
git clone https://ccx.te2000.cz/git/skalibs
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fd_lock.c (522B)

      1 /* ISC license. */
      2 
      3 #include <unistd.h>
      4 #include <errno.h>
      5 
      6 #include <skalibs/error.h>
      7 #include <skalibs/fcntl.h>
      8 #include <skalibs/djbunix.h>
      9 
     10 int fd_lock (int fd, int w, int nb)
     11 {
     12   struct flock fl =
     13   {
     14     .l_type = w ? F_WRLCK : F_RDLCK,
     15     .l_whence = SEEK_SET,
     16     .l_start = 0,
     17     .l_len = 0
     18   } ;
     19   int e = errno ;
     20   int r ;
     21   do r = fcntl(fd, nb ? F_SETLK : F_SETLKW, &fl) ;
     22   while (r == -1 && errno == EINTR) ;
     23   return r != -1 ? 1 :
     24     errno == EACCES || error_isagain(errno) ? (errno = e, 0) :
     25     -1 ;
     26 }