s6

Mirror/fork of https://skarnet.org/software/s6/
git clone https://ccx.te2000.cz/git/s6
Log | Files | Refs | README | LICENSE

s6-setlock.c (2363B)

      1 /* ISC license. */
      2 
      3 #include <unistd.h>
      4 #include <errno.h>
      5 #include <signal.h>
      6 
      7 #include <skalibs/sgetopt.h>
      8 #include <skalibs/strerr.h>
      9 #include <skalibs/types.h>
     10 #include <skalibs/tai.h>
     11 #include <skalibs/sig.h>
     12 #include <skalibs/alarm.h>
     13 #include <skalibs/djbunix.h>
     14 #include <skalibs/exec.h>
     15 
     16 #include <s6/config.h>
     17 
     18 #define USAGE "s6-setlock [ -r | -w ] [ -n | -N ] [ -t timeout ] [ -d fd ] lockfile prog..."
     19 #define dieusage() strerr_dieusage(100, USAGE)
     20 
     21 static char const *file ;
     22 
     23 static void sigalrm_handler (int sig)
     24 {
     25   (void)sig ;
     26   strerr_dief3x(1, "lock ", file, ": timed out") ;
     27 }
     28 
     29 int main (int argc, char const *const *argv)
     30 {
     31   unsigned int nb = 0, ex = 1 ;
     32   unsigned int timeout = 0 ;
     33   int dest = -1 ;
     34   int fd ;
     35   int r ;
     36   PROG = "s6-setlock" ;
     37   
     38   for (;;)
     39   {
     40     int opt = lgetopt(argc, argv, "nNrwt:d:") ;
     41     if (opt == -1) break ;
     42     switch (opt)
     43     {
     44       case 'n' : nb = 1 ; break ;
     45       case 'N' : nb = 0 ; break ;
     46       case 'r' : ex = 0 ; break ;
     47       case 'w' : ex = 1 ; break ;
     48       case 't' : if (!uint0_scan(subgetopt_here.arg, &timeout)) dieusage() ; break ;
     49       case 'd' : { unsigned int u ; if (!uint0_scan(subgetopt_here.arg, &u)) dieusage() ; dest = u ; break ; }
     50       default : dieusage() ;
     51     }
     52   }
     53   argc -= subgetopt_here.ind ; argv += subgetopt_here.ind ;
     54   if (argc < 2) dieusage() ;
     55   file = argv[0] ;
     56 
     57   if (ex)
     58   {
     59     fd = open_create(file) ;
     60     if (fd == -1) strerr_diefu3sys(111, "open ", file, " for writing") ;
     61   }
     62   else
     63   {
     64     fd = open_read(file) ;
     65     if (fd == -1)
     66     {
     67       if (errno != ENOENT) strerr_diefu3sys(111, "open ", file, " for reading") ;
     68       fd = open_create(file) ;
     69       if (fd == -1) strerr_diefu2sys(111, "create ", file) ;
     70       fd_close(fd) ;
     71       fd = open_read(file) ;
     72       if (fd == -1) strerr_diefu3sys(111, "open ", file, " for reading") ;
     73     }
     74   }
     75 
     76   if (timeout)
     77   {
     78     tain tto ;
     79     tain_from_millisecs(&tto, timeout) ;
     80     if (!sig_catch(SIGALRM, &sigalrm_handler))
     81       strerr_diefu1sys(111, "set SIGALRM handler") ;
     82     if (!alarm_timeout(&tto))
     83       strerr_diefu1sys(111, "set timer") ;
     84   }
     85   r = fd_lock(fd, ex, nb) ;
     86   if (timeout) alarm_disable() ;
     87 
     88   if (!r) errno = EBUSY ;
     89   if (r < 1) strerr_diefu2sys(1, "lock ", file) ;
     90 
     91   if (dest >= 0 && fd_move(dest, fd) == -1)
     92     strerr_diefu1sys(111, "move lock descriptor") ;
     93   xexec(argv+1) ;
     94 }