src/flock.c

   1 #include <stdio.h>
   2 #include <stdlib.h>
   3 #include <sys/time.h>
   4 #include <sys/types.h>
   5 #include <sys/wait.h>
   6 #include <signal.h>
   7 #include <unistd.h>
   8 #include <fcntl.h>
   9 #include <string.h>
  10 #include <limits.h>
  11 #include <getopt.h>
  12 #include <sys/file.h>
  13
  14 #define failf(name) do { fprintf(stderr,"%s: ",pname); perror(name"()"); exit(EXIT_FAILURE); } while (0)
  15 const char version[]="This is FLock, version 1.0\n";
  16
  17 int verbose;
  18
  19 char *pname;
  20
  21 static void usage(void) __attribute__((noreturn));
  22 static void usage(void)
  23 {
  24         fprintf(stderr,"\
  25 %s\
  26 This command acts as an interface to flock(2):\n\
  27 \n\
  28 Usage: flock [{-s|--shared}|{-x|--exclusive}] [-n|--nonblock]\n\
  29              [-v|--verbose] [-h|--help] [-V|--version]\n\
  30              <lockname> <command>\n\
  31 \n\
  32   -s, --shared\tCreate shared lock (LOCK_SH) - DEFAULT\n\
  33   -x, --exclusive\tCreate exclusive lock (LOCK_EX)\n\
  34   -n, --nonblock\tFail immediately if req. lock is busy\n\
  35   -v, --verbose\tDisplay progress during locking\n\
  36   -h, --help\tPrint a summary of the options\n\
  37   -V, --version\tPrint the version number\n\
  38 ",version);
  39         exit(EXIT_FAILURE);
  40 }
  41
  42 const struct option longopts[]={
  43 {"shared"   ,0,0,'s'},
  44 {"exclusive",0,0,'x'},
  45 {"nonblock" ,0,0,'n'},
  46 {"verbose"  ,0,0,'v'},
  47 {"help"     ,0,0,'h'},
  48 {"version"  ,0,0,'V'},
  49 {NULL       ,0,0,0  }};
  50
  51 int main(int argc,char **argv)
  52 {
  53 char *fn,*cmd;
  54 int locktype=LOCK_SH,nonblock=0,fd,optc;
  55
  56         pname=*argv;
  57         while ((optc=getopt_long(argc,argv,"sxnvhV",longopts,NULL))!=EOF) switch (optc) {
  58                 case 's':
  59                         locktype=LOCK_SH;
  60                         break;
  61                 case 'x':
  62                         locktype=LOCK_EX;
  63                         break;
  64                 case 'n':
  65                         nonblock=LOCK_NB;
  66                         break;
  67                 case 'v':
  68                         verbose=1;
  69                         break;
  70                 case 'V':
  71                         fprintf(stderr,version);
  72                         exit(EXIT_FAILURE);
  73                 default: /* also 'h' */
  74                         usage();
  75                         break;
  76                 }
  77         if (optind+2!=argc) {
  78                 fprintf(stderr,"%s: Incorrect number of parameters (command needs quoting?)!\n",pname);
  79                 exit(EXIT_FAILURE);
  80                 }
  81         fn=argv[optind];
  82         cmd=argv[optind+1];
  83         if (verbose) { fprintf(stderr,"%s: Opening \"%s\"...",pname,fn); fflush(stderr); }
  84         if ((fd=open(fn,O_RDONLY|(nonblock?O_NONBLOCK:0)))==-1) failf("open");
  85         if (verbose) { fprintf(stderr,"done\n%s: Locking \"%s\"...",pname,fn); fflush(stderr); }
  86         if (flock(fd,locktype|nonblock)) failf("flock");
  87         if (verbose) { fprintf(stderr,"done\n%s: Running \"%s\"...",pname,cmd); fflush(stderr); }
  88         if (system(cmd)==-1) failf("system");
  89         if (verbose) { fprintf(stderr,"done\n%s: Finishing - removing lock.\n",pname); }
  90         return(EXIT_SUCCESS);
  91 }