svsem/svsem_op.c

+/* svsem_op.c
+
+   Perform groups of operations on a System V semaphore set.
+
+   Usage as shown in usageError().
+*/
 #include <sys/types.h>
 #include <sys/sem.h>
 #include <ctype.h>
 #include "curr_time.h"          /* Declaration of currTime() */
 #include "tlpi_hdr.h"
 
 #define MAX_SEMOPS 1000         /* Maximum operations that we permit for
                                    a single semop() */
 
 static void
 usageError(const char *progName)
 {
     fprintf(stderr, "Usage: %s semid op[,op...] ...\n\n", progName);
     fprintf(stderr, "'op' is either: <sem#>{+|-}<value>[n][u]\n");
     fprintf(stderr, "            or: <sem#>=0[n]\n");
     fprintf(stderr, "       \"n\" means include IPC_NOWAIT in 'op'\n");
     fprintf(stderr, "       \"u\" means include SEM_UNDO in 'op'\n\n");
     fprintf(stderr, "The operations in each argument are "
                     "performed in a single semop() call\n\n");
     fprintf(stderr, "e.g.: %s 12345 0+1,1-2un\n", progName);
     fprintf(stderr, "      %s 12345 0=0n 1+1,2-1u 1=0\n", progName);
     exit(EXIT_FAILURE);
 }
 
 /* Parse comma-delimited operations in 'arg', returning them in the
    array 'sops'. Return number of operations as function result. */
 
 static int
 parseOps(char *arg, struct sembuf sops[])
 {
     char *comma, *sign, *remaining, *flags;
     int numOps;                 /* Number of operations in 'arg' */
 
     for (numOps = 0, remaining = arg; ; numOps++) {
         if (numOps >= MAX_SEMOPS)
             cmdLineErr("Too many operations (maximum=%d): \"%s\"\n",
                         MAX_SEMOPS, arg);
 
         if (*remaining == '\0')
             fatal("Trailing comma or empty argument: \"%s\"", arg);
         if (!isdigit((unsigned char) *remaining))
             cmdLineErr("Expected initial digit: \"%s\"\n", arg);
 
         sops[numOps].sem_num = strtol(remaining, &sign, 10);
 
         if (*sign == '\0' || strchr("+-=", *sign) == NULL)
             cmdLineErr("Expected '+', '-', or '=' in \"%s\"\n", arg);
         if (!isdigit((unsigned char) *(sign + 1)))
             cmdLineErr("Expected digit after '%c' in \"%s\"\n", *sign, arg);
 
         sops[numOps].sem_op = strtol(sign + 1, &flags, 10);
 
         if (*sign == '-')                       /* Reverse sign of operation */
             sops[numOps].sem_op = - sops[numOps].sem_op;
         else if (*sign == '=')                  /* Should be '=0' */
             if (sops[numOps].sem_op != 0)
                 cmdLineErr("Expected \"=0\" in \"%s\"\n", arg);
 
         sops[numOps].sem_flg = 0;
         for (;; flags++) {
             if (*flags == 'n')
                 sops[numOps].sem_flg |= IPC_NOWAIT;
             else if (*flags == 'u')
                 sops[numOps].sem_flg |= SEM_UNDO;
             else
                 break;
         }
 
         if (*flags != ',' && *flags != '\0')
             cmdLineErr("Bad trailing character (%c) in \"%s\"\n", *flags, arg);
 
         comma = strchr(remaining, ',');
         if (comma == NULL)
             break;                              /* No comma --> no more ops */
         else
             remaining = comma + 1;
     }
 
     return numOps + 1;
 }
 
 int
 main(int argc, char *argv[])
 {
     struct sembuf sops[MAX_SEMOPS];
     int ind, nsops;
 
     if (argc < 2 || strcmp(argv[1], "--help") == 0)
         usageError(argv[0]);
 
     for (ind = 2; argv[ind] != NULL; ind++) {
         nsops = parseOps(argv[ind], sops);
 
         printf("%5ld, %s: about to semop()  [%s]\n", (long) getpid(),
                 currTime("%T"), argv[ind]);
 
         if (semop(getInt(argv[1], 0, "semid"), sops, nsops) == -1)
             errExit("semop (PID=%ld)", (long) getpid());
 
         printf("%5ld, %s: semop() completed [%s]\n", (long) getpid(),
                 currTime("%T"), argv[ind]);
     }
 
     exit(EXIT_SUCCESS);
 }