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Annotation of researchv8dc/cmd/upas/print/semaphore.c, revision 1.1.1.1

1.1       root        1: #include <stdio.h>
                      2: #include <sys/types.h>
                      3: #include <sys/stat.h>
                      4: #include "mail.h"
                      5: #include "string.h"
                      6: 
                      7: /* imported */
                      8: extern char *getenv();
                      9: extern int getpid();
                     10: extern char *ttyname();
                     11: 
                     12: /* global to the module */
                     13: static char semaphore[PATHSIZE];
                     14: static char tty[64];
                     15: 
                     16: extern void
                     17: V()
                     18: {
                     19:        unlink(semaphore);
                     20: }
                     21: 
                     22: /* return name of tty if file is already being read, NULL otherwise */
                     23: extern char *
                     24: P()
                     25: {
                     26:        char file[PATHSIZE];
                     27:        struct stat sbuf;
                     28:        FILE *fp;
                     29:        int pid;
                     30:        char *home = getenv("HOME");
                     31: 
                     32:        if (home == NULL)
                     33:                return NULL;
                     34:        (void)strcpy(file, home);
                     35:        (void)strcat(file, "/.Maillock");
                     36:        if (stat(file, &sbuf) >= 0) {
                     37: 
                     38:                /* lock file exists */
                     39:                fp = fopen(file, "r");
                     40:                if (fp == NULL)
                     41:                        return "another tty";
                     42:                fscanf(fp, "%d %s", &pid, tty);
                     43:                fclose(fp);
                     44:                if (kill(pid, 0) == 0)
                     45:                        return tty;
                     46:        }
                     47: 
                     48:        /* create a semaphore file */
                     49:        strcpy(semaphore, file);
                     50:        V();
                     51:        fp = fopen(semaphore, "w");
                     52:        if (fp == NULL)
                     53:                return 0;               /* nothing else we can do */
                     54:        fprintf(fp, "%d %s\n", getpid(), ttyname(2));
                     55:        fclose(fp);
                     56:        return 0;
                     57: }
                     58: 

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