usr/src/cmd/who.c

/*
 * who
 */

#include <stdio.h>
#include <utmp.h>
#include <pwd.h>
struct utmp utmp;
struct passwd *pw;
struct passwd *getpwuid();

char *ttyname(), *rindex(), *ctime(), *strcpy(), *index();
main(argc, argv)
char **argv;
{
        register char *tp, *s;
        register FILE *fi;

        s = "/etc/utmp";
        if(argc == 2)
                s = argv[1];
        if (argc==3) {
                tp = ttyname(0);
                if (tp)
                        tp = index(tp+1, '/') + 1;
                else {  /* no tty - use best guess from passwd file */
                        pw = getpwuid(getuid());
                        strcpy(utmp.ut_name, pw?pw->pw_name: "?");
                        strcpy(utmp.ut_line, "tty??");
                        time(&utmp.ut_time);
                        putline();
                        exit(0);
                }
        }
        if ((fi = fopen(s, "r")) == NULL) {
                puts("who: cannot open utmp");
                exit(1);
        }
        while (fread((char *)&utmp, sizeof(utmp), 1, fi) == 1) {
                if(argc==3) {
                        if (strcmp(utmp.ut_line, tp))
                                continue;
#ifdef interdata
                        printf("(Interdata) ");
#endif
                        putline();
                        exit(0);
                }
                if(utmp.ut_name[0] == '\0' && argc==1)
                        continue;
                putline();
        }
}

putline()
{
        register char *cbuf;

        printf("%-8.8s %-8.8s", utmp.ut_name, utmp.ut_line);
        cbuf = ctime(&utmp.ut_time);
        printf("%.12s\n", cbuf+4);
}