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[unix-history] / usr / src / usr.bin / passwd / chsh.sh

#ifndef lint
static char *sccsid = "@(#)chsh.sh      4.5 (Berkeley) %G%";
#endif

/*
* chsh
*/
#include <stdio.h>
#include <signal.h>
#include <pwd.h>
#include <sys/file.h>
#include <time.h>
#include <resource.h>

char    passwd[] = "/etc/passwd";
char    temp[]   = "/etc/ptmp";
struct  passwd *pwd;
struct  passwd *getpwent();
int     endpwent();
char    *crypt();
char    *getpass();
char    *strcat();
char    buf[BUFSIZ];

main(argc, argv)
register char *argv[];
{
       register int u, fd;
       register FILE *tf;

       if (argc < 2 || argc > 3) {
               printf("Usage: chsh user [ /bin/csh ]\n");
               exit(1);
       }
       if (argc == 2)
               argv[2] = "";
       else {
               if (argv[2][0] != '/')
                       argv[2] = strcat(
                           "/bin/\0 12345678901234567890123456789", argv[2]);
               if (strcmp(argv[2], "/bin/csh") &&
                   strcmp(argv[2], "/bin/oldcsh") &&
                   strcmp(argv[2], "/bin/newcsh") &&
                   strcmp(argv[2], "/usr/new/csh") &&
                       /* and, for cretins who can't read the manual */
                   strcmp(argv[2], "/bin/sh") &&
                   getuid()) {
                       printf(
                           "Only /bin/csh may be specified\n"
                       );
                       exit(1);
               }
               if (access(argv[2], 1) < 0) {
                       printf("%s is not available\n", argv[2]);
                       exit(1);
               }
       }
       unlimit(RLIMIT_CPU);
       unlimit(RLIMIT_FSIZE);
       while ((pwd=getpwent()) != NULL) {
               if (strcmp(pwd->pw_name, argv[1]) == 0) {
                       u = getuid();
                       if (u!=0 && u != pwd->pw_uid) {
                               printf("Permission denied.\n");
                               exit(1);
                       }
                       break;
               }
       }
       endpwent();

       signal(SIGHUP, SIG_IGN);
       signal(SIGINT, SIG_IGN);
       signal(SIGQUIT, SIG_IGN);
       signal(SIGTSTP, SIG_IGN);
       if ((fd = open(temp, O_CREAT|O_EXCL|O_RDWR, 0644)) < 0) {
               printf("Temporary file busy -- try again\n");
               exit(1);
       }
       if ((tf=fdopen(fd, "w")) == NULL) {
               printf("Absurd fdopen failure - seek help\n");
               goto out;
       }
       /*
        * Copy passwd to temp, replacing matching lines
        * with new shell.
        */
       while ((pwd=getpwent()) != NULL) {
               if (strcmp(pwd->pw_name, argv[1]) == 0) {
                       u = getuid();
                       if (u != 0 && u != pwd->pw_uid) {
                               printf("Permission denied.\n");
                               goto out;
                       }
                       pwd->pw_shell = argv[2];
               }
               if (strcmp(pwd->pw_shell, "/bin/sh") == 0)
                       pwd->pw_shell = "";
               fprintf(tf, "%s:%s:%d:%d:%s:%s:%s\n"
                       , pwd->pw_name
                       , pwd->pw_passwd
                       , pwd->pw_uid
                       , pwd->pw_gid
                       , pwd->pw_gecos
                       , pwd->pw_dir
                       , pwd->pw_shell
               );
       }
       endpwent();
       if (rename(temp, passwd) < 0) {
               fprintf(stderr, "chsh: "); perror("rename");
 out:
               unlink(temp);
               exit(1);
       }
       fclose(tf);
       exit(0);
}

unlimit(lim)
{
       struct rlimit rlim;

       rlim.rlim_cur = rlim.rlim_max = RLIM_INFINITY;
       setrlimit(lim, &rlim);
}