diff options
Diffstat (limited to 'login-utils/chsh.c')
| -rw-r--r-- | login-utils/chsh.c | 313 |
1 files changed, 313 insertions, 0 deletions
diff --git a/login-utils/chsh.c b/login-utils/chsh.c new file mode 100644 index 000000000..9a9a52e85 --- /dev/null +++ b/login-utils/chsh.c @@ -0,0 +1,313 @@ +/* + * chsh.c -- change your login shell + * (c) 1994 by salvatore valente <svalente@athena.mit.edu> + * + * this program is free software. you can redistribute it and + * modify it under the terms of the gnu general public license. + * there is no warranty. + * + * faith + * 1.1.1.1 + * 1995/02/22 19:09:23 + * + */ + +#define _POSIX_SOURCE 1 + +#include <sys/types.h> +#include <stdio.h> +#include <string.h> +#include <stdlib.h> +#include <unistd.h> +#include <pwd.h> +#include <errno.h> +#include <ctype.h> +#include <getopt.h> + +#undef P +#if __STDC__ +#define P(foo) foo +#else +#define P(foo) () +#endif + +typedef unsigned char boolean; +#define false 0 +#define true 1 + +static char *version_string = "chsh 0.9 beta"; +static char *whoami; + +static char buf[FILENAME_MAX]; + +struct sinfo { + char *username; + char *shell; +}; + +static void parse_argv P((int argc, char *argv[], struct sinfo *pinfo)); +static void usage P((FILE *fp)); +static char *prompt P((char *question, char *def_val)); +static int check_shell P((char *shell)); +static boolean get_shell_list P((char *shell)); +static void *xmalloc P((int bytes)); +extern int setpwnam P((struct passwd *pwd)); +#define memzero(ptr, size) memset((char *) ptr, 0, size) + +int main (argc, argv) + int argc; + char *argv[]; +{ + char *cp, *shell; + uid_t uid; + struct sinfo info; + struct passwd *pw; + extern int errno; + + /* whoami is the program name for error messages */ + whoami = argv[0]; + if (! whoami) whoami = "chsh"; + for (cp = whoami; *cp; cp++) + if (*cp == '/') whoami = cp + 1; + + umask (022); + + uid = getuid (); + memzero (&info, sizeof (info)); + + parse_argv (argc, argv, &info); + pw = NULL; + if (! info.username) { + pw = getpwuid (uid); + if (! pw) { + fprintf (stderr, "%s: you (user %d) don't exist.\n", whoami, uid); + return (-1); } + } + else { + pw = getpwnam (info.username); + if (! pw) { + cp = info.username; + fprintf (stderr, "%s: user \"%s\" does not exist.\n", whoami, cp); + return (-1); } + } + + /* reality check */ + if (uid != 0 && uid != pw->pw_uid) { + errno = EACCES; + perror (whoami); + return (-1); + } + + shell = info.shell; + if (! shell) { + printf ("Changing shell for %s.\n", pw->pw_name); + shell = prompt ("New shell", pw->pw_shell); + if (! shell) return 0; + } + if (check_shell (shell) < 0) return (-1); + + if (! strcmp (pw->pw_shell, shell)) { + printf ("Shell not changed.\n"); + return 0; + } + pw->pw_shell = shell; + if (setpwnam (pw) < 0) { + perror ("setpwnam"); + return (-1); + } + printf ("Shell changed.\n"); + return 0; +} + +/* + * parse_argv () -- + * parse the command line arguments, and fill in "pinfo" with any + * information from the command line. + */ +static void parse_argv (argc, argv, pinfo) + int argc; + char *argv[]; + struct sinfo *pinfo; +{ + int index, c; + + static struct option long_options[] = { + { "shell", required_argument, 0, 's' }, + { "list-shells", no_argument, 0, 'l' }, + { "help", no_argument, 0, 'u' }, + { "version", no_argument, 0, 'v' }, + { NULL, no_argument, 0, '0' }, + }; + + optind = c = 0; + while (c != EOF) { + c = getopt_long (argc, argv, "s:luv", long_options, &index); + switch (c) { + case EOF: + break; + case 'v': + printf ("%s\n", version_string); + exit (0); + case 'u': + usage (stdout); + exit (0); + case 'l': + get_shell_list (NULL); + exit (0); + case 's': + if (! optarg) { + usage (stderr); + exit (-1); + } + pinfo->shell = optarg; + break; + default: + usage (stderr); + exit (-1); + } + } + /* done parsing arguments. check for a username. */ + if (optind < argc) { + if (optind + 1 < argc) { + usage (stderr); + exit (-1); + } + pinfo->username = argv[optind]; + } +} + +/* + * usage () -- + * print out a usage message. + */ +static void usage (fp) + FILE *fp; +{ + fprintf (fp, "Usage: %s [ -s shell ] ", whoami); + fprintf (fp, "[ --list-shells ] [ --help ] [ --version ]\n"); + fprintf (fp, " [ username ]\n"); +} + +/* + * prompt () -- + * ask the user for a given field and return it. + */ +static char *prompt (question, def_val) + char *question; + char *def_val; +{ + int len; + char *ans, *cp; + + if (! def_val) def_val = ""; + printf("%s [%s]: ", question, def_val); + *buf = 0; + if (fgets (buf, sizeof (buf), stdin) == NULL) { + printf ("\nAborted.\n"); + exit (-1); + } + /* remove the newline at the end of buf. */ + ans = buf; + while (isspace (*ans)) ans++; + len = strlen (ans); + while (len > 0 && isspace (ans[len-1])) len--; + if (len <= 0) return NULL; + ans[len] = 0; + cp = (char *) xmalloc (len + 1); + strcpy (cp, buf); + return cp; +} + +/* + * check_shell () -- if the shell is completely invalid, print + * an error and return (-1). + * if the shell is a bad idea, print a warning. + */ +static int check_shell (shell) + char *shell; +{ + int i, c; + + if (*shell != '/') { + printf ("%s: shell must be a full path name.\n", whoami); + return (-1); + } + if (access (shell, F_OK) < 0) { + printf ("%s: \"%s\" does not exist.\n", whoami, shell); + return (-1); + } + if (access (shell, X_OK) < 0) { + printf ("%s: \"%s\" is not executable.\n", whoami, shell); + return (-1); + } + /* keep /etc/passwd clean. */ + for (i = 0; i < strlen (shell); i++) { + c = shell[i]; + if (c == ',' || c == ':' || c == '=' || c == '"' || c == '\n') { + printf ("%s: '%c' is not allowed.\n", whoami, c); + return (-1); + } + if (iscntrl (c)) { + printf ("%s: Control characters are not allowed.\n", whoami); + return (-1); + } + } + if (! get_shell_list (shell)) + printf ("warning: \"%s\" is not listed as a valid shell.\n", shell); + return 0; +} + +/* + * get_shell_list () -- if the given shell appears in /etc/shells, + * return true. if not, return false. + * if the given shell is NULL, /etc/shells is outputted to stdout. + */ +static boolean get_shell_list (shell_name) + char *shell_name; +{ + FILE *fp; + boolean found; + int len; + + found = false; + fp = fopen ("/etc/shells", "r"); + if (! fp) { + if (! shell_name) printf ("No known shells.\n"); + return true; + } + while (fgets (buf, sizeof (buf), fp) != NULL) { + /* ignore comments */ + if (*buf == '#') continue; + len = strlen (buf); + /* strip the ending newline */ + if (buf[len - 1] == '\n') buf[len - 1] = 0; + /* ignore lines that are too damn long */ + else continue; + /* check or output the shell */ + if (shell_name) { + if (! strcmp (shell_name, buf)) { + found = true; + break; + } + } + else printf ("%s\n", buf); + } + fclose (fp); + return found; +} + +/* + * xmalloc () -- malloc that never fails. + */ +static void *xmalloc (bytes) + int bytes; +{ + void *vp; + + vp = malloc (bytes); + if (! vp && bytes > 0) { + perror ("malloc failed"); + exit (-1); + } + return vp; +} |