#define PATH_VI "/bin/vi" /* location of vi */
#endif
-static const char *CDir = CRONTABS;
-
-static void EditFile(const char *user, const char *file);
-static int GetReplaceStream(const char *user, const char *file);
-static int ChangeUser(const char *user, short dochdir);
-
-int crontab_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
-int crontab_main(int ac, char **av)
+static void change_user(const struct passwd *pas)
{
- enum { NONE, EDIT, LIST, REPLACE, DELETE } option = NONE;
- const struct passwd *pas;
- const char *repFile = NULL;
- int repFd = 0;
- int i;
- char caller[256]; /* user that ran program */
- char buf[1024];
- int UserId;
-
- UserId = getuid();
- pas = getpwuid(UserId);
- if (pas == NULL)
- bb_perror_msg_and_die("getpwuid");
-
- safe_strncpy(caller, pas->pw_name, sizeof(caller));
-
- i = 1;
- if (ac > 1) {
- if (LONE_DASH(av[1])) {
- option = REPLACE;
- ++i;
- } else if (av[1][0] != '-') {
- option = REPLACE;
- ++i;
- repFile = av[1];
- }
- }
+ setenv("USER", pas->pw_name, 1);
+ setenv("HOME", pas->pw_dir, 1);
+ setenv("SHELL", DEFAULT_SHELL, 1);
- for (; i < ac; ++i) {
- char *ptr = av[i];
+ /* initgroups, setgid, setuid */
+ change_identity(pas);
- if (*ptr != '-')
- break;
- ptr += 2;
-
- switch (ptr[-1]) {
- case 'l':
- if (ptr[-1] == 'l')
- option = LIST;
- /* fall through */
- case 'e':
- if (ptr[-1] == 'e')
- option = EDIT;
- /* fall through */
- case 'd':
- if (ptr[-1] == 'd')
- option = DELETE;
- /* fall through */
- case 'u':
- if (i + 1 < ac && av[i+1][0] != '-') {
- ++i;
- if (getuid() == geteuid()) {
- pas = getpwnam(av[i]);
- if (pas) {
- UserId = pas->pw_uid;
- } else {
- bb_error_msg_and_die("user %s unknown", av[i]);
- }
- } else {
- bb_error_msg_and_die("only the superuser may specify a user");
- }
- }
- break;
- case 'c':
- if (getuid() == geteuid()) {
- CDir = (*ptr) ? ptr : av[++i];
- } else {
- bb_error_msg_and_die("-c option: superuser only");
- }
- break;
- default:
- i = ac;
- break;
- }
+ if (chdir(pas->pw_dir) < 0) {
+ bb_perror_msg("chdir(%s) by %s failed",
+ pas->pw_dir, pas->pw_name);
+ xchdir(TMPDIR);
}
- if (i != ac || option == NONE)
- bb_show_usage();
-
- /*
- * Get password entry
- */
-
- pas = getpwuid(UserId);
- if (pas == NULL)
- bb_perror_msg_and_die("getpwuid");
-
- /*
- * If there is a replacement file, obtain a secure descriptor to it.
- */
+}
- if (repFile) {
- repFd = GetReplaceStream(caller, repFile);
- if (repFd < 0)
- bb_error_msg_and_die("cannot read replacement file");
+static void edit_file(const struct passwd *pas, const char *file)
+{
+ const char *ptr;
+ int pid = vfork();
+
+ if (pid < 0) /* failure */
+ bb_perror_msg_and_die("vfork");
+ if (pid) { /* parent */
+ wait4pid(pid);
+ return;
}
- /*
- * Change directory to our crontab directory
- */
-
- xchdir(CDir);
+ /* CHILD - change user and run editor */
+ change_user(pas);
+ ptr = getenv("VISUAL");
+ if (!ptr) {
+ ptr = getenv("EDITOR");
+ if (!ptr)
+ ptr = PATH_VI;
+ }
- /*
- * Handle options as appropriate
- */
+ /* TODO: clean up the environment!!! */
+ /* not execlp - we won't use PATH */
+ execl(ptr, ptr, file, NULL);
+ bb_perror_msg_and_die("exec %s", ptr);
+}
- switch (option) {
- case LIST:
- {
- FILE *fi;
-
- fi = fopen(pas->pw_name, "r");
- if (fi) {
- while (fgets(buf, sizeof(buf), fi) != NULL)
- fputs(buf, stdout);
- fclose(fi);
- } else {
- bb_error_msg("no crontab for %s", pas->pw_name);
- }
- }
- break;
- case EDIT:
- {
-/* FIXME: messy code here! we have file copying helpers for this! */
- FILE *fi;
- int fd;
- int n;
- char tmp[128];
-
- snprintf(tmp, sizeof(tmp), TMPDIR "/crontab.%d", getpid());
- fd = xopen3(tmp, O_RDWR|O_CREAT|O_TRUNC|O_EXCL, 0600);
-/* race, use fchown */
- chown(tmp, getuid(), getgid());
- fi = fopen(pas->pw_name, "r");
- if (fi) {
- while ((n = fread(buf, 1, sizeof(buf), fi)) > 0)
- full_write(fd, buf, n);
- }
- EditFile(caller, tmp);
- remove(tmp);
- lseek(fd, 0L, SEEK_SET);
- repFd = fd;
- }
- option = REPLACE;
- /* fall through */
- case REPLACE:
- {
-/* same here */
- char path[1024];
- int fd;
- int n;
-
- snprintf(path, sizeof(path), "%s.new", pas->pw_name);
- fd = open(path, O_CREAT|O_TRUNC|O_APPEND|O_WRONLY, 0600);
- if (fd >= 0) {
- while ((n = read(repFd, buf, sizeof(buf))) > 0) {
- full_write(fd, buf, n);
- }
- close(fd);
- rename(path, pas->pw_name);
- } else {
- bb_error_msg("cannot create %s/%s", CDir, path);
- }
- close(repFd);
- }
- break;
- case DELETE:
- remove(pas->pw_name);
- break;
- case NONE:
- default:
- break;
+static int open_as_user(const struct passwd *pas, const char *file)
+{
+ int filedes[2];
+ pid_t pid;
+ char c;
+
+ xpipe(filedes);
+ pid = vfork();
+ if (pid < 0) /* ERROR */
+ bb_perror_msg_and_die("vfork");
+ if (pid) { /* PARENT */
+ int n = safe_read(filedes[0], &c, 1);
+ close(filedes[0]);
+ close(filedes[1]);
+ if (n > 0) /* child says it can read */
+ return open(file, O_RDONLY);
+ return -1;
}
- /*
- * Bump notification file. Handle window where crond picks file up
- * before we can write our entry out.
- */
+ /* CHILD */
- if (option == REPLACE || option == DELETE) {
- FILE *fo;
- struct stat st;
+ /* initgroups, setgid, setuid */
+ change_identity(pas);
- while ((fo = fopen(CRONUPDATE, "a"))) {
- fprintf(fo, "%s\n", pas->pw_name);
- fflush(fo);
- if (fstat(fileno(fo), &st) != 0 || st.st_nlink != 0) {
- fclose(fo);
- break;
- }
- fclose(fo);
- /* loop */
- }
- if (fo == NULL) {
- bb_error_msg("cannot append to %s/%s", CDir, CRONUPDATE);
- }
- }
- return 0;
+ /* We just try to read one byte. If that works, file is readable
+ * under this user. We signal that by sending one byte to parent. */
+ if (safe_read(xopen(file, O_RDONLY), &c, 1) == 1)
+ safe_write(filedes[1], &c, 1); /* "papa, I can read!" */
+ _exit(0);
}
-static int GetReplaceStream(const char *user, const char *file)
+int crontab_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
+int crontab_main(int argc, char **argv)
{
- int filedes[2];
- int pid;
+ const struct passwd *pas;
+ const char *crontab_dir = CRONTABS;
+ char *tmp_fname;
+ char *new_fname;
+ char *user_name; /* -u USER */
int fd;
- int n;
- char buf[1024];
-
- if (pipe(filedes) < 0) {
- perror("pipe");
- return -1;
- }
- pid = fork();
- if (pid < 0) {
- perror("fork");
- return -1;
+ int opt_ler;
+ uid_t my_uid;
+
+ /* file [opts] Replace crontab from file
+ * - [opts] Replace crontab from stdin
+ * -u user User
+ * -c dir Crontab directory
+ * -l List crontab for user
+ * -e Edit crontab for user
+ * -r Delete crontab for user
+ * bbox also supports -d == -r, but most other crontab
+ * implementations do not. Deprecated.
+ */
+ enum {
+ OPT_u = (1 << 0),
+ OPT_c = (1 << 1),
+ OPT_l = (1 << 2),
+ OPT_e = (1 << 3),
+ OPT_r = (1 << 4),
+ OPT_ler = OPT_l + OPT_e + OPT_r,
+ };
+
+ my_uid = getuid();
+
+ opt_complementary = "?1:dr"; /* max one argument; -d implies -r */
+ opt_ler = getopt32(argv, "u:c:lerd", &user_name, &crontab_dir);
+ argv += optind;
+
+ if (opt_ler & (OPT_u|OPT_c))
+ if (my_uid != geteuid())
+ bb_error_msg_and_die("only root can use -c or -u");
+
+ if (opt_ler & OPT_u) {
+ pas = getpwnam(user_name);
+ if (!pas)
+ bb_error_msg_and_die("user %s is not known", user_name);
+ my_uid = pas->pw_uid;
+ } else {
+ pas = getpwuid(my_uid);
+ if (!pas)
+ bb_perror_msg_and_die("no user record for UID %u",
+ (unsigned)my_uid);
}
- if (pid > 0) {
- /*
- * PARENT
- */
- close(filedes[1]);
- if (read(filedes[0], buf, 1) != 1) {
- close(filedes[0]);
- filedes[0] = -1;
+#define user_name DONT_USE_ME_BEYOND_THIS_POINT
+#define my_uid DONT_USE_ME_BEYOND_THIS_POINT
+
+ /* From now on, keep only -l, -e, -r bits */
+ opt_ler &= OPT_ler;
+ if ((opt_ler - 1) & opt_ler) /* more than one bit set? */
+ bb_show_usage();
+
+ /* Read replacement file under user's UID/GID/group vector */
+ if (!opt_ler) { /* Replace? */
+ if (!argv[0])
+ bb_show_usage();
+ if (NOT_LONE_DASH(argv[0])) {
+ fd = open_as_user(pas, argv[0]);
+ if (fd < 0)
+ bb_error_msg_and_die("user %s cannot read %s",
+ pas->pw_name, argv[0]);
+ xmove_fd(fd, STDIN_FILENO);
}
- return filedes[0];
}
- /*
- * CHILD
- */
+ /* cd to our crontab directory */
+ xchdir(crontab_dir);
- close(filedes[0]);
+ tmp_fname = NULL;
- if (ChangeUser(user, 0) < 0)
- exit(0);
+ /* Handle requested operation */
+ switch (opt_ler) {
- xfunc_error_retval = 0;
- fd = xopen(file, O_RDONLY);
- buf[0] = 0;
- write(filedes[1], buf, 1);
- while ((n = read(fd, buf, sizeof(buf))) > 0) {
- write(filedes[1], buf, n);
- }
- exit(0);
-}
-
-static void EditFile(const char *user, const char *file)
-{
- int pid = fork();
-
- if (pid == 0) {
- /*
- * CHILD - change user and run editor
- */
- const char *ptr;
-
- if (ChangeUser(user, 1) < 0)
- exit(0);
- ptr = getenv("VISUAL");
- if (ptr == NULL)
- ptr = getenv("EDITOR");
- if (ptr == NULL)
- ptr = PATH_VI;
+ default: /* case OPT_r: Delete */
+ remove(pas->pw_name);
+ break;
- ptr = xasprintf("%s %s", ptr, file);
- execl(DEFAULT_SHELL, DEFAULT_SHELL, "-c", ptr, NULL);
- bb_perror_msg_and_die("exec");
- }
- if (pid < 0) {
- /*
- * PARENT - failure
- */
- bb_perror_msg_and_die("fork");
- }
- wait4(pid, NULL, 0, NULL);
-}
+ case OPT_l: /* List */
+ {
+ char *args[2] = { pas->pw_name, NULL };
+ return bb_cat(args);
+ /* list exits,
+ * the rest go play with cron update file */
+ }
-static int ChangeUser(const char *user, short dochdir)
-{
- struct passwd *pas;
+ case OPT_e: /* Edit */
+ tmp_fname = xasprintf(TMPDIR "/crontab.%u", (unsigned)getpid());
+ fd = xopen3(tmp_fname, O_RDWR|O_CREAT|O_TRUNC|O_EXCL, 0600);
+ xmove_fd(fd, STDIN_FILENO);
+ fd = open(pas->pw_name, O_RDONLY);
+ if (fd >= 0) {
+ bb_copyfd_eof(fd, STDIN_FILENO);
+ close(fd);
+ }
+ fchown(STDIN_FILENO, pas->pw_uid, pas->pw_gid);
+ edit_file(pas, tmp_fname);
+ xlseek(STDIN_FILENO, 0, SEEK_SET);
+ /* fall through */
- /*
- * Obtain password entry and change privileges
- */
+ case 0: /* Replace (no -l, -e, or -r were given) */
+ new_fname = xasprintf("%s.new", pas->pw_name);
+ fd = open(new_fname, O_WRONLY|O_CREAT|O_TRUNC|O_APPEND, 0600);
+ if (fd >= 0) {
+ bb_copyfd_eof(STDIN_FILENO, fd);
+ close(fd);
+ rename(new_fname, pas->pw_name);
+ } else {
+ bb_error_msg("cannot create %s/%s",
+ crontab_dir, new_fname);
+ }
+ if (tmp_fname)
+ remove(tmp_fname);
+ /*free(tmp_fname);*/
+ /*free(new_fname);*/
- pas = getpwnam(user);
- if (pas == NULL) {
- bb_perror_msg_and_die("cannot get uid for %s", user);
- }
- setenv("USER", pas->pw_name, 1);
- setenv("HOME", pas->pw_dir, 1);
- setenv("SHELL", DEFAULT_SHELL, 1);
+ } /* switch */
- /*
- * Change running state to the user in question
+ /* Bump notification file. Handle window where crond picks file up
+ * before we can write our entry out.
*/
- change_identity(pas);
+ while ((fd = open(CRONUPDATE, O_WRONLY|O_CREAT|O_APPEND)) >= 0) {
+ struct stat st;
- if (dochdir) {
- if (chdir(pas->pw_dir) < 0) {
- bb_perror_msg("chdir(%s) by %s failed", pas->pw_dir, user);
- xchdir(TMPDIR);
+ fdprintf(fd, "%s\n", pas->pw_name);
+ if (fstat(fd, &st) != 0 || st.st_nlink != 0) {
+ /*close(fd);*/
+ break;
}
+ /* st.st_nlink == 0:
+ * file was deleted, maybe crond missed our notification */
+ close(fd);
+ /* loop */
}
- return pas->pw_uid;
+ if (fd < 0) {
+ bb_error_msg("cannot append to %s/%s",
+ crontab_dir, CRONUPDATE);
+ }
+ return 0;
}
projects / oweals / busybox.git / commitdiff