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069e34786

Denis Vlasenko

2008-02-16

FAILED Duration: 20s

Subject

crontab: almost complete rewrite crontab: make options consistent with other implementations

Binary

No binary (build failed)

Architecture & Compiler Flags

Architecture: x86_64-linux-gnu Compiler: gcc (Ubuntu 11.4.0-1ubuntu1~22.04.3) 11.4.0

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Build Log

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Commit Diff GitHub →

include/usage.h +7 -8 miscutils/crontab.c +187 -283

include/usage.h+7 -8

@@ -510,15 +510,14 @@ USE_FEATURE_BRCTL_FANCY("\n" \
	" -c dir Working dir"

	#define crontab_trivial_usage \
-	"[-c dir] {file\|-}\|[-u\|-l\|-e\|-d user]"
+	"[-c DIR] [-u USER] [-ler]\|[FILE]"
	#define crontab_full_usage \
-	" file [opts] Replace crontab from file\n" \
-	" - [opts] Replace crontab from stdin\n" \
-	" -u user User\n" \
-	" -l [user] List crontab for user\n" \
-	" -e [user] Edit crontab for user\n" \
-	" -d [user] Delete crontab for user\n" \
-	" -c dir Crontab directory"
+	" -c Crontab directory" \
+	"\n -u User" \
+	"\n -l List crontab" \
+	"\n -e Edit crontab" \
+	"\n -r Delete crontab" \
+	"\n FILE Replace crontab by FILE ('-': stdin)" \

	#define cryptpw_trivial_usage \
	"[-a des\|md5] [string]"

miscutils/crontab.c+187 -283

@@ -25,321 +25,225 @@
	#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;
	}