crontab: almost complete rewrite

crontab: make options consistent with other implementations

   text    data     bss     dec     hex filename
   2042       4       0    2046     7fe busybox.t1/miscutils/crontab.o
   1331       0       0    1331     533 busybox.t2/miscutils/crontab.o

function                                             old     new   delta
edit_file                                            733     956    +223
open_as_user                                           -     171    +171
packed_usage                                       23652   23650      -2
CDir                                                   8       4      -4
ChangeUser                                           139       -    -139
crontab_main                                        1522     616    -906
------------------------------------------------------------------------------
(add/remove: 1/1 grow/shrink: 1/3 up/down: 394/-1051)        Total: -657 bytes
This commit is contained in:
Denis Vlasenko 2008-02-16 13:17:13 +00:00
parent cd5c61cd3b
commit 069e347863
2 changed files with 219 additions and 316 deletions

View File

@ -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]"

View File

@ -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];
}
}
for (; i < ac; ++i) {
char *ptr = av[i];
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 (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");
}
/*
* Change directory to our crontab directory
*/
xchdir(CDir);
/*
* Handle options as appropriate
*/
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;
}
/*
* Bump notification file. Handle window where crond picks file up
* before we can write our entry out.
*/
if (option == REPLACE || option == DELETE) {
FILE *fo;
struct stat st;
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;
}
static int GetReplaceStream(const char *user, const char *file)
{
int filedes[2];
int pid;
int fd;
int n;
char buf[1024];
if (pipe(filedes) < 0) {
perror("pipe");
return -1;
}
pid = fork();
if (pid < 0) {
perror("fork");
return -1;
}
if (pid > 0) {
/*
* PARENT
*/
close(filedes[1]);
if (read(filedes[0], buf, 1) != 1) {
close(filedes[0]);
filedes[0] = -1;
}
return filedes[0];
}
/*
* CHILD
*/
close(filedes[0]);
if (ChangeUser(user, 0) < 0)
exit(0);
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;
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);
}
static int ChangeUser(const char *user, short dochdir)
{
struct passwd *pas;
/*
* Obtain password entry and change privileges
*/
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);
/*
* Change running state to the user in question
*/
/* initgroups, setgid, setuid */
change_identity(pas);
if (dochdir) {
if (chdir(pas->pw_dir) < 0) {
bb_perror_msg("chdir(%s) by %s failed", pas->pw_dir, user);
bb_perror_msg("chdir(%s) by %s failed",
pas->pw_dir, pas->pw_name);
xchdir(TMPDIR);
}
}
return pas->pw_uid;
}
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;
}
/* CHILD - change user and run editor */
change_user(pas);
ptr = getenv("VISUAL");
if (!ptr) {
ptr = getenv("EDITOR");
if (!ptr)
ptr = PATH_VI;
}
/* 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);
}
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;
}
/* CHILD */
/* initgroups, setgid, setuid */
change_identity(pas);
/* 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);
}
int crontab_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
int crontab_main(int argc, char **argv)
{
const struct passwd *pas;
const char *crontab_dir = CRONTABS;
char *tmp_fname;
char *new_fname;
char *user_name; /* -u USER */
int fd;
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);
}
#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);
}
}
/* cd to our crontab directory */
xchdir(crontab_dir);
tmp_fname = NULL;
/* Handle requested operation */
switch (opt_ler) {
default: /* case OPT_r: Delete */
remove(pas->pw_name);
break;
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 */
}
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 */
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);*/
} /* switch */
/* Bump notification file. Handle window where crond picks file up
* before we can write our entry out.
*/
while ((fd = open(CRONUPDATE, O_WRONLY|O_CREAT|O_APPEND)) >= 0) {
struct stat st;
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 */
}
if (fd < 0) {
bb_error_msg("cannot append to %s/%s",
crontab_dir, CRONUPDATE);
}
return 0;
}