last_patch63 from vodz: add in crond and crontab applets

1 files changed, 393 insertions, 0 deletions

diff --git a/miscutils/crontab.c b/miscutils/crontab.c
new file mode 100644
index 0000000..c869906
--- /dev/null
+++ b/miscutils/crontab.c
@@ -0,0 +1,393 @@
+/*
+ * CRONTAB
+ *
+ * usually setuid root, -c option only works if getuid() == geteuid()
+ *
+ * Copyright 1994 Matthew Dillon (dillon@apollo.west.oic.com)
+ * May be distributed under the GNU General Public License
+ *
+ * Vladimir Oleynik <dzo@simtreas.ru> (C) 2002 to be used in busybox
+ *
+ */
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <stdarg.h>
+#include <string.h>
+#include <errno.h>
+#include <time.h>
+#include <dirent.h>
+#include <fcntl.h>
+#include <pwd.h>
+#include <unistd.h>
+#include <grp.h>
+#include <syslog.h>
+#include <signal.h>
+#include <getopt.h>
+#include <sys/ioctl.h>
+#include <sys/wait.h>
+#include <sys/stat.h>
+#include <sys/resource.h>
+
+#ifndef CRONTABS
+#define CRONTABS        "/var/spool/cron/crontabs"
+#endif
+#ifndef TMPDIR
+#define TMPDIR          "/var/spool/cron"
+#endif
+#ifndef CRONUPDATE
+#define CRONUPDATE      "cron.update"
+#endif
+#ifndef PATH_VI
+#define PATH_VI         "/usr/bin/vi"   /* location of vi       */
+#endif
+
+#include "busybox.h"
+
+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 ac, char **av)
+{
+    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 */
+    int   UserId;
+
+    UserId = getuid();
+    if ((pas = getpwuid(UserId)) == NULL)
+	perror_msg_and_die("getpwuid");
+
+    strncpy(caller, pas->pw_name, sizeof(caller));
+
+    i = 1;
+    if (ac > 1) {
+	if (av[1][0] == '-' && av[1][1] == 0) {
+	    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 {
+			error_msg_and_die("user %s unknown", av[i]);
+		    }
+		} else {
+		    error_msg_and_die("only the superuser may specify a user");
+		}
+	    }
+	    break;
+	case 'c':
+	    if (getuid() == geteuid()) {
+		CDir = (*ptr) ? ptr : av[++i];
+	    } else {
+		error_msg_and_die("-c option: superuser only");
+	    }
+	    break;
+	default:
+	    i = ac;
+	    break;
+	}
+    }
+    if (i != ac || option == NONE)
+	show_usage();
+
+    /*
+     * Get password entry
+     */
+
+    if ((pas = getpwuid(UserId)) == NULL)
+	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)
+	    error_msg_and_die("unable to read replacement file");
+    }
+
+    /*
+     * Change directory to our crontab directory
+     */
+
+    if (chdir(CDir) < 0)
+	perror_msg_and_die("cannot change dir to %s", CDir);
+
+    /*
+     * Handle options as appropriate
+     */
+
+    switch(option) {
+    case LIST:
+	{
+	    FILE *fi;
+	    char buf[1024];
+
+	    if ((fi = fopen(pas->pw_name, "r"))) {
+		while (fgets(buf, sizeof(buf), fi) != NULL)
+		    fputs(buf, stdout);
+		fclose(fi);
+	    } else {
+		error_msg("no crontab for %s", pas->pw_name);
+	    }
+	}
+	break;
+    case EDIT:
+	{
+	    FILE *fi;
+	    int fd;
+	    int n;
+	    char tmp[128];
+	    char buf[1024];
+
+	    snprintf(tmp, sizeof(tmp), TMPDIR "/crontab.%d", getpid());
+	    if ((fd = open(tmp, O_RDWR|O_CREAT|O_TRUNC|O_EXCL, 0600)) >= 0) {
+		chown(tmp, getuid(), getgid());
+		if ((fi = fopen(pas->pw_name, "r"))) {
+		    while ((n = fread(buf, 1, sizeof(buf), fi)) > 0)
+			write(fd, buf, n);
+		}
+		EditFile(caller, tmp);
+		remove(tmp);
+		lseek(fd, 0L, 0);
+		repFd = fd;
+	    } else {
+		error_msg_and_die("unable to create %s", tmp);
+	    }
+
+	}
+	option = REPLACE;
+	/* fall through */
+    case REPLACE:
+	{
+	    char buf[1024];
+	    char path[1024];
+	    int fd;
+	    int n;
+
+	    snprintf(path, sizeof(path), "%s.new", pas->pw_name);
+	    if ((fd = open(path, O_CREAT|O_TRUNC|O_EXCL|O_APPEND|O_WRONLY, 0600)) >= 0) {
+		while ((n = read(repFd, buf, sizeof(buf))) > 0) {
+		    write(fd, buf, n);
+		}
+		close(fd);
+		rename(path, pas->pw_name);
+	    } else {
+		error_msg("unable to create %s/%s", CDir, buf);
+	    }
+	    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) {
+	    error_msg("unable to 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);
+    }
+    if ((pid = fork()) < 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);
+
+    fd = open(file, O_RDONLY);
+    if (fd < 0) {
+	error_msg("unable to open %s", file);
+	exit(0);
+    }
+    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;
+
+    if ((pid = fork()) == 0) {
+	/*
+	 * CHILD - change user and run editor
+	 */
+	char *ptr;
+	char visual[1024];
+
+	if (ChangeUser(user, 1) < 0)
+	    exit(0);
+	if ((ptr = getenv("VISUAL")) == NULL || strlen(ptr) > 256)
+	    ptr = PATH_VI;
+
+	snprintf(visual, sizeof(visual), "%s %s", ptr, file);
+	execl("/bin/sh", "/bin/sh", "-c", visual, NULL);
+	perror("exec");
+	exit(0);
+    }
+    if (pid < 0) {
+	/*
+	 * PARENT - failure
+	 */
+	perror_msg_and_die("fork");
+    }
+    wait4(pid, NULL, 0, NULL);
+}
+
+static void
+log(const char *ctl, ...)
+{
+    va_list va;
+    char buf[1024];
+
+    va_start(va, ctl);
+    vsnprintf(buf, sizeof(buf), ctl, va);
+    syslog(LOG_NOTICE, "%s",buf );
+    va_end(va);
+}
+
+static int
+ChangeUser(const char *user, short dochdir)
+{
+    struct passwd *pas;
+
+    /*
+     * Obtain password entry and change privilages
+     */
+
+    if ((pas = getpwnam(user)) == 0) {
+	log("failed to get uid for %s", user);
+	return(-1);
+    }
+    setenv("USER", pas->pw_name, 1);
+    setenv("HOME", pas->pw_dir, 1);
+    setenv("SHELL", "/bin/sh", 1);
+
+    /*
+     * Change running state to the user in question
+     */
+
+    if (initgroups(user, pas->pw_gid) < 0) {
+	log("initgroups failed: %s %m", user);
+	return(-1);
+    }
+    if (setregid(pas->pw_gid, pas->pw_gid) < 0) {
+	log("setregid failed: %s %d", user, pas->pw_gid);
+	return(-1);
+    }
+    if (setreuid(pas->pw_uid, pas->pw_uid) < 0) {
+	log("setreuid failed: %s %d", user, pas->pw_uid);
+	return(-1);
+    }
+    if (dochdir) {
+	if (chdir(pas->pw_dir) < 0) {
+	    if (chdir(TMPDIR) < 0) {
+		log("chdir failed: %s %s", user, pas->pw_dir);
+		log("chdir failed: %s " TMPDIR, user);
+		return(-1);
+	    }
+	}
+    }
+    return(pas->pw_uid);
+}