1 files changed, 368 insertions, 0 deletions

diff --git a/busybox/miscutils/crontab.c b/busybox/miscutils/crontab.c
new file mode 100644
index 000000000..89e13775f
--- /dev/null
+++ b/busybox/miscutils/crontab.c
@@ -0,0 +1,368 @@
+/*
+ * 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 <unistd.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         "/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)
+        bb_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 {
+                        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
+     */
+
+    if ((pas = getpwuid(UserId)) == 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("unable to read replacement file");
+    }
+
+    /*
+     * Change directory to our crontab directory
+     */
+
+    if (chdir(CDir) < 0)
+        bb_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 {
+                bb_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 {
+                bb_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_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 {
+                bb_error_msg("unable to 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("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) {
+        bb_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(DEFAULT_SHELL, DEFAULT_SHELL, "-c", visual, NULL);
+        perror("exec");
+        exit(0);
+    }
+    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
+     */
+
+    if ((pas = getpwnam(user)) == 0) {
+        bb_perror_msg_and_die("failed to get uid for %s", user);
+        return(-1);
+    }
+    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
+     */
+    change_identity(pas);
+
+    if (dochdir) {
+        if (chdir(pas->pw_dir) < 0) {
+            bb_perror_msg_and_die("chdir failed: %s %s", user, pas->pw_dir);
+            if (chdir(TMPDIR) < 0) {
+                bb_perror_msg_and_die("chdir failed: %s %s", user, TMPDIR);
+                return(-1);
+            }
+        }
+    }
+    return(pas->pw_uid);
+}