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misc.c

/* Copyright 1988,1990,1993,1994 by Paul Vixie
 * All rights reserved
 *
 * Distribute freely, except: don't remove my name from the source or
 * documentation (don't take credit for my work), mark your changes (don't
 * get me blamed for your possible bugs), don't alter or remove this
 * notice.  May be sold if buildable source is provided to buyer.  No
 * warrantee of any kind, express or implied, is included with this
 * software; use at your own risk, responsibility for damages (if any) to
 * anyone resulting from the use of this software rests entirely with the
 * user.
 *
 * Send bug reports, bug fixes, enhancements, requests, flames, etc., and
 * I'll try to keep a version up to date.  I can be reached as follows:
 * Paul Vixie          <paul@vix.com>          uunet!decwrl!vixie!paul
 */

#if !defined(lint) && !defined(LINT)
static char rcsid[] = "$Id: misc.c,v 2.9 1994/01/15 20:43:43 vixie Exp $";
#endif

/* vix 26jan87 [RCS has the rest of the log]
 * vix 30dec86 [written]
 */


#include "cron.h"
#if SYS_TIME_H
# include <sys/time.h>
#else
# include <time.h>
#endif
#include <sys/file.h>
#include <sys/stat.h>
#include <errno.h>
#include <string.h>
#include <fcntl.h>
#ifdef WITH_AUDIT
#include <libaudit.h>
#endif
#if defined(SYSLOG)
# include <syslog.h>
#endif


#if defined(LOG_DAEMON) && !defined(LOG_CRON)
#define LOG_CRON LOG_DAEMON
#endif


static int        LogFD = ERR;


int
strcmp_until(left, right, until)
      char  *left;
      char  *right;
      int   until;
{
      register int      diff;

      while (*left && *left != until && *left == *right) {
            left++;
            right++;
      }

      if ((*left=='\0' || *left == until) &&
          (*right=='\0' || *right == until)) {
            diff = 0;
      } else {
            diff = *left - *right;
      }

      return diff;
}


/* strdtb(s) - delete trailing blanks in string 's' and return new length
 */
int
strdtb(s)
      char  *s;
{
      char  *x = s;

      /* scan forward to the null
       */
      while (*x)
            x++;

      /* scan backward to either the first character before the string,
       * or the last non-blank in the string, whichever comes first.
       */
      do    {x--;}
      while (x >= s && isspace(*x));

      /* one character beyond where we stopped above is where the null
       * goes.
       */
      *++x = '\0';

      /* the difference between the position of the null character and
       * the position of the first character of the string is the length.
       */
      return x - s;
}


int
set_debug_flags(flags)
      char  *flags;
{
      /* debug flags are of the form    flag[,flag ...]
       *
       * if an error occurs, print a message to stdout and return FALSE.
       * otherwise return TRUE after setting ERROR_FLAGS.
       */

#if !DEBUGGING

      printf("this program was compiled without debugging enabled\n");
      return FALSE;

#else /* DEBUGGING */

      char  *pc = flags;

      DebugFlags = 0;

      while (*pc) {
            char  **test;
            int   mask;

            /* try to find debug flag name in our list.
             */
            for ( test = DebugFlagNames, mask = 1;
                  *test && strcmp_until(*test, pc, ',');
                  test++, mask <<= 1
                )
                  ;

            if (!*test) {
                  fprintf(stderr,
                        "unrecognized debug flag <%s> <%s>\n",
                        flags, pc);
                  return FALSE;
            }

            DebugFlags |= mask;

            /* skip to the next flag
             */
            while (*pc && *pc != ',')
                  pc++;
            if (*pc == ',')
                  pc++;
      }

      if (DebugFlags) {
            int   flag;

            fprintf(stderr, "debug flags enabled:");

            for (flag = 0;  DebugFlagNames[flag];  flag++)
                  if (DebugFlags & (1 << flag))
                        fprintf(stderr, " %s", DebugFlagNames[flag]);
            fprintf(stderr, "\n");
      }

      return TRUE;

#endif /* DEBUGGING */
}


void
set_cron_uid()
{
#if defined(BSD) || defined(POSIX)
      if (seteuid(ROOT_UID) < OK) {
            perror("seteuid");
            exit(ERROR_EXIT);
      }
#else
      if (setuid(ROOT_UID) < OK) {
            perror("setuid");
            exit(ERROR_EXIT);
      }
#endif
}


void
set_cron_cwd()
{
      struct stat sb;

      /* first check for CRONDIR ("/var/cron" or some such)
       */
      if (stat(CRONDIR, &sb) < OK && errno == ENOENT) {
            perror(CRONDIR);
            if (OK == mkdir(CRONDIR, 0700)) {
                  fprintf(stderr, "%s: created\n", CRONDIR);
                  stat(CRONDIR, &sb);
            } else {
                  fprintf(stderr, "%s: mkdir: %s\n", CRONDIR, strerror(errno));
                  exit(ERROR_EXIT);
            }
      }
      if (!(sb.st_mode & S_IFDIR)) {
            fprintf(stderr, "'%s' is not a directory, bailing out.\n",
                  CRONDIR);
            exit(ERROR_EXIT);
      }
      if (chdir(CRONDIR) < OK) {
            fprintf(stderr, "%s: chdir: %s\n", CRONDIR, strerror(errno));
            exit(ERROR_EXIT);
      }

      /* CRONDIR okay (now==CWD), now look at SPOOL_DIR ("tabs" or some such)
       */
      if (stat(SPOOL_DIR, &sb) < OK && errno == ENOENT) {
            perror(SPOOL_DIR);
            if (OK == mkdir(SPOOL_DIR, 0700)) {
                  fprintf(stderr, "%s: created\n", SPOOL_DIR);
                  stat(SPOOL_DIR, &sb);
            } else {
                  fprintf(stderr, "%s: mkdir: %s\n", SPOOL_DIR, strerror(errno));
                  exit(ERROR_EXIT);
            }
      }
      if (!(sb.st_mode & S_IFDIR)) {
            fprintf(stderr, "'%s' is not a directory, bailing out.\n",
                  SPOOL_DIR);
            exit(ERROR_EXIT);
      }
}


/* acquire_daemonlock() - write our PID into /etc/crond.pid, unless
 *    another daemon is already running, which we detect here.
 *
 * note: main() calls us twice; once before forking, once after.
 *    we maintain static storage of the file pointer so that we
 *    can rewrite our PID into the PIDFILE after the fork.
 *
 * it would be great if fflush() disassociated the file buffer.
 */
void
acquire_daemonlock(closeflag)
      int closeflag;
{
      static      FILE  *fp = NULL;

      if (closeflag && fp) {
            fclose(fp);
            fp = NULL;
            return;
      }

      if (!fp) {
            char  pidfile[MAX_FNAME];
            char  buf[MAX_TEMPSTR];
            int   fd, otherpid;

            (void) snprintf(pidfile, MAX_FNAME, PIDFILE, PIDDIR);
            if ((-1 == (fd = open(pidfile, O_RDWR|O_CREAT, 0644)))
                || (NULL == (fp = fdopen(fd, "r+")))
                ) {
                  snprintf(buf, MAX_TEMPSTR, "can't open or create %s: %s",
                        pidfile, strerror(errno));
                  fprintf(stderr, "%s: %s\n", ProgramName, buf);
                  log_it("CRON", getpid(), "DEATH", buf);
                  exit(ERROR_EXIT);
            }

            if (flock(fd, LOCK_EX|LOCK_NB) < OK) {
                  int save_errno = errno;

                  fscanf(fp, "%d", &otherpid);
                  snprintf(buf, MAX_TEMPSTR, "can't lock %s, otherpid may be %d: %s",
                        pidfile, otherpid, strerror(save_errno));
                  fprintf(stderr, "%s: %s\n", ProgramName, buf);
                  log_it("CRON", getpid(), "DEATH", buf);
                  exit(ERROR_EXIT);
            }
            snprintf(buf, MAX_TEMPSTR, "pidfile fd = %d", fd);
            log_it("CRON", getpid(), "INFO", buf);
            (void) fcntl(fd, F_SETFD, 1);
      }

      rewind(fp);
      fprintf(fp, "%d\n", getpid());
      fflush(fp);
      (void) ftruncate(fileno(fp), ftell(fp));

      /* abandon fd and fp even though the file is open. we need to
       * keep it open and locked, but we don't need the handles elsewhere.
       */
      
}

/* get_char(file) : like getc() but increment LineNumber on newlines
 */
int
get_char(file)
      FILE  *file;
{
      int   ch;

      ch = getc(file);
      if (ch == '\n')
            Set_LineNum(LineNumber + 1);
      return ch;
}


/* unget_char(ch, file) : like ungetc but do LineNumber processing
 */
void
unget_char(ch, file)
      int   ch;
      FILE  *file;
{
      ungetc(ch, file);
      if (ch == '\n')
             Set_LineNum(LineNumber - 1);
}


/* get_string(str, max, file, termstr) : like fgets() but
 *          (1) has terminator string which should include \n
 *          (2) will always leave room for the null
 *          (3) uses get_char() so LineNumber will be accurate
 *          (4) returns EOF or terminating character, whichever
 */
int
get_string(string, size, file, terms)
      char  *string;
      int   size;
      FILE  *file;
      char  *terms;
{
      int   ch;

      while (EOF != (ch = get_char(file)) && !strchr(terms, ch)) {
            if (size > 1) {
                  *string++ = (char) ch;
                  size--;
            }
      }

      if (size > 0)
            *string = '\0';

      return ch;
}


/* skip_comments(file) : read past comment (if any)
 */
void
skip_comments(file)
      FILE  *file;
{
      int   ch;

      while (EOF != (ch = get_char(file))) {
            /* ch is now the first character of a line.
             */

            while (ch == ' ' || ch == '\t')
                  ch = get_char(file);

            if (ch == EOF)
                  break;

            /* ch is now the first non-blank character of a line.
             */

            if (ch != '\n' && ch != '#')
                  break;

            /* ch must be a newline or comment as first non-blank
             * character on a line.
             */

            while (ch != '\n' && ch != EOF)
                  ch = get_char(file);

            /* ch is now the newline of a line which we're going to
             * ignore.
             */
      }
      if (ch != EOF)
            unget_char(ch, file);
}


/* int in_file(char *string, FILE *file)
 *    return TRUE if one of the lines in file matches string exactly,
 *    FALSE otherwise.
 */
static int
in_file(string, file)
      char *string;
      FILE *file;
{
      char line[MAX_TEMPSTR];

      rewind(file);
      while (fgets(line, MAX_TEMPSTR, file)) {
            if (line[0] != '\0')
                  line[strlen(line)-1] = '\0';
            if (0 == strcmp(line, string))
                  return TRUE;
      }
      return FALSE;
}


/* int allowed(char *username)
 *    returns TRUE if (ALLOW_FILE exists and user is listed)
 *    or (DENY_FILE exists and user is NOT listed)
 *    or (neither file exists but user=="root" so it's okay)
 */
int
allowed(username)
      char *username;
{
      static int  init = FALSE;
      static FILE *allow, *deny;
      int     isallowed;

        /* Root cannot be denied execution of cron jobs even if in the
       * 'DENY_FILE' so we return inmediately */
        if (strcmp(username, ROOT_USER) == 0)
                return (TRUE);

      isallowed = FALSE;
#if defined(ALLOW_ONLY_ROOT)
      Debug(DMISC, "only root access is allowed")
#else
      if (!init) {
            init = TRUE;
#if defined(ALLOW_FILE) && defined(DENY_FILE)
            allow = fopen(ALLOW_FILE, "r");
            deny = fopen(DENY_FILE, "r");
            Debug(DMISC, ("allow/deny enabled, %d/%d\n", !!allow, !!deny))
#else
            allow = NULL;
            deny = NULL;
#endif
      }

      if (allow) 
            isallowed = in_file(username, allow);
      else
            isallowed = TRUE; /* Allow access if ALLOW_FILE does not exist */
      if (deny && !allow)
            isallowed = !in_file(username, deny);
#endif

#ifdef WITH_AUDIT
       /* Log an audit message if the user is rejected */ 
       if (isallowed == FALSE) {
               int audit_fd = audit_open();
               audit_log_user_message(audit_fd, AUDIT_USER_START, "cron deny",
                       NULL, NULL, NULL, 0);
               close(audit_fd);
       }
#endif
      return isallowed;
}


void
log_it(username, xpid, event, detail)
      char  *username;
      int   xpid;
      char  *event;
      char  *detail;
{
#if defined(LOG_FILE)
      PID_T             pid = xpid;
      char              *msg;
      TIME_T                  now = time((TIME_T) 0);
      register struct tm      *t = localtime(&now);
      int               msg_size;
#endif /*LOG_FILE*/


#if defined(LOG_FILE)
      /* we assume that MAX_TEMPSTR will hold the date, time, &punctuation.
       */
      msg_size = strlen(username) + strlen(event) + strlen(detail) + MAX_TEMPSTR;
      msg = malloc(msg_size);
      if (msg == NULL) {
          /* damn, out of mem and we did not test that before... */
          fprintf(stderr, "%s: Run OUT OF MEMORY while %s\n",
                ProgramName, __FUNCTION__);
          return;
      }
      if (LogFD < OK) {
            LogFD = open(LOG_FILE, O_WRONLY|O_APPEND|O_CREAT, 0600);
            if (LogFD < OK) {
                  fprintf(stderr, "%s: %s: open: %s\n",
                        ProgramName, LOG_FILE, strerror(errno));
            } else {
                  (void) fcntl(LogFD, F_SETFD, 1);
            }
      }

      /* we have to snprintf() it because fprintf() doesn't always write
       * everything out in one chunk and this has to be atomically appended
       * to the log file.
       */
      snprintf(msg, msg_size, "%s (%02d/%02d-%02d:%02d:%02d-%d) %s (%s)\n",
            username,
            t->tm_mon+1, t->tm_mday, t->tm_hour, t->tm_min, t->tm_sec, pid,
            event, detail);

      /* we have to run strlen() because snprintf() returns (char*) on old BSD
       */
      if (LogFD < OK || write(LogFD, msg, strlen(msg)) < OK) {
            if (LogFD >= OK)
                  perror(LOG_FILE);
            fprintf(stderr, "%s: can't write to log file\n", ProgramName);
            write(STDERR, msg, strlen(msg));
      }

      free(msg);
#endif /*LOG_FILE*/

#if defined(SYSLOG)


          /* we don't use LOG_PID since the pid passed to us by
           * our client may not be our own.  therefore we want to
           * print the pid ourselves.
           */
          /* SteveG says: That comment is not consistent with the
             code, and makes no sense -- I suspect it's a remnant
             of a cut-n-paster... */
# ifdef LOG_CRON
      openlog(ProgramName, LOG_PID, LOG_CRON);
# else
      openlog(ProgramName, LOG_PID);
# endif
        
      syslog(LOG_INFO, "(%s) %s (%s)", username, event, detail);

      closelog();
#endif /*SYSLOG*/

#if DEBUGGING
      if (DebugFlags) {
            fprintf(stderr, "log_it: (%s %d) %s (%s)\n",
                  username, xpid, event, detail);
      }
#endif
}


void
log_close() {
#if defined(LOG_FILE)
      if (LogFD != ERR) {
            close(LogFD);
            LogFD = ERR;
      }
#endif
#if defined(SYSLOG)
      closelog();
#endif
}


/* two warnings:
 *    (1) this routine is fairly slow
 *    (2) it returns a pointer to static storage
 */
char *
first_word(s, t)
      register char *s; /* string we want the first word of */
      register char *t; /* terminators, implicitly including \0 */
{
      static char retbuf[2][MAX_TEMPSTR + 1];   /* sure wish C had GC */
      static int retsel = 0;
      register char *rb, *rp;

      /* select a return buffer */
      retsel = 1-retsel;
      rb = &retbuf[retsel][0];
      rp = rb;

      /* skip any leading terminators */
      while (*s && (NULL != strchr(t, *s))) {
            s++;
      }

      /* copy until next terminator or full buffer */
      while (*s && (NULL == strchr(t, *s)) && (rp < &rb[MAX_TEMPSTR])) {
            *rp++ = *s++;
      }

      /* finish the return-string and return it */
      *rp = '\0';
      return rb;
}


/* warning:
 *    heavily ascii-dependent.
 */
void
mkprint(dst, src, len)
      register char *dst;
      register unsigned char *src;
      register int len;
{
      while (len-- > 0)
      {
            register unsigned char ch = *src++;

            if (ch < ' ') {               /* control character */
                  *dst++ = '^';
                  *dst++ = ch + '@';
            } else if (ch < 0177) {       /* printable */
                  *dst++ = ch;
            } else if (ch == 0177) {      /* delete/rubout */
                  *dst++ = '^';
                  *dst++ = '?';
            } else {                /* parity character */
                /* well, the following snprintf is paranoid, but that will
                 * keep grep happy */
                snprintf(dst, 5, "\\%03o", ch);
                dst += 4;
            }
      }
      *dst = '\0';
}


/* warning:
 *    returns a pointer to malloc'd storage, you must call free yourself.
 */
char *
mkprints(src, len)
      register unsigned char *src;
      register unsigned int len;
{
      register char *dst = malloc(len*4 + 1);

      if (dst)
            mkprint(dst, src, len);

      return dst;
}


#ifdef MAIL_DATE
/* Sat, 27 Feb 1993 11:44:51 -0800 (CST)
 * 1234567890123456789012345678901234567
 */
char *
arpadate(clock)
      time_t *clock;
{
      static char ret[64];    /* zone name might be >3 chars */
      time_t t = clock ? *clock : time(NULL);
      struct tm *tm = localtime(&t);
      char *qmark;
      size_t len;
        long gmtoff = get_gmtoff(&t, tm);
        int hours = gmtoff / 3600;
        int minutes = (gmtoff - (hours * 3600)) / 60;

      if (minutes < 0)
            minutes = -minutes;

      /* Defensive coding (almost) never hurts... */
      len = strftime(ret, sizeof(ret), "%a, %e %b %Y %T ????? (%Z)", tm);
      if (len == 0) {
            ret[0] = '?';
            ret[1] = '\0';
            return ret;
      }
      qmark = strchr(ret, '?');
      if (qmark && len - (qmark - ret) >= 6) {
            snprintf(qmark, 6, "% .2d%.2d", hours, minutes);
            qmark[5] = ' ';
      }
      return ret;
}
#endif /*MAIL_DATE*/


#ifdef HAVE_SAVED_UIDS
static uid_t save_euid, save_egid;
int swap_uids()
{
      save_euid = geteuid(); save_egid = getegid();
      return (setegid(getgid()) || seteuid(getuid())) ? -1 : 0;
}
int swap_uids_back()
{
      return (setegid(save_egid) || seteuid(save_euid)) ? -1 : 0;
}
#else /*HAVE_SAVED_UIDS*/
int swap_uids()
{
      return (setregid(getegid(), getgid()) || setreuid(geteuid(), getuid()))
            ? -1 : 0;
}
int swap_uids_back() { return swap_uids(); }
#endif /*HAVE_SAVED_UIDS*/


/* Return the offset from GMT in seconds (algorithm taken from sendmail).
 *
 * warning:
 *    clobbers the static storage space used by localtime() and gmtime().
 *    If the local pointer is non-NULL it *must* point to a local copy.
 */
#ifndef HAVE_TM_GMTOFF
long get_gmtoff(time_t *clock, struct tm *local)
{
      struct tm gmt;
      long offset;

      gmt = *gmtime(clock);
      if (local == NULL)
            local = localtime(clock);

      offset = (local->tm_sec - gmt.tm_sec) +
          ((local->tm_min - gmt.tm_min) * 60) +
          ((local->tm_hour - gmt.tm_hour) * 3600);

      /* Timezone may cause year rollover to happen on a different day. */
      if (local->tm_year < gmt.tm_year)
            offset -= 24 * 3600;
      else if (local->tm_year > gmt.tm_year)
            offset += 24 * 3600;
      else if (local->tm_yday < gmt.tm_yday)
            offset -= 24 * 3600;
      else if (local->tm_yday > gmt.tm_yday)
            offset += 24 * 3600;

      return (offset);
}
#endif /* HAVE_TM_GMTOFF */

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