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entry.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: entry.c,v 2.12 1994/01/17 03:20:37 vixie Exp $";
#endif

/* vix 26jan87 [RCS'd; rest of log is in RCS file]
 * vix 01jan87 [added line-level error recovery]
 * vix 31dec86 [added /step to the from-to range, per bob@acornrc]
 * vix 30dec86 [written]
 */


#include "cron.h"


typedef     enum ecode {
      e_none, e_minute, e_hour, e_dom, e_month, e_dow,
      e_cmd, e_timespec, e_username
} ecode_e;

static char get_list __P((bitstr_t *, int, int, char *[], int, FILE *)),
            get_range __P((bitstr_t *, int, int, char *[], int, FILE *)),
            get_number __P((int *, int, char *[], int, FILE *));
static int  set_element __P((bitstr_t *, int, int, int));

static char *ecodes[] =
      {
            "no error",
            "bad minute",
            "bad hour",
            "bad day-of-month",
            "bad month",
            "bad day-of-week",
            "bad command",
            "bad time specifier",
            "bad username",
      };


void
free_entry(e)
      entry *e;
{
      free(e->cmd);
      env_free(e->envp);
      free(e);
}


/* return NULL if eof or syntax error occurs;
 * otherwise return a pointer to a new entry.
 */
entry *
load_entry(file, error_func, pw, envp)
      FILE        *file;
      void        (*error_func)();
      struct passwd     *pw;
      char        **envp;
{
      /* this function reads one crontab entry -- the next -- from a file.
       * it skips any leading blank lines, ignores comments, and returns
       * EOF if for any reason the entry can't be read and parsed.
       *
       * the entry is also parsed here.
       *
       * syntax:
       *   user crontab:
       *    minutes hours doms months dows cmd\n
       *   system crontab (/etc/crontab):
       *    minutes hours doms months dows USERNAME cmd\n
       */

      ecode_e     ecode = e_none;
      entry *e;
      int   ch;
      char  cmd[MAX_COMMAND];
      char  envstr[MAX_ENVSTR];
      char  **tenvp;

      Debug(DPARS, ("load_entry()...about to eat comments\n"))

      skip_comments(file);

      ch = get_char(file);
      if (ch == EOF)
            return NULL;

      /* ch is now the first useful character of a useful line.
       * it may be an @special or it may be the first character
       * of a list of minutes.
       */

      e = (entry *) calloc(sizeof(entry), sizeof(char));

      if (ch == '@') {
            /* all of these should be flagged and load-limited; i.e.,
             * instead of @hourly meaning "0 * * * *" it should mean
             * "close to the front of every hour but not 'til the
             * system load is low".  Problems are: how do you know
             * what "low" means? (save me from /etc/cron.conf!) and:
             * how to guarantee low variance (how low is low?), which
             * means how to we run roughly every hour -- seems like
             * we need to keep a history or let the first hour set
             * the schedule, which means we aren't load-limited
             * anymore.  too much for my overloaded brain. (vix, jan90)
             * HINT
             */
            ch = get_string(cmd, MAX_COMMAND, file, " \t\n");
            if (!strcmp("reboot", cmd)) {
                  e->flags |= WHEN_REBOOT;
            } else if (!strcmp("yearly", cmd) || !strcmp("annually", cmd)){
                  bit_set(e->minute, 0);
                  bit_set(e->hour, 0);
                  bit_set(e->dom, 0);
                  bit_set(e->month, 0);
                  bit_nset(e->dow, 0, (LAST_DOW-FIRST_DOW+1));
                        e->flags |= DOW_STAR; 
            } else if (!strcmp("monthly", cmd)) {
                  bit_set(e->minute, 0);
                  bit_set(e->hour, 0);
                  bit_set(e->dom, 0);
                  bit_nset(e->month, 0, (LAST_MONTH-FIRST_MONTH+1));
                  bit_nset(e->dow, 0, (LAST_DOW-FIRST_DOW+1));
                        e->flags |= DOW_STAR;
            } else if (!strcmp("weekly", cmd)) {
                  bit_set(e->minute, 0);
                  bit_set(e->hour, 0);
                  bit_nset(e->dom, 0, (LAST_DOM-FIRST_DOM+1));
                  e->flags |= DOM_STAR;
                  bit_nset(e->month, 0, (LAST_MONTH-FIRST_MONTH+1));
                  bit_nset(e->dow, 0,0);
            } else if (!strcmp("daily", cmd) || !strcmp("midnight", cmd)) {
                  bit_set(e->minute, 0);
                  bit_set(e->hour, 0);
                  bit_nset(e->dom, 0, (LAST_DOM-FIRST_DOM+1));
                  bit_nset(e->month, 0, (LAST_MONTH-FIRST_MONTH+1));
                  bit_nset(e->dow, 0, (LAST_DOW-FIRST_DOW+1));
            } else if (!strcmp("hourly", cmd)) {
                  bit_set(e->minute, 0);
                  bit_nset(e->hour, 0, (LAST_HOUR-FIRST_HOUR+1));
                  bit_nset(e->dom, 0, (LAST_DOM-FIRST_DOM+1));
                  bit_nset(e->month, 0, (LAST_MONTH-FIRST_MONTH+1));
                  bit_nset(e->dow, 0, (LAST_DOW-FIRST_DOW+1));
                  e->flags |= HR_STAR;
            } else {
                  ecode = e_timespec;
                  goto eof;
            }
      } else {
            Debug(DPARS, ("load_entry()...about to parse numerics\n"))

            if (ch == '*')
                  e->flags |= MIN_STAR;
            ch = get_list(e->minute, FIRST_MINUTE, LAST_MINUTE,
                        PPC_NULL, ch, file);
            if (ch == EOF) {
                  ecode = e_minute;
                  goto eof;
            }

            /* hours
             */

            if (ch == '*')
                  e->flags |= HR_STAR;
            ch = get_list(e->hour, FIRST_HOUR, LAST_HOUR,
                        PPC_NULL, ch, file);
            if (ch == EOF) {
                  ecode = e_hour;
                  goto eof;
            }

            /* DOM (days of month)
             */

            if (ch == '*')
                  e->flags |= DOM_STAR;
            ch = get_list(e->dom, FIRST_DOM, LAST_DOM,
                        PPC_NULL, ch, file);
            if (ch == EOF) {
                  ecode = e_dom;
                  goto eof;
            }

            /* month
             */

            ch = get_list(e->month, FIRST_MONTH, LAST_MONTH,
                        MonthNames, ch, file);
            if (ch == EOF) {
                  ecode = e_month;
                  goto eof;
            }

            /* DOW (days of week)
             */

            if (ch == '*')
                  e->flags |= DOW_STAR;
            ch = get_list(e->dow, FIRST_DOW, LAST_DOW,
                        DowNames, ch, file);
            if (ch == EOF) {
                  ecode = e_dow;
                  goto eof;
            }
      }

      /* make sundays equivilent */
      if (bit_test(e->dow, 0) || bit_test(e->dow, 7)) {
            bit_set(e->dow, 0);
            bit_set(e->dow, 7);
      }

      /* If we used one of the @commands, we may be pointing at
       blanks, and if we don't skip over them, we'll miss the user/command */ 
    Skip_Blanks(ch, file);
      /* ch is the first character of a command, or a username */
      unget_char(ch, file);

      if (!pw) {
            char        *username = cmd;  /* temp buffer */

            Debug(DPARS, ("load_entry()...about to parse username\n"))
            ch = get_string(username, MAX_COMMAND, file, " \t");

            Debug(DPARS, ("load_entry()...got %s\n",username))
            if (ch == EOF) {
                  ecode = e_cmd;
                  goto eof;
            }

            pw = getpwnam(username);
            if (pw == NULL) {
                  ecode = e_username;
                  goto eof;
            }
            Debug(DPARS, ("load_entry()...uid %d, gid %d\n",e->uid,e->gid))
      } else if (ch == '*') {
            ecode = e_cmd;
            goto eof;
      }

      e->uid = pw->pw_uid;
      e->gid = pw->pw_gid;

      /* copy and fix up environment.  some variables are just defaults and
       * others are overrides.
       */
      if ((e->envp = env_copy(envp)) == NULL) {
            ecode = e_none;
            goto eof;
      }
      if (!env_get("SHELL", e->envp)) {
            snprintf(envstr, MAX_ENVSTR, "SHELL=%s", _PATH_BSHELL);
            if ((tenvp = env_set(e->envp, envstr))) {
                  e->envp = tenvp;
            } else {
                  ecode = e_none;
                  goto eof;
            }
      }
      if (!env_get("HOME", e->envp)) {
            snprintf(envstr, MAX_ENVSTR, "HOME=%s", pw->pw_dir);
            if ((tenvp = env_set(e->envp, envstr))) {
                  e->envp = tenvp;
            } else {
                  ecode = e_none;
                  goto eof;
            }
      }
      if (!env_get("PATH", e->envp)) {
            snprintf(envstr, MAX_ENVSTR, "PATH=%s", _PATH_DEFPATH);
            if ((tenvp = env_set(e->envp, envstr))) {
                  e->envp = tenvp;
            } else {
                  ecode = e_none;
                  goto eof;
            }
      }
      snprintf(envstr, MAX_ENVSTR, "%s=%s", "LOGNAME", pw->pw_name);
      if ((tenvp = env_set(e->envp, envstr))) {
            e->envp = tenvp;
      } else {
            ecode = e_none;
            goto eof;
      }
#if defined(BSD)
      snprintf(envstr, MAX_ENVSTR, "%s=%s", "USER", pw->pw_name);
      if ((tenvp = env_set(e->envp, envstr))) {
            e->envp = tenvp;
      } else {
            ecode = e_none;
            goto eof;
      }
#endif

      Debug(DPARS, ("load_entry()...about to parse command\n"))

      /* Everything up to the next \n or EOF is part of the command...
       * too bad we don't know in advance how long it will be, since we
       * need to malloc a string for it... so, we limit it to MAX_COMMAND.
       * XXX - should use realloc().
       */ 
      ch = get_string(cmd, MAX_COMMAND, file, "\n");

      /* a file without a \n before the EOF is rude, so we'll complain...
       */
      if (ch == EOF) {
            ecode = e_cmd;
                log_it("CRON",getpid(),"DEBUG","detected early eof");
            goto eof;
      }

      /* got the command in the 'cmd' string; save it in *e.
       */
      if ((e->cmd = strdup(cmd)) == NULL) {
            ecode = e_none;
            goto eof;
      }

      Debug(DPARS, ("load_entry()...returning successfully\n"))

      /* success, fini, return pointer to the entry we just created...
       */
      return e;

 eof:
      if (e->envp)
            env_free(e->envp);
      if (e->cmd)
            free(e->cmd);
      free(e);
      if (ecode != e_none && error_func)
            (*error_func)(ecodes[(int)ecode]);
      while (ch != EOF && ch != '\n')
            ch = get_char(file);
      return NULL;
}


static char
get_list(bits, low, high, names, ch, file)
      bitstr_t    *bits;            /* one bit per flag, default=FALSE */
      int         low, high;  /* bounds, impl. offset for bitstr */
      char        *names[];   /* NULL or *[] of names for these elements */
      int         ch;         /* current character being processed */
      FILE        *file;            /* file being read */
{
      register int      done;

      /* we know that we point to a non-blank character here;
       * must do a Skip_Blanks before we exit, so that the
       * next call (or the code that picks up the cmd) can
       * assume the same thing.
       */

      Debug(DPARS|DEXT, ("get_list()...entered\n"))

      /* list = range {"," range}
       */
      
      /* clear the bit string, since the default is 'off'.
       */
      bit_nclear(bits, 0, (high-low+1));

      /* process all ranges
       */
      done = FALSE;
      while (!done) {
            ch = get_range(bits, low, high, names, ch, file);
            if (ch == ',')
                  ch = get_char(file);
            else
                  done = TRUE;
      }

      /* exiting.  skip to some blanks, then skip over the blanks.
       */
      Skip_Nonblanks(ch, file)
      Skip_Blanks(ch, file)

      Debug(DPARS|DEXT, ("get_list()...exiting w/ %02x\n", ch))

      return ch;
}


static char
get_range(bits, low, high, names, ch, file)
      bitstr_t    *bits;            /* one bit per flag, default=FALSE */
      int         low, high;  /* bounds, impl. offset for bitstr */
      char        *names[];   /* NULL or names of elements */
      int         ch;         /* current character being processed */
      FILE        *file;            /* file being read */
{
      /* range = number | number "-" number [ "/" number ]
       */

      register int      i;
      auto int    num1, num2, num3;

      Debug(DPARS|DEXT, ("get_range()...entering, exit won't show\n"))

      if (ch == '*') {
            /* '*' means "first-last" but can still be modified by /step
             */
            num1 = low;
            num2 = high;
            ch = get_char(file);
            if (ch == EOF)
                  return EOF;
      } else {
            if (EOF == (ch = get_number(&num1, low, names, ch, file)))
                  return EOF;

            if (ch != '-') {
                  /* not a range, it's a single number.
                   */
                  if (EOF == set_element(bits, low, high, num1))
                        return EOF;
                  return ch;
            } else {
                  /* eat the dash
                   */
                  ch = get_char(file);
                  if (ch == EOF)
                        return EOF;

                  /* get the number following the dash
                   */
                  ch = get_number(&num2, low, names, ch, file);
                  if (ch == EOF)
                        return EOF;
            }
      }

      /* check for step size
       */
      if (ch == '/') {
            /* eat the slash
             */
            ch = get_char(file);
            if (ch == EOF)
                  return EOF;

            /* get the step size -- note: we don't pass the
             * names here, because the number is not an
             * element id, it's a step size.  'low' is
             * sent as a 0 since there is no offset either.
             */
            ch = get_number(&num3, 0, PPC_NULL, ch, file);
            if (ch == EOF || num3 <= 0)
                  return EOF;
      } else {
            /* no step.  default==1.
             */
            num3 = 1;
      }

      /* range. set all elements from num1 to num2, stepping
       * by num3.  (the step is a downward-compatible extension
       * proposed conceptually by bob@acornrc, syntactically
       * designed then implmented by paul vixie).
       */
      for (i = num1;  i <= num2;  i += num3)
            if (EOF == set_element(bits, low, high, i))
                  return EOF;

      return ch;
}


static char
get_number(numptr, low, names, ch, file)
      int   *numptr;    /* where does the result go? */
      int   low;        /* offset applied to result if symbolic enum used */
      char  *names[];   /* symbolic names, if any, for enums */
      int   ch;         /* current character */
      FILE  *file;            /* source */
{
      char  temp[MAX_TEMPSTR], *pc;
      int   len, i, all_digits;

      /* collect alphanumerics into our fixed-size temp array
       */
      pc = temp;
      len = 0;
      all_digits = TRUE;
      while (isalnum(ch)) {
            if (++len >= MAX_TEMPSTR)
                  return EOF;

            *pc++ = ch;

            if (!isdigit(ch))
                  all_digits = FALSE;

            ch = get_char(file);
      }
      *pc = '\0';

        if (len == 0) {
            return EOF;
        }

      /* try to find the name in the name list
       */
      if (names) {
            for (i = 0;  names[i] != NULL;  i++) {
                  Debug(DPARS|DEXT,
                        ("get_num, compare(%s,%s)\n", names[i], temp))
                  if (!strcasecmp(names[i], temp)) {
                        *numptr = i+low;
                        return ch;
                  }
            }
      }

      /* no name list specified, or there is one and our string isn't
       * in it.  either way: if it's all digits, use its magnitude.
       * otherwise, it's an error.
       */
      if (all_digits) {
            *numptr = atoi(temp);
            return ch;
      }

      return EOF;
}


static int
set_element(bits, low, high, number)
      bitstr_t    *bits;            /* one bit per flag, default=FALSE */
      int         low;
      int         high;
      int         number;
{
      Debug(DPARS|DEXT, ("set_element(?,%d,%d,%d)\n", low, high, number))

      if (number < low || number > high)
            return EOF;

      bit_set(bits, (number-low));
      return OK;
}

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