Patrick Welche <prlw1@cam.ac.uk>

[netbsd-mini2440.git] / libexec / cron / do_command.c

/* Copyright 1988,1990,1993 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: do_command.c,v 1.1 1994/01/05 20:40:14 jtc Exp $";
#endif


#include "cron.h"
#include "externs.h"
#include <pwd.h>
#ifdef USE_SIGCHLD
# include <sys/signal.h>
#endif
#if defined(sequent)
# include <sys/universe.h>
#endif
#if defined(SYSLOG)
# include <syslog.h>
#endif


static void             child_process __P((entry *, user *)),
                        do_univ __P((user *));


void
do_command(e, u)
        entry   *e;
        user    *u;
{
        Debug(DPROC, ("[%d] do_command(%s, (%s,%d,%d))\n",
                getpid(), e->cmd, env_get("LOGNAME", u->envp), u->uid, u->gid))

        /* fork to become asynchronous -- parent process is done immediately,
         * and continues to run the normal cron code, which means return to
         * tick().  the child and grandchild don't leave this function, alive.
         *
         * vfork() is unsuitable, since we have much to do, and the parent
         * needs to be able to run off and fork other processes.
         */
        switch (fork()) {
        case -1:
                log_it("CRON",getpid(),"error","can't fork");
                break;
        case 0:
                /* child process */
                acquire_daemonlock(1);
                child_process(e, u);
                Debug(DPROC, ("[%d] child process done, exiting\n", getpid()))
                _exit(OK_EXIT);
                break;
        default:
                /* parent process */
                break;
        }
        Debug(DPROC, ("[%d] main process returning to work\n", getpid()))
}


static void
child_process(e, u)
        entry   *e;
        user    *u;
{
        int             stdin_pipe[2], stdout_pipe[2];
        register char   *input_data, *usernm, *mailto;
#ifdef USE_SIGCHLD
        int             children = 0;
#endif

        Debug(DPROC, ("[%d] child_process('%s')\n", getpid(), e->cmd))

        /* mark ourselves as different to PS command watchers by upshifting
         * our program name.  This has no effect on some kernels.
         */
        /*local*/{
                register char   *pch;

                for (pch = ProgramName;  *pch;  pch++)
                        *pch = MkUpper(*pch);
        }

        /* discover some useful and important environment settings
         */
        usernm = env_get("LOGNAME", u->envp);
        mailto = env_get("MAILTO", u->envp);

#ifdef USE_SIGCHLD
        /* our parent is watching for our death by catching SIGCHLD.  we
         * do not care to watch for our children's deaths this way -- we
         * use wait() explictly.  so we have to disable the signal (which
         * was inherited from the parent).
         *
         * this isn't needed for system V, since our parent is already
         * SIG_IGN on SIGCLD -- which, hopefully, will cause children to
         * simply vanish when they die.
         */
        (void) signal(SIGCHLD, SIG_IGN);
#endif /*BSD*/

        /* create some pipes to talk to our future child
         */
        pipe(stdin_pipe);       /* child's stdin */
        pipe(stdout_pipe);      /* child's stdout */
        
        /* since we are a forked process, we can diddle the command string
         * we were passed -- nobody else is going to use it again, right?
         *
         * if a % is present in the command, previous characters are the
         * command, and subsequent characters are the additional input to
         * the command.  Subsequent %'s will be transformed into newlines,
         * but that happens later.
         */
        /*local*/{
                register int escaped = FALSE;
                register int ch;

                for (input_data = e->cmd;  ch = *input_data;  input_data++) {
                        if (escaped) {
                                escaped = FALSE;
                                continue;
                        }
                        if (ch == '\\') {
                                escaped = TRUE;
                                continue;
                        }
                        if (ch == '%') {
                                *input_data++ = '\0';
                                break;
                        }
                }
        }

        /* fork again, this time so we can exec the user's command.  Vfork()
         * is okay this time, since we are going to exec() pretty quickly.
         */
        if (vfork() == 0) {
                Debug(DPROC, ("[%d] grandchild process Vfork()'ed\n", getpid()))

                /* write a log message.  we've waited this long to do it
                 * because it was not until now that we knew the PID that
                 * the actual user command shell was going to get and the
                 * PID is part of the log message.
                 */
                /*local*/{
                        char *x = mkprints((u_char *)e->cmd, strlen(e->cmd));

                        log_it(usernm, getpid(), "CMD", x);
                        free(x);
                }

                /* that's the last thing we'll log.  close the log files.
                 */
#ifdef SYSLOG
                closelog();
#endif

                /* get new pgrp, void tty, etc.
                 */
                (void) setsid();

                /* close the pipe ends that we won't use.  this doesn't affect
                 * the parent, who has to read and write them; it keeps the
                 * kernel from recording us as a potential client TWICE --
                 * which would keep it from sending SIGPIPE in otherwise
                 * appropriate circumstances.
                 */
                close(stdin_pipe[WRITE_PIPE]);
                close(stdout_pipe[READ_PIPE]);

                /* grandchild process.  make std{in,out} be the ends of
                 * pipes opened by our daddy; make stderr go to stdout.
                 */
                close(STDIN);   dup2(stdin_pipe[READ_PIPE], STDIN);
                close(STDOUT);  dup2(stdout_pipe[WRITE_PIPE], STDOUT);
                close(STDERR);  dup2(STDOUT, STDERR);

                /* close the pipes we just dup'ed.  The resources will remain.
                 */
                close(stdin_pipe[READ_PIPE]);
                close(stdout_pipe[WRITE_PIPE]);

                /* set our login universe.  Do this in the grandchild
                 * so that the child can invoke /usr/lib/sendmail
                 * without surprises.
                 */
                do_univ(u);

                /* set our directory, uid and gid.  Set gid first, since once
                 * we set uid, we've lost root privledges.
                 */
                setgid(u->gid);
# if defined(BSD)
                initgroups(env_get("LOGNAME", u->envp), u->gid);
# endif
                /*
                 * switch to specified user id.  exec_uid is only
                 * valid for /etc/crontab, in other environments it
                 * will be 0.  Note that it is overloaded for root
                 * because if 0 it will still pickup u->uid which will
                 * still be 0.
                 */
                setuid(e->exec_uid ? e->exec_uid : u->uid);
                /* you aren't root after this... */
                chdir(env_get("HOME", u->envp));

                /* exec the command.
                 */
                {
                        char    *shell = env_get("SHELL", u->envp);

# if DEBUGGING
                        if (DebugFlags & DTEST) {
                                fprintf(stderr,
                                "debug DTEST is on, not exec'ing command.\n");
                                fprintf(stderr,
                                "\tcmd='%s' shell='%s'\n", e->cmd, shell);
                                _exit(OK_EXIT);
                        }
# endif /*DEBUGGING*/
                        execle(shell, shell, "-c", e->cmd, (char *)0, u->envp);
                        fprintf(stderr, "execl: couldn't exec `%s'\n", shell);
                        perror("execl");
                        _exit(ERROR_EXIT);
                }
        }

#ifdef USE_SIGCHLD
        children++;
#endif

        /* middle process, child of original cron, parent of process running
         * the user's command.
         */

        Debug(DPROC, ("[%d] child continues, closing pipes\n", getpid()))

        /* close the ends of the pipe that will only be referenced in the
         * grandchild process...
         */
        close(stdin_pipe[READ_PIPE]);
        close(stdout_pipe[WRITE_PIPE]);

        /*
         * write, to the pipe connected to child's stdin, any input specified
         * after a % in the crontab entry.  while we copy, convert any
         * additional %'s to newlines.  when done, if some characters were
         * written and the last one wasn't a newline, write a newline.
         *
         * Note that if the input data won't fit into one pipe buffer (2K
         * or 4K on most BSD systems), and the child doesn't read its stdin,
         * we would block here.  thus we must fork again.
         */

        if (*input_data && fork() == 0) {
                register FILE   *out = fdopen(stdin_pipe[WRITE_PIPE], "w");
                register int    need_newline = FALSE;
                register int    escaped = FALSE;
                register int    ch;

                Debug(DPROC, ("[%d] child2 sending data to grandchild\n", getpid()))

                /* close the pipe we don't use, since we inherited it and
                 * are part of its reference count now.
                 */
                close(stdout_pipe[READ_PIPE]);

                /* translation:
                 *      \% -> %
                 *      %  -> \n
                 *      \x -> \x        for all x != %
                 */
                while (ch = *input_data++) {
                        if (escaped) {
                                if (ch != '%')
                                        putc('\\', out);
                        } else {
                                if (ch == '%')
                                        ch = '\n';
                        }

                        if (!(escaped = (ch == '\\'))) {
                                putc(ch, out);
                                need_newline = (ch != '\n');
                        }
                }
                if (escaped)
                        putc('\\', out);
                if (need_newline)
                        putc('\n', out);

                /* close the pipe, causing an EOF condition.  fclose causes
                 * stdin_pipe[WRITE_PIPE] to be closed, too.
                 */
                fclose(out);

                Debug(DPROC, ("[%d] child2 done sending to grandchild\n", getpid()))
                exit(0);
        }

        /* close the pipe to the grandkiddie's stdin, since its wicked uncle
         * ernie back there has it open and will close it when he's done.
         */
        close(stdin_pipe[WRITE_PIPE]);

#ifdef USE_SIGCHLD
        children++;
#endif

        /*
         * read output from the grandchild.  it's stderr has been redirected to
         * it's stdout, which has been redirected to our pipe.  if there is any
         * output, we'll be mailing it to the user whose crontab this is...
         * when the grandchild exits, we'll get EOF.
         */

        Debug(DPROC, ("[%d] child reading output from grandchild\n", getpid()))

        /*local*/{
                register FILE   *in = fdopen(stdout_pipe[READ_PIPE], "r");
                register int    ch = getc(in);

                if (ch != EOF) {
                        register FILE   *mail;
                        register int    bytes = 1;
                        int             status = 0;

                        Debug(DPROC|DEXT,
                                ("[%d] got data (%x:%c) from grandchild\n",
                                        getpid(), ch, ch))

                        /* get name of recipient.  this is MAILTO if set to a
                         * valid local username; USER otherwise.
                         */
                        if (mailto) {
                                /* MAILTO was present in the environment
                                 */
                                if (!*mailto) {
                                        /* ... but it's empty. set to NULL
                                         */
                                        mailto = NULL;
                                }
                        } else {
                                /* MAILTO not present, set to USER.
                                 */
                                mailto = usernm;
                        }
                
                        /* if we are supposed to be mailing, MAILTO will
                         * be non-NULL.  only in this case should we set
                         * up the mail command and subjects and stuff...
                         */

                        if (mailto) {
                                register char   **env;
                                auto char       mailcmd[MAX_COMMAND];
                                auto char       hostname[MAXHOSTNAMELEN];

                                (void) gethostname(hostname, MAXHOSTNAMELEN);
                                (void) sprintf(mailcmd, MAILARGS,
                                               MAILCMD, mailto);
                                if (!(mail = cron_popen(mailcmd, "w"))) {
                                        perror(MAILCMD);
                                        (void) _exit(ERROR_EXIT);
                                }
                                fprintf(mail, "From: root (Cron Daemon)\n");
                                fprintf(mail, "To: %s\n", mailto);
                                fprintf(mail, "Subject: Cron <%s@%s> %s\n",
                                        usernm, first_word(hostname, "."),
                                        e->cmd);
# if defined(MAIL_DATE)
                                fprintf(mail, "Date: %s\n",
                                        arpadate(&TargetTime));
# endif /* MAIL_DATE */
                                for (env = u->envp;  *env;  env++)
                                        fprintf(mail, "X-Cron-Env: <%s>\n",
                                                *env);
                                fprintf(mail, "\n");

                                /* this was the first char from the pipe
                                 */
                                putc(ch, mail);
                        }

                        /* we have to read the input pipe no matter whether
                         * we mail or not, but obviously we only write to
                         * mail pipe if we ARE mailing.
                         */

                        while (EOF != (ch = getc(in))) {
                                bytes++;
                                if (mailto)
                                        putc(ch, mail);
                        }

                        /* only close pipe if we opened it -- i.e., we're
                         * mailing...
                         */

                        if (mailto) {
                                Debug(DPROC, ("[%d] closing pipe to mail\n",
                                        getpid()))
                                /* Note: the pclose will probably see
                                 * the termination of the grandchild
                                 * in addition to the mail process, since
                                 * it (the grandchild) is likely to exit
                                 * after closing its stdout.
                                 */
                                status = cron_pclose(mail);
                        }

                        /* if there was output and we could not mail it,
                         * log the facts so the poor user can figure out
                         * what's going on.
                         */
                        if (mailto && status) {
                                char buf[MAX_TEMPSTR];

                                sprintf(buf,
                        "mailed %d byte%s of output but got status 0x%04x\n",
                                        bytes, (bytes==1)?"":"s",
                                        status);
                                log_it(usernm, getpid(), "MAIL", buf);
                        }

                } /*if data from grandchild*/

                Debug(DPROC, ("[%d] got EOF from grandchild\n", getpid()))

                fclose(in);     /* also closes stdout_pipe[READ_PIPE] */
        }

#ifdef USE_SIGCHLD
        /* wait for children to die.
         */
        for (;  children > 0;  children--)
        {
                int             pid;
                WAIT_T          waiter;

                Debug(DPROC, ("[%d] waiting for grandchild #%d to finish\n",
                        getpid(), children))
                pid = wait(&waiter);
                if (pid < OK) {
                        Debug(DPROC, ("[%d] no more grandchildren--mail written?\n",
                                getpid()))
                        break;
                }
                Debug(DPROC, ("[%d] grandchild #%d finished, status=%04x",
                        getpid(), pid, WEXITSTATUS(waiter)))
                if (WIFSIGNALED(waiter) && WCOREDUMP(waiter))
                        Debug(DPROC, (", dumped core"))
                Debug(DPROC, ("\n"))
        }
#endif /*BSD*/
}


static void
do_univ(u)
        user    *u;
{
#if defined(sequent)
/* Dynix (Sequent) hack to put the user associated with
 * the passed user structure into the ATT universe if
 * necessary.  We have to dig the gecos info out of
 * the user's password entry to see if the magic
 * "universe(att)" string is present.  If we do change
 * the universe, also set "LOGNAME".
 */

        struct  passwd  *p;
        char    *s;
        int     i;
        char    envstr[MAX_ENVSTR], **env_set();

        p = getpwuid(u->uid);
        (void) endpwent();

        if (p == NULL)
                return;

        s = p->pw_gecos;

        for (i = 0; i < 4; i++)
        {
                if ((s = strchr(s, ',')) == NULL)
                        return;
                s++;
        }
        if (strcmp(s, "universe(att)"))
                return;

        (void) sprintf(envstr, "LOGNAME=%s", p->pw_name);
        u->envp = env_set(u->envp, envstr);

        (void) universe(U_ATT);
#endif
}