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popen.c

/*    $OpenBSD: popen.c,v 1.34 2004/09/15 22:21:11 deraadt Exp $  */
/*    $NetBSD: popen.c,v 1.6 1997/05/13 06:48:42 mikel Exp $      */

/*
 * Copyright (c) 1980, 1993
 *    The Regents of the University of California.  All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */

#ifndef lint
#if 0
static const char sccsid[] = "@(#)popen.c 8.1 (Berkeley) 6/6/93";
#else
static const char rcsid[] = "$OpenBSD: popen.c,v 1.34 2004/09/15 22:21:11 deraadt Exp $";
#endif
#endif /* not lint */

#include "rcv.h"
#include <sys/wait.h>
#include <fcntl.h>
#include <errno.h>
#include <stdarg.h>
#include <lockfile.h>
#include "extern.h"

#define READ 0
#define WRITE 1

struct fp {
      FILE *fp;
      int pipe;
      pid_t pid;
      struct fp *link;
};
static struct fp *fp_head;

struct child {
      pid_t pid;
      char done;
      char free;
      int status;
      struct child *link;
};
static struct child *child, *child_freelist = NULL;

static struct child *findchild(pid_t, int);
static void delchild(struct child *);
static pid_t file_pid(FILE *);
static int handle_spool_locks(int);

FILE *
Fopen(char *file, char *mode)
{
      FILE *fp;

      if ((fp = fopen(file, mode)) != NULL) {
            register_file(fp, 0, 0);
            (void)fcntl(fileno(fp), F_SETFD, 1);
      }
      return(fp);
}

FILE *
Fdopen(int fd, char *mode)
{
      FILE *fp;

      if ((fp = fdopen(fd, mode)) != NULL) {
            register_file(fp, 0, 0);
            (void)fcntl(fileno(fp), F_SETFD, 1);
      }
      return(fp);
}

int
Fclose(FILE *fp)
{

      unregister_file(fp);
      return(fclose(fp));
}

FILE *
Popen(char *cmd, char *mode)
{
      int p[2];
      int myside, hisside, fd0, fd1;
      pid_t pid;
      sigset_t nset;
      FILE *fp;

      if (pipe(p) < 0)
            return(NULL);
      (void)fcntl(p[READ], F_SETFD, 1);
      (void)fcntl(p[WRITE], F_SETFD, 1);
      if (*mode == 'r') {
            myside = p[READ];
            hisside = fd0 = fd1 = p[WRITE];
      } else {
            myside = p[WRITE];
            hisside = fd0 = p[READ];
            fd1 = -1;
      }
      sigemptyset(&nset);
      pid = start_command(value("SHELL"), &nset, fd0, fd1, "-c", cmd, NULL);
      if (pid < 0) {
            (void)close(p[READ]);
            (void)close(p[WRITE]);
            return(NULL);
      }
      (void)close(hisside);
      if ((fp = fdopen(myside, mode)) != NULL)
            register_file(fp, 1, pid);
      return(fp);
}

int
Pclose(FILE *ptr)
{
      int i;
      sigset_t nset, oset;

      i = file_pid(ptr);
      unregister_file(ptr);
      (void)fclose(ptr);
      sigemptyset(&nset);
      sigaddset(&nset, SIGINT);
      sigaddset(&nset, SIGHUP);
      sigprocmask(SIG_BLOCK, &nset, &oset);
      i = wait_child(i);
      sigprocmask(SIG_SETMASK, &oset, NULL);
      return(i);
}

void
close_all_files(void)
{

      while (fp_head)
            if (fp_head->pipe)
                  (void)Pclose(fp_head->fp);
            else
                  (void)Fclose(fp_head->fp);
}

void
register_file(FILE *fp, int pipe, pid_t pid)
{
      struct fp *fpp;

      if ((fpp = (struct fp *)malloc(sizeof(*fpp))) == NULL)
            errx(1, "Out of memory");
      fpp->fp = fp;
      fpp->pipe = pipe;
      fpp->pid = pid;
      fpp->link = fp_head;
      fp_head = fpp;
}

void
unregister_file(FILE *fp)
{
      struct fp **pp, *p;

      for (pp = &fp_head; (p = *pp) != NULL; pp = &p->link)
            if (p->fp == fp) {
                  *pp = p->link;
                  (void)free(p);
                  return;
            }
      errx(1, "Invalid file pointer");
}

static pid_t
file_pid(FILE *fp)
{
      struct fp *p;

      for (p = fp_head; p; p = p->link)
            if (p->fp == fp)
                  return(p->pid);
      errx(1, "Invalid file pointer");
      /*NOTREACHED*/
}

/*
 * Run a command without a shell, with optional arguments and splicing
 * of stdin (-1 means none) and stdout.  The command name can be a sequence
 * of words.
 * Signals must be handled by the caller.
 * "nset" contains the signals to ignore in the new process.
 * SIGINT is enabled unless it's in "nset".
 */
pid_t
start_commandv(char *cmd, sigset_t *nset, int infd, int outfd, va_list args)
{
      pid_t pid;

      if ((pid = fork()) < 0) {
            warn("fork");
            return(-1);
      }
      if (pid == 0) {
            char *argv[100];
            int i = getrawlist(cmd, argv, sizeof(argv)/ sizeof(*argv));

            while ((argv[i++] = va_arg(args, char *)))
                  ;
            argv[i] = NULL;
            prepare_child(nset, infd, outfd);
            execvp(argv[0], argv);
            warn("%s", argv[0]);
            _exit(1);
      }
      return(pid);
}

int
run_command(char *cmd, sigset_t *nset, int infd, int outfd, ...)
{
      pid_t pid;
      va_list args;

      va_start(args, outfd);
      pid = start_commandv(cmd, nset, infd, outfd, args);
      va_end(args);
      if (pid < 0)
            return(-1);
      return(wait_command(pid));
}

int
start_command(char *cmd, sigset_t *nset, int infd, int outfd, ...)
{
      va_list args;
      int r;

      va_start(args, outfd);
      r = start_commandv(cmd, nset, infd, outfd, args);
      va_end(args);
      return(r);
}

void
prepare_child(sigset_t *nset, int infd, int outfd)
{
      int i;
      sigset_t eset;

      /*
       * All file descriptors other than 0, 1, and 2 are supposed to be
       * close-on-exec.
       */
      if (infd > 0) {
            dup2(infd, 0);
      } else if (infd != 0) {
            /* we don't want the child stealing my stdin input */
            close(0);
            open(_PATH_DEVNULL, O_RDONLY, 0);
      }
      if (outfd >= 0 && outfd != 1)
            dup2(outfd, 1);
      if (nset == NULL)
            return;
      if (nset != NULL) {
            for (i = 1; i < NSIG; i++)
                  if (sigismember(nset, i))
                        (void)signal(i, SIG_IGN);
      }
      if (nset == NULL || !sigismember(nset, SIGINT))
            (void)signal(SIGINT, SIG_DFL);
      sigemptyset(&eset);
      (void)sigprocmask(SIG_SETMASK, &eset, NULL);
}

int
wait_command(pid_t pid)
{
      int ret; 
      ret = wait_child(pid);
      if (ret > 0) {
            printf("Fatal error, process exited with code %d.\n", ret);
            return(-1);
      } else if (ret < 0) {
            puts("Fatal error in process.");
            return(-1);
      }
      return(0);
}

static struct child *
findchild(pid_t pid, int dont_alloc)
{
      struct child **cpp;

      for (cpp = &child; *cpp != NULL && (*cpp)->pid != pid;
           cpp = &(*cpp)->link)
                  ;
      if (*cpp == NULL) {
            if (dont_alloc)
                  return(NULL);
            if (child_freelist) {
                  *cpp = child_freelist;
                  child_freelist = (*cpp)->link;
            } else {
                  *cpp = (struct child *)malloc(sizeof(struct child));
                  if (*cpp == NULL)
                        errx(1, "Out of memory");
            }
            (*cpp)->pid = pid;
            (*cpp)->done = (*cpp)->free = 0;
            (*cpp)->link = NULL;
      }
      return(*cpp);
}

static void
delchild(struct child *cp)
{
      struct child **cpp;

      for (cpp = &child; *cpp != cp; cpp = &(*cpp)->link)
            ;
      *cpp = cp->link;
      cp->link = child_freelist;
      child_freelist = cp;
}

/* ARGSUSED */
void
sigchild(int signo)
{
      pid_t pid;
      int status;
      struct child *cp;
      int save_errno = errno;

      while ((pid = waitpid((pid_t)-1, &status, WNOHANG)) > 0) {
            cp = findchild(pid, 1);
            if (!cp)
                  continue;
            if (cp->free)
                  delchild(cp);
            else {
                  cp->done = 1;
                  cp->status = status;
            }
      }
      errno = save_errno;
}

int wait_status;

/*
 * Wait for a specific child to die.
 */
int
wait_child(pid_t pid)
{
      struct child *cp;
      sigset_t nset, oset;
      pid_t rv = 0;

      sigemptyset(&nset);
      sigaddset(&nset, SIGCHLD);
      sigprocmask(SIG_BLOCK, &nset, &oset);
      /*
       * If we have not already waited on the pid (via sigchild)
       * wait on it now.  Otherwise, use the wait status stashed
       * by sigchild.
       */
      cp = findchild(pid, 1);
      if (cp == NULL || !cp->done)
            rv = waitpid(pid, &wait_status, 0);
      else
            wait_status = cp->status;
      if (cp != NULL)
            delchild(cp);
      sigprocmask(SIG_SETMASK, &oset, NULL);
      if (rv >= 0 && (WIFEXITED(wait_status)))
            return (WEXITSTATUS(wait_status));
      else
            return(-1);
}

/*
 * Mark a child as don't care.
 */
void
free_child(pid_t pid)
{
      struct child *cp;
      sigset_t nset, oset;

      sigemptyset(&nset);
      sigaddset(&nset, SIGCHLD);
      sigprocmask(SIG_BLOCK, &nset, &oset);
      if ((cp = findchild(pid, 0)) != NULL) {
            if (cp->done)
                  delchild(cp);
            else
                  cp->free = 1;
      }
      sigprocmask(SIG_SETMASK, &oset, NULL);
}

/*
 * Lock(1)/unlock(0) mail spool using lockspool(1).
 * Returns 1 for success, 0 for failure, -1 for bad usage.
 */
static int
handle_spool_locks(int action)
{
#ifndef DEBIAN
      static FILE *lockfp = NULL;

      if (action == 0) {
            /* Clear the lock */
            if (lockfp == NULL) {
                  fputs("handle_spool_locks: no spool lock to remove.\n",
                      stderr);
                  return(-1);
            }
            (void)Pclose(lockfp);
            lockfp = NULL;
      } else if (action == 1) {
            char *cmd;
            char buf[sizeof(_PATH_LOCKSPOOL) + MAXLOGNAME + 1];

            /* XXX - lockspool requires root for user arg, we do not */
            if (uflag) {
                  snprintf(buf, sizeof(buf), "%s %s", _PATH_LOCKSPOOL,
                      myname);
                  cmd = buf;
            } else
                  cmd = _PATH_LOCKSPOOL;

            /* Create the lock */
            lockfp = Popen(cmd, "r");
            if (lockfp == NULL)
                  return(0);
            if (getc(lockfp) != '1') {
                  (void)Pclose(lockfp);
                  lockfp = NULL;
                  return(0);
            }
      } else {
            (void)fprintf(stderr, "handle_spool_locks: unknown action %d\n",
                action);
            return(-1);
      }

      return(1);
#else
      int retval; 
      char lockpath[PATHSIZE];

      snprintf(lockpath, PATHSIZE - 1, "%s.lock", mailname);
      lockpath[PATHSIZE - 1] = '\0';            

      if (action == 0) {
            /* Clear the lock */
            retval = lockfile_remove(lockpath);
            if (retval == 0)  
                  return(1);
            else
                  warn("Cannot remove lockfile %s", lockpath);    
            
      } else if (action == 1) {

            retval = lockfile_create(lockpath, 3, 0);
            switch (retval) {
                  case L_SUCCESS:
                        return(1);
                        
                  case L_NAMELEN:
                        warnx( "Cannot create lockfile %s: %s", 
                               lockpath,
                               "Recipient name too long."
                             );
                        break;
                  
                  case L_TMPLOCK:   
                        warnx( "Cannot create lockfile %s: %s", 
                               lockpath,
                               "Error creating temporary lockfile"
                             );
                        break;

                  case L_TMPWRITE:  
                        warnx( "Cannot create lockfile %s: %s", 
                               lockpath,
                               "Failed to write pid into tmp lockfile."
                             );
                        break;
                  
                  case L_MAXTRYS:
                        warnx( "Cannot create lockfile %s: %s", 
                               lockpath,
                               "Failed after max tries."
                             );
                        break;
            
                  case L_ERROR:
                  default:
                        warn( "Cannot create lockfile %s", 
                               lockpath
                            );
                        break;
                        
            }     
      }
            
      return(0);
#endif
}

int
spool_lock(void)
{

      return(handle_spool_locks(1));
}

int
spool_unlock(void)
{

      return(handle_spool_locks(0));
}

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