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popen.c

/*
 * Heirloom mailx - a mail user agent derived from Berkeley Mail.
 *
 * Copyright (c) 2000-2004 Gunnar Ritter, Freiburg i. Br., Germany.
 */
/*
 * 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. All advertising materials mentioning features or use of this software
 *    must display the following acknowledgement:
 *    This product includes software developed by the University of
 *    California, Berkeley and its contributors.
 * 4. 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
#ifdef      DOSCCS
static char sccsid[] = "@(#)popen.c 2.20 (gritter) 3/4/06";
#endif
#endif /* not lint */

#include "rcv.h"
#include "extern.h"
#include <sys/stat.h>
#include <fcntl.h>
#include <unistd.h>
#include <sys/wait.h>
#include <errno.h>

#ifndef     NSIG
#define     NSIG  32
#endif

#define READ 0
#define WRITE 1

struct fp {
      FILE *fp;
      struct fp *link;
      char *realfile;
      long offset;
      int omode;
      int pipe;
      int pid;
      enum {
            FP_UNCOMPRESSED   = 00,
            FP_GZIPPED  = 01,
            FP_BZIP2ED  = 02,
            FP_IMAP           = 03,
            FP_MAILDIR  = 04,
            FP_MASK           = 0177,
            FP_READONLY = 0200
      } compressed;
};
static struct fp *fp_head;

struct child {
      int pid;
      char done;
      char free;
      int status;
      struct child *link;
};
static struct child     *child;

static int scan_mode(const char *mode, int *omode);
static void register_file(FILE *fp, int omode, int pipe, int pid,
            int compressed, const char *realfile, long offset);
static enum okay compress(struct fp *fpp);
static int decompress(int compression, int input, int output);
static enum okay unregister_file(FILE *fp);
static int file_pid(FILE *fp);
static int wait_command(int pid);
static struct child *findchild(int pid);
static void delchild(struct child *cp);

/*
 * Provide BSD-like signal() on all systems.
 */
sighandler_type
safe_signal(int signum, sighandler_type handler)
{
      struct sigaction nact, oact;

      nact.sa_handler = handler;
      sigemptyset(&nact.sa_mask);
      nact.sa_flags = 0;
#ifdef      SA_RESTART
      nact.sa_flags |= SA_RESTART;
#endif
      if (sigaction(signum, &nact, &oact) != 0)
            return SIG_ERR;
      return oact.sa_handler;
}

static int 
scan_mode(const char *mode, int *omode)
{

      if (!strcmp(mode, "r")) {
            *omode = O_RDONLY;
      } else if (!strcmp(mode, "w")) {
            *omode = O_WRONLY | O_CREAT | O_TRUNC;
      } else if (!strcmp(mode, "wx")) {
            *omode = O_WRONLY | O_CREAT | O_EXCL;
      } else if (!strcmp(mode, "a")) {
            *omode = O_WRONLY | O_APPEND | O_CREAT;
      } else if (!strcmp(mode, "a+")) {
            *omode = O_RDWR | O_APPEND;
      } else if (!strcmp(mode, "r+")) {
            *omode = O_RDWR;
      } else if (!strcmp(mode, "w+")) {
            *omode = O_RDWR   | O_CREAT | O_EXCL;
      } else {
            fprintf(stderr, catgets(catd, CATSET, 152,
                  "Internal error: bad stdio open mode %s\n"), mode);
            errno = EINVAL;
            return -1;
      }
      return 0;
}

FILE *
safe_fopen(const char *file, const char *mode, int *omode)
{
      int  fd;

      if (scan_mode(mode, omode) < 0) 
            return NULL;
      if ((fd = open(file, *omode, 0666)) < 0)
            return NULL;
      return fdopen(fd, mode);
}

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

      if ((fp = safe_fopen(file, mode, &omode)) != NULL) {
            register_file(fp, omode, 0, 0, FP_UNCOMPRESSED, NULL, 0L);
            fcntl(fileno(fp), F_SETFD, FD_CLOEXEC);
      }
      return fp;
}

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

      scan_mode(mode, &omode);
      if ((fp = fdopen(fd, mode)) != NULL) {
            register_file(fp, omode, 0, 0, FP_UNCOMPRESSED, NULL, 0L);
            fcntl(fileno(fp), F_SETFD, FD_CLOEXEC);
      }
      return fp;
}

int
Fclose(FILE *fp)
{
      int   i = 0;
      if (unregister_file(fp) == OKAY)
            i |= 1;
      if (fclose(fp) == 0)
            i |= 2;
      return i == 3 ? 0 : EOF;
}

FILE *
Zopen(const char *file, const char *mode, int *compression)
{
      int   input;
      FILE  *output;
      const char  *rp;
      int   omode;
      char  *tempfn;
      int   bits;
      int   _compression;
      long  offset;
      char  *extension;
      enum protocol     p;

      if (scan_mode(mode, &omode) < 0)
            return NULL;
      if (compression == NULL)
            compression = &_compression;
      bits = R_OK | (omode == O_RDONLY ? 0 : W_OK);
      if (omode & O_APPEND && ((p = which_protocol(file)) == PROTO_IMAP ||
                  p == PROTO_MAILDIR)) {
            *compression = p == PROTO_IMAP ? FP_IMAP : FP_MAILDIR;
            omode = O_RDWR | O_APPEND | O_CREAT;
            rp = file;
            input = -1;
            goto open;
      }
      if ((extension = strrchr(file, '.')) != NULL) {
            rp = file;
            if (strcmp(extension, ".gz") == 0)
                  goto gzip;
            if (strcmp(extension, ".bz2") == 0)
                  goto bz2;
      }
      if (access(file, F_OK) == 0) {
            *compression = FP_UNCOMPRESSED;
            return Fopen(file, mode);
      } else if (access(rp=savecat(file, ".gz"), bits) == 0) {
      gzip: *compression = FP_GZIPPED;
      } else if (access(rp=savecat(file, ".bz2"), bits) == 0) {
      bz2:  *compression = FP_BZIP2ED;
      } else {
            *compression = FP_UNCOMPRESSED;
            return Fopen(file, mode);
      }
      if (access(rp, W_OK) < 0)
            *compression |= FP_READONLY;
      if ((input = open(rp, bits & W_OK ? O_RDWR : O_RDONLY)) < 0
                  && ((omode&O_CREAT) == 0 || errno != ENOENT))
            return NULL;
open: if ((output = Ftemp(&tempfn, "Rz", "w+", 0600, 0)) == NULL) {
            perror(catgets(catd, CATSET, 167, "tmpfile"));
            close(input);
            return NULL;
      }
      unlink(tempfn);
      if (input >= 0 || (*compression&FP_MASK) == FP_IMAP ||
                  (*compression&FP_MASK) == FP_MAILDIR) {
            if (decompress(*compression, input, fileno(output)) < 0) {
                  close(input);
                  Fclose(output);
                  return NULL;
            }
      } else {
            if ((input = creat(rp, 0666)) < 0) {
                  Fclose(output);
                  return NULL;
            }
      }
      close(input);
      fflush(output);
      if (omode & O_APPEND) {
            int   flags;

            if ((flags = fcntl(fileno(output), F_GETFL)) != -1)
                  fcntl(fileno(output), F_SETFL, flags | O_APPEND);
            offset = ftell(output);
      } else {
            rewind(output);
            offset = 0;
      }
      register_file(output, omode, 0, 0, *compression, rp, offset);
      return output;
}

FILE *
Popen(const char *cmd, const char *mode, const char *shell, int newfd1)
{
      int p[2];
      int myside, hisside, fd0, fd1;
      int pid;
      char mod[2] = { '0', '\0' };
      sigset_t nset;
      FILE *fp;

      if (pipe(p) < 0)
            return NULL;
      fcntl(p[READ], F_SETFD, FD_CLOEXEC);
      fcntl(p[WRITE], F_SETFD, FD_CLOEXEC);
      if (*mode == 'r') {
            myside = p[READ];
            fd0 = -1;
            hisside = fd1 = p[WRITE];
            mod[0] = *mode;
      } else if (*mode == 'W') {
            myside = p[WRITE];
            hisside = fd0 = p[READ];
            fd1 = newfd1;
            mod[0] = 'w';
      } else {
            myside = p[WRITE];
            hisside = fd0 = p[READ];
            fd1 = -1;
            mod[0] = 'w';
      }
      sigemptyset(&nset);
      if (shell == NULL) {
            pid = start_command(cmd, &nset, fd0, fd1, NULL, NULL, NULL);
      } else {
            pid = start_command(shell, &nset, fd0, fd1, "-c", cmd, NULL);
      }
      if (pid < 0) {
            close(p[READ]);
            close(p[WRITE]);
            return NULL;
      }
      close(hisside);
      if ((fp = fdopen(myside, mod)) != NULL)
            register_file(fp, 0, 1, pid, FP_UNCOMPRESSED, NULL, 0L);
      return fp;
}

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

      i = file_pid(ptr);
      if (i < 0)
            return 0;
      unregister_file(ptr);
      fclose(ptr);
      sigemptyset(&nset);
      sigaddset(&nset, SIGINT);
      sigaddset(&nset, SIGHUP);
      sigprocmask(SIG_BLOCK, &nset, &oset);
      i = wait_child(i);
      sigprocmask(SIG_SETMASK, &oset, (sigset_t *)NULL);
      return i;
}

void 
close_all_files(void)
{

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

static void
register_file(FILE *fp, int omode, int pipe, int pid, int compressed,
            const char *realfile, long offset)
{
      struct fp *fpp;

      fpp = (struct fp*)smalloc(sizeof *fpp);
      fpp->fp = fp;
      fpp->omode = omode;
      fpp->pipe = pipe;
      fpp->pid = pid;
      fpp->link = fp_head;
      fpp->compressed = compressed;
      fpp->realfile = realfile ? sstrdup(realfile) : NULL;
      fpp->offset = offset;
      fp_head = fpp;
}

static enum okay
compress(struct fp *fpp)
{
      int   output;
      char  *command[2];
      enum okay   ok;

      if (fpp->omode == O_RDONLY)
            return OKAY;
      fflush(fpp->fp);
      clearerr(fpp->fp);
      fseek(fpp->fp, fpp->offset, SEEK_SET);
      if ((fpp->compressed&FP_MASK) == FP_IMAP) {
            return imap_append(fpp->realfile, fpp->fp);
      }
      if ((fpp->compressed&FP_MASK) == FP_MAILDIR) {
            return maildir_append(fpp->realfile, fpp->fp);
      }
      if ((output = open(fpp->realfile,
                  (fpp->omode|O_CREAT)&~O_EXCL,
                  0666)) < 0) {
            fprintf(stderr, "Fatal: cannot create ");
            perror(fpp->realfile);
            return STOP;
      }
      if ((fpp->omode & O_APPEND) == 0)
            ftruncate(output, 0);
      switch (fpp->compressed & FP_MASK) {
      case FP_GZIPPED:
            command[0] = "gzip"; command[1] = "-c"; break;
      case FP_BZIP2ED:
            command[0] = "bzip2"; command[1] = "-c"; break;
      default:
            command[0] = "cat"; command[1] = NULL; break;
      }
      if (run_command(command[0], 0, fileno(fpp->fp), output,
                        command[1], NULL, NULL) < 0)
            ok = STOP;
      else
            ok = OKAY;
      close(output);
      return ok;
}

static int
decompress(int compression, int input, int output)
{
      char  *command[2];

      /*
       * Note that it is not possible to handle 'pack' or 'compress'
       * formats because appending data does not work with them.
       */
      switch (compression & FP_MASK) {
      case FP_GZIPPED:  command[0] = "gzip"; command[1] = "-cd"; break;
      case FP_BZIP2ED:  command[0] = "bzip2"; command[1] = "-cd"; break;
      case FP_IMAP:           return 0;
      case FP_MAILDIR:  return 0;
      default:          command[0] = "cat"; command[1] = NULL;
      }
      return run_command(command[0], 0, input, output,
                  command[1], NULL, NULL);
}

static enum okay
unregister_file(FILE *fp)
{
      struct fp **pp, *p;
      enum okay   ok = OKAY;

      for (pp = &fp_head; (p = *pp) != (struct fp *)NULL; pp = &p->link)
            if (p->fp == fp) {
                  if ((p->compressed&FP_MASK) != FP_UNCOMPRESSED)
                        ok = compress(p);
                  *pp = p->link;
                  free(p);
                  return ok;
            }
      panic(catgets(catd, CATSET, 153, "Invalid file pointer"));
      /*NOTREACHED*/
      return STOP;
}

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

      for (p = fp_head; p; p = p->link)
            if (p->fp == fp)
                  return (p->pid);
      return -1;
}

/*
 * Run a command without a shell, with optional arguments and splicing
 * of stdin and stdout.  The command name can be a sequence of words.
 * Signals must be handled by the caller.
 * "Mask" contains the signals to ignore in the new process.
 * SIGINT is enabled unless it's in the mask.
 */
/*VARARGS4*/
int
run_command(char *cmd, sigset_t *mask, int infd, int outfd,
            char *a0, char *a1, char *a2)
{
      int pid;

      if ((pid = start_command(cmd, mask, infd, outfd, a0, a1, a2)) < 0)
            return -1;
      return wait_command(pid);
}

/*VARARGS4*/
int
start_command(const char *cmd, sigset_t *mask, int infd, int outfd,
            const char *a0, const char *a1, const char *a2)
{
      int pid;

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

            if ((argv[i++] = (char *)a0) != NULL &&
                (argv[i++] = (char *)a1) != NULL &&
                (argv[i++] = (char *)a2) != NULL)
                  argv[i] = NULL;
            prepare_child(mask, infd, outfd);
            execvp(argv[0], argv);
            perror(argv[0]);
            _exit(1);
      }
      return pid;
}

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

      /*
       * All file descriptors other than 0, 1, and 2 are supposed to be
       * close-on-exec.
       */
      if (infd >= 0)
            dup2(infd, 0);
      if (outfd >= 0)
            dup2(outfd, 1);
      if (nset) {
            for (i = 1; i < NSIG; i++)
                  if (sigismember(nset, i))
                        safe_signal(i, SIG_IGN);
            if (!sigismember(nset, SIGINT))
                  safe_signal(SIGINT, SIG_DFL);
      }
      sigfillset(&fset);
      sigprocmask(SIG_UNBLOCK, &fset, (sigset_t *)NULL);
}

static int 
wait_command(int pid)
{

      if (wait_child(pid) < 0 && (value("bsdcompat") || value("bsdmsgs"))) {
            printf(catgets(catd, CATSET, 154, "Fatal error in process.\n"));
            return -1;
      }
      return 0;
}

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

      for (cpp = &child; *cpp != (struct child *)NULL && (*cpp)->pid != pid;
           cpp = &(*cpp)->link)
                  ;
      if (*cpp == (struct child *)NULL) {
            *cpp = (struct child *) smalloc(sizeof (struct child));
            (*cpp)->pid = pid;
            (*cpp)->done = (*cpp)->free = 0;
            (*cpp)->link = (struct child *)NULL;
      }
      return *cpp;
}

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

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

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

again:
      while ((pid = waitpid(-1, (int*)&status, WNOHANG)) > 0) {
            cp = findchild(pid);
            if (cp->free)
                  delchild(cp);
            else {
                  cp->done = 1;
                  cp->status = status;
            }
      }
      if (pid == -1 && errno == EINTR)
            goto again;
}

int wait_status;

/*
 * Mark a child as don't care.
 */
void 
free_child(int pid)
{
      sigset_t nset, oset;
      struct child *cp = findchild(pid);
      sigemptyset(&nset);
      sigaddset(&nset, SIGCHLD);
      sigprocmask(SIG_BLOCK, &nset, &oset);

      if (cp->done)
            delchild(cp);
      else
            cp->free = 1;
      sigprocmask(SIG_SETMASK, &oset, (sigset_t *)NULL);
}

/*
 * Wait for a specific child to die.
 */
#if 0
/*
 * This version is correct code, but causes harm on some loosing
 * systems. So we use the second one instead.
 */
int 
wait_child(int pid)
{
      sigset_t nset, oset;
      struct child *cp = findchild(pid);
      sigemptyset(&nset);
      sigaddset(&nset, SIGCHLD);
      sigprocmask(SIG_BLOCK, &nset, &oset);

      while (!cp->done)
            sigsuspend(&oset);
      wait_status = cp->status;
      delchild(cp);
      sigprocmask(SIG_SETMASK, &oset, (sigset_t *)NULL);

      if (WIFEXITED(wait_status) && (WEXITSTATUS(wait_status) == 0))
            return 0;
      return -1;
}
#endif
int 
wait_child(int pid)
{
      pid_t term;
      struct child *cp;
      struct sigaction nact, oact;
      
      nact.sa_handler = SIG_DFL;
      sigemptyset(&nact.sa_mask);
      nact.sa_flags = SA_NOCLDSTOP;
      sigaction(SIGCHLD, &nact, &oact);
      
      cp = findchild(pid);
      if (!cp->done) {
            do {
                  term = wait(&wait_status);
                  if (term == -1 && errno == EINTR)
                        continue;
                  if (term == 0 || term == -1)
                        break;
                  cp = findchild(term);
                  if (cp->free || term == pid) {
                        delchild(cp);
                  } else {
                        cp->done = 1;
                        cp->status = wait_status;
                  }
            } while (term != pid);
      } else {
            wait_status = cp->status;
            delchild(cp);
      }
      
      sigaction(SIGCHLD, &oact, NULL);
      /*
       * Make sure no zombies are left.
       */
      sigchild(SIGCHLD);
      
      if (WIFEXITED(wait_status) && (WEXITSTATUS(wait_status) == 0))
            return 0;
      return -1;
}

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