533d2abbab
- preallocate child struct, since the signal handler can be called before wait_child, and we cannot allocate a child struct there. there is a signal race still here if the program exits and the signal handler is called before we allocate the struct.
533 lines
11 KiB
C
533 lines
11 KiB
C
/* $NetBSD: popen.c,v 1.26 2010/01/12 14:43:31 christos Exp $ */
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/*
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* Copyright (c) 1980, 1993
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* The Regents of the University of California. All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 3. Neither the name of the University nor the names of its contributors
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* may be used to endorse or promote products derived from this software
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* without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*/
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#include <sys/cdefs.h>
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#ifndef lint
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#if 0
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static char sccsid[] = "@(#)popen.c 8.1 (Berkeley) 6/6/93";
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#else
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__RCSID("$NetBSD: popen.c,v 1.26 2010/01/12 14:43:31 christos Exp $");
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#endif
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#endif /* not lint */
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#include <errno.h>
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#include <fcntl.h>
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#include <stdarg.h>
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#include <util.h>
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#include <sys/wait.h>
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#include "rcv.h"
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#include "extern.h"
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#include "sig.h"
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#define READ 0
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#define WRITE 1
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struct fp {
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FILE *fp;
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int pipe;
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pid_t pid;
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struct fp *link;
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};
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static struct fp *fp_head;
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struct child {
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pid_t pid;
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char done;
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char free;
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int status;
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struct child *link;
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};
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static struct child *child, *child_freelist = NULL;
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static struct child *findchild(pid_t, int);
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#if 0 /* XXX - debugging stuff. This should go away eventually! */
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static void
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show_one_file(FILE *fo, struct fp *fpp)
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{
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(void)fprintf(fo, ">>> fp: %p, pipe: %d, pid: %d, link: %p\n",
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fpp->fp, fpp->pipe, fpp->pid, fpp->link);
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}
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void show_all_files(FILE *fo);
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__unused
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PUBLIC void
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show_all_files(FILE *fo)
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{
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struct fp *fpp;
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(void)fprintf(fo, ">> FILES\n");
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for (fpp = fp_head; fpp; fpp = fpp->link)
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show_one_file(fo, fpp);
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(void)fprintf(fo, ">> -------\n");
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(void)fflush(fo);
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}
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#endif /* end debugging stuff */
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static void
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unregister_file(FILE *fp)
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{
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struct fp **pp, *p;
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for (pp = &fp_head; (p = *pp) != NULL; pp = &p->link)
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if (p->fp == fp) {
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*pp = p->link;
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(void)free(p);
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return;
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}
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errx(EXIT_FAILURE, "Invalid file pointer");
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}
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PUBLIC void
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register_file(FILE *fp, int pipefd, pid_t pid)
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{
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struct fp *fpp;
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fpp = emalloc(sizeof(*fpp));
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fpp->fp = fp;
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fpp->pipe = pipefd;
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fpp->pid = pid;
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fpp->link = fp_head;
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fp_head = fpp;
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}
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PUBLIC FILE *
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Fopen(const char *fn, const char *mode)
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{
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FILE *fp;
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if ((fp = fopen(fn, mode)) != NULL) {
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register_file(fp, 0, 0);
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(void)fcntl(fileno(fp), F_SETFD, FD_CLOEXEC);
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}
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return fp;
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}
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PUBLIC FILE *
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Fdopen(int fd, const char *mode)
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{
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FILE *fp;
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if ((fp = fdopen(fd, mode)) != NULL) {
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register_file(fp, 0, 0);
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(void)fcntl(fileno(fp), F_SETFD, FD_CLOEXEC);
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}
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return fp;
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}
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PUBLIC int
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Fclose(FILE *fp)
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{
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if (fp == NULL)
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return 0;
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unregister_file(fp);
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return fclose(fp);
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}
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PUBLIC void
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prepare_child(sigset_t *nset, int infd, int outfd)
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{
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int i;
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sigset_t eset;
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/*
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* All file descriptors other than 0, 1, and 2 are supposed to be
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* close-on-exec.
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*/
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if (infd > 0) {
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(void)dup2(infd, 0);
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} else if (infd != 0) {
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/* we don't want the child stealing my stdin input */
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(void)close(0);
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(void)open(_PATH_DEVNULL, O_RDONLY, 0);
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}
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if (outfd >= 0 && outfd != 1)
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(void)dup2(outfd, 1);
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if (nset != NULL) {
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for (i = 1; i < NSIG; i++) {
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if (sigismember(nset, i))
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(void)signal(i, SIG_IGN);
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}
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if (!sigismember(nset, SIGINT))
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(void)signal(SIGINT, SIG_DFL);
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(void)sigemptyset(&eset);
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(void)sigprocmask(SIG_SETMASK, &eset, NULL);
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}
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}
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/*
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* Run a command without a shell, with optional arguments and splicing
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* of stdin (-1 means none) and stdout. The command name can be a sequence
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* of words.
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* Signals must be handled by the caller.
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* "nset" contains the signals to ignore in the new process.
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* SIGINT is enabled unless it's in "nset".
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*/
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static pid_t
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start_commandv(const char *cmd, sigset_t *nset, int infd, int outfd,
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va_list args)
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{
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pid_t pid;
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sig_check();
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if ((pid = fork()) < 0) {
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warn("fork");
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return -1;
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}
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if (pid == 0) {
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char *argv[100];
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size_t i;
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i = getrawlist(cmd, argv, (int)__arraycount(argv));
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while (i < __arraycount(argv) - 1 &&
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(argv[i++] = va_arg(args, char *)) != NULL)
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continue;
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argv[i] = NULL;
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prepare_child(nset, infd, outfd);
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(void)execvp(argv[0], argv);
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warn("%s", argv[0]);
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_exit(1);
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}
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(void)findchild(pid, 0);
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return pid;
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}
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PUBLIC int
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start_command(const char *cmd, sigset_t *nset, int infd, int outfd, ...)
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{
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va_list args;
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int r;
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va_start(args, outfd);
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r = start_commandv(cmd, nset, infd, outfd, args);
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va_end(args);
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return r;
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}
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PUBLIC FILE *
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Popen(const char *cmd, const char *mode)
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{
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int p[2];
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int myside, hisside, fd0, fd1;
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pid_t pid;
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sigset_t nset;
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FILE *fp;
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char *shellcmd;
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if (pipe(p) < 0)
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return NULL;
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(void)fcntl(p[READ], F_SETFD, FD_CLOEXEC);
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(void)fcntl(p[WRITE], F_SETFD, FD_CLOEXEC);
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if (*mode == 'r') {
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myside = p[READ];
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hisside = fd0 = fd1 = p[WRITE];
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} else {
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myside = p[WRITE];
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hisside = fd0 = p[READ];
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fd1 = -1;
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}
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(void)sigemptyset(&nset);
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if ((shellcmd = value(ENAME_SHELL)) == NULL)
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shellcmd = __UNCONST(_PATH_CSHELL);
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pid = start_command(shellcmd, &nset, fd0, fd1, "-c", cmd, NULL);
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if (pid < 0) {
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(void)close(p[READ]);
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(void)close(p[WRITE]);
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return NULL;
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}
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(void)close(hisside);
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if ((fp = fdopen(myside, mode)) != NULL)
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register_file(fp, 1, pid);
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return fp;
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}
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static struct child *
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findchild(pid_t pid, int dont_alloc)
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{
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struct child **cpp;
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for (cpp = &child; *cpp != NULL && (*cpp)->pid != pid;
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cpp = &(*cpp)->link)
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continue;
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if (*cpp == NULL) {
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if (dont_alloc)
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return NULL;
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if (child_freelist) {
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*cpp = child_freelist;
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child_freelist = (*cpp)->link;
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} else
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*cpp = emalloc(sizeof(**cpp));
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(*cpp)->pid = pid;
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(*cpp)->done = (*cpp)->free = 0;
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(*cpp)->link = NULL;
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}
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return *cpp;
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}
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static void
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delchild(struct child *cp)
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{
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struct child **cpp;
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for (cpp = &child; *cpp != cp; cpp = &(*cpp)->link)
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continue;
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*cpp = cp->link;
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cp->link = child_freelist;
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child_freelist = cp;
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}
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/*
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* Wait for a specific child to die.
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*/
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PUBLIC int
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wait_child(pid_t pid)
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{
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struct child *cp;
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sigset_t nset, oset;
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pid_t rv = 0;
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(void)sigemptyset(&nset);
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(void)sigaddset(&nset, SIGCHLD);
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(void)sigprocmask(SIG_BLOCK, &nset, &oset);
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/*
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* If we have not already waited on the pid (via sigchild)
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* wait on it now. Otherwise, use the wait status stashed
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* by sigchild.
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*/
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cp = findchild(pid, 1);
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if (cp == NULL || !cp->done)
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rv = waitpid(pid, &wait_status, 0);
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else
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wait_status = cp->status;
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if (cp != NULL)
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delchild(cp);
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(void)sigprocmask(SIG_SETMASK, &oset, NULL);
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if (rv == -1 || (WIFEXITED(wait_status) && WEXITSTATUS(wait_status)))
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return -1;
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else
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return 0;
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}
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static pid_t
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file_pid(FILE *fp)
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{
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struct fp *p;
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for (p = fp_head; p; p = p->link)
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if (p->fp == fp)
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return p->pid;
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errx(EXIT_FAILURE, "Invalid file pointer");
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/*NOTREACHED*/
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}
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PUBLIC int
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Pclose(FILE *ptr)
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{
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int i;
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sigset_t nset, oset;
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if (ptr == NULL)
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return 0;
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i = file_pid(ptr);
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unregister_file(ptr);
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(void)fclose(ptr);
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(void)sigemptyset(&nset);
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(void)sigaddset(&nset, SIGINT);
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(void)sigaddset(&nset, SIGHUP);
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(void)sigprocmask(SIG_BLOCK, &nset, &oset);
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i = wait_child(i);
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(void)sigprocmask(SIG_SETMASK, &oset, NULL);
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return i;
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}
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PUBLIC void
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close_all_files(void)
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{
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while (fp_head)
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if (fp_head->pipe)
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(void)Pclose(fp_head->fp);
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else
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(void)Fclose(fp_head->fp);
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}
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PUBLIC FILE *
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last_registered_file(int last_pipe)
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{
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struct fp *fpp;
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if (last_pipe == 0)
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return fp_head ? fp_head->fp : NULL;
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for (fpp = fp_head; fpp; fpp = fpp->link)
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if (fpp->pipe)
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return fpp->fp;
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return NULL;
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}
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PUBLIC void
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close_top_files(FILE *fp_stop)
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{
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while (fp_head && fp_head->fp != fp_stop)
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if (fp_head->pipe)
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(void)Pclose(fp_head->fp);
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else
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(void)Fclose(fp_head->fp);
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}
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#ifdef MIME_SUPPORT
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PUBLIC void
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flush_files(FILE *fo, int only_pipes)
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{
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struct fp *fpp;
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if (fo)
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(void)fflush(fo);
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for (fpp = fp_head; fpp; fpp = fpp->link)
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if (!only_pipes || fpp->pipe)
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(void)fflush(fpp->fp);
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(void)fflush(stdout);
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}
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#endif /* MIME_SUPPORT */
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static int
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wait_command(pid_t pid)
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{
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if (wait_child(pid) < 0) {
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(void)puts("Fatal error in process.");
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return -1;
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}
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return 0;
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}
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PUBLIC int
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run_command(const char *cmd, sigset_t *nset, int infd, int outfd, ...)
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{
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pid_t pid;
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va_list args;
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int rval;
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#ifdef BROKEN_EXEC_TTY_RESTORE
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struct termios ttybuf;
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int tcrval;
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/*
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* XXX - grab the tty settings as currently they can get
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* trashed by emacs-21 when suspending with bash-3.2.25 as the
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* shell.
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*
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* 1) from the mail editor, start "emacs -nw" (21.4)
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* 2) suspend emacs to the shell (bash 3.2.25)
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* 3) resume emacs
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* 4) exit emacs back to the mail editor
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* 5) discover the tty is screwed: the mail editor is no
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* longer receiving characters
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*
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* - This occurs on both i386 and amd64.
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* - This did _NOT_ occur before 4.99.10.
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* - This does _NOT_ occur if the editor is vi(1) or if the shell
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* is /bin/sh.
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* - This _DOES_ happen with the old mail(1) from 2006-01-01 (long
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* before my changes).
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*
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* This is the commit that introduced this "feature":
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* http://mail-index.netbsd.org/source-changes/2007/02/09/0020.html
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*/
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if ((tcrval = tcgetattr(fileno(stdin), &ttybuf)) == -1)
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warn("tcgetattr");
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#endif
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va_start(args, outfd);
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pid = start_commandv(cmd, nset, infd, outfd, args);
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va_end(args);
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if (pid < 0)
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return -1;
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rval = wait_command(pid);
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#ifdef BROKEN_EXEC_TTY_RESTORE
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if (tcrval != -1 && tcsetattr(fileno(stdin), TCSADRAIN, &ttybuf) == -1)
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warn("tcsetattr");
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#endif
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return rval;
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}
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/*ARGSUSED*/
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PUBLIC void
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sigchild(int signo __unused)
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{
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pid_t pid;
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int status;
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struct child *cp;
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int save_errno;
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save_errno = errno;
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while ((pid = waitpid((pid_t)-1, &status, WNOHANG)) > 0) {
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cp = findchild(pid, 1); /* async-signal-safe: we don't alloc */
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if (!cp)
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continue;
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if (cp->free)
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delchild(cp); /* async-signal-safe: list changes */
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else {
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cp->done = 1;
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cp->status = status;
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}
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}
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errno = save_errno;
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}
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/*
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* Mark a child as don't care.
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*/
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PUBLIC void
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free_child(pid_t pid)
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{
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struct child *cp;
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sigset_t nset, oset;
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(void)sigemptyset(&nset);
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(void)sigaddset(&nset, SIGCHLD);
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(void)sigprocmask(SIG_BLOCK, &nset, &oset);
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if ((cp = findchild(pid, 0)) != NULL) {
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if (cp->done)
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delchild(cp);
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else
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cp->free = 1;
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}
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(void)sigprocmask(SIG_SETMASK, &oset, NULL);
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}
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