7e1c72660f
should slightly reduce the number of system calls in critical portions of the shell, and select a more efficient path through the fdalloc code. Reviewed by: bde
348 lines
8.1 KiB
C
348 lines
8.1 KiB
C
/*-
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* Copyright (c) 1991, 1993
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* The Regents of the University of California. All rights reserved.
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*
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* This code is derived from software contributed to Berkeley by
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* Kenneth Almquist.
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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. All advertising materials mentioning features or use of this software
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* must display the following acknowledgement:
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* This product includes software developed by the University of
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* California, Berkeley and its contributors.
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* 4. 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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#ifndef lint
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#if 0
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static char sccsid[] = "@(#)redir.c 8.2 (Berkeley) 5/4/95";
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#endif
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#endif /* not lint */
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#include <sys/cdefs.h>
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__FBSDID("$FreeBSD$");
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#include <sys/types.h>
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#include <sys/stat.h>
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#include <signal.h>
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#include <string.h>
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#include <fcntl.h>
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#include <errno.h>
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#include <unistd.h>
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#include <stdlib.h>
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/*
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* Code for dealing with input/output redirection.
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*/
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#include "shell.h"
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#include "nodes.h"
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#include "jobs.h"
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#include "expand.h"
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#include "redir.h"
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#include "output.h"
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#include "memalloc.h"
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#include "error.h"
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#include "options.h"
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#define EMPTY -2 /* marks an unused slot in redirtab */
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#define PIPESIZE 4096 /* amount of buffering in a pipe */
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MKINIT
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struct redirtab {
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struct redirtab *next;
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int renamed[10];
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};
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MKINIT struct redirtab *redirlist;
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/*
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* We keep track of whether or not fd0 has been redirected. This is for
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* background commands, where we want to redirect fd0 to /dev/null only
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* if it hasn't already been redirected.
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*/
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STATIC int fd0_redirected = 0;
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STATIC void openredirect(union node *, char[10 ]);
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STATIC int openhere(union node *);
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/*
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* Process a list of redirection commands. If the REDIR_PUSH flag is set,
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* old file descriptors are stashed away so that the redirection can be
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* undone by calling popredir. If the REDIR_BACKQ flag is set, then the
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* standard output, and the standard error if it becomes a duplicate of
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* stdout, is saved in memory.
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*/
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void
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redirect(union node *redir, int flags)
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{
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union node *n;
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struct redirtab *sv = NULL;
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int i;
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int fd;
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int try;
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char memory[10]; /* file descriptors to write to memory */
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for (i = 10 ; --i >= 0 ; )
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memory[i] = 0;
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memory[1] = flags & REDIR_BACKQ;
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if (flags & REDIR_PUSH) {
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sv = ckmalloc(sizeof (struct redirtab));
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for (i = 0 ; i < 10 ; i++)
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sv->renamed[i] = EMPTY;
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sv->next = redirlist;
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redirlist = sv;
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}
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for (n = redir ; n ; n = n->nfile.next) {
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fd = n->nfile.fd;
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try = 0;
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if ((n->nfile.type == NTOFD || n->nfile.type == NFROMFD) &&
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n->ndup.dupfd == fd)
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continue; /* redirect from/to same file descriptor */
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if ((flags & REDIR_PUSH) && sv->renamed[fd] == EMPTY) {
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INTOFF;
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again:
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if ((i = fcntl(fd, F_DUPFD, 10)) == -1) {
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switch (errno) {
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case EBADF:
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if (!try) {
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openredirect(n, memory);
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try++;
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goto again;
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}
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/* FALLTHROUGH*/
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default:
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INTON;
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error("%d: %s", fd, strerror(errno));
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break;
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}
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}
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if (!try) {
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sv->renamed[fd] = i;
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}
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INTON;
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}
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if (fd == 0)
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fd0_redirected++;
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if (!try)
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openredirect(n, memory);
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}
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if (memory[1])
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out1 = &memout;
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if (memory[2])
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out2 = &memout;
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}
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STATIC void
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openredirect(union node *redir, char memory[10])
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{
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struct stat sb;
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int fd = redir->nfile.fd;
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char *fname;
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int f;
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/*
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* We suppress interrupts so that we won't leave open file
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* descriptors around. This may not be such a good idea because
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* an open of a device or a fifo can block indefinitely.
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*/
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INTOFF;
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memory[fd] = 0;
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switch (redir->nfile.type) {
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case NFROM:
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fname = redir->nfile.expfname;
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if ((f = open(fname, O_RDONLY)) < 0)
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error("cannot open %s: %s", fname, strerror(errno));
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movefd:
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if (f != fd) {
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dup2(f, fd);
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close(f);
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}
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break;
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case NFROMTO:
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fname = redir->nfile.expfname;
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if ((f = open(fname, O_RDWR|O_CREAT, 0666)) < 0)
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error("cannot create %s: %s", fname, strerror(errno));
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goto movefd;
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case NTO:
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fname = redir->nfile.expfname;
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if (Cflag && stat(fname, &sb) != -1 && S_ISREG(sb.st_mode))
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error("cannot create %s: %s", fname,
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strerror(EEXIST));
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if ((f = open(fname, O_WRONLY|O_CREAT|O_TRUNC, 0666)) < 0)
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error("cannot create %s: %s", fname, strerror(errno));
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goto movefd;
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case NCLOBBER:
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fname = redir->nfile.expfname;
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if ((f = open(fname, O_WRONLY|O_CREAT|O_TRUNC, 0666)) < 0)
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error("cannot create %s: %s", fname, strerror(errno));
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goto movefd;
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case NAPPEND:
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fname = redir->nfile.expfname;
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if ((f = open(fname, O_WRONLY|O_CREAT|O_APPEND, 0666)) < 0)
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error("cannot create %s: %s", fname, strerror(errno));
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goto movefd;
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case NTOFD:
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case NFROMFD:
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if (redir->ndup.dupfd >= 0) { /* if not ">&-" */
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if (memory[redir->ndup.dupfd])
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memory[fd] = 1;
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else
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dup2(redir->ndup.dupfd, fd);
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} else {
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close(fd);
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}
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break;
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case NHERE:
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case NXHERE:
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f = openhere(redir);
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goto movefd;
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default:
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abort();
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}
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INTON;
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}
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/*
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* Handle here documents. Normally we fork off a process to write the
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* data to a pipe. If the document is short, we can stuff the data in
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* the pipe without forking.
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*/
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STATIC int
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openhere(union node *redir)
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{
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int pip[2];
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int len = 0;
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if (pipe(pip) < 0)
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error("Pipe call failed: %s", strerror(errno));
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if (redir->type == NHERE) {
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len = strlen(redir->nhere.doc->narg.text);
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if (len <= PIPESIZE) {
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xwrite(pip[1], redir->nhere.doc->narg.text, len);
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goto out;
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}
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}
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if (forkshell((struct job *)NULL, (union node *)NULL, FORK_NOJOB) == 0) {
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close(pip[0]);
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signal(SIGINT, SIG_IGN);
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signal(SIGQUIT, SIG_IGN);
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signal(SIGHUP, SIG_IGN);
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signal(SIGTSTP, SIG_IGN);
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signal(SIGPIPE, SIG_DFL);
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if (redir->type == NHERE)
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xwrite(pip[1], redir->nhere.doc->narg.text, len);
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else
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expandhere(redir->nhere.doc, pip[1]);
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_exit(0);
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}
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out:
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close(pip[1]);
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return pip[0];
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}
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/*
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* Undo the effects of the last redirection.
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*/
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void
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popredir(void)
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{
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struct redirtab *rp = redirlist;
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int i;
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for (i = 0 ; i < 10 ; i++) {
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if (rp->renamed[i] != EMPTY) {
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if (i == 0)
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fd0_redirected--;
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if (rp->renamed[i] >= 0) {
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dup2(rp->renamed[i], i);
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close(rp->renamed[i]);
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} else {
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close(i);
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}
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}
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}
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INTOFF;
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redirlist = rp->next;
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ckfree(rp);
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INTON;
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}
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/*
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* Undo all redirections. Called on error or interrupt.
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*/
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#ifdef mkinit
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INCLUDE "redir.h"
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RESET {
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while (redirlist)
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popredir();
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}
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SHELLPROC {
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clearredir();
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}
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#endif
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/* Return true if fd 0 has already been redirected at least once. */
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int
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fd0_redirected_p(void)
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{
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return fd0_redirected != 0;
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}
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/*
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* Discard all saved file descriptors.
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*/
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void
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clearredir(void)
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{
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struct redirtab *rp;
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int i;
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for (rp = redirlist ; rp ; rp = rp->next) {
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for (i = 0 ; i < 10 ; i++) {
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if (rp->renamed[i] >= 0) {
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close(rp->renamed[i]);
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}
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rp->renamed[i] = EMPTY;
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}
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}
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}
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