554 lines
12 KiB
C
554 lines
12 KiB
C
/* $NetBSD: redir.c,v 1.47 2016/05/12 13:31:37 kre Exp $ */
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/*-
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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. 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[] = "@(#)redir.c 8.2 (Berkeley) 5/4/95";
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#else
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__RCSID("$NetBSD: redir.c,v 1.47 2016/05/12 13:31:37 kre Exp $");
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#endif
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#endif /* not lint */
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#include <sys/types.h>
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#include <sys/param.h> /* PIPE_BUF */
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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 "main.h"
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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 "options.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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#define EMPTY -2 /* marks an unused slot in redirtab */
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#define CLOSED -1 /* fd was not open before redir */
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#ifndef PIPE_BUF
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# define PIPESIZE 4096 /* amount of buffering in a pipe */
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#else
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# define PIPESIZE PIPE_BUF
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#endif
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MKINIT
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struct renamelist {
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struct renamelist *next;
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int orig;
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int into;
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};
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MKINIT
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struct redirtab {
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struct redirtab *next;
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struct renamelist *renamed;
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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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/*
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* And also where to put internal use fds that should be out of the
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* way of user defined fds (normally)
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*/
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STATIC int big_sh_fd = 0;
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STATIC const struct renamelist *is_renamed(const struct renamelist *, int);
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STATIC void fd_rename(struct redirtab *, int, int);
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STATIC void free_rl(struct redirtab *, int);
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STATIC void openredirect(union node *, char[10], int);
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STATIC int openhere(const union node *);
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STATIC int copyfd(int, int, int);
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STATIC void find_big_fd(void);
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STATIC const struct renamelist *
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is_renamed(const struct renamelist *rl, int fd)
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{
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while (rl != NULL) {
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if (rl->orig == fd)
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return rl;
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rl = rl->next;
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}
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return NULL;
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}
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STATIC void
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free_rl(struct redirtab *rt, int reset)
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{
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struct renamelist *rl, *rn = rt->renamed;
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while ((rl = rn) != NULL) {
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rn = rl->next;
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if (rl->orig == 0)
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fd0_redirected--;
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if (reset) {
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if (rl->into < 0)
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close(rl->orig);
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else
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movefd(rl->into, rl->orig);
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}
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ckfree(rl);
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}
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rt->renamed = NULL;
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}
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STATIC void
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fd_rename(struct redirtab *rt, int from, int to)
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{
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struct renamelist *rl = ckmalloc(sizeof(struct renamelist));
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rl->next = rt->renamed;
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rt->renamed = rl;
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rl->orig = from;
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rl->into = to;
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}
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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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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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/* We don't have to worry about REDIR_VFORK here, as
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* flags & REDIR_PUSH is never true if REDIR_VFORK is set.
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*/
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sv = ckmalloc(sizeof (struct redirtab));
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sv->renamed = NULL;
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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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if ((n->nfile.type == NTOFD || n->nfile.type == NFROMFD) &&
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n->ndup.dupfd == fd) {
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/* redirect from/to same file descriptor */
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/* make sure it stays open */
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if (fcntl(fd, F_SETFD, 0) < 0)
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error("fd %d: %s", fd, strerror(errno));
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continue;
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}
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if ((flags & REDIR_PUSH) && !is_renamed(sv->renamed, fd)) {
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INTOFF;
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if (big_sh_fd < 10)
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find_big_fd();
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if ((i = fcntl(fd, F_DUPFD, big_sh_fd)) == -1) {
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switch (errno) {
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case EBADF:
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i = CLOSED;
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break;
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case EMFILE:
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case EINVAL:
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find_big_fd();
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i = fcntl(fd, F_DUPFD, big_sh_fd);
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if (i >= 0)
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break;
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/* FALLTHRU */
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default:
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i = errno;
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INTON; /* XXX not needed here ? */
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error("%d: %s", fd, strerror(i));
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/* NOTREACHED */
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}
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}
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if (i >= 0)
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(void)fcntl(i, F_SETFD, FD_CLOEXEC);
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fd_rename(sv, fd, i);
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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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openredirect(n, memory, flags);
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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], int flags)
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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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int eflags, cloexec;
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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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if (fd < 10)
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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 (flags & REDIR_VFORK)
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eflags = O_NONBLOCK;
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else
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eflags = 0;
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if ((f = open(fname, O_RDONLY|eflags)) < 0)
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goto eopen;
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if (eflags)
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(void)fcntl(f, F_SETFL, fcntl(f, F_GETFL, 0) & ~eflags);
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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|O_TRUNC, 0666)) < 0)
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goto ecreate;
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break;
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case NTO:
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if (Cflag) {
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fname = redir->nfile.expfname;
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if ((f = open(fname, O_WRONLY)) == -1) {
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if ((f = open(fname, O_WRONLY|O_CREAT|O_EXCL,
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0666)) < 0)
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goto ecreate;
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} else if (fstat(f, &sb) == -1) {
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int serrno = errno;
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close(f);
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errno = serrno;
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goto ecreate;
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} else if (S_ISREG(sb.st_mode)) {
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close(f);
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errno = EEXIST;
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goto ecreate;
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}
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break;
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}
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/* FALLTHROUGH */
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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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goto ecreate;
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break;
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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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goto ecreate;
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break;
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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 (fd < 10 && redir->ndup.dupfd < 10 &&
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memory[redir->ndup.dupfd])
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memory[fd] = 1;
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else if (copyfd(redir->ndup.dupfd, fd,
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(flags&(REDIR_PUSH|REDIR_KEEP)) == REDIR_PUSH) < 0)
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error("Redirect (from %d to %d) failed: %s",
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redir->ndup.dupfd, fd, strerror(errno));
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} else
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(void) close(fd);
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INTON;
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return;
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case NHERE:
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case NXHERE:
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f = openhere(redir);
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break;
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default:
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abort();
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}
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cloexec = fd > 2 && (flags & REDIR_KEEP) == 0;
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if (f != fd) {
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if (copyfd(f, fd, cloexec) < 0) {
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int e = errno;
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close(f);
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error("redirect reassignment (fd %d) failed: %s", fd,
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strerror(e));
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}
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close(f);
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} else if (cloexec)
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(void)fcntl(f, F_SETFD, FD_CLOEXEC);
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INTON;
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return;
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ecreate:
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exerrno = 1;
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error("cannot create %s: %s", fname, errmsg(errno, E_CREAT));
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eopen:
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exerrno = 1;
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error("cannot open %s: %s", fname, errmsg(errno, E_OPEN));
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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(const 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");
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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(NULL, 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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#ifdef SIGTSTP
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signal(SIGTSTP, SIG_IGN);
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#endif
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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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INTOFF;
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free_rl(rp, 1);
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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(0);
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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(int vforked)
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{
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struct redirtab *rp;
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struct renamelist *rl;
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for (rp = redirlist ; rp ; rp = rp->next) {
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if (!vforked)
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free_rl(rp, 0);
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else for (rl = rp->renamed; rl; rl = rl->next)
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if (rl->into >= 0)
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close(rl->into);
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}
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}
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/*
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* Copy a file descriptor to be == to.
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* cloexec indicates if we want close-on-exec or not.
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* Returns -1 if any error occurs.
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*/
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STATIC int
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copyfd(int from, int to, int cloexec)
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{
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int newfd;
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if (cloexec && to > 2)
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newfd = dup3(from, to, O_CLOEXEC);
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else
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newfd = dup2(from, to);
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return newfd;
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}
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/*
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* rename fd from to be fd to (closing from).
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* close-on-exec is never set on 'to' (unless
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* from==to and it was set on from) - ie: a no-op
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* returns to (or errors() if an error occurs).
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*
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* This is mostly used for rearranging the
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* results from pipe().
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*/
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int
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movefd(int from, int to)
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{
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if (from == to)
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return to;
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(void) close(to);
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if (copyfd(from, to, 0) != to) {
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int e = errno;
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(void) close(from);
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error("Unable to make fd %d: %s", to, strerror(e));
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}
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(void) close(from);
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return to;
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}
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STATIC void
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find_big_fd(void)
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{
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int i, fd;
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for (i = (1 << 10); i >= 10; i >>= 1) {
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if ((fd = fcntl(0, F_DUPFD, i - 1)) >= 0) {
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close(fd);
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break;
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}
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}
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fd = (i / 5) * 4;
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if ((i - fd) > 100)
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fd = i - 100;
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else if (fd < 10)
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fd = 10;
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big_sh_fd = fd;
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}
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/*
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* If possible, move file descriptor fd out of the way
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* of expected user fd values. Returns the new fd
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* (which may be the input fd if things do not go well.)
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* Always set close-on-exec on the result, and close
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* the input fd unless it is to be our result.
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*/
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int
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to_upper_fd(int fd)
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{
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int i;
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if (big_sh_fd < 10)
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find_big_fd();
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do {
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i = fcntl(fd, F_DUPFD_CLOEXEC, big_sh_fd);
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if (i >= 0) {
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if (fd != i)
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close(fd);
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return i;
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}
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if (errno != EMFILE)
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break;
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find_big_fd();
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} while (big_sh_fd > 10);
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/*
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* If we wanted to move this fd to some random high number
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* we certainly do not intend to pass it through exec, even
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* if the reassignment failed.
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*/
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(void)fcntl(fd, F_SETFD, FD_CLOEXEC);
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return fd;
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}
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