7236eb0dda
Use non-blocking I/O to write as much as the pipe will accept (often 64K, but it can be as little as 4K), avoiding the need for the ugly PIPESIZE constant. If PIPESIZE was set too high, a deadlock would occur.
365 lines
8.5 KiB
C
365 lines
8.5 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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* 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 CLOSED -1 /* fd was not open before redir */
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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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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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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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if ((i = fcntl(fd, F_DUPFD, 10)) == -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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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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} else
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(void)fcntl(i, F_SETFD, FD_CLOEXEC);
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sv->renamed[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);
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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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int e;
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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. Because the signal handler remains
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* installed and we do not use system call restart, interrupts
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* will still abort blocking opens such as fifos (they will fail
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* with EINTR). There is, however, a race condition if an interrupt
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* arrives after INTOFF and before open blocks.
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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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if (dup2(f, fd) == -1) {
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e = errno;
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close(f);
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error("%d: %s", fd, strerror(e));
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}
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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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if (Cflag) {
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fname = redir->nfile.expfname;
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if (stat(fname, &sb) == -1) {
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if ((f = open(fname, O_WRONLY|O_CREAT|O_EXCL, 0666)) < 0)
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error("cannot create %s: %s", fname, strerror(errno));
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} else if (!S_ISREG(sb.st_mode)) {
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if ((f = open(fname, O_WRONLY, 0666)) < 0)
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error("cannot create %s: %s", fname, strerror(errno));
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if (fstat(f, &sb) != -1 && S_ISREG(sb.st_mode)) {
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close(f);
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error("cannot create %s: %s", fname,
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strerror(EEXIST));
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}
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} else
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error("cannot create %s: %s", fname,
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strerror(EEXIST));
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goto movefd;
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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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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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if (dup2(redir->ndup.dupfd, fd) < 0)
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error("%d: %s", redir->ndup.dupfd,
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strerror(errno));
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}
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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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char *p;
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int pip[2];
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size_t len = 0;
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int flags;
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ssize_t written = 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 == NXHERE)
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p = redir->nhere.expdoc;
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else
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p = redir->nhere.doc->narg.text;
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len = strlen(p);
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if (len == 0)
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goto out;
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flags = fcntl(pip[1], F_GETFL, 0);
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if (flags != -1 && fcntl(pip[1], F_SETFL, flags | O_NONBLOCK) != -1) {
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written = write(pip[1], p, len);
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if (written < 0)
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written = 0;
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if ((size_t)written == len)
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goto out;
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fcntl(pip[1], F_SETFL, flags);
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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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xwrite(pip[1], p + written, len - written);
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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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#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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