/*	$NetBSD: redir.c,v 1.29 2004/07/08 03:57:33 christos Exp $	*/

/*-
 * Copyright (c) 1991, 1993
 *	The Regents of the University of California.  All rights reserved.
 *
 * This code is derived from software contributed to Berkeley by
 * Kenneth Almquist.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */

#if 0
#ifndef lint
static char sccsid[] = "@(#)redir.c	8.2 (Berkeley) 5/4/95";
#else
__RCSID("$NetBSD: redir.c,v 1.29 2004/07/08 03:57:33 christos Exp $");
#endif /* not lint */
#endif

#include <sys/types.h>
#include <limits.h>         /* PIPE_BUF */
#include <string.h>
#include <errno.h>
#include <stddef.h>
#include <stdlib.h>

/*
 * Code for dealing with input/output redirection.
 */

#include "main.h"
#include "shell.h"
#include "nodes.h"
#include "jobs.h"
#include "options.h"
#include "expand.h"
#include "redir.h"
#include "output.h"
#include "memalloc.h"
#include "error.h"
#include "shinstance.h"


#define EMPTY -2		/* marks an unused slot in redirtab */
#define PIPESIZE SHFILE_PIPE_SIZE


//MKINIT struct redirtab *redirlist;

/*
 * We keep track of whether or not fd0 has been redirected.  This is for
 * background commands, where we want to redirect fd0 to /dev/null only
 * if it hasn't already been redirected.
*/
//int fd0_redirected = 0;

STATIC void openredirect(shinstance *, union node *, char[10], int, const char *);
STATIC int openhere(shinstance *, union node *);


#ifndef SH_FORKED_MODE
void
subshellinitredir(shinstance *psh, shinstance *inherit)
{
    /* We can have a redirlist here if we're handling backtick while expanding
       arguments, just copy it even if the subshell probably doesn't need it. */
    struct redirtab *src = inherit->redirlist;
    if (src)
    {
        struct redirtab **dstp = &psh->redirlist;
	do
	{
	    struct redirtab *dst = ckmalloc(psh, sizeof(*dst));
	    memcpy(dst->renamed, src->renamed, sizeof(dst->renamed));
	    *dstp = dst;
	    dstp = &dst->next;
	    src = src->next;
	} while (src);
	*dstp = NULL;

        psh->fd0_redirected = inherit->fd0_redirected;
    }

    /* Copy the expanded redirection filenames (stack), but only the last entry
       as the subshell does not have the ability to unwind stack in the parent
       and therefore cannot get to the earlier redirection stuff: */
    if (inherit->expfnames)
    {
	redirexpfnames * const expfnamesrc = inherit->expfnames;
	unsigned i = expfnamesrc->count;
	redirexpfnames *dst = stalloc(psh, offsetof(redirexpfnames, names) + sizeof(dst->names[0]) * i);
	dst->count = i;
	dst->depth = 1;
	dst->prev = NULL;
	while (i-- > 0)
	    dst->names[i] = stsavestr(psh, expfnamesrc->names[i]);
	psh->expfnames = dst;
    }
}
#endif /* !SH_FORKED_MODE */


/*
 * Process a list of redirection commands.  If the REDIR_PUSH flag is set,
 * old file descriptors are stashed away so that the redirection can be
 * undone by calling popredir.  If the REDIR_BACKQ flag is set, then the
 * standard output, and the standard error if it becomes a duplicate of
 * stdout, is saved in memory.
 */

void
redirect(shinstance *psh, union node *redir, int flags)
{
	union node *n;
	struct redirtab *sv = NULL;
	int i;
	int fd;
	int try;
	char memory[10];	/* file descriptors to write to memory */
	unsigned idxexpfname;

	for (i = 10 ; --i >= 0 ; )
		memory[i] = 0;
	memory[1] = flags & REDIR_BACKQ;
	if (flags & REDIR_PUSH) {
		sv = ckmalloc(psh, sizeof (struct redirtab));
		for (i = 0 ; i < 10 ; i++)
			sv->renamed[i] = EMPTY;
		sv->next = psh->redirlist;
		psh->redirlist = sv;
	}
	idxexpfname = 0;
	for (n = redir, idxexpfname = 0 ; n ; n = n->nfile.next, idxexpfname++) {
		kHlpAssert(idxexpfname < psh->expfnames->count);
		fd = n->nfile.fd;
		try = 0;
		if ((n->nfile.type == NTOFD || n->nfile.type == NFROMFD) &&
		    n->ndup.dupfd == fd)
			continue; /* redirect from/to same file descriptor */

		if ((flags & REDIR_PUSH) && sv->renamed[fd] == EMPTY) {
			INTOFF;
again:
			if ((i = shfile_fcntl(&psh->fdtab, fd, F_DUPFD, 10)) == -1) {
				switch (errno) {
				case EBADF:
					if (!try) {
						openredirect(psh, n, memory, flags, psh->expfnames->names[idxexpfname]);
						try++;
						goto again;
					}
					/* FALLTHROUGH*/
				default:
					INTON;
					error(psh, "%d: %s", fd, sh_strerror(psh, errno));
					/* NOTREACHED */
				}
			}
			if (!try) {
				sv->renamed[fd] = i;
				shfile_close(&psh->fdtab, fd);
			}
			INTON;
		} else {
			shfile_close(&psh->fdtab, fd);
		}
                if (fd == 0)
                        psh->fd0_redirected++;
		if (!try)
			openredirect(psh, n, memory, flags, psh->expfnames->names[idxexpfname]);
	}
	kHlpAssert(!redir || idxexpfname == psh->expfnames->count);
	if (memory[1])
		psh->out1 = &psh->memout;
	if (memory[2])
		psh->out2 = &psh->memout;
}


STATIC void
openredirect(shinstance *psh, union node *redir, char memory[10], int flags, const char *fname)
{
	int fd = redir->nfile.fd;
	int f;
	int oflags = O_WRONLY|O_CREAT|O_TRUNC;

	/*
	 * We suppress interrupts so that we won't leave open file
	 * descriptors around.  This may not be such a good idea because
	 * an open of a device or a fifo can block indefinitely.
	 */
	INTOFF;
	memory[fd] = 0;
	switch (redir->nfile.type) {
	case NFROM:
		if ((f = shfile_open(&psh->fdtab, fname, O_RDONLY, 0)) < 0)
			goto eopen;
		break;
	case NFROMTO:
		if ((f = shfile_open(&psh->fdtab, fname, O_RDWR|O_CREAT|O_TRUNC, 0666)) < 0)
			goto ecreate;
		break;
	case NTO:
		if (Cflag(psh))
			oflags |= O_EXCL;
		/* FALLTHROUGH */
	case NCLOBBER:
		if ((f = shfile_open(&psh->fdtab, fname, oflags, 0666)) < 0)
			goto ecreate;
		break;
	case NAPPEND:
		if ((f = shfile_open(&psh->fdtab, fname, O_WRONLY|O_CREAT|O_APPEND, 0666)) < 0)
			goto ecreate;
		break;
	case NTOFD:
	case NFROMFD:
		if (redir->ndup.dupfd >= 0) {	/* if not ">&-" */
			if (memory[redir->ndup.dupfd])
				memory[fd] = 1;
			else
				copyfd(psh, redir->ndup.dupfd, fd);
		}
		INTON;
		return;
	case NHERE:
	case NXHERE:
		f = openhere(psh, redir);
		break;
	default:
		sh_abort(psh);
	}

	if (f != fd) {
		movefd(psh, f, fd);
	}
	INTON;
	return;
ecreate:
	error(psh, "cannot create %s: %s", fname, errmsg(psh, errno, E_CREAT));
eopen:
	error(psh, "cannot open %s: %s", fname, errmsg(psh, errno, E_OPEN));
}

#ifdef KASH_USE_FORKSHELL2
struct openherechild
{
	int pip[2];
	size_t len;
};
static int openhere_child(shinstance *psh, union node *n, void *argp)
{
	struct openherechild args = *(struct openherechild *)argp;

	shfile_close(&psh->fdtab, args.pip[0]);
	sh_signal(psh, SIGINT, SH_SIG_IGN);
	sh_signal(psh, SIGQUIT, SH_SIG_IGN);
	sh_signal(psh, SIGHUP, SH_SIG_IGN);
# ifdef SIGTSTP
	sh_signal(psh, SIGTSTP, SH_SIG_IGN);
# endif
	sh_signal(psh, SIGPIPE, SH_SIG_DFL);
	if (n->type == NHERE)
		xwrite(psh, args.pip[1], n->nhere.doc->narg.text, args.len);
	else
		expandhere(psh, n->nhere.doc, args.pip[1]);
	return 0;
}

#endif /* KASH_USE_FORKSHELL2*/

/*
 * Handle here documents.  Normally we fork off a process to write the
 * data to a pipe.  If the document is short, we can stuff the data in
 * the pipe without forking.
 */

STATIC int
openhere(shinstance *psh, union node *redir)
{
	int pip[2];
	size_t len = 0;

	if (shfile_pipe(&psh->fdtab, pip) < 0)
		error(psh, "Pipe call failed");
	if (redir->type == NHERE) {
		len = strlen(redir->nhere.doc->narg.text);
		if (len <= PIPESIZE) {
			xwrite(psh, pip[1], redir->nhere.doc->narg.text, len);
			goto out;
		}
	}
#ifdef KASH_USE_FORKSHELL2
	{
		struct openherechild args;
		args.pip[0] = pip[0];
		args.pip[1] = pip[1];
		args.len = len;
		forkshell2(psh, (struct job *)NULL, redir,
			   FORK_NOJOB | FORK_JUST_IO,
			   openhere_child, redir, &args, sizeof(args), NULL);
	}
#else
	if (forkshell(psh, (struct job *)NULL, (union node *)NULL, FORK_NOJOB) == 0) {
		shfile_close(&psh->fdtab, pip[0]);
		sh_signal(psh, SIGINT, SH_SIG_IGN);
		sh_signal(psh, SIGQUIT, SH_SIG_IGN);
		sh_signal(psh, SIGHUP, SH_SIG_IGN);
#ifdef SIGTSTP
		sh_signal(psh, SIGTSTP, SH_SIG_IGN);
#endif
		sh_signal(psh, SIGPIPE, SH_SIG_DFL);
		if (redir->type == NHERE)
			xwrite(psh, pip[1], redir->nhere.doc->narg.text, len);
		else
			expandhere(psh, redir->nhere.doc, pip[1]);
		sh__exit(psh, 0);
	}
#endif
out:
	shfile_close(&psh->fdtab, pip[1]);
	return pip[0];
}



/*
 * Undo the effects of the last redirection.
 */

void
popredir(shinstance *psh)
{
	struct redirtab *rp = psh->redirlist;
	int i;

	for (i = 0 ; i < 10 ; i++) {
		if (rp->renamed[i] != EMPTY) {
			if (i == 0)
				psh->fd0_redirected--;
			if (rp->renamed[i] >= 0) {
				movefd(psh, rp->renamed[i], i);
			} else {
				shfile_close(&psh->fdtab, i);
			}
		}
	}
	INTOFF;
	psh->redirlist = rp->next;
	ckfree(psh, rp);
	INTON;
}

/*
 * Undo all redirections.  Called on error or interrupt.
 */

#ifdef mkinit

INCLUDE "redir.h"

RESET {
	while (psh->redirlist)
		popredir(psh);
}

SHELLPROC {
	clearredir(psh);
}

#endif

/* Return true if fd 0 has already been redirected at least once.  */
int
fd0_redirected_p(shinstance *psh) {
        return psh->fd0_redirected != 0;
}

/*
 * Discard all saved file descriptors.
 */

void
clearredir(shinstance *psh)
{
	struct redirtab *rp;
	int i;

	for (rp = psh->redirlist ; rp ; rp = rp->next) {
		for (i = 0 ; i < 10 ; i++) {
			if (rp->renamed[i] >= 0) {
				shfile_close(&psh->fdtab, rp->renamed[i]);
			}
			rp->renamed[i] = EMPTY;
		}
	}
}



/*
 * Copy a file descriptor to be >= to.  Returns -1
 * if the source file descriptor is closed, EMPTY if there are no unused
 * file descriptors left.
 */

int
copyfd(shinstance *psh, int from, int to)
{
	int newfd;

	newfd = shfile_fcntl(&psh->fdtab, from, F_DUPFD, to);
	if (newfd < 0) {
		if (errno == EMFILE)
			return EMPTY;
		error(psh, "%d: %s", from, sh_strerror(psh, errno));
	}
	return newfd;
}


/*
 * Move a file descriptor to be == to.  Returns -1
 * if the source file descriptor is closed, EMPTY if there are no unused
 * file descriptors left.
 */

int
movefd(shinstance *psh, int from, int to)
{
	int newfd;

	newfd = shfile_movefd(&psh->fdtab, from, to);
	if (newfd < 0) {
		if (errno == EMFILE)
			return EMPTY;
		error(psh, "%d: %s", from, sh_strerror(psh, errno));
	}
	return newfd;
}


/*
 * Move a file descriptor to be >= to.  Returns -1
 * if the source file descriptor is closed, EMPTY if there are no unused
 * file descriptors left.
 */

int
movefd_above(shinstance *psh, int from, int to)
{
	int newfd;

	newfd = shfile_movefd_above(&psh->fdtab, from, to);
	if (newfd < 0) {
		if (errno == EMFILE)
			return EMPTY;
		error(psh, "%d: %s", from, sh_strerror(psh, errno));
	}
	return newfd;
}