src/input.c

/*-
 * Copyright (c) 1991, 1993
 *	The Regents of the University of California.  All rights reserved.
 * Copyright (c) 1997-2005
 *	Herbert Xu <herbert@gondor.apana.org.au>.  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.
 */

#include <fcntl.h>
#include <stdbool.h>
#include <stdio.h>	/* defines BUFSIZ */
#include <stdlib.h>
#include <string.h>
#include <termios.h>
#include <unistd.h>

/*
 * This file implements the input routines used by the parser.
 */

#include "alias.h"
#include "error.h"
#include "eval.h"
#include "input.h"
#include "main.h"
#include "memalloc.h"
#include "myhistedit.h"
#include "options.h"
#include "output.h"
#include "parser.h"
#include "redir.h"
#include "shell.h"
#include "syntax.h"
#include "system.h"
#include "trap.h"

#define IBUFSIZ (BUFSIZ + PUNGETC_MAX + 1)

MKINIT
struct stdin_state {
	off_t seekable;
	int pip[2];
	int pending;
	tcflag_t bufferable;
};

MKINIT struct parsefile basepf;	/* top level input file */
MKINIT char basebuf[IBUFSIZ];	/* buffer for top level input file */
MKINIT struct parsefile *toppf = &basepf;
MKINIT struct stdin_state stdin_state;
struct parsefile *parsefile = &basepf;	/* current input file */
int whichprompt;		/* 1 == PS1, 2 == PS2 */
int stdin_istty = -1;

STATIC void pushfile(void);
static void popstring(void);
static int preadfd(void);
static void setinputfd(int fd, int push);
static int preadbuffer(void);

#ifdef mkinit
INCLUDE <stdio.h>
INCLUDE <string.h>
INCLUDE <termios.h>
INCLUDE <unistd.h>
INCLUDE "input.h"
INCLUDE "error.h"
INCLUDE "syntax.h"

INIT {
	basepf.nextc = basepf.buf = basebuf;
	basepf.linno = 1;
}

RESET {
	int c;

	/* clear input buffer */
	popallfiles();

	c = PEOF;
	if (toppf->nextc - toppf->buf > toppf->unget)
		c = toppf->nextc[-toppf->unget - 1];
	while (c != '\n' && c != PEOF && !int_pending())
		c = pgetc();
}

FORKRESET {
	popallfiles();
	if (parsefile->fd > 0) {
		close(parsefile->fd);
		parsefile->fd = 0;
	}
	if (stdin_state.pip[0]) {
		close(stdin_state.pip[0]);
		close(stdin_state.pip[1]);
		memset(stdin_state.pip, 0, sizeof(stdin_state.pip));
	}
}

POSTEXITRESET {
	flush_input();
}
#endif

void input_init(void)
{
	struct stdin_state *st = &stdin_state;
	struct termios tios;
	int istty;

	istty = tcgetattr(0, &tios) + 1;
	stdin_istty = istty;
	if (istty)
		st->bufferable = tios.c_lflag & ICANON;
	else {
		st->seekable = lseek(0, 0, SEEK_CUR) + 1;
		st->bufferable = !!st->seekable;
	}
}

static bool stdin_bufferable(void)
{
	struct stdin_state *st = &stdin_state;

	if (stdin_istty < 0)
		input_init();

	return st->bufferable;
}

static void flush_tee(void *buf, int nr, int pending)
{
	while (pending > 0) {
		int err;

		err = read(0, buf, nr > pending ? pending : nr);
		if (err > 0)
			pending -= err;
	}
}

static int stdin_tee(void *buf, int nr)
{
	int err;

	if (!stdin_state.pip[0]) {
		sh_pipe(stdin_state.pip, 0);
		if (stdin_state.pip[0] < 10)
			stdin_state.pip[0] = savefd(stdin_state.pip[0],
						    stdin_state.pip[0]);
		if (stdin_state.pip[1] < 10)
			stdin_state.pip[1] = savefd(stdin_state.pip[1],
						    stdin_state.pip[1]);
	}

	flush_tee(buf, nr, stdin_state.pending);

	if (USE_TEE)
		err = tee(0, stdin_state.pip[1], nr, 0);
	else {
		errno = EINVAL;
		err = -1;
	}
	stdin_state.pending = err;
	return err;
}

static void freestrings(struct strpush *sp)
{
	INTOFF;
	do {
		struct strpush *psp;

		if (sp->ap) {
			sp->ap->flag &= ~ALIASINUSE;
			if (sp->ap->flag & ALIASDEAD) {
				unalias(sp->ap->name);
			}
		}

		psp = sp;
		sp = sp->spfree;

		if (psp != &(parsefile->basestrpush))
			ckfree(psp);
	} while (sp);

	parsefile->spfree = NULL;
	INTON;
}


/*
 * Read a character from the script, returning PEOF on end of file.
 * Nul characters in the input are silently discarded.
 */

int __attribute__((noinline)) pgetc(void)
{
	struct strpush *sp = parsefile->spfree;
	int c;

	if (unlikely(sp))
		freestrings(sp);

again:
	if (parsefile->unget) {
		long unget = -(long)(unsigned)parsefile->unget--;

		return (signed char)parsefile->nextc[unget];
	}

nextc:
	if (likely(parsefile->nleft > 0)) {
		parsefile->nleft--;
		c = (signed char)*parsefile->nextc++;
	} else if (unlikely(parsefile->strpush)) {
		popstring();
		/* The freestrings call must be delayed til the next
		 * pgetc call for PEOA to work properly.
		 */
		goto again;
	} else
		c = preadbuffer();

	/* delete nul characters */
	if (IS_DEFINED_SMALL && unlikely(!c)) {
		parsefile->nextc = memmove(parsefile->nextc - 1,
					   parsefile->nextc, parsefile->nleft);
		goto nextc;
	}

	return c;
}

int pgetc_eoa(void)
{
	return parsefile->strpush && parsefile->nleft == -1 &&
	       parsefile->strpush->ap ? PEOA : pgetc();
}

static int stdin_clear_nonblock(void)
{
	int flags = fcntl(0, F_GETFL, 0);

	if (flags >= 0) {
		flags &=~ O_NONBLOCK;
		flags = fcntl(0, F_SETFL, flags);
	}

	return flags;
}

static int
preadfd(void)
{
	char *buf = parsefile->buf;
	int fd = parsefile->fd;
	bool use_tee;
	int unget;
	int pnr;
	int nr;

	nr = input_get_lleft(parsefile);

	unget = parsefile->nextc - buf;
	if (unget > PUNGETC_MAX)
		unget = PUNGETC_MAX;

	memmove(buf, parsefile->nextc - unget, unget + nr);
	buf += unget;
	parsefile->nextc = buf;
	buf += nr;

	nr = BUFSIZ - nr;
	if (!IS_DEFINED_SMALL && !nr)
		return nr;

	use_tee = likely(!fd) &&
#ifndef SMALL
		  !el &&
#endif
		  !stdin_bufferable();

	pnr = nr;
retry:
	nr = pnr;
#ifndef SMALL
	if (fd == 0 && el) {
		static const char *rl_cp;
		static int el_len;

		if (rl_cp == NULL) {
			struct stackmark smark;
			pushstackmark(&smark, stackblocksize());
			rl_cp = el_gets(el, &el_len);
			popstackmark(&smark);
		}
		if (rl_cp == NULL)
			nr = 0;
		else {
			if (nr > el_len)
				nr = el_len;
			memcpy(buf, rl_cp, nr);
			if (nr != el_len) {
				el_len -= nr;
				rl_cp += nr;
			} else
				rl_cp = 0;
		}

		return nr;
	}
#endif

	if (likely(use_tee)) {
		nr = stdin_tee(buf, nr);
		if (nr >= 0)
			fd = stdin_state.pip[0];
		else if (errno == EINVAL) {
			use_tee = false;
			nr = pnr = 1;
		}
	}

	if (nr > 0)
		nr = read(fd, buf, nr);

	if (nr < 0) {
		if (errno == EINTR && !(basepf.prev && pending_sig))
			goto retry;
		if (fd == 0 && errno == EWOULDBLOCK &&
		    stdin_clear_nonblock() >= 0) {
			out2str("sh: turning off NDELAY mode\n");
			goto retry;
		}
	}
	return nr;
}

/*
 * Refill the input buffer and return the next input character:
 *
 * 1) If a string was pushed back on the input, pop it;
 * 2) If we are reading from a string we can't refill the buffer, return EOF.
 * 3) If there is more stuff in this buffer, use it else call read to fill it.
 * 4) Process input up to the next newline, deleting nul characters.
 */

static int preadbuffer(void)
{
	int first = whichprompt == 1;
	int something;
	char savec;
	int more;
	char *q;

	if (parsefile->eof & 2) {
eof:
		parsefile->eof = 3;
		return PEOF;
	}
	flushall();

	q = parsefile->nextc;
	something = !first;

	more = input_get_lleft(parsefile);

	INTOFF;
	if (more <= 0) {
		int nr;

again:
		nr = q - parsefile->nextc;
		input_set_lleft(parsefile, nr);
		more = preadfd();
		q = parsefile->nextc + nr;
		if (more <= 0) {
			input_set_lleft(parsefile, parsefile->nleft = 0);
			if (!IS_DEFINED_SMALL && nr > 0)
				goto save;
			INTON;
			goto eof;
		}
	}

	if (IS_DEFINED_SMALL) {
		q += more;
		more = 0;
		goto done;
	}

	/* delete nul characters */
	for (;;) {
		int c;

		more--;
		c = *q;

		if (!c) {
			memmove(q, q + 1, more);
			goto check;
		}

		q++;

		switch (c) {
		case '\n':
			goto done;

		default:
			something = 1;
			/* fall through */

		case '\t':
		case ' ':
			break;
		}

check:
		if (more <= 0)
			goto again;
	}
done:
	input_set_lleft(parsefile, more);

save:
	parsefile->nleft = q - parsefile->nextc - 1;
	if (!IS_DEFINED_SMALL)
		savec = *q;
	*q = '\0';

	if (parsefile->fd == 0 && hist && something) {
		HistEvent he;
		history(hist, &he, first ? H_ENTER : H_APPEND,
			parsefile->nextc);
	}
	INTON;

	if (vflag) {
		out2str(parsefile->nextc);
#ifdef FLUSHERR
		flushout(out2);
#endif
	}

	if (!IS_DEFINED_SMALL)
		*q = savec;

	return (signed char)*parsefile->nextc++;
}

void pungetn(int n)
{
	parsefile->unget += n;
}

/*
 * Undo a call to pgetc.  Only two characters may be pushed back.
 * PEOF may be pushed back.
 */

void
pungetc(void)
{
	pungetn(1 - (parsefile->eof & 1));
	parsefile->eof &= ~1;
}

/*
 * Push a string back onto the input at this current parsefile level.
 * We handle aliases this way.
 */
void
pushstring(char *s, void *ap)
{
	struct strpush *sp;
	size_t len;

	len = strlen(s);
	INTOFF;
/*dprintf("*** calling pushstring: %s, %d\n", s, len);*/
	if ((unsigned long)parsefile->strpush |
	    (unsigned long)parsefile->spfree) {
		sp = ckmalloc(sizeof (struct strpush));
		sp->prev = parsefile->strpush;
		parsefile->strpush = sp;
	} else
		sp = parsefile->strpush = &(parsefile->basestrpush);
	sp->prevstring = parsefile->nextc;
	sp->prevnleft = parsefile->nleft;
	sp->unget = parsefile->unget;
	sp->spfree = parsefile->spfree;
	sp->ap = (struct alias *)ap;
	if (ap) {
		((struct alias *)ap)->flag |= ALIASINUSE;
		sp->string = ((struct alias *)ap)->name;
	}
	parsefile->nextc = s;
	parsefile->nleft = len;
	parsefile->unget = 0;
	parsefile->spfree = NULL;
	INTON;
}

static void popstring(void)
{
	struct strpush *sp = parsefile->strpush;

	INTOFF;
	if (sp->ap && parsefile->nextc > sp->string) {
		if (parsefile->nextc[-1] == ' ' ||
		    parsefile->nextc[-1] == '\t') {
			checkkwd |= CHKALIAS;
		}
		if (sp->string != sp->ap->name) {
			ckfree(sp->string);
		}
	}
	parsefile->nextc = sp->prevstring;
	parsefile->nleft = sp->prevnleft;
	parsefile->unget = sp->unget;
/*dprintf("*** calling popstring: restoring to '%s'\n", parsenextc);*/
	parsefile->strpush = sp->prev;
	parsefile->spfree = sp;
	INTON;
}

/*
 * Set the input to take input from a file.  If push is set, push the
 * old input onto the stack first.
 */

int
setinputfile(const char *fname, int flags)
{
	int fd;

	INTOFF;
	fd = sh_open(fname, O_RDONLY, flags & INPUT_NOFILE_OK);
	if (fd < 0)
		goto out;
	if (fd < 10)
		fd = savefd(fd, fd);
	setinputfd(fd, flags & INPUT_PUSH_FILE);
out:
	INTON;
	return fd;
}


/*
 * Like setinputfile, but takes an open file descriptor.  Call this with
 * interrupts off.
 */

static void
setinputfd(int fd, int push)
{
	pushfile();
	if (!push)
		toppf = parsefile;
	parsefile->fd = fd;
	parsefile->nextc = parsefile->buf = ckmalloc(IBUFSIZ);
}


/*
 * Like setinputfile, but takes input from a string.
 */

void
setinputstring(char *string)
{
	INTOFF;
	pushfile();
	parsefile->nextc = string;
	parsefile->nleft = strlen(string);
	parsefile->eof = 2;
	INTON;
}



/*
 * To handle the "." command, a stack of input files is used.  Pushfile
 * adds a new entry to the stack and popfile restores the previous level.
 */

STATIC void
pushfile(void)
{
	struct parsefile *pf;

	pf = (struct parsefile *)ckmalloc(sizeof (struct parsefile));
	memset(pf, 0, sizeof(*pf));
	pf->prev = parsefile;
	pf->linno = 1;
	pf->fd = -1;
	parsefile = pf;
}

void pushstdin(void)
{
	INTOFF;
	basepf.prev = parsefile;
	parsefile = &basepf;
	INTON;
}

void
popfile(void)
{
	struct parsefile *pf = parsefile;

	INTOFF;
	parsefile = pf->prev;
	pf->prev = NULL;
	if (pf == &basepf)
		goto out;

	if (pf->fd >= 0)
		close(pf->fd);
	ckfree(pf->buf);
	if (parsefile->spfree)
		freestrings(parsefile->spfree);
	while (pf->strpush) {
		popstring();
		freestrings(parsefile->spfree);
	}
	ckfree(pf);

out:
	INTON;
}


void __attribute__((noinline)) unwindfiles(struct parsefile *stop)
{
	while (basepf.prev || parsefile != stop)
		popfile();
}


/*
 * Return to top level.
 */

void
popallfiles(void)
{
	unwindfiles(toppf);
}

void __attribute__((noinline)) flush_input(void)
{
	int left = basepf.nleft + input_get_lleft(&basepf);

	INTOFF;
	if (stdin_state.seekable && left)
		lseek(0, -left, SEEK_CUR);
	else if (stdin_state.pending > left) {
		flush_tee(basebuf, BUFSIZ, stdin_state.pending - left);
		stdin_state.pending = 0;
	}
	input_set_lleft(&basepf, basepf.nleft = 0);
	INTON;
}

void reset_input(void)
{
	stdin_istty = -1;
	basepf.eof = 0;
	flush_input();
}