input.c revision 1.1 
1/*-
2 * Copyright (c) 1991 The Regents of the University of California.
3 * All rights reserved.
4 *
5 * This code is derived from software contributed to Berkeley by
6 * Kenneth Almquist.
7 *
8 * Redistribution and use in source and binary forms, with or without
9 * modification, are permitted provided that the following conditions
10 * are met:
11 * 1. Redistributions of source code must retain the above copyright
12 *    notice, this list of conditions and the following disclaimer.
13 * 2. Redistributions in binary form must reproduce the above copyright
14 *    notice, this list of conditions and the following disclaimer in the
15 *    documentation and/or other materials provided with the distribution.
16 * 3. All advertising materials mentioning features or use of this software
17 *    must display the following acknowledgement:
18 *	This product includes software developed by the University of
19 *	California, Berkeley and its contributors.
20 * 4. Neither the name of the University nor the names of its contributors
21 *    may be used to endorse or promote products derived from this software
22 *    without specific prior written permission.
23 *
24 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
25 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
26 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
27 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
28 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
29 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
30 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
31 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
32 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
33 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
34 * SUCH DAMAGE.
35 */
36
37#ifndef lint
38static char sccsid[] = "@(#)input.c	5.4 (Berkeley) 7/1/91";
39#endif /* not lint */
40
41/*
42 * This file implements the input routines used by the parser.
43 */
44
45#include <stdio.h>	/* defines BUFSIZ */
46#include "shell.h"
47#include <fcntl.h>
48#include <errno.h>
49#include "syntax.h"
50#include "input.h"
51#include "output.h"
52#include "memalloc.h"
53#include "error.h"
54
55#define EOF_NLEFT -99		/* value of parsenleft when EOF pushed back */
56
57
58/*
59 * The parsefile structure pointed to by the global variable parsefile
60 * contains information about the current file being read.
61 */
62
63MKINIT
64struct parsefile {
65	int linno;		/* current line */
66	int fd;			/* file descriptor (or -1 if string) */
67	int nleft;		/* number of chars left in buffer */
68	char *nextc;		/* next char in buffer */
69	struct parsefile *prev;	/* preceding file on stack */
70	char *buf;		/* input buffer */
71};
72
73
74int plinno = 1;			/* input line number */
75MKINIT int parsenleft;		/* copy of parsefile->nleft */
76char *parsenextc;		/* copy of parsefile->nextc */
77MKINIT struct parsefile basepf;	/* top level input file */
78char basebuf[BUFSIZ];		/* buffer for top level input file */
79struct parsefile *parsefile = &basepf;	/* current input file */
80char *pushedstring;		/* copy of parsenextc when text pushed back */
81int pushednleft;		/* copy of parsenleft when text pushed back */
82
83#ifdef __STDC__
84STATIC void pushfile(void);
85#else
86STATIC void pushfile();
87#endif
88
89
90
91#ifdef mkinit
92INCLUDE "input.h"
93INCLUDE "error.h"
94
95INIT {
96	extern char basebuf[];
97
98	basepf.nextc = basepf.buf = basebuf;
99}
100
101RESET {
102	if (exception != EXSHELLPROC)
103		parsenleft = 0;            /* clear input buffer */
104	popallfiles();
105}
106
107SHELLPROC {
108	popallfiles();
109}
110#endif
111
112
113/*
114 * Read a line from the script.
115 */
116
117char *
118pfgets(line, len)
119	char *line;
120	{
121	register char *p = line;
122	int nleft = len;
123	int c;
124
125	while (--nleft > 0) {
126		c = pgetc_macro();
127		if (c == PEOF) {
128			if (p == line)
129				return NULL;
130			break;
131		}
132		*p++ = c;
133		if (c == '\n')
134			break;
135	}
136	*p = '\0';
137	return line;
138}
139
140
141
142/*
143 * Read a character from the script, returning PEOF on end of file.
144 * Nul characters in the input are silently discarded.
145 */
146
147int
148pgetc() {
149	return pgetc_macro();
150}
151
152
153/*
154 * Refill the input buffer and return the next input character:
155 *
156 * 1) If a string was pushed back on the input, switch back to the regular
157 *    buffer.
158 * 2) If an EOF was pushed back (parsenleft == EOF_NLEFT) or we are reading
159 *    from a string so we can't refill the buffer, return EOF.
160 * 3) Call read to read in the characters.
161 * 4) Delete all nul characters from the buffer.
162 */
163
164int
165preadbuffer() {
166	register char *p, *q;
167	register int i;
168
169	if (pushedstring) {
170		parsenextc = pushedstring;
171		pushedstring = NULL;
172		parsenleft = pushednleft;
173		if (--parsenleft >= 0)
174			return *parsenextc++;
175	}
176	if (parsenleft == EOF_NLEFT || parsefile->buf == NULL)
177		return PEOF;
178	flushout(&output);
179	flushout(&errout);
180retry:
181	p = parsenextc = parsefile->buf;
182	i = read(parsefile->fd, p, BUFSIZ);
183	if (i <= 0) {
184                if (i < 0) {
185                        if (errno == EINTR)
186                                goto retry;
187                        if (parsefile->fd == 0 && errno == EWOULDBLOCK) {
188                                int flags = fcntl(0, F_GETFL, 0);
189                                if (flags >= 0 && flags & O_NONBLOCK) {
190                                        flags &=~ O_NONBLOCK;
191                                        if (fcntl(0, F_SETFL, flags) >= 0) {
192						out2str("sh: turning off NDELAY mode\n");
193                                                goto retry;
194                                        }
195                                }
196                        }
197                }
198                parsenleft = EOF_NLEFT;
199                return PEOF;
200	}
201	parsenleft = i - 1;
202
203	/* delete nul characters */
204	for (;;) {
205		if (*p++ == '\0')
206			break;
207		if (--i <= 0)
208			return *parsenextc++;		/* no nul characters */
209	}
210	q = p - 1;
211	while (--i > 0) {
212		if (*p != '\0')
213			*q++ = *p;
214		p++;
215	}
216	if (q == parsefile->buf)
217		goto retry;			/* buffer contained nothing but nuls */
218	parsenleft = q - parsefile->buf - 1;
219	return *parsenextc++;
220}
221
222
223/*
224 * Undo the last call to pgetc.  Only one character may be pushed back.
225 * PEOF may be pushed back.
226 */
227
228void
229pungetc() {
230	parsenleft++;
231	parsenextc--;
232}
233
234
235/*
236 * Push a string back onto the input.  This code doesn't work if the user
237 * tries to push back more than one string at once.
238 */
239
240void
241ppushback(string, length)
242	char *string;
243	{
244	pushedstring = parsenextc;
245	pushednleft = parsenleft;
246	parsenextc = string;
247	parsenleft = length;
248}
249
250
251
252/*
253 * Set the input to take input from a file.  If push is set, push the
254 * old input onto the stack first.
255 */
256
257void
258setinputfile(fname, push)
259	char *fname;
260	{
261	int fd;
262	int fd2;
263
264	INTOFF;
265	if ((fd = open(fname, O_RDONLY)) < 0)
266		error("Can't open %s", fname);
267	if (fd < 10) {
268		fd2 = copyfd(fd, 10);
269		close(fd);
270		if (fd2 < 0)
271			error("Out of file descriptors");
272		fd = fd2;
273	}
274	setinputfd(fd, push);
275	INTON;
276}
277
278
279/*
280 * Like setinputfile, but takes an open file descriptor.  Call this with
281 * interrupts off.
282 */
283
284void
285setinputfd(fd, push) {
286	if (push) {
287		pushfile();
288		parsefile->buf = ckmalloc(BUFSIZ);
289	}
290	if (parsefile->fd > 0)
291		close(parsefile->fd);
292	parsefile->fd = fd;
293	if (parsefile->buf == NULL)
294		parsefile->buf = ckmalloc(BUFSIZ);
295	parsenleft = 0;
296	plinno = 1;
297}
298
299
300/*
301 * Like setinputfile, but takes input from a string.
302 */
303
304void
305setinputstring(string, push)
306	char *string;
307	{
308	INTOFF;
309	if (push)
310		pushfile();
311	parsenextc = string;
312	parsenleft = strlen(string);
313	parsefile->buf = NULL;
314	plinno = 1;
315	INTON;
316}
317
318
319
320/*
321 * To handle the "." command, a stack of input files is used.  Pushfile
322 * adds a new entry to the stack and popfile restores the previous level.
323 */
324
325STATIC void
326pushfile() {
327	struct parsefile *pf;
328
329	parsefile->nleft = parsenleft;
330	parsefile->nextc = parsenextc;
331	parsefile->linno = plinno;
332	pf = (struct parsefile *)ckmalloc(sizeof (struct parsefile));
333	pf->prev = parsefile;
334	pf->fd = -1;
335	parsefile = pf;
336}
337
338
339void
340popfile() {
341	struct parsefile *pf = parsefile;
342
343	INTOFF;
344	if (pf->fd >= 0)
345		close(pf->fd);
346	if (pf->buf)
347		ckfree(pf->buf);
348	parsefile = pf->prev;
349	ckfree(pf);
350	parsenleft = parsefile->nleft;
351	parsenextc = parsefile->nextc;
352	plinno = parsefile->linno;
353	INTON;
354}
355
356
357/*
358 * Return to top level.
359 */
360
361void
362popallfiles() {
363	while (parsefile != &basepf)
364		popfile();
365}
366
367
368
369/*
370 * Close the file(s) that the shell is reading commands from.  Called
371 * after a fork is done.
372 */
373
374void
375closescript() {
376	popallfiles();
377	if (parsefile->fd > 0) {
378		close(parsefile->fd);
379		parsefile->fd = 0;
380	}
381}
382