ch.c revision 195941 
1/*
2 * Copyright (C) 1984-2009  Mark Nudelman
3 *
4 * You may distribute under the terms of either the GNU General Public
5 * License or the Less License, as specified in the README file.
6 *
7 * For more information about less, or for information on how to
8 * contact the author, see the README file.
9 */
10
11
12/*
13 * Low level character input from the input file.
14 * We use these special purpose routines which optimize moving
15 * both forward and backward from the current read pointer.
16 */
17
18#include "less.h"
19#if MSDOS_COMPILER==WIN32C
20#include <errno.h>
21#include <windows.h>
22#endif
23
24#if HAVE_STAT_INO
25#include <sys/stat.h>
26extern dev_t curr_dev;
27extern ino_t curr_ino;
28#endif
29
30typedef POSITION BLOCKNUM;
31
32public int ignore_eoi;
33
34/*
35 * Pool of buffers holding the most recently used blocks of the input file.
36 * The buffer pool is kept as a doubly-linked circular list,
37 * in order from most- to least-recently used.
38 * The circular list is anchored by the file state "thisfile".
39 */
40struct bufnode {
41	struct bufnode *next, *prev;
42	struct bufnode *hnext, *hprev;
43};
44
45#define	LBUFSIZE	8192
46struct buf {
47	struct bufnode node;
48	BLOCKNUM block;
49	unsigned int datasize;
50	unsigned char data[LBUFSIZE];
51};
52#define bufnode_buf(bn)  ((struct buf *) bn)
53
54/*
55 * The file state is maintained in a filestate structure.
56 * A pointer to the filestate is kept in the ifile structure.
57 */
58#define	BUFHASH_SIZE	64
59struct filestate {
60	struct bufnode buflist;
61	struct bufnode hashtbl[BUFHASH_SIZE];
62	int file;
63	int flags;
64	POSITION fpos;
65	int nbufs;
66	BLOCKNUM block;
67	unsigned int offset;
68	POSITION fsize;
69};
70
71#define	ch_bufhead	thisfile->buflist.next
72#define	ch_buftail	thisfile->buflist.prev
73#define	ch_nbufs	thisfile->nbufs
74#define	ch_block	thisfile->block
75#define	ch_offset	thisfile->offset
76#define	ch_fpos		thisfile->fpos
77#define	ch_fsize	thisfile->fsize
78#define	ch_flags	thisfile->flags
79#define	ch_file		thisfile->file
80
81#define	END_OF_CHAIN	(&thisfile->buflist)
82#define	END_OF_HCHAIN(h) (&thisfile->hashtbl[h])
83#define BUFHASH(blk)	((blk) & (BUFHASH_SIZE-1))
84
85/*
86 * Macros to manipulate the list of buffers in thisfile->buflist.
87 */
88#define	FOR_BUFS(bn) \
89	for (bn = ch_bufhead;  bn != END_OF_CHAIN;  bn = bn->next)
90
91#define BUF_RM(bn) \
92	(bn)->next->prev = (bn)->prev; \
93	(bn)->prev->next = (bn)->next;
94
95#define BUF_INS_HEAD(bn) \
96	(bn)->next = ch_bufhead; \
97	(bn)->prev = END_OF_CHAIN; \
98	ch_bufhead->prev = (bn); \
99	ch_bufhead = (bn);
100
101#define BUF_INS_TAIL(bn) \
102	(bn)->next = END_OF_CHAIN; \
103	(bn)->prev = ch_buftail; \
104	ch_buftail->next = (bn); \
105	ch_buftail = (bn);
106
107/*
108 * Macros to manipulate the list of buffers in thisfile->hashtbl[n].
109 */
110#define	FOR_BUFS_IN_CHAIN(h,bn) \
111	for (bn = thisfile->hashtbl[h].hnext;  \
112	     bn != END_OF_HCHAIN(h);  bn = bn->hnext)
113
114#define	BUF_HASH_RM(bn) \
115	(bn)->hnext->hprev = (bn)->hprev; \
116	(bn)->hprev->hnext = (bn)->hnext;
117
118#define	BUF_HASH_INS(bn,h) \
119	(bn)->hnext = thisfile->hashtbl[h].hnext; \
120	(bn)->hprev = END_OF_HCHAIN(h); \
121	thisfile->hashtbl[h].hnext->hprev = (bn); \
122	thisfile->hashtbl[h].hnext = (bn);
123
124static struct filestate *thisfile;
125static int ch_ungotchar = -1;
126static int maxbufs = -1;
127
128extern int autobuf;
129extern int sigs;
130extern int secure;
131extern int screen_trashed;
132extern int follow_mode;
133extern constant char helpdata[];
134extern constant int size_helpdata;
135extern IFILE curr_ifile;
136#if LOGFILE
137extern int logfile;
138extern char *namelogfile;
139#endif
140
141static int ch_addbuf();
142
143
144/*
145 * Get the character pointed to by the read pointer.
146 */
147	int
148ch_get()
149{
150	register struct buf *bp;
151	register struct bufnode *bn;
152	register int n;
153	register int slept;
154	register int h;
155	POSITION pos;
156	POSITION len;
157
158	if (thisfile == NULL)
159		return (EOI);
160
161	/*
162	 * Quick check for the common case where
163	 * the desired char is in the head buffer.
164	 */
165	if (ch_bufhead != END_OF_CHAIN)
166	{
167		bp = bufnode_buf(ch_bufhead);
168		if (ch_block == bp->block && ch_offset < bp->datasize)
169			return bp->data[ch_offset];
170	}
171
172	slept = FALSE;
173
174	/*
175	 * Look for a buffer holding the desired block.
176	 */
177	h = BUFHASH(ch_block);
178	FOR_BUFS_IN_CHAIN(h, bn)
179	{
180		bp = bufnode_buf(bn);
181		if (bp->block == ch_block)
182		{
183			if (ch_offset >= bp->datasize)
184				/*
185				 * Need more data in this buffer.
186				 */
187				break;
188			goto found;
189		}
190	}
191	if (bn == END_OF_HCHAIN(h))
192	{
193		/*
194		 * Block is not in a buffer.
195		 * Take the least recently used buffer
196		 * and read the desired block into it.
197		 * If the LRU buffer has data in it,
198		 * then maybe allocate a new buffer.
199		 */
200		if (ch_buftail == END_OF_CHAIN ||
201			bufnode_buf(ch_buftail)->block != -1)
202		{
203			/*
204			 * There is no empty buffer to use.
205			 * Allocate a new buffer if:
206			 * 1. We can't seek on this file and -b is not in effect; or
207			 * 2. We haven't allocated the max buffers for this file yet.
208			 */
209			if ((autobuf && !(ch_flags & CH_CANSEEK)) ||
210				(maxbufs < 0 || ch_nbufs < maxbufs))
211				if (ch_addbuf())
212					/*
213					 * Allocation failed: turn off autobuf.
214					 */
215					autobuf = OPT_OFF;
216		}
217		bn = ch_buftail;
218		bp = bufnode_buf(bn);
219		BUF_HASH_RM(bn); /* Remove from old hash chain. */
220		bp->block = ch_block;
221		bp->datasize = 0;
222		BUF_HASH_INS(bn, h); /* Insert into new hash chain. */
223	}
224
225    read_more:
226	pos = (ch_block * LBUFSIZE) + bp->datasize;
227	if ((len = ch_length()) != NULL_POSITION && pos >= len)
228		/*
229		 * At end of file.
230		 */
231		return (EOI);
232
233	if (pos != ch_fpos)
234	{
235		/*
236		 * Not at the correct position: must seek.
237		 * If input is a pipe, we're in trouble (can't seek on a pipe).
238		 * Some data has been lost: just return "?".
239		 */
240		if (!(ch_flags & CH_CANSEEK))
241			return ('?');
242		if (lseek(ch_file, (off_t)pos, SEEK_SET) == BAD_LSEEK)
243		{
244 			error("seek error", NULL_PARG);
245			clear_eol();
246			return (EOI);
247 		}
248 		ch_fpos = pos;
249 	}
250
251	/*
252	 * Read the block.
253	 * If we read less than a full block, that's ok.
254	 * We use partial block and pick up the rest next time.
255	 */
256	if (ch_ungotchar != -1)
257	{
258		bp->data[bp->datasize] = ch_ungotchar;
259		n = 1;
260		ch_ungotchar = -1;
261	} else if (ch_flags & CH_HELPFILE)
262	{
263		bp->data[bp->datasize] = helpdata[ch_fpos];
264		n = 1;
265	} else
266	{
267		n = iread(ch_file, &bp->data[bp->datasize],
268			(unsigned int)(LBUFSIZE - bp->datasize));
269	}
270
271	if (n == READ_INTR)
272		return (EOI);
273	if (n < 0)
274	{
275#if MSDOS_COMPILER==WIN32C
276		if (errno != EPIPE)
277#endif
278		{
279			error("read error", NULL_PARG);
280			clear_eol();
281		}
282		n = 0;
283	}
284
285#if LOGFILE
286	/*
287	 * If we have a log file, write the new data to it.
288	 */
289	if (!secure && logfile >= 0 && n > 0)
290		write(logfile, (char *) &bp->data[bp->datasize], n);
291#endif
292
293	ch_fpos += n;
294	bp->datasize += n;
295
296	/*
297	 * If we have read to end of file, set ch_fsize to indicate
298	 * the position of the end of file.
299	 */
300	if (n == 0)
301	{
302		ch_fsize = pos;
303		if (ignore_eoi)
304		{
305			/*
306			 * We are ignoring EOF.
307			 * Wait a while, then try again.
308			 */
309			if (!slept)
310			{
311				PARG parg;
312				parg.p_string = wait_message();
313				ierror("%s", &parg);
314			}
315#if !MSDOS_COMPILER
316	 		sleep(1);
317#else
318#if MSDOS_COMPILER==WIN32C
319			Sleep(1000);
320#endif
321#endif
322			slept = TRUE;
323
324#if HAVE_STAT_INO
325			if (follow_mode == FOLLOW_NAME)
326			{
327				/* See whether the file's i-number has changed.
328				 * If so, force the file to be closed and
329				 * reopened. */
330				struct stat st;
331				int r = stat(get_filename(curr_ifile), &st);
332				if (r == 0 && (st.st_ino != curr_ino ||
333					st.st_dev != curr_dev))
334				{
335					/* screen_trashed=2 causes
336					 * make_display to reopen the file. */
337					screen_trashed = 2;
338					return (EOI);
339				}
340			}
341#endif
342		}
343		if (sigs)
344			return (EOI);
345	}
346
347    found:
348	if (ch_bufhead != bn)
349	{
350		/*
351		 * Move the buffer to the head of the buffer chain.
352		 * This orders the buffer chain, most- to least-recently used.
353		 */
354		BUF_RM(bn);
355		BUF_INS_HEAD(bn);
356
357		/*
358		 * Move to head of hash chain too.
359		 */
360		BUF_HASH_RM(bn);
361		BUF_HASH_INS(bn, h);
362	}
363
364	if (ch_offset >= bp->datasize)
365		/*
366		 * After all that, we still don't have enough data.
367		 * Go back and try again.
368		 */
369		goto read_more;
370
371	return (bp->data[ch_offset]);
372}
373
374/*
375 * ch_ungetchar is a rather kludgy and limited way to push
376 * a single char onto an input file descriptor.
377 */
378	public void
379ch_ungetchar(c)
380	int c;
381{
382	if (c != -1 && ch_ungotchar != -1)
383		error("ch_ungetchar overrun", NULL_PARG);
384	ch_ungotchar = c;
385}
386
387#if LOGFILE
388/*
389 * Close the logfile.
390 * If we haven't read all of standard input into it, do that now.
391 */
392	public void
393end_logfile()
394{
395	static int tried = FALSE;
396
397	if (logfile < 0)
398		return;
399	if (!tried && ch_fsize == NULL_POSITION)
400	{
401		tried = TRUE;
402		ierror("Finishing logfile", NULL_PARG);
403		while (ch_forw_get() != EOI)
404			if (ABORT_SIGS())
405				break;
406	}
407	close(logfile);
408	logfile = -1;
409	namelogfile = NULL;
410}
411
412/*
413 * Start a log file AFTER less has already been running.
414 * Invoked from the - command; see toggle_option().
415 * Write all the existing buffered data to the log file.
416 */
417	public void
418sync_logfile()
419{
420	register struct buf *bp;
421	register struct bufnode *bn;
422	int warned = FALSE;
423	BLOCKNUM block;
424	BLOCKNUM nblocks;
425
426	nblocks = (ch_fpos + LBUFSIZE - 1) / LBUFSIZE;
427	for (block = 0;  block < nblocks;  block++)
428	{
429		int wrote = FALSE;
430		FOR_BUFS(bn)
431		{
432			bp = bufnode_buf(bn);
433			if (bp->block == block)
434			{
435				write(logfile, (char *) bp->data, bp->datasize);
436				wrote = TRUE;
437				break;
438			}
439		}
440		if (!wrote && !warned)
441		{
442			error("Warning: log file is incomplete",
443				NULL_PARG);
444			warned = TRUE;
445		}
446	}
447}
448
449#endif
450
451/*
452 * Determine if a specific block is currently in one of the buffers.
453 */
454	static int
455buffered(block)
456	BLOCKNUM block;
457{
458	register struct buf *bp;
459	register struct bufnode *bn;
460	register int h;
461
462	h = BUFHASH(block);
463	FOR_BUFS_IN_CHAIN(h, bn)
464	{
465		bp = bufnode_buf(bn);
466		if (bp->block == block)
467			return (TRUE);
468	}
469	return (FALSE);
470}
471
472/*
473 * Seek to a specified position in the file.
474 * Return 0 if successful, non-zero if can't seek there.
475 */
476	public int
477ch_seek(pos)
478	register POSITION pos;
479{
480	BLOCKNUM new_block;
481	POSITION len;
482
483	if (thisfile == NULL)
484		return (0);
485
486	len = ch_length();
487	if (pos < ch_zero() || (len != NULL_POSITION && pos > len))
488		return (1);
489
490	new_block = pos / LBUFSIZE;
491	if (!(ch_flags & CH_CANSEEK) && pos != ch_fpos && !buffered(new_block))
492	{
493		if (ch_fpos > pos)
494			return (1);
495		while (ch_fpos < pos)
496		{
497			if (ch_forw_get() == EOI)
498				return (1);
499			if (ABORT_SIGS())
500				return (1);
501		}
502		return (0);
503	}
504	/*
505	 * Set read pointer.
506	 */
507	ch_block = new_block;
508	ch_offset = pos % LBUFSIZE;
509	return (0);
510}
511
512/*
513 * Seek to the end of the file.
514 */
515	public int
516ch_end_seek()
517{
518	POSITION len;
519
520	if (thisfile == NULL)
521		return (0);
522
523	if (ch_flags & CH_CANSEEK)
524		ch_fsize = filesize(ch_file);
525
526	len = ch_length();
527	if (len != NULL_POSITION)
528		return (ch_seek(len));
529
530	/*
531	 * Do it the slow way: read till end of data.
532	 */
533	while (ch_forw_get() != EOI)
534		if (ABORT_SIGS())
535			return (1);
536	return (0);
537}
538
539/*
540 * Seek to the beginning of the file, or as close to it as we can get.
541 * We may not be able to seek there if input is a pipe and the
542 * beginning of the pipe is no longer buffered.
543 */
544	public int
545ch_beg_seek()
546{
547	register struct bufnode *bn;
548	register struct bufnode *firstbn;
549
550	/*
551	 * Try a plain ch_seek first.
552	 */
553	if (ch_seek(ch_zero()) == 0)
554		return (0);
555
556	/*
557	 * Can't get to position 0.
558	 * Look thru the buffers for the one closest to position 0.
559	 */
560	firstbn = ch_bufhead;
561	if (firstbn == END_OF_CHAIN)
562		return (1);
563	FOR_BUFS(bn)
564	{
565		if (bufnode_buf(bn)->block < bufnode_buf(firstbn)->block)
566			firstbn = bn;
567	}
568	ch_block = bufnode_buf(firstbn)->block;
569	ch_offset = 0;
570	return (0);
571}
572
573/*
574 * Return the length of the file, if known.
575 */
576	public POSITION
577ch_length()
578{
579	if (thisfile == NULL)
580		return (NULL_POSITION);
581	if (ignore_eoi)
582		return (NULL_POSITION);
583	if (ch_flags & CH_HELPFILE)
584		return (size_helpdata);
585	return (ch_fsize);
586}
587
588/*
589 * Return the current position in the file.
590 */
591	public POSITION
592ch_tell()
593{
594	if (thisfile == NULL)
595		return (NULL_POSITION);
596	return (ch_block * LBUFSIZE) + ch_offset;
597}
598
599/*
600 * Get the current char and post-increment the read pointer.
601 */
602	public int
603ch_forw_get()
604{
605	register int c;
606
607	if (thisfile == NULL)
608		return (EOI);
609	c = ch_get();
610	if (c == EOI)
611		return (EOI);
612	if (ch_offset < LBUFSIZE-1)
613		ch_offset++;
614	else
615	{
616		ch_block ++;
617		ch_offset = 0;
618	}
619	return (c);
620}
621
622/*
623 * Pre-decrement the read pointer and get the new current char.
624 */
625	public int
626ch_back_get()
627{
628	if (thisfile == NULL)
629		return (EOI);
630	if (ch_offset > 0)
631		ch_offset --;
632	else
633	{
634		if (ch_block <= 0)
635			return (EOI);
636		if (!(ch_flags & CH_CANSEEK) && !buffered(ch_block-1))
637			return (EOI);
638		ch_block--;
639		ch_offset = LBUFSIZE-1;
640	}
641	return (ch_get());
642}
643
644/*
645 * Set max amount of buffer space.
646 * bufspace is in units of 1024 bytes.  -1 mean no limit.
647 */
648	public void
649ch_setbufspace(bufspace)
650	int bufspace;
651{
652	if (bufspace < 0)
653		maxbufs = -1;
654	else
655	{
656		maxbufs = ((bufspace * 1024) + LBUFSIZE-1) / LBUFSIZE;
657		if (maxbufs < 1)
658			maxbufs = 1;
659	}
660}
661
662/*
663 * Flush (discard) any saved file state, including buffer contents.
664 */
665	public void
666ch_flush()
667{
668	register struct bufnode *bn;
669
670	if (thisfile == NULL)
671		return;
672
673	if (!(ch_flags & CH_CANSEEK))
674	{
675		/*
676		 * If input is a pipe, we don't flush buffer contents,
677		 * since the contents can't be recovered.
678		 */
679		ch_fsize = NULL_POSITION;
680		return;
681	}
682
683	/*
684	 * Initialize all the buffers.
685	 */
686	FOR_BUFS(bn)
687	{
688		bufnode_buf(bn)->block = -1;
689	}
690
691	/*
692	 * Figure out the size of the file, if we can.
693	 */
694	ch_fsize = filesize(ch_file);
695
696	/*
697	 * Seek to a known position: the beginning of the file.
698	 */
699	ch_fpos = 0;
700	ch_block = 0; /* ch_fpos / LBUFSIZE; */
701	ch_offset = 0; /* ch_fpos % LBUFSIZE; */
702
703#if 1
704	/*
705	 * This is a kludge to workaround a Linux kernel bug: files in
706	 * /proc have a size of 0 according to fstat() but have readable
707	 * data.  They are sometimes, but not always, seekable.
708	 * Force them to be non-seekable here.
709	 */
710	if (ch_fsize == 0)
711	{
712		ch_fsize = NULL_POSITION;
713		ch_flags &= ~CH_CANSEEK;
714	}
715#endif
716
717	if (lseek(ch_file, (off_t)0, SEEK_SET) == BAD_LSEEK)
718	{
719		/*
720		 * Warning only; even if the seek fails for some reason,
721		 * there's a good chance we're at the beginning anyway.
722		 * {{ I think this is bogus reasoning. }}
723		 */
724		error("seek error to 0", NULL_PARG);
725	}
726}
727
728/*
729 * Allocate a new buffer.
730 * The buffer is added to the tail of the buffer chain.
731 */
732	static int
733ch_addbuf()
734{
735	register struct buf *bp;
736	register struct bufnode *bn;
737
738	/*
739	 * Allocate and initialize a new buffer and link it
740	 * onto the tail of the buffer list.
741	 */
742	bp = (struct buf *) calloc(1, sizeof(struct buf));
743	if (bp == NULL)
744		return (1);
745	ch_nbufs++;
746	bp->block = -1;
747	bn = &bp->node;
748
749	BUF_INS_TAIL(bn);
750	BUF_HASH_INS(bn, 0);
751	return (0);
752}
753
754/*
755 *
756 */
757	static void
758init_hashtbl()
759{
760	register int h;
761
762	for (h = 0;  h < BUFHASH_SIZE;  h++)
763	{
764		thisfile->hashtbl[h].hnext = END_OF_HCHAIN(h);
765		thisfile->hashtbl[h].hprev = END_OF_HCHAIN(h);
766	}
767}
768
769/*
770 * Delete all buffers for this file.
771 */
772	static void
773ch_delbufs()
774{
775	register struct bufnode *bn;
776
777	while (ch_bufhead != END_OF_CHAIN)
778	{
779		bn = ch_bufhead;
780		BUF_RM(bn);
781		free(bufnode_buf(bn));
782	}
783	ch_nbufs = 0;
784	init_hashtbl();
785}
786
787/*
788 * Is it possible to seek on a file descriptor?
789 */
790	public int
791seekable(f)
792	int f;
793{
794#if MSDOS_COMPILER
795	extern int fd0;
796	if (f == fd0 && !isatty(fd0))
797	{
798		/*
799		 * In MS-DOS, pipes are seekable.  Check for
800		 * standard input, and pretend it is not seekable.
801		 */
802		return (0);
803	}
804#endif
805	return (lseek(f, (off_t)1, SEEK_SET) != BAD_LSEEK);
806}
807
808/*
809 * Initialize file state for a new file.
810 */
811	public void
812ch_init(f, flags)
813	int f;
814	int flags;
815{
816	/*
817	 * See if we already have a filestate for this file.
818	 */
819	thisfile = (struct filestate *) get_filestate(curr_ifile);
820	if (thisfile == NULL)
821	{
822		/*
823		 * Allocate and initialize a new filestate.
824		 */
825		thisfile = (struct filestate *)
826				calloc(1, sizeof(struct filestate));
827		thisfile->buflist.next = thisfile->buflist.prev = END_OF_CHAIN;
828		thisfile->nbufs = 0;
829		thisfile->flags = 0;
830		thisfile->fpos = 0;
831		thisfile->block = 0;
832		thisfile->offset = 0;
833		thisfile->file = -1;
834		thisfile->fsize = NULL_POSITION;
835		ch_flags = flags;
836		init_hashtbl();
837		/*
838		 * Try to seek; set CH_CANSEEK if it works.
839		 */
840		if ((flags & CH_CANSEEK) && !seekable(f))
841			ch_flags &= ~CH_CANSEEK;
842		set_filestate(curr_ifile, (void *) thisfile);
843	}
844	if (thisfile->file == -1)
845		thisfile->file = f;
846	ch_flush();
847}
848
849/*
850 * Close a filestate.
851 */
852	public void
853ch_close()
854{
855	int keepstate = FALSE;
856
857	if (thisfile == NULL)
858		return;
859
860	if (ch_flags & (CH_CANSEEK|CH_POPENED|CH_HELPFILE))
861	{
862		/*
863		 * We can seek or re-open, so we don't need to keep buffers.
864		 */
865		ch_delbufs();
866	} else
867		keepstate = TRUE;
868	if (!(ch_flags & CH_KEEPOPEN))
869	{
870		/*
871		 * We don't need to keep the file descriptor open
872		 * (because we can re-open it.)
873		 * But don't really close it if it was opened via popen(),
874		 * because pclose() wants to close it.
875		 */
876		if (!(ch_flags & (CH_POPENED|CH_HELPFILE)))
877			close(ch_file);
878		ch_file = -1;
879	} else
880		keepstate = TRUE;
881	if (!keepstate)
882	{
883		/*
884		 * We don't even need to keep the filestate structure.
885		 */
886		free(thisfile);
887		thisfile = NULL;
888		set_filestate(curr_ifile, (void *) NULL);
889	}
890}
891
892/*
893 * Return ch_flags for the current file.
894 */
895	public int
896ch_getflags()
897{
898	if (thisfile == NULL)
899		return (0);
900	return (ch_flags);
901}
902
903#if 0
904	public void
905ch_dump(struct filestate *fs)
906{
907	struct buf *bp;
908	struct bufnode *bn;
909	unsigned char *s;
910
911	if (fs == NULL)
912	{
913		printf(" --no filestate\n");
914		return;
915	}
916	printf(" file %d, flags %x, fpos %x, fsize %x, blk/off %x/%x\n",
917		fs->file, fs->flags, fs->fpos,
918		fs->fsize, fs->block, fs->offset);
919	printf(" %d bufs:\n", fs->nbufs);
920	for (bn = fs->next; bn != &fs->buflist;  bn = bn->next)
921	{
922		bp = bufnode_buf(bn);
923		printf("%x: blk %x, size %x \"",
924			bp, bp->block, bp->datasize);
925		for (s = bp->data;  s < bp->data + 30;  s++)
926			if (*s >= ' ' && *s < 0x7F)
927				printf("%c", *s);
928			else
929				printf(".");
930		printf("\"\n");
931	}
932}
933#endif
934