Head

GCC Code Coverage Report

Directory:	./		Exec	Total	Coverage
File:	usr.bin/less/less/../linenum.c	Lines:	87	132	65.9 %
Date:	2017-11-07	Branches:	55	98	56.1 %


/*
 * Copyright (C) 1984-2012  Mark Nudelman
 * Modified for use with illumos by Garrett D'Amore.
 * Copyright 2014 Garrett D'Amore <garrett@damore.org>
 *
 * You may distribute under the terms of either the GNU General Public
 * License or the Less License, as specified in the README file.
 *
 * For more information, see the README file.
 */

/*
 * Code to handle displaying line numbers.
 *
 * Finding the line number of a given file position is rather tricky.
 * We don't want to just start at the beginning of the file and
 * count newlines, because that is slow for large files (and also
 * wouldn't work if we couldn't get to the start of the file; e.g.
 * if input is a long pipe).
 *
 * So we use the function add_lnum to cache line numbers.
 * We try to be very clever and keep only the more interesting
 * line numbers when we run out of space in our table.  A line
 * number is more interesting than another when it is far from
 * other line numbers.   For example, we'd rather keep lines
 * 100,200,300 than 100,101,300.  200 is more interesting than
 * 101 because 101 can be derived very cheaply from 100, while
 * 200 is more expensive to derive from 100.
 *
 * The function currline() returns the line number of a given
 * position in the file.  As a side effect, it calls add_lnum
 * to cache the line number.  Therefore currline is occasionally
 * called to make sure we cache line numbers often enough.
 */

#include "less.h"

/*
 * Structure to keep track of a line number and the associated file position.
 * A doubly-linked circular list of line numbers is kept ordered by line number.
 */
struct linenum_info {
	struct linenum_info *next;	/* Link to next in the list */
	struct linenum_info *prev;	/* Line to previous in the list */
	off_t pos;			/* File position */
	off_t gap;			/* Gap between prev and next */
	off_t line;			/* Line number */
};
/*
 * "gap" needs some explanation: the gap of any particular line number
 * is the distance between the previous one and the next one in the list.
 * ("Distance" means difference in file position.)  In other words, the
 * gap of a line number is the gap which would be introduced if this
 * line number were deleted.  It is used to decide which one to replace
 * when we have a new one to insert and the table is full.
 */

#define	NPOOL	200			/* Size of line number pool */

#define	LONGTIME	(2)		/* In seconds */

static struct linenum_info anchor;	/* Anchor of the list */
static struct linenum_info *freelist;	/* Anchor of the unused entries */
static struct linenum_info pool[NPOOL];	/* The pool itself */
static struct linenum_info *spare;	/* We always keep one spare entry */

extern int linenums;
extern volatile sig_atomic_t sigs;
extern int sc_height;
extern int screen_trashed;

/*
 * Initialize the line number structures.
 */
void
clr_linenum(void)
{
	struct linenum_info *p;

	/*
	 * Put all the entries on the free list.
	 * Leave one for the "spare".
	 */
	for (p = pool; p < &pool[NPOOL-2]; p++)
		p->next = p+1;
	pool[NPOOL-2].next = NULL;
	freelist = pool;

	spare = &pool[NPOOL-1];

	/*
	 * Initialize the anchor.
	 */
	anchor.next = anchor.prev = &anchor;
	anchor.gap = 0;
	anchor.pos = 0;
	anchor.line = 1;
}

/*
 * Calculate the gap for an entry.
 */
static void
calcgap(struct linenum_info *p)
{
	/*
	 * Don't bother to compute a gap for the anchor.
	 * Also don't compute a gap for the last one in the list.
	 * The gap for that last one should be considered infinite,
	 * but we never look at it anyway.
	 */
	if (p == &anchor || p->next == &anchor)
		return;
	p->gap = p->next->pos - p->prev->pos;
}

/*
 * Add a new line number to the cache.
 * The specified position (pos) should be the file position of the
 * FIRST character in the specified line.
 */
void
add_lnum(off_t linenum, off_t pos)
{
	struct linenum_info *p;
	struct linenum_info *new;
	struct linenum_info *nextp;
	struct linenum_info *prevp;
	off_t mingap;

	/*
	 * Find the proper place in the list for the new one.
	 * The entries are sorted by position.
	 */
	for (p = anchor.next; p != &anchor && p->pos < pos; p = p->next)
		if (p->line == linenum)
			/* We already have this one. */
			return;
	nextp = p;
	prevp = p->prev;

	if (freelist != NULL) {
		/*
		 * We still have free (unused) entries.
		 * Use one of them.
		 */
		new = freelist;
		freelist = freelist->next;
	} else {
		/*
		 * No free entries.
		 * Use the "spare" entry.
		 */
		new = spare;
		spare = NULL;
	}

	/*
	 * Fill in the fields of the new entry,
	 * and insert it into the proper place in the list.
	 */
	new->next = nextp;
	new->prev = prevp;
	new->pos = pos;
	new->line = linenum;

	nextp->prev = new;
	prevp->next = new;

	/*
	 * Recalculate gaps for the new entry and the neighboring entries.
	 */
	calcgap(new);
	calcgap(nextp);
	calcgap(prevp);

	if (spare == NULL) {
		/*
		 * We have used the spare entry.
		 * Scan the list to find the one with the smallest
		 * gap, take it out and make it the spare.
		 * We should never remove the last one, so stop when
		 * we get to p->next == &anchor.  This also avoids
		 * looking at the gap of the last one, which is
		 * not computed by calcgap.
		 */
		mingap = anchor.next->gap;
		for (p = anchor.next; p->next != &anchor; p = p->next) {
			if (p->gap <= mingap) {
				spare = p;
				mingap = p->gap;
			}
		}
		spare->next->prev = spare->prev;
		spare->prev->next = spare->next;
	}
}

static int loopcount;
static time_t startime;

static void
longish(void)
{
	if (loopcount >= 0 && ++loopcount > 100) {
		loopcount = 0;
		if (time(NULL) >= startime + LONGTIME) {
			ierror("Calculating line numbers", NULL);
			loopcount = -1;
		}
	}
}

/*
 * Turn off line numbers because the user has interrupted
 * a lengthy line number calculation.
 */
static void
abort_long(void)
{
	if (linenums == OPT_ONPLUS)
		/*
		 * We were displaying line numbers, so need to repaint.
		 */
		screen_trashed = 1;
	linenums = 0;
	error("Line numbers turned off", NULL);
}

/*
 * Find the line number associated with a given position.
 * Return 0 if we can't figure it out.
 */
off_t
find_linenum(off_t pos)
{
	struct linenum_info *p;
	off_t linenum;
	off_t cpos;

	if (!linenums)
		/*
		 * We're not using line numbers.
		 */
		return (0);
	if (pos == -1)
		/*
		 * Caller doesn't know what he's talking about.
		 */
		return (0);
	if (pos <= ch_zero())
		/*
		 * Beginning of file is always line number 1.
		 */
		return (1);

	/*
	 * Find the entry nearest to the position we want.
	 */
	for (p = anchor.next; p != &anchor && p->pos < pos; p = p->next)
		continue;
	if (p->pos == pos)
		/* Found it exactly. */
		return (p->line);

	/*
	 * This is the (possibly) time-consuming part.
	 * We start at the line we just found and start
	 * reading the file forward or backward till we
	 * get to the place we want.
	 *
	 * First decide whether we should go forward from the
	 * previous one or backwards from the next one.
	 * The decision is based on which way involves
	 * traversing fewer bytes in the file.
	 */
	startime = time(NULL);
	if (p == &anchor || pos - p->prev->pos < p->pos - pos) {
		/*
		 * Go forward.
		 */
		p = p->prev;
		if (ch_seek(p->pos))
			return (0);
		loopcount = 0;
		for (linenum = p->line, cpos = p->pos; cpos < pos; linenum++) {
			/*
			 * Allow a signal to abort this loop.
			 */
			cpos = forw_raw_line(cpos, NULL, NULL);
			if (ABORT_SIGS()) {
				abort_long();
				return (0);
			}
			if (cpos == -1)
				return (0);
			longish();
		}
		/*
		 * We might as well cache it.
		 */
		add_lnum(linenum, cpos);
		/*
		 * If the given position is not at the start of a line,
		 * make sure we return the correct line number.
		 */
		if (cpos > pos)
			linenum--;
	} else {
		/*
		 * Go backward.
		 */
		if (ch_seek(p->pos))
			return (0);
		loopcount = 0;
		for (linenum = p->line, cpos = p->pos; cpos > pos; linenum--) {
			/*
			 * Allow a signal to abort this loop.
			 */
			cpos = back_raw_line(cpos, NULL, NULL);
			if (ABORT_SIGS()) {
				abort_long();
				return (0);
			}
			if (cpos == -1)
				return (0);
			longish();
		}
		/*
		 * We might as well cache it.
		 */
		add_lnum(linenum, cpos);
	}

	return (linenum);
}

/*
 * Find the position of a given line number.
 * Return -1 if we can't figure it out.
 */
off_t
find_pos(off_t linenum)
{
	struct linenum_info *p;
	off_t cpos;
	off_t clinenum;

	if (linenum <= 1)
		/*
		 * Line number 1 is beginning of file.
		 */
		return (ch_zero());

	/*
	 * Find the entry nearest to the line number we want.
	 */
	for (p = anchor.next; p != &anchor && p->line < linenum; p = p->next)
		continue;
	if (p->line == linenum)
		/* Found it exactly. */
		return (p->pos);

	if (p == &anchor || linenum - p->prev->line < p->line - linenum) {
		/*
		 * Go forward.
		 */
		p = p->prev;
		if (ch_seek(p->pos))
			return (-1);
		for (clinenum = p->line, cpos = p->pos;
		    clinenum < linenum;
		    clinenum++) {
			/*
			 * Allow a signal to abort this loop.
			 */
			cpos = forw_raw_line(cpos, NULL, NULL);
			if (ABORT_SIGS())
				return (-1);
			if (cpos == -1)
				return (-1);
		}
	} else {
		/*
		 * Go backward.
		 */
		if (ch_seek(p->pos))
			return (-1);
		for (clinenum = p->line, cpos = p->pos;
		    clinenum > linenum;
		    clinenum--) {
			/*
			 * Allow a signal to abort this loop.
			 */
			cpos = back_raw_line(cpos, (char **)NULL, (int *)NULL);
			if (ABORT_SIGS())
				return (-1);
			if (cpos == -1)
				return (-1);
		}
	}
	/*
	 * We might as well cache it.
	 */
	add_lnum(clinenum, cpos);
	return (cpos);
}

/*
 * Return the line number of the "current" line.
 * The argument "where" tells which line is to be considered
 * the "current" line (e.g. TOP, BOTTOM, MIDDLE, etc).
 */
off_t
currline(int where)
{
	off_t pos;
	off_t len;
	off_t linenum;

	pos = position(where);
	len = ch_length();
	while (pos == -1 && where >= 0 && where < sc_height)
		pos = position(++where);
	if (pos == -1)
		pos = len;
	linenum = find_linenum(pos);
	if (pos == len)
		linenum--;
	return (linenum);
}


Generated by: GCOVR (Version 3.3)

Line	Branch	Exec	Source
1			/*
2			* Copyright (C) 1984-2012 Mark Nudelman
3			* Modified for use with illumos by Garrett D'Amore.
4			* Copyright 2014 Garrett D'Amore <garrett@damore.org>
5			*
6			* You may distribute under the terms of either the GNU General Public
7			* License or the Less License, as specified in the README file.
8			*
9			* For more information, see the README file.
10			*/
11
12			/*
13			* Code to handle displaying line numbers.
14			*
15			* Finding the line number of a given file position is rather tricky.
16			* We don't want to just start at the beginning of the file and
17			* count newlines, because that is slow for large files (and also
18			* wouldn't work if we couldn't get to the start of the file; e.g.
19			* if input is a long pipe).
20			*
21			* So we use the function add_lnum to cache line numbers.
22			* We try to be very clever and keep only the more interesting
23			* line numbers when we run out of space in our table. A line
24			* number is more interesting than another when it is far from
25			* other line numbers. For example, we'd rather keep lines
26			* 100,200,300 than 100,101,300. 200 is more interesting than
27			* 101 because 101 can be derived very cheaply from 100, while
28			* 200 is more expensive to derive from 100.
29			*
30			* The function currline() returns the line number of a given
31			* position in the file. As a side effect, it calls add_lnum
32			* to cache the line number. Therefore currline is occasionally
33			* called to make sure we cache line numbers often enough.
34			*/
35
36			#include "less.h"
37
38			/*
39			* Structure to keep track of a line number and the associated file position.
40			* A doubly-linked circular list of line numbers is kept ordered by line number.
41			*/
42			struct linenum_info {
43			struct linenum_info next; / Link to next in the list */
44			struct linenum_info prev; / Line to previous in the list */
45			off_t pos; /* File position */
46			off_t gap; /* Gap between prev and next */
47			off_t line; /* Line number */
48			};
49			/*
50			* "gap" needs some explanation: the gap of any particular line number
51			* is the distance between the previous one and the next one in the list.
52			* ("Distance" means difference in file position.) In other words, the
53			* gap of a line number is the gap which would be introduced if this
54			* line number were deleted. It is used to decide which one to replace
55			* when we have a new one to insert and the table is full.
56			*/
57
58			#define NPOOL 200 /* Size of line number pool */
59
60			#define LONGTIME (2) /* In seconds */
61
62			static struct linenum_info anchor; /* Anchor of the list */
63			static struct linenum_info freelist; / Anchor of the unused entries */
64			static struct linenum_info pool[NPOOL]; /* The pool itself */
65			static struct linenum_info spare; / We always keep one spare entry */
66
67			extern int linenums;
68			extern volatile sig_atomic_t sigs;
69			extern int sc_height;
70			extern int screen_trashed;
71
72			/*
73			* Initialize the line number structures.
74			*/
75			void
76			clr_linenum(void)
77			{
78			struct linenum_info *p;
79
80			/*
81			* Put all the entries on the free list.
82			* Leave one for the "spare".
83			*/
84	✓✓	14763	for (p = pool; p < &pool[NPOOL-2]; p++)
85		7326	p->next = p+1;
86		37	pool[NPOOL-2].next = NULL;
87		37	freelist = pool;
88
89		37	spare = &pool[NPOOL-1];
90
91			/*
92			* Initialize the anchor.
93			*/
94		37	anchor.next = anchor.prev = &anchor;
95		37	anchor.gap = 0;
96		37	anchor.pos = 0;
97		37	anchor.line = 1;
98		37	}
99
100			/*
101			* Calculate the gap for an entry.
102			*/
103			static void
104			calcgap(struct linenum_info *p)
105			{
106			/*
107			* Don't bother to compute a gap for the anchor.
108			* Also don't compute a gap for the last one in the list.
109			* The gap for that last one should be considered infinite,
110			* but we never look at it anyway.
111			*/
112	✓✓✓✓	7444	if (p == &anchor \|\| p->next == &anchor)
113			return;
114		1304	p->gap = p->next->pos - p->prev->pos;
115		3986	}
116
117			/*
118			* Add a new line number to the cache.
119			* The specified position (pos) should be the file position of the
120			* FIRST character in the specified line.
121			*/
122			void
123			add_lnum(off_t linenum, off_t pos)
124			{
125			struct linenum_info *p;
126			struct linenum_info *new;
127			struct linenum_info *nextp;
128			struct linenum_info *prevp;
129			off_t mingap;
130
131			/*
132			* Find the proper place in the list for the new one.
133			* The entries are sorted by position.
134			*/
135	✓✓✓✓	405545	for (p = anchor.next; p != &anchor && p->pos < pos; p = p->next)
136	✗✓	100410	if (p->line == linenum)
137			/* We already have this one. */
138			return;
139			nextp = p;
140		894	prevp = p->prev;
141
142	✓✓	894	if (freelist != NULL) {
143			/*
144			* We still have free (unused) entries.
145			* Use one of them.
146			*/
147			new = freelist;
148		517	freelist = freelist->next;
149		517	} else {
150			/*
151			* No free entries.
152			* Use the "spare" entry.
153			*/
154		377	new = spare;
155		377	spare = NULL;
156			}
157
158			/*
159			* Fill in the fields of the new entry,
160			* and insert it into the proper place in the list.
161			*/
162		894	new->next = nextp;
163		894	new->prev = prevp;
164		894	new->pos = pos;
165		894	new->line = linenum;
166
167		894	nextp->prev = new;
168		894	prevp->next = new;
169
170			/*
171			* Recalculate gaps for the new entry and the neighboring entries.
172			*/
173		894	calcgap(new);
174		894	calcgap(nextp);
175		894	calcgap(prevp);
176
177	✓✓	894	if (spare == NULL) {
178			/*
179			* We have used the spare entry.
180			* Scan the list to find the one with the smallest
181			* gap, take it out and make it the spare.
182			* We should never remove the last one, so stop when
183			* we get to p->next == &anchor. This also avoids
184			* looking at the gap of the last one, which is
185			* not computed by calcgap.
186			*/
187		377	mingap = anchor.next->gap;
188	✓✓	150800	for (p = anchor.next; p->next != &anchor; p = p->next) {
189	✓✓	75023	if (p->gap <= mingap) {
190		2622	spare = p;
191		2622	mingap = p->gap;
192		2622	}
193			}
194		377	spare->next->prev = spare->prev;
195		377	spare->prev->next = spare->next;
196		377	}
197		1788	}
198
199			static int loopcount;
200			static time_t startime;
201
202			static void
203			longish(void)
204			{
205	✓✗✓✓	112032	if (loopcount >= 0 && ++loopcount > 100) {
206		156	loopcount = 0;
207	✗✓	156	if (time(NULL) >= startime + LONGTIME) {
208			ierror("Calculating line numbers", NULL);
209			loopcount = -1;
210			}
211			}
212		37344	}
213
214			/*
215			* Turn off line numbers because the user has interrupted
216			* a lengthy line number calculation.
217			*/
218			static void
219			abort_long(void)
220			{
221			if (linenums == OPT_ONPLUS)
222			/*
223			* We were displaying line numbers, so need to repaint.
224			*/
225			screen_trashed = 1;
226			linenums = 0;
227			error("Line numbers turned off", NULL);
228			}
229
230			/*
231			* Find the line number associated with a given position.
232			* Return 0 if we can't figure it out.
233			*/
234			off_t
235			find_linenum(off_t pos)
236			{
237			struct linenum_info *p;
238			off_t linenum;
239			off_t cpos;
240
241	✗✓	2176	if (!linenums)
242			/*
243			* We're not using line numbers.
244			*/
245			return (0);
246	✗✓	1088	if (pos == -1)
247			/*
248			* Caller doesn't know what he's talking about.
249			*/
250			return (0);
251	✓✓	1088	if (pos <= ch_zero())
252			/*
253			* Beginning of file is always line number 1.
254			*/
255		5	return (1);
256
257			/*
258			* Find the entry nearest to the position we want.
259			*/
260	✓✓✓✓	327614	for (p = anchor.next; p != &anchor && p->pos < pos; p = p->next)
261			continue;
262	✓✓	1083	if (p->pos == pos)
263			/* Found it exactly. */
264		192	return (p->line);
265
266			/*
267			* This is the (possibly) time-consuming part.
268			* We start at the line we just found and start
269			* reading the file forward or backward till we
270			* get to the place we want.
271			*
272			* First decide whether we should go forward from the
273			* previous one or backwards from the next one.
274			* The decision is based on which way involves
275			* traversing fewer bytes in the file.
276			*/
277		891	startime = time(NULL);
278	✓✓✓✓	1220	if (p == &anchor \|\| pos - p->prev->pos < p->pos - pos) {
279			/*
280			* Go forward.
281			*/
282		718	p = p->prev;
283	✗✓	718	if (ch_seek(p->pos))
284			return (0);
285		718	loopcount = 0;
286	✓✓	62266	for (linenum = p->line, cpos = p->pos; cpos < pos; linenum++) {
287			/*
288			* Allow a signal to abort this loop.
289			*/
290		30415	cpos = forw_raw_line(cpos, NULL, NULL);
291	✗✓	30415	if (ABORT_SIGS()) {
292			abort_long();
293			return (0);
294			}
295	✗✓	30415	if (cpos == -1)
296			return (0);
297		30415	longish();
298			}
299			/*
300			* We might as well cache it.
301			*/
302		718	add_lnum(linenum, cpos);
303			/*
304			* If the given position is not at the start of a line,
305			* make sure we return the correct line number.
306			*/
307	✓✓	718	if (cpos > pos)
308		156	linenum--;
309			} else {
310			/*
311			* Go backward.
312			*/
313	✗✓	173	if (ch_seek(p->pos))
314			return (0);
315		173	loopcount = 0;
316	✓✓	14204	for (linenum = p->line, cpos = p->pos; cpos > pos; linenum--) {
317			/*
318			* Allow a signal to abort this loop.
319			*/
320		6929	cpos = back_raw_line(cpos, NULL, NULL);
321	✗✓	6929	if (ABORT_SIGS()) {
322			abort_long();
323			return (0);
324			}
325	✗✓	6929	if (cpos == -1)
326			return (0);
327		6929	longish();
328			}
329			/*
330			* We might as well cache it.
331			*/
332		173	add_lnum(linenum, cpos);
333			}
334
335		891	return (linenum);
336		1088	}
337
338			/*
339			* Find the position of a given line number.
340			* Return -1 if we can't figure it out.
341			*/
342			off_t
343			find_pos(off_t linenum)
344			{
345			struct linenum_info *p;
346			off_t cpos;
347			off_t clinenum;
348
349	✓✗	10	if (linenum <= 1)
350			/*
351			* Line number 1 is beginning of file.
352			*/
353		5	return (ch_zero());
354
355			/*
356			* Find the entry nearest to the line number we want.
357			*/
358			for (p = anchor.next; p != &anchor && p->line < linenum; p = p->next)
359			continue;
360			if (p->line == linenum)
361			/* Found it exactly. */
362			return (p->pos);
363
364			if (p == &anchor \|\| linenum - p->prev->line < p->line - linenum) {
365			/*
366			* Go forward.
367			*/
368			p = p->prev;
369			if (ch_seek(p->pos))
370			return (-1);
371			for (clinenum = p->line, cpos = p->pos;
372			clinenum < linenum;
373			clinenum++) {
374			/*
375			* Allow a signal to abort this loop.
376			*/
377			cpos = forw_raw_line(cpos, NULL, NULL);
378			if (ABORT_SIGS())
379			return (-1);
380			if (cpos == -1)
381			return (-1);
382			}
383			} else {
384			/*
385			* Go backward.
386			*/
387			if (ch_seek(p->pos))
388			return (-1);
389			for (clinenum = p->line, cpos = p->pos;
390			clinenum > linenum;
391			clinenum--) {
392			/*
393			* Allow a signal to abort this loop.
394			*/
395			cpos = back_raw_line(cpos, (char *)NULL, (int )NULL);
396			if (ABORT_SIGS())
397			return (-1);
398			if (cpos == -1)
399			return (-1);
400			}
401			}
402			/*
403			* We might as well cache it.
404			*/
405			add_lnum(clinenum, cpos);
406			return (cpos);
407		5	}
408
409			/*
410			* Return the line number of the "current" line.
411			* The argument "where" tells which line is to be considered
412			* the "current" line (e.g. TOP, BOTTOM, MIDDLE, etc).
413			*/
414			off_t
415			currline(int where)
416			{
417			off_t pos;
418			off_t len;
419			off_t linenum;
420
421		1968	pos = position(where);
422		984	len = ch_length();
423	✗✓✗✗	1968	while (pos == -1 && where >= 0 && where < sc_height)
424			pos = position(++where);
425	✓✓	984	if (pos == -1)
426		22	pos = len;
427		984	linenum = find_linenum(pos);
428	✓✓	984	if (pos == len)
429		22	linenum--;
430		984	return (linenum);
431			}