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GCC Code Coverage Report

Directory:	./		Exec	Total	Coverage
File:	lib/libc/string/strstr.c	Lines:	54	73	74.0 %
Date:	2017-11-07	Branches:	52	86	60.5 %


/*	$OpenBSD: strstr.c,v 1.7 2017/04/12 16:06:12 millert Exp $ */

/*
 * Copyright (c) 2005-2014 Rich Felker
 *
 * Permission is hereby granted, free of charge, to any person obtaining
 * a copy of this software and associated documentation files (the
 * "Software"), to deal in the Software without restriction, including
 * without limitation the rights to use, copy, modify, merge, publish,
 * distribute, sublicense, and/or sell copies of the Software, and to
 * permit persons to whom the Software is furnished to do so, subject to
 * the following conditions:
 *
 * The above copyright notice and this permission notice shall be
 * included in all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
 * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
 * IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
 * CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
 * TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
 * SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
 */

#include <string.h>
#include <stdlib.h>
#include <stdint.h>

static char *
twobyte_strstr(const unsigned char *h, const unsigned char *n)
{
	uint16_t nw = n[0]<<8 | n[1], hw = h[0]<<8 | h[1];
	for (h++; *h && hw != nw; hw = hw<<8 | *++h);
	return *h ? (char *)h-1 : 0;
}

static char *
threebyte_strstr(const unsigned char *h, const unsigned char *n)
{
	uint32_t nw = n[0]<<24 | n[1]<<16 | n[2]<<8;
	uint32_t hw = h[0]<<24 | h[1]<<16 | h[2]<<8;
	for (h+=2; *h && hw != nw; hw = (hw|*++h)<<8);
	return *h ? (char *)h-2 : 0;
}

static char *
fourbyte_strstr(const unsigned char *h, const unsigned char *n)
{
	uint32_t nw = n[0]<<24 | n[1]<<16 | n[2]<<8 | n[3];
	uint32_t hw = h[0]<<24 | h[1]<<16 | h[2]<<8 | h[3];
	for (h+=3; *h && hw != nw; hw = hw<<8 | *++h);
	return *h ? (char *)h-3 : 0;
}

#define MAX(a,b) ((a)>(b)?(a):(b))
#define MIN(a,b) ((a)<(b)?(a):(b))

#define BITOP(a,b,op) \
 ((a)[(size_t)(b)/(8*sizeof *(a))] op (size_t)1<<((size_t)(b)%(8*sizeof *(a))))

/*
 * Maxime Crochemore and Dominique Perrin, Two-way string-matching,
 * Journal of the ACM, 38(3):651-675, July 1991.
 */
static char *
twoway_strstr(const unsigned char *h, const unsigned char *n)
{
	const unsigned char *z;
	size_t l, ip, jp, k, p, ms, p0, mem, mem0;
	size_t byteset[32 / sizeof(size_t)] = { 0 };
	size_t shift[256];

	/* Computing length of needle and fill shift table */
	for (l=0; n[l] && h[l]; l++)
		BITOP(byteset, n[l], |=), shift[n[l]] = l+1;
	if (n[l]) return 0; /* hit the end of h */

	/* Compute maximal suffix */
	ip = -1; jp = 0; k = p = 1;
	while (jp+k<l) {
		if (n[ip+k] == n[jp+k]) {
			if (k == p) {
				jp += p;
				k = 1;
			} else k++;
		} else if (n[ip+k] > n[jp+k]) {
			jp += k;
			k = 1;
			p = jp - ip;
		} else {
			ip = jp++;
			k = p = 1;
		}
	}
	ms = ip;
	p0 = p;

	/* And with the opposite comparison */
	ip = -1; jp = 0; k = p = 1;
	while (jp+k<l) {
		if (n[ip+k] == n[jp+k]) {
			if (k == p) {
				jp += p;
				k = 1;
			} else k++;
		} else if (n[ip+k] < n[jp+k]) {
			jp += k;
			k = 1;
			p = jp - ip;
		} else {
			ip = jp++;
			k = p = 1;
		}
	}
	if (ip+1 > ms+1) ms = ip;
	else p = p0;

	/* Periodic needle? */
	if (memcmp(n, n+p, ms+1)) {
		mem0 = 0;
		p = MAX(ms, l-ms-1) + 1;
	} else mem0 = l-p;
	mem = 0;

	/* Initialize incremental end-of-haystack pointer */
	z = h;

	/* Search loop */
	for (;;) {
		/* Update incremental end-of-haystack pointer */
		if (z-h < l) {
			/* Fast estimate for MIN(l,63) */
			size_t grow = l | 63;
			const unsigned char *z2 = memchr(z, 0, grow);
			if (z2) {
				z = z2;
				if (z-h < l) return 0;
			} else z += grow;
		}

		/* Check last byte first; advance by shift on mismatch */
		if (BITOP(byteset, h[l-1], &)) {
			k = l-shift[h[l-1]];
#ifdef DEBUG
			printf("adv by %zu (on %c) at [%s] (%zu;l=%zu)\n", k, h[l-1], h, shift[h[l-1]], l);
#endif
			if (k) {
				if (mem0 && mem && k < p) k = l-p;
				h += k;
				mem = 0;
				continue;
			}
		} else {
			h += l;
			mem = 0;
			continue;
		}

		/* Compare right half */
		for (k=MAX(ms+1,mem); n[k] && n[k] == h[k]; k++);
		if (n[k]) {
			h += k-ms;
			mem = 0;
			continue;
		}
		/* Compare left half */
		for (k=ms+1; k>mem && n[k-1] == h[k-1]; k--);
		if (k <= mem) return (char *)h;
		h += p;
		mem = mem0;
	}
}

char *
strstr(const char *h, const char *n)
{
	/* Return immediately on empty needle */
	if (!n[0]) return (char *)h;

	/* Use faster algorithms for short needles */
	h = strchr(h, *n);
	if (!h || !n[1]) return (char *)h;
	if (!h[1]) return 0;
	if (!n[2]) return twobyte_strstr((void *)h, (void *)n);
	if (!h[2]) return 0;
	if (!n[3]) return threebyte_strstr((void *)h, (void *)n);
	if (!h[3]) return 0;
	if (!n[4]) return fourbyte_strstr((void *)h, (void *)n);

	return twoway_strstr((void *)h, (void *)n);
}
DEF_STRONG(strstr);


Generated by: GCOVR (Version 3.3)

Line	Branch	Exec	Source
1			/* $OpenBSD: strstr.c,v 1.7 2017/04/12 16:06:12 millert Exp $ */
2
3			/*
4			* Copyright (c) 2005-2014 Rich Felker
5			*
6			* Permission is hereby granted, free of charge, to any person obtaining
7			* a copy of this software and associated documentation files (the
8			* "Software"), to deal in the Software without restriction, including
9			* without limitation the rights to use, copy, modify, merge, publish,
10			* distribute, sublicense, and/or sell copies of the Software, and to
11			* permit persons to whom the Software is furnished to do so, subject to
12			* the following conditions:
13			*
14			* The above copyright notice and this permission notice shall be
15			* included in all copies or substantial portions of the Software.
16			*
17			* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
18			* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
19			* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
20			* IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
21			* CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
22			* TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
23			* SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
24			*/
25
26			#include <string.h>
27			#include <stdlib.h>
28			#include <stdint.h>
29
30			static char *
31			twobyte_strstr(const unsigned char h, const unsigned char n)
32			{
33		4120	uint16_t nw = n[0]<<8 \| n[1], hw = h[0]<<8 \| h[1];
34	✓✓✓✓	8750	for (h++; h && hw != nw; hw = hw<<8 \| ++h);
35		2060	return h ? (char )h-1 : 0;
36			}
37
38			static char *
39			threebyte_strstr(const unsigned char h, const unsigned char n)
40			{
41		100	uint32_t nw = n[0]<<24 \| n[1]<<16 \| n[2]<<8;
42		50	uint32_t hw = h[0]<<24 \| h[1]<<16 \| h[2]<<8;
43	✓✗✗✓	150	for (h+=2; h && hw != nw; hw = (hw\|++h)<<8);
44		50	return h ? (char )h-2 : 0;
45			}
46
47			static char *
48			fourbyte_strstr(const unsigned char h, const unsigned char n)
49			{
50			uint32_t nw = n[0]<<24 \| n[1]<<16 \| n[2]<<8 \| n[3];
51			uint32_t hw = h[0]<<24 \| h[1]<<16 \| h[2]<<8 \| h[3];
52			for (h+=3; h && hw != nw; hw = hw<<8 \| ++h);
53			return h ? (char )h-3 : 0;
54			}
55
56			#define MAX(a,b) ((a)>(b)?(a):(b))
57			#define MIN(a,b) ((a)<(b)?(a):(b))
58
59			#define BITOP(a,b,op) \
60			((a)[(size_t)(b)/(8sizeof (a))] op (size_t)1<<((size_t)(b)%(8sizeof (a))))
61
62			/*
63			* Maxime Crochemore and Dominique Perrin, Two-way string-matching,
64			* Journal of the ACM, 38(3):651-675, July 1991.
65			*/
66			static char *
67			twoway_strstr(const unsigned char h, const unsigned char n)
68			{
69			const unsigned char *z;
70			size_t l, ip, jp, k, p, ms, p0, mem, mem0;
71		2620	size_t byteset[32 / sizeof(size_t)] = { 0 };
72		1310	size_t shift[256];
73
74			/* Computing length of needle and fill shift table */
75	✓✓✓✓	30610	for (l=0; n[l] && h[l]; l++)
76		6670	BITOP(byteset, n[l], \|=), shift[n[l]] = l+1;
77	✗✓	1310	if (n[l]) return 0; /* hit the end of h */
78
79			/* Compute maximal suffix */
80			ip = -1; jp = 0; k = p = 1;
81	✓✓	7980	while (jp+k<l) {
82	✗✓	5360	if (n[ip+k] == n[jp+k]) {
83			if (k == p) {
84			jp += p;
85			k = 1;
86			} else k++;
87	✓✓	5360	} else if (n[ip+k] > n[jp+k]) {
88			jp += k;
89			k = 1;
90		2700	p = jp - ip;
91		2700	} else {
92		2660	ip = jp++;
93			k = p = 1;
94			}
95			}
96			ms = ip;
97			p0 = p;
98
99			/* And with the opposite comparison */
100			ip = -1; jp = 0; k = p = 1;
101	✓✓	7980	while (jp+k<l) {
102	✗✓	5360	if (n[ip+k] == n[jp+k]) {
103			if (k == p) {
104			jp += p;
105			k = 1;
106			} else k++;
107	✓✓	5360	} else if (n[ip+k] < n[jp+k]) {
108			jp += k;
109			k = 1;
110		4050	p = jp - ip;
111		4050	} else {
112		1310	ip = jp++;
113			k = p = 1;
114			}
115			}
116	✓✓	1350	if (ip+1 > ms+1) ms = ip;
117			else p = p0;
118
119			/* Periodic needle? */
120	✓✗	1310	if (memcmp(n, n+p, ms+1)) {
121			mem0 = 0;
122	✓✗	3930	p = MAX(ms, l-ms-1) + 1;
123		1310	} else mem0 = l-p;
124			mem = 0;
125
126			/* Initialize incremental end-of-haystack pointer */
127			z = h;
128
129			/* Search loop */
130		1310	for (;;) {
131			/* Update incremental end-of-haystack pointer */
132	✓✗	1310	if (z-h < l) {
133			/* Fast estimate for MIN(l,63) */
134		1310	size_t grow = l \| 63;
135		1310	const unsigned char *z2 = memchr(z, 0, grow);
136	✓✗	1310	if (z2) {
137			z = z2;
138	✗✓	1310	if (z-h < l) return 0;
139			} else z += grow;
140	✓✗	1310	}
141
142			/* Check last byte first; advance by shift on mismatch */
143	✓✗	1310	if (BITOP(byteset, h[l-1], &)) {
144		1310	k = l-shift[h[l-1]];
145			#ifdef DEBUG
146			printf("adv by %zu (on %c) at [%s] (%zu;l=%zu)\n", k, h[l-1], h, shift[h[l-1]], l);
147			#endif
148	✗✓	1310	if (k) {
149			if (mem0 && mem && k < p) k = l-p;
150			h += k;
151			mem = 0;
152			continue;
153			}
154			} else {
155			h += l;
156			mem = 0;
157			continue;
158			}
159
160			/* Compare right half */
161	✓✓✓✗	6550	for (k=MAX(ms+1,mem); n[k] && n[k] == h[k]; k++);
162	✗✓	1310	if (n[k]) {
163			h += k-ms;
164			mem = 0;
165			continue;
166			}
167			/* Compare left half */
168	✓✓✓✗	18700	for (k=ms+1; k>mem && n[k-1] == h[k-1]; k--);
169	✓✗	2620	if (k <= mem) return (char *)h;
170			h += p;
171			mem = mem0;
172			}
173		1310	}
174
175			char *
176			strstr(const char h, const char n)
177			{
178			/* Return immediately on empty needle */
179	✗✓	35056	if (!n[0]) return (char *)h;
180
181			/* Use faster algorithms for short needles */
182		17528	h = strchr(h, *n);
183	✓✓✓✓	35116	if (!h \|\| !n[1]) return (char *)h;
184	✗✓	3420	if (!h[1]) return 0;
185	✓✓	5480	if (!n[2]) return twobyte_strstr((void )h, (void )n);
186	✗✓	1360	if (!h[2]) return 0;
187	✓✓	1410	if (!n[3]) return threebyte_strstr((void )h, (void )n);
188	✗✓	1310	if (!h[3]) return 0;
189	✗✓	1310	if (!n[4]) return fourbyte_strstr((void )h, (void )n);
190
191		1310	return twoway_strstr((void )h, (void )n);
192		17528	}
193			DEF_STRONG(strstr);