1/* Machine-independant string function optimizations.
2 Copyright (C) 1997-2017 Free Software Foundation, Inc.
3 This file is part of the GNU C Library.
4 Contributed by Ulrich Drepper <drepper@cygnus.com>, 1997.
5
6 The GNU C Library is free software; you can redistribute it and/or
7 modify it under the terms of the GNU Lesser General Public
8 License as published by the Free Software Foundation; either
9 version 2.1 of the License, or (at your option) any later version.
10
11 The GNU C Library is distributed in the hope that it will be useful,
12 but WITHOUT ANY WARRANTY; without even the implied warranty of
13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
14 Lesser General Public License for more details.
15
16 You should have received a copy of the GNU Lesser General Public
17 License along with the GNU C Library; if not, see
18 <http://www.gnu.org/licenses/>. */
19
20#ifndef _STRING_H
21# error "Never use <bits/string2.h> directly; include <string.h> instead."
22#endif
23
24#ifndef __NO_STRING_INLINES
25
26/* Unlike the definitions in the header <bits/string.h> the
27 definitions contained here are not optimized down to assembler
28 level. Those optimizations are not always a good idea since this
29 means the code size increases a lot. Instead the definitions here
30 optimize some functions in a way which do not dramatically
31 increase the code size and which do not use assembler. The main
32 trick is to use GCC's `__builtin_constant_p' function.
33
34 Every function XXX which has a defined version in
35 <bits/string.h> must be accompanied by a symbol _HAVE_STRING_ARCH_XXX
36 to make sure we don't get redefinitions.
37
38 We must use here macros instead of inline functions since the
39 trick won't work with the latter. */
40
41#ifndef __STRING_INLINE
42# ifdef __cplusplus
43# define __STRING_INLINE inline
44# else
45# define __STRING_INLINE __extern_inline
46# endif
47#endif
48
49/* Dereferencing a pointer arg to run sizeof on it fails for the void
50 pointer case, so we use this instead.
51 Note that __x is evaluated twice. */
52#define __string2_1bptr_p(__x) \
53 ((size_t)(const void *)((__x) + 1) - (size_t)(const void *)(__x) == 1)
54
55/* Set N bytes of S to 0. */
56#if !defined _HAVE_STRING_ARCH_memset
57# define __bzero(s, n) __builtin_memset (s, '\0', n)
58#endif
59
60
61#ifndef _HAVE_STRING_ARCH_strchr
62extern void *__rawmemchr (const void *__s, int __c);
63# define strchr(s, c) \
64 (__extension__ (__builtin_constant_p (c) && !__builtin_constant_p (s) \
65 && (c) == '\0' \
66 ? (char *) __rawmemchr (s, c) \
67 : __builtin_strchr (s, c)))
68#endif
69
70
71/* Copy SRC to DEST, returning pointer to final NUL byte. */
72#ifdef __USE_GNU
73# ifndef _HAVE_STRING_ARCH_stpcpy
74# define __stpcpy(dest, src) __builtin_stpcpy (dest, src)
75/* In glibc we use this function frequently but for namespace reasons
76 we have to use the name `__stpcpy'. */
77# define stpcpy(dest, src) __stpcpy (dest, src)
78# endif
79#endif
80
81
82/* Copy no more than N characters of SRC to DEST. */
83#ifndef _HAVE_STRING_ARCH_strncpy
84# define strncpy(dest, src, n) __builtin_strncpy (dest, src, n)
85#endif
86
87
88/* Append no more than N characters from SRC onto DEST. */
89#ifndef _HAVE_STRING_ARCH_strncat
90# ifdef _USE_STRING_ARCH_strchr
91# define strncat(dest, src, n) \
92 (__extension__ ({ char *__dest = (dest); \
93 __builtin_constant_p (src) && __builtin_constant_p (n) \
94 ? (strlen (src) < ((size_t) (n)) \
95 ? strcat (__dest, src) \
96 : (*((char *) __mempcpy (strchr (__dest, '\0'), \
97 src, n)) = '\0', __dest)) \
98 : strncat (dest, src, n); }))
99# else
100# define strncat(dest, src, n) __builtin_strncat (dest, src, n)
101# endif
102#endif
103
104
105/* Compare characters of S1 and S2. */
106#ifndef _HAVE_STRING_ARCH_strcmp
107# define strcmp(s1, s2) \
108 __extension__ \
109 ({ size_t __s1_len, __s2_len; \
110 (__builtin_constant_p (s1) && __builtin_constant_p (s2) \
111 && (__s1_len = strlen (s1), __s2_len = strlen (s2), \
112 (!__string2_1bptr_p (s1) || __s1_len >= 4) \
113 && (!__string2_1bptr_p (s2) || __s2_len >= 4)) \
114 ? __builtin_strcmp (s1, s2) \
115 : (__builtin_constant_p (s1) && __string2_1bptr_p (s1) \
116 && (__s1_len = strlen (s1), __s1_len < 4) \
117 ? (__builtin_constant_p (s2) && __string2_1bptr_p (s2) \
118 ? __builtin_strcmp (s1, s2) \
119 : __strcmp_cg (s1, s2, __s1_len)) \
120 : (__builtin_constant_p (s2) && __string2_1bptr_p (s2) \
121 && (__s2_len = strlen (s2), __s2_len < 4) \
122 ? (__builtin_constant_p (s1) && __string2_1bptr_p (s1) \
123 ? __builtin_strcmp (s1, s2) \
124 : -__strcmp_cg (s2, s1, __s2_len)) \
125 : __builtin_strcmp (s1, s2)))); })
126
127# define __strcmp_cg(s1, s2, l1) \
128 (__extension__ ({ const unsigned char *__s2 = \
129 (const unsigned char *) (const char *) (s2); \
130 int __result = \
131 (((const unsigned char *) (const char *) (s1))[0] \
132 - __s2[0]); \
133 if (l1 > 0 && __result == 0) \
134 { \
135 __result = (((const unsigned char *) \
136 (const char *) (s1))[1] - __s2[1]); \
137 if (l1 > 1 && __result == 0) \
138 { \
139 __result = (((const unsigned char *) \
140 (const char *) (s1))[2] - __s2[2]); \
141 if (l1 > 2 && __result == 0) \
142 __result = (((const unsigned char *) \
143 (const char *) (s1))[3] \
144 - __s2[3]); \
145 } \
146 } \
147 __result; }))
148#endif
149
150
151/* Compare N characters of S1 and S2. */
152#ifndef _HAVE_STRING_ARCH_strncmp
153# define strncmp(s1, s2, n) \
154 (__extension__ (__builtin_constant_p (n) \
155 && ((__builtin_constant_p (s1) \
156 && strlen (s1) < ((size_t) (n))) \
157 || (__builtin_constant_p (s2) \
158 && strlen (s2) < ((size_t) (n)))) \
159 ? strcmp (s1, s2) : strncmp (s1, s2, n)))
160#endif
161
162
163/* Return the length of the initial segment of S which
164 consists entirely of characters not in REJECT. */
165#ifndef _HAVE_STRING_ARCH_strcspn
166# define strcspn(s, reject) __builtin_strcspn (s, reject)
167#endif
168
169
170/* Return the length of the initial segment of S which
171 consists entirely of characters in ACCEPT. */
172#ifndef _HAVE_STRING_ARCH_strspn
173# define strspn(s, accept) __builtin_strspn (s, accept)
174#endif
175
176
177/* Find the first occurrence in S of any character in ACCEPT. */
178#ifndef _HAVE_STRING_ARCH_strpbrk
179# define strpbrk(s, accept) __builtin_strpbrk (s, accept)
180#endif
181
182
183/* We need the memory allocation functions for inline strdup().
184 Referring to stdlib.h (even minimally) is not allowed
185 in any of the tight standards compliant modes. */
186#ifdef __USE_MISC
187
188# if !defined _HAVE_STRING_ARCH_strdup || !defined _HAVE_STRING_ARCH_strndup
189# define __need_malloc_and_calloc
190# include <stdlib.h>
191# endif
192
193# ifndef _HAVE_STRING_ARCH_strdup
194
195extern char *__strdup (const char *__string) __THROW __attribute_malloc__;
196# define __strdup(s) \
197 (__extension__ (__builtin_constant_p (s) && __string2_1bptr_p (s) \
198 ? (((const char *) (s))[0] == '\0' \
199 ? (char *) calloc ((size_t) 1, (size_t) 1) \
200 : ({ size_t __len = strlen (s) + 1; \
201 char *__retval = (char *) malloc (__len); \
202 if (__retval != NULL) \
203 __retval = (char *) memcpy (__retval, s, __len); \
204 __retval; })) \
205 : __strdup (s)))
206
207# if defined __USE_XOPEN_EXTENDED || defined __USE_XOPEN2K8
208# define strdup(s) __strdup (s)
209# endif
210# endif
211
212# ifndef _HAVE_STRING_ARCH_strndup
213
214extern char *__strndup (const char *__string, size_t __n)
215 __THROW __attribute_malloc__;
216# define __strndup(s, n) \
217 (__extension__ (__builtin_constant_p (s) && __string2_1bptr_p (s) \
218 ? (((const char *) (s))[0] == '\0' \
219 ? (char *) calloc ((size_t) 1, (size_t) 1) \
220 : ({ size_t __len = strlen (s) + 1; \
221 size_t __n = (n); \
222 char *__retval; \
223 if (__n < __len) \
224 __len = __n + 1; \
225 __retval = (char *) malloc (__len); \
226 if (__retval != NULL) \
227 { \
228 __retval[__len - 1] = '\0'; \
229 __retval = (char *) memcpy (__retval, s, \
230 __len - 1); \
231 } \
232 __retval; })) \
233 : __strndup (s, n)))
234
235# ifdef __USE_XOPEN2K8
236# define strndup(s, n) __strndup (s, n)
237# endif
238# endif
239
240#endif /* Use misc. or use GNU. */
241
242#ifndef _FORCE_INLINES
243# undef __STRING_INLINE
244#endif
245
246#endif /* No string inlines. */
247