Line data Source code
1 : /*-------------------------------------------------------------------------
2 : *
3 : * pgstrcasecmp.c
4 : * Portable SQL-like case-independent comparisons and conversions.
5 : *
6 : * SQL99 specifies Unicode-aware case normalization, which we don't yet
7 : * have the infrastructure for. Instead we use tolower() to provide a
8 : * locale-aware translation. However, there are some locales where this
9 : * is not right either (eg, Turkish may do strange things with 'i' and
10 : * 'I'). Our current compromise is to use tolower() for characters with
11 : * the high bit set, and use an ASCII-only downcasing for 7-bit
12 : * characters.
13 : *
14 : * NB: this code should match downcase_truncate_identifier() in scansup.c.
15 : *
16 : * We also provide strict ASCII-only case conversion functions, which can
17 : * be used to implement C/POSIX case folding semantics no matter what the
18 : * C library thinks the locale is.
19 : *
20 : *
21 : * Portions Copyright (c) 1996-2017, PostgreSQL Global Development Group
22 : *
23 : * src/port/pgstrcasecmp.c
24 : *
25 : *-------------------------------------------------------------------------
26 : */
27 : #include "c.h"
28 :
29 : #include <ctype.h>
30 :
31 :
32 : /*
33 : * Case-independent comparison of two null-terminated strings.
34 : */
35 : int
36 918 : pg_strcasecmp(const char *s1, const char *s2)
37 : {
38 : for (;;)
39 : {
40 918 : unsigned char ch1 = (unsigned char) *s1++;
41 918 : unsigned char ch2 = (unsigned char) *s2++;
42 :
43 918 : if (ch1 != ch2)
44 : {
45 906 : if (ch1 >= 'A' && ch1 <= 'Z')
46 902 : ch1 += 'a' - 'A';
47 4 : else if (IS_HIGHBIT_SET(ch1) && isupper(ch1))
48 0 : ch1 = tolower(ch1);
49 :
50 906 : if (ch2 >= 'A' && ch2 <= 'Z')
51 28 : ch2 += 'a' - 'A';
52 878 : else if (IS_HIGHBIT_SET(ch2) && isupper(ch2))
53 0 : ch2 = tolower(ch2);
54 :
55 906 : if (ch1 != ch2)
56 906 : return (int) ch1 - (int) ch2;
57 : }
58 12 : if (ch1 == 0)
59 2 : break;
60 10 : }
61 2 : return 0;
62 : }
63 :
64 : /*
65 : * Case-independent comparison of two not-necessarily-null-terminated strings.
66 : * At most n bytes will be examined from each string.
67 : */
68 : int
69 0 : pg_strncasecmp(const char *s1, const char *s2, size_t n)
70 : {
71 0 : while (n-- > 0)
72 : {
73 0 : unsigned char ch1 = (unsigned char) *s1++;
74 0 : unsigned char ch2 = (unsigned char) *s2++;
75 :
76 0 : if (ch1 != ch2)
77 : {
78 0 : if (ch1 >= 'A' && ch1 <= 'Z')
79 0 : ch1 += 'a' - 'A';
80 0 : else if (IS_HIGHBIT_SET(ch1) && isupper(ch1))
81 0 : ch1 = tolower(ch1);
82 :
83 0 : if (ch2 >= 'A' && ch2 <= 'Z')
84 0 : ch2 += 'a' - 'A';
85 0 : else if (IS_HIGHBIT_SET(ch2) && isupper(ch2))
86 0 : ch2 = tolower(ch2);
87 :
88 0 : if (ch1 != ch2)
89 0 : return (int) ch1 - (int) ch2;
90 : }
91 0 : if (ch1 == 0)
92 0 : break;
93 : }
94 0 : return 0;
95 : }
96 :
97 : /*
98 : * Fold a character to upper case.
99 : *
100 : * Unlike some versions of toupper(), this is safe to apply to characters
101 : * that aren't lower case letters. Note however that the whole thing is
102 : * a bit bogus for multibyte character sets.
103 : */
104 : unsigned char
105 0 : pg_toupper(unsigned char ch)
106 : {
107 0 : if (ch >= 'a' && ch <= 'z')
108 0 : ch += 'A' - 'a';
109 0 : else if (IS_HIGHBIT_SET(ch) && islower(ch))
110 0 : ch = toupper(ch);
111 0 : return ch;
112 : }
113 :
114 : /*
115 : * Fold a character to lower case.
116 : *
117 : * Unlike some versions of tolower(), this is safe to apply to characters
118 : * that aren't upper case letters. Note however that the whole thing is
119 : * a bit bogus for multibyte character sets.
120 : */
121 : unsigned char
122 0 : pg_tolower(unsigned char ch)
123 : {
124 0 : if (ch >= 'A' && ch <= 'Z')
125 0 : ch += 'a' - 'A';
126 0 : else if (IS_HIGHBIT_SET(ch) && isupper(ch))
127 0 : ch = tolower(ch);
128 0 : return ch;
129 : }
130 :
131 : /*
132 : * Fold a character to upper case, following C/POSIX locale rules.
133 : */
134 : unsigned char
135 0 : pg_ascii_toupper(unsigned char ch)
136 : {
137 0 : if (ch >= 'a' && ch <= 'z')
138 0 : ch += 'A' - 'a';
139 0 : return ch;
140 : }
141 :
142 : /*
143 : * Fold a character to lower case, following C/POSIX locale rules.
144 : */
145 : unsigned char
146 0 : pg_ascii_tolower(unsigned char ch)
147 : {
148 0 : if (ch >= 'A' && ch <= 'Z')
149 0 : ch += 'a' - 'A';
150 0 : return ch;
151 : }
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