1 /*-------------------------------------------------------------------------
2 *
3 * scansup.c
4 * scanner support routines used by the core lexer
5 *
6 * Portions Copyright (c) 1996-2021, PostgreSQL Global Development Group
7 * Portions Copyright (c) 1994, Regents of the University of California
8 *
9 *
10 * IDENTIFICATION
11 * src/backend/parser/scansup.c
12 *
13 *-------------------------------------------------------------------------
14 */
15 #include "postgres.h"
16
17 #include <ctype.h>
18
19 #include "mb/pg_wchar.h"
20 #include "parser/scansup.h"
21
22
23 /*
24 * downcase_truncate_identifier() --- do appropriate downcasing and
25 * truncation of an unquoted identifier. Optionally warn of truncation.
26 *
27 * Returns a palloc'd string containing the adjusted identifier.
28 *
29 * Note: in some usages the passed string is not null-terminated.
30 *
31 * Note: the API of this function is designed to allow for downcasing
32 * transformations that increase the string length, but we don't yet
33 * support that. If you want to implement it, you'll need to fix
34 * SplitIdentifierString() in utils/adt/varlena.c.
35 */
36 char *
downcase_truncate_identifier(const char * ident,int len,bool warn)37 downcase_truncate_identifier(const char *ident, int len, bool warn)
38 {
39 return downcase_identifier(ident, len, warn, true);
40 }
41
42 /*
43 * a workhorse for downcase_truncate_identifier
44 */
45 char *
downcase_identifier(const char * ident,int len,bool warn,bool truncate)46 downcase_identifier(const char *ident, int len, bool warn, bool truncate)
47 {
48 char *result;
49 int i;
50 bool enc_is_single_byte;
51
52 result = palloc(len + 1);
53 enc_is_single_byte = pg_database_encoding_max_length() == 1;
54
55 /*
56 * SQL99 specifies Unicode-aware case normalization, which we don't yet
57 * have the infrastructure for. Instead we use tolower() to provide a
58 * locale-aware translation. However, there are some locales where this
59 * is not right either (eg, Turkish may do strange things with 'i' and
60 * 'I'). Our current compromise is to use tolower() for characters with
61 * the high bit set, as long as they aren't part of a multi-byte
62 * character, and use an ASCII-only downcasing for 7-bit characters.
63 */
64 for (i = 0; i < len; i++)
65 {
66 unsigned char ch = (unsigned char) ident[i];
67
68 if (ch >= 'A' && ch <= 'Z')
69 ch += 'a' - 'A';
70 else if (enc_is_single_byte && IS_HIGHBIT_SET(ch) && isupper(ch))
71 ch = tolower(ch);
72 result[i] = (char) ch;
73 }
74 result[i] = '\0';
75
76 if (i >= NAMEDATALEN && truncate)
77 truncate_identifier(result, i, warn);
78
79 return result;
80 }
81
82
83 /*
84 * truncate_identifier() --- truncate an identifier to NAMEDATALEN-1 bytes.
85 *
86 * The given string is modified in-place, if necessary. A warning is
87 * issued if requested.
88 *
89 * We require the caller to pass in the string length since this saves a
90 * strlen() call in some common usages.
91 */
92 void
truncate_identifier(char * ident,int len,bool warn)93 truncate_identifier(char *ident, int len, bool warn)
94 {
95 if (len >= NAMEDATALEN)
96 {
97 len = pg_mbcliplen(ident, len, NAMEDATALEN - 1);
98 if (warn)
99 ereport(NOTICE,
100 (errcode(ERRCODE_NAME_TOO_LONG),
101 errmsg("identifier \"%s\" will be truncated to \"%.*s\"",
102 ident, len, ident)));
103 ident[len] = '\0';
104 }
105 }
106
107 /*
108 * scanner_isspace() --- return true if flex scanner considers char whitespace
109 *
110 * This should be used instead of the potentially locale-dependent isspace()
111 * function when it's important to match the lexer's behavior.
112 *
113 * In principle we might need similar functions for isalnum etc, but for the
114 * moment only isspace seems needed.
115 */
116 bool
scanner_isspace(char ch)117 scanner_isspace(char ch)
118 {
119 /* This must match scan.l's list of {space} characters */
120 if (ch == ' ' ||
121 ch == '\t' ||
122 ch == '\n' ||
123 ch == '\r' ||
124 ch == '\f')
125 return true;
126 return false;
127 }
128