1/*--------------------------------------------------------------------
2 * Symbols referenced in this file:
3 * - truncate_identifier
4 * - downcase_truncate_identifier
5 * - downcase_identifier
6 * - scanner_isspace
7 *--------------------------------------------------------------------
8 */
9
10/*-------------------------------------------------------------------------
11 *
12 * scansup.c
13 * support routines for the lex/flex scanner, used by both the normal
14 * backend as well as the bootstrap backend
15 *
16 * Portions Copyright (c) 1996-2017, PostgreSQL Global Development PGGroup
17 * Portions Copyright (c) 1994, Regents of the University of California
18 *
19 *
20 * IDENTIFICATION
21 * src/backend/parser/scansup.c
22 *
23 *-------------------------------------------------------------------------
24 */
25#include "pg_functions.hpp"
26#include <string.h>
27
28#include <ctype.h>
29
30#include "parser/scansup.hpp"
31#include "mb/pg_wchar.hpp"
32
33
34/* ----------------
35 * scanstr
36 *
37 * if the string passed in has escaped codes, map the escape codes to actual
38 * chars
39 *
40 * the string returned is palloc'd and should eventually be pfree'd by the
41 * caller!
42 * ----------------
43 */
44
45
46
47
48/*
49 * downcase_truncate_identifier() --- do appropriate downcasing and
50 * truncation of an unquoted identifier. Optionally warn of truncation.
51 *
52 * Returns a palloc'd string containing the adjusted identifier.
53 *
54 * Note: in some usages the passed string is not null-terminated.
55 *
56 * Note: the API of this function is designed to allow for downcasing
57 * transformations that increase the string length, but we don't yet
58 * support that. If you want to implement it, you'll need to fix
59 * SplitIdentifierString() in utils/adt/varlena.c.
60 */
61char *
62downcase_truncate_identifier(const char *ident, int len, bool warn)
63{
64 return downcase_identifier(ident, len, warn, true);
65}
66
67/*
68 * a workhorse for downcase_truncate_identifier
69 */
70char *
71downcase_identifier(const char *ident, int len, bool warn, bool truncate)
72{
73 char *result;
74 int i;
75 bool enc_is_single_byte;
76
77 result = (char*) palloc(len + 1);
78 enc_is_single_byte = pg_database_encoding_max_length() == 1;
79
80 /*
81 * SQL99 specifies Unicode-aware case normalization, which we don't yet
82 * have the infrastructure for. Instead we use tolower() to provide a
83 * locale-aware translation. However, there are some locales where this
84 * is not right either (eg, Turkish may do strange things with 'i' and
85 * 'I'). Our current compromise is to use tolower() for characters with
86 * the high bit set, as long as they aren't part of a multi-byte
87 * character, and use an ASCII-only downcasing for 7-bit characters.
88 */
89 for (i = 0; i < len; i++)
90 {
91 unsigned char ch = (unsigned char) ident[i];
92
93 if (ch >= 'A' && ch <= 'Z')
94 ch += 'a' - 'A';
95 else if (enc_is_single_byte && IS_HIGHBIT_SET(ch) && isupper(ch))
96 ch = tolower(ch);
97 result[i] = (char) ch;
98 }
99 result[i] = '\0';
100
101 if (i >= NAMEDATALEN && truncate)
102 truncate_identifier(result, i, warn);
103
104 return result;
105}
106
107
108/*
109 * truncate_identifier() --- truncate an identifier to NAMEDATALEN-1 bytes.
110 *
111 * The given string is modified in-place, if necessary. A warning is
112 * issued if requested.
113 *
114 * We require the caller to pass in the string length since this saves a
115 * strlen() call in some common usages.
116 */
117void
118truncate_identifier(char *ident, int len, bool warn)
119{
120 if (len >= NAMEDATALEN)
121 {
122 len = pg_mbcliplen(ident, len, NAMEDATALEN - 1);
123 if (warn)
124 {
125 /*
126 * We avoid using %.*s here because it can misbehave if the data
127 * is not valid in what libc thinks is the prevailing encoding.
128 */
129 char buf[NAMEDATALEN];
130
131 memcpy(buf, ident, len);
132 buf[len] = '\0';
133 ereport(PGNOTICE,
134 (errcode(ERRCODE_NAME_TOO_LONG),
135 errmsg("identifier \"%s\" will be truncated to \"%s\"",
136 ident, buf)));
137 }
138 ident[len] = '\0';
139 }
140}
141
142/*
143 * scanner_isspace() --- return true if flex scanner considers char whitespace
144 *
145 * This should be used instead of the potentially locale-dependent isspace()
146 * function when it's important to match the lexer's behavior.
147 *
148 * In principle we might need similar functions for isalnum etc, but for the
149 * moment only isspace seems needed.
150 */
151bool
152scanner_isspace(char ch)
153{
154 /* This must match scan.l's list of {space} characters */
155 if (ch == ' ' ||
156 ch == '\t' ||
157 ch == '\n' ||
158 ch == '\r' ||
159 ch == '\f')
160 return true;
161 return false;
162}
163