PostgreSQL Source Code: src/common/percentrepl.c Source File

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percentrepl.c
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1/*-------------------------------------------------------------------------
2 *
3 * percentrepl.c
4 * Common routines to replace percent placeholders in strings
5 *
6 * Portions Copyright (c) 1996-2025, PostgreSQL Global Development Group
7 * Portions Copyright (c) 1994, Regents of the University of California
8 *
9 *
10 * IDENTIFICATION
11 * src/common/percentrepl.c
12 *
13 *-------------------------------------------------------------------------
14 */
15
16#ifndef FRONTEND
17#include "postgres.h"
18#else
19#include "postgres_fe.h"
20#include "common/logging.h"
21#endif
22
23#include "common/percentrepl.h"
24#include "lib/stringinfo.h"
25
26/*
27 * replace_percent_placeholders
28 *
29 * Replace percent-letter placeholders in input string with the supplied
30 * values. For example, to replace %f with foo and %b with bar, call
31 *
32 * replace_percent_placeholders(instr, "param_name", "bf", bar, foo);
33 *
34 * The return value is palloc'd.
35 *
36 * "%%" is replaced by a single "%".
37 *
38 * This throws an error for an unsupported placeholder or a "%" at the end of
39 * the input string.
40 *
41 * A value may be NULL. If the corresponding placeholder is found in the
42 * input string, it will be treated as if an unsupported placeholder was used.
43 * This allows callers to share a "letters" specification but vary the
44 * actually supported placeholders at run time.
45 *
46 * This functions is meant for cases where all the values are readily
47 * available or cheap to compute and most invocations will use most values
48 * (for example for archive_command). Also, it requires that all values are
49 * strings. It won't be a good match for things like log prefixes or prompts
50 * that use a mix of data types and any invocation will only use a few of the
51 * possible values.
52 *
53 * param_name is the name of the underlying GUC parameter, for error
54 * reporting. At the moment, this function is only used for GUC parameters.
55 * If other kinds of uses were added, the error reporting would need to be
56 * revised.
57 */
58char *
59 replace_percent_placeholders(const char *instr, const char *param_name, const char *letters,...)
60{
61 StringInfoData result;
62
63 initStringInfo(&result);
64
65 for (const char *sp = instr; *sp; sp++)
66 {
67 if (*sp == '%')
68 {
69 if (sp[1] == '%')
70 {
71 /* Convert %% to a single % */
72 sp++;
73 appendStringInfoChar(&result, *sp);
74 }
75 else if (sp[1] == '0円')
76 {
77 /* Incomplete escape sequence, expected a character afterward */
78#ifdef FRONTEND
79 pg_log_error("invalid value for parameter \"%s\": \"%s\"", param_name, instr);
80 pg_log_error_detail("String ends unexpectedly after escape character \"%%\".");
81 exit(1);
82#else
83 ereport(ERROR,
84 errcode(ERRCODE_INVALID_PARAMETER_VALUE),
85 errmsg("invalid value for parameter \"%s\": \"%s\"", param_name, instr),
86 errdetail("String ends unexpectedly after escape character \"%%\"."));
87#endif
88 }
89 else
90 {
91 /* Look up placeholder character */
92 bool found = false;
93 va_list ap;
94
95 sp++;
96
97 va_start(ap, letters);
98 for (const char *lp = letters; *lp; lp++)
99 {
100 char *val = va_arg(ap, char *);
101
102 if (*sp == *lp)
103 {
104 if (val)
105 {
106 appendStringInfoString(&result, val);
107 found = true;
108 }
109 /* If val is NULL, we will report an error. */
110 break;
111 }
112 }
113 va_end(ap);
114 if (!found)
115 {
116 /* Unknown placeholder */
117#ifdef FRONTEND
118 pg_log_error("invalid value for parameter \"%s\": \"%s\"", param_name, instr);
119 pg_log_error_detail("String contains unexpected placeholder \"%%%c\".", *sp);
120 exit(1);
121#else
122 ereport(ERROR,
123 errcode(ERRCODE_INVALID_PARAMETER_VALUE),
124 errmsg("invalid value for parameter \"%s\": \"%s\"", param_name, instr),
125 errdetail("String contains unexpected placeholder \"%%%c\".", *sp));
126#endif
127 }
128 }
129 }
130 else
131 {
132 appendStringInfoChar(&result, *sp);
133 }
134 }
135
136 return result.data;
137}
int errdetail(const char *fmt,...)
Definition: elog.c:1207
int errcode(int sqlerrcode)
Definition: elog.c:854
int errmsg(const char *fmt,...)
Definition: elog.c:1071
#define ERROR
Definition: elog.h:39
#define ereport(elevel,...)
Definition: elog.h:150
long val
Definition: informix.c:689
#define pg_log_error(...)
Definition: logging.h:106
#define pg_log_error_detail(...)
Definition: logging.h:109
char * replace_percent_placeholders(const char *instr, const char *param_name, const char *letters,...)
Definition: percentrepl.c:59
void appendStringInfoString(StringInfo str, const char *s)
Definition: stringinfo.c:230
void appendStringInfoChar(StringInfo str, char ch)
Definition: stringinfo.c:242
void initStringInfo(StringInfo str)
Definition: stringinfo.c:97
char * data
Definition: stringinfo.h:48

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