Line data Source code
1 : /*-------------------------------------------------------------------------
2 : *
3 : * conversioncmds.c
4 : * conversion creation command support code
5 : *
6 : * Portions Copyright (c) 1996-2026, PostgreSQL Global Development Group
7 : * Portions Copyright (c) 1994, Regents of the University of California
8 : *
9 : *
10 : * IDENTIFICATION
11 : * src/backend/commands/conversioncmds.c
12 : *
13 : *-------------------------------------------------------------------------
14 : */
15 : #include "postgres.h"
16 :
17 : #include "catalog/pg_conversion.h"
18 : #include "catalog/pg_namespace.h"
19 : #include "catalog/pg_proc.h"
20 : #include "catalog/pg_type.h"
21 : #include "commands/conversioncmds.h"
22 : #include "fmgr.h"
23 : #include "mb/pg_wchar.h"
24 : #include "miscadmin.h"
25 : #include "parser/parse_func.h"
26 : #include "utils/acl.h"
27 : #include "utils/lsyscache.h"
28 :
29 : /*
30 : * CREATE CONVERSION
31 : */
32 : ObjectAddress
33 42 : CreateConversionCommand(CreateConversionStmt *stmt)
34 : {
35 : Oid namespaceId;
36 : char *conversion_name;
37 : AclResult aclresult;
38 : int from_encoding;
39 : int to_encoding;
40 : Oid funcoid;
41 42 : const char *from_encoding_name = stmt->for_encoding_name;
42 42 : const char *to_encoding_name = stmt->to_encoding_name;
43 42 : List *func_name = stmt->func_name;
44 : static const Oid funcargs[] = {INT4OID, INT4OID, CSTRINGOID, INTERNALOID, INT4OID, BOOLOID};
45 : char result[1];
46 : Datum funcresult;
47 :
48 : /* Convert list of names to a name and namespace */
49 42 : namespaceId = QualifiedNameGetCreationNamespace(stmt->conversion_name,
50 : &conversion_name);
51 :
52 : /* Check we have creation rights in target namespace */
53 42 : aclresult = object_aclcheck(NamespaceRelationId, namespaceId, GetUserId(), ACL_CREATE);
54 42 : if (aclresult != ACLCHECK_OK)
55 0 : aclcheck_error(aclresult, OBJECT_SCHEMA,
56 0 : get_namespace_name(namespaceId));
57 :
58 : /* Check the encoding names */
59 42 : from_encoding = pg_char_to_encoding(from_encoding_name);
60 42 : if (from_encoding < 0)
61 0 : ereport(ERROR,
62 : (errcode(ERRCODE_UNDEFINED_OBJECT),
63 : errmsg("source encoding \"%s\" does not exist",
64 : from_encoding_name)));
65 :
66 42 : to_encoding = pg_char_to_encoding(to_encoding_name);
67 42 : if (to_encoding < 0)
68 0 : ereport(ERROR,
69 : (errcode(ERRCODE_UNDEFINED_OBJECT),
70 : errmsg("destination encoding \"%s\" does not exist",
71 : to_encoding_name)));
72 :
73 : /*
74 : * We consider conversions to or from SQL_ASCII to be meaningless. (If
75 : * you wish to change this, note that pg_do_encoding_conversion() and its
76 : * sister functions have hard-wired fast paths for any conversion in which
77 : * the source or target encoding is SQL_ASCII, so that an encoding
78 : * conversion function declared for such a case will never be used.)
79 : */
80 42 : if (from_encoding == PG_SQL_ASCII || to_encoding == PG_SQL_ASCII)
81 0 : ereport(ERROR,
82 : (errcode(ERRCODE_INVALID_OBJECT_DEFINITION),
83 : errmsg("encoding conversion to or from \"SQL_ASCII\" is not supported")));
84 :
85 : /*
86 : * Check the existence of the conversion function. Function name could be
87 : * a qualified name.
88 : */
89 42 : funcoid = LookupFuncName(func_name, sizeof(funcargs) / sizeof(Oid),
90 : funcargs, false);
91 :
92 : /* Check it returns int4, else it's probably the wrong function */
93 42 : if (get_func_rettype(funcoid) != INT4OID)
94 0 : ereport(ERROR,
95 : (errcode(ERRCODE_INVALID_OBJECT_DEFINITION),
96 : errmsg("encoding conversion function %s must return type %s",
97 : NameListToString(func_name), "integer")));
98 :
99 : /* Check we have EXECUTE rights for the function */
100 42 : aclresult = object_aclcheck(ProcedureRelationId, funcoid, GetUserId(), ACL_EXECUTE);
101 42 : if (aclresult != ACLCHECK_OK)
102 0 : aclcheck_error(aclresult, OBJECT_FUNCTION,
103 0 : NameListToString(func_name));
104 :
105 : /*
106 : * Check that the conversion function is suitable for the requested source
107 : * and target encodings. We do that by calling the function with an empty
108 : * string; the conversion function should throw an error if it can't
109 : * perform the requested conversion.
110 : */
111 42 : funcresult = OidFunctionCall6(funcoid,
112 : Int32GetDatum(from_encoding),
113 : Int32GetDatum(to_encoding),
114 : CStringGetDatum(""),
115 : CStringGetDatum(result),
116 : Int32GetDatum(0),
117 : BoolGetDatum(false));
118 :
119 : /*
120 : * The function should return 0 for empty input. Might as well check that,
121 : * too.
122 : */
123 42 : if (DatumGetInt32(funcresult) != 0)
124 0 : ereport(ERROR,
125 : (errcode(ERRCODE_INVALID_OBJECT_DEFINITION),
126 : errmsg("encoding conversion function %s returned incorrect result for empty input",
127 : NameListToString(func_name))));
128 :
129 : /*
130 : * All seem ok, go ahead (possible failure would be a duplicate conversion
131 : * name)
132 : */
133 42 : return ConversionCreate(conversion_name, namespaceId, GetUserId(),
134 42 : from_encoding, to_encoding, funcoid, stmt->def);
135 : }
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