Line data Source code
1 : /*-------------------------------------------------------------------------
2 : *
3 : * pseudotypes.c
4 : * Functions for the system pseudo-types.
5 : *
6 : * A pseudo-type isn't really a type and never has any operations, but
7 : * we do need to supply input and output functions to satisfy the links
8 : * in the pseudo-type's entry in pg_type. In most cases the functions
9 : * just throw an error if invoked. (XXX the error messages here cover
10 : * the most common case, but might be confusing in some contexts. Can
11 : * we do better?)
12 : *
13 : *
14 : * Portions Copyright (c) 1996-2020, PostgreSQL Global Development Group
15 : * Portions Copyright (c) 1994, Regents of the University of California
16 : *
17 : *
18 : * IDENTIFICATION
19 : * src/backend/utils/adt/pseudotypes.c
20 : *
21 : *-------------------------------------------------------------------------
22 : */
23 : #include "postgres.h"
24 :
25 : #include "libpq/pqformat.h"
26 : #include "utils/array.h"
27 : #include "utils/builtins.h"
28 : #include "utils/rangetypes.h"
29 :
30 :
31 : /*
32 : * These macros generate input and output functions for a pseudo-type that
33 : * will reject all input and output attempts. (But for some types, only
34 : * the input function need be dummy.)
35 : */
36 : #define PSEUDOTYPE_DUMMY_INPUT_FUNC(typname) \
37 : Datum \
38 : typname##_in(PG_FUNCTION_ARGS) \
39 : { \
40 : ereport(ERROR, \
41 : (errcode(ERRCODE_FEATURE_NOT_SUPPORTED), \
42 : errmsg("cannot accept a value of type %s", #typname))); \
43 : \
44 : PG_RETURN_VOID(); /* keep compiler quiet */ \
45 : } \
46 : \
47 : extern int no_such_variable
48 :
49 : #define PSEUDOTYPE_DUMMY_IO_FUNCS(typname) \
50 : PSEUDOTYPE_DUMMY_INPUT_FUNC(typname); \
51 : \
52 : Datum \
53 : typname##_out(PG_FUNCTION_ARGS) \
54 : { \
55 : ereport(ERROR, \
56 : (errcode(ERRCODE_FEATURE_NOT_SUPPORTED), \
57 : errmsg("cannot display a value of type %s", #typname))); \
58 : \
59 : PG_RETURN_VOID(); /* keep compiler quiet */ \
60 : } \
61 : \
62 : extern int no_such_variable
63 :
64 : /*
65 : * Likewise for binary send/receive functions. We don't bother with these
66 : * at all for many pseudotypes, but some have them. (By convention, if
67 : * a type has a send function it should have a receive function, even if
68 : * that's only dummy.)
69 : */
70 : #define PSEUDOTYPE_DUMMY_RECEIVE_FUNC(typname) \
71 : Datum \
72 : typname##_recv(PG_FUNCTION_ARGS) \
73 : { \
74 : ereport(ERROR, \
75 : (errcode(ERRCODE_FEATURE_NOT_SUPPORTED), \
76 : errmsg("cannot accept a value of type %s", #typname))); \
77 : \
78 : PG_RETURN_VOID(); /* keep compiler quiet */ \
79 : } \
80 : \
81 : extern int no_such_variable
82 :
83 : #define PSEUDOTYPE_DUMMY_BINARY_IO_FUNCS(typname) \
84 : PSEUDOTYPE_DUMMY_RECEIVE_FUNC(typname); \
85 : \
86 : Datum \
87 : typname##_send(PG_FUNCTION_ARGS) \
88 : { \
89 : ereport(ERROR, \
90 : (errcode(ERRCODE_FEATURE_NOT_SUPPORTED), \
91 : errmsg("cannot display a value of type %s", #typname))); \
92 : \
93 : PG_RETURN_VOID(); /* keep compiler quiet */ \
94 : } \
95 : \
96 : extern int no_such_variable
97 :
98 :
99 : /*
100 : * cstring
101 : *
102 : * cstring is marked as a pseudo-type because we don't want people using it
103 : * in tables. But it's really a perfectly functional type, so provide
104 : * a full set of working I/O functions for it. Among other things, this
105 : * allows manual invocation of datatype I/O functions, along the lines of
106 : * "SELECT foo_in('blah')" or "SELECT foo_out(some-foo-value)".
107 : */
108 : Datum
109 12 : cstring_in(PG_FUNCTION_ARGS)
110 : {
111 12 : char *str = PG_GETARG_CSTRING(0);
112 :
113 12 : PG_RETURN_CSTRING(pstrdup(str));
114 : }
115 :
116 : Datum
117 28 : cstring_out(PG_FUNCTION_ARGS)
118 : {
119 28 : char *str = PG_GETARG_CSTRING(0);
120 :
121 28 : PG_RETURN_CSTRING(pstrdup(str));
122 : }
123 :
124 : Datum
125 0 : cstring_recv(PG_FUNCTION_ARGS)
126 : {
127 0 : StringInfo buf = (StringInfo) PG_GETARG_POINTER(0);
128 : char *str;
129 : int nbytes;
130 :
131 0 : str = pq_getmsgtext(buf, buf->len - buf->cursor, &nbytes);
132 0 : PG_RETURN_CSTRING(str);
133 : }
134 :
135 : Datum
136 0 : cstring_send(PG_FUNCTION_ARGS)
137 : {
138 0 : char *str = PG_GETARG_CSTRING(0);
139 : StringInfoData buf;
140 :
141 0 : pq_begintypsend(&buf);
142 0 : pq_sendtext(&buf, str, strlen(str));
143 0 : PG_RETURN_BYTEA_P(pq_endtypsend(&buf));
144 : }
145 :
146 : /*
147 : * anyarray
148 : *
149 : * We need to allow output of anyarray so that, e.g., pg_statistic columns
150 : * can be printed. Input has to be disallowed, however.
151 : *
152 : * XXX anyarray_recv could actually be made to work, since the incoming
153 : * array data would contain the element type OID. It seems unlikely that
154 : * it'd be sufficiently type-safe, though.
155 : */
156 0 : PSEUDOTYPE_DUMMY_INPUT_FUNC(anyarray);
157 0 : PSEUDOTYPE_DUMMY_RECEIVE_FUNC(anyarray);
158 :
159 : Datum
160 34 : anyarray_out(PG_FUNCTION_ARGS)
161 : {
162 34 : return array_out(fcinfo);
163 : }
164 :
165 : Datum
166 0 : anyarray_send(PG_FUNCTION_ARGS)
167 : {
168 0 : return array_send(fcinfo);
169 : }
170 :
171 : /*
172 : * anycompatiblearray
173 : *
174 : * We may as well allow output, since we do for anyarray.
175 : */
176 0 : PSEUDOTYPE_DUMMY_INPUT_FUNC(anycompatiblearray);
177 0 : PSEUDOTYPE_DUMMY_RECEIVE_FUNC(anycompatiblearray);
178 :
179 : Datum
180 0 : anycompatiblearray_out(PG_FUNCTION_ARGS)
181 : {
182 0 : return array_out(fcinfo);
183 : }
184 :
185 : Datum
186 0 : anycompatiblearray_send(PG_FUNCTION_ARGS)
187 : {
188 0 : return array_send(fcinfo);
189 : }
190 :
191 : /*
192 : * anyenum
193 : *
194 : * We may as well allow output, since enum_out will in fact work.
195 : */
196 0 : PSEUDOTYPE_DUMMY_INPUT_FUNC(anyenum);
197 :
198 : Datum
199 0 : anyenum_out(PG_FUNCTION_ARGS)
200 : {
201 0 : return enum_out(fcinfo);
202 : }
203 :
204 : /*
205 : * anyrange
206 : *
207 : * We may as well allow output, since range_out will in fact work.
208 : */
209 4 : PSEUDOTYPE_DUMMY_INPUT_FUNC(anyrange);
210 :
211 : Datum
212 40 : anyrange_out(PG_FUNCTION_ARGS)
213 : {
214 40 : return range_out(fcinfo);
215 : }
216 :
217 : /*
218 : * anycompatiblerange
219 : *
220 : * We may as well allow output, since range_out will in fact work.
221 : */
222 0 : PSEUDOTYPE_DUMMY_INPUT_FUNC(anycompatiblerange);
223 :
224 : Datum
225 0 : anycompatiblerange_out(PG_FUNCTION_ARGS)
226 : {
227 0 : return range_out(fcinfo);
228 : }
229 :
230 : /*
231 : * void
232 : *
233 : * We support void_in so that PL functions can return VOID without any
234 : * special hack in the PL handler. Whatever value the PL thinks it's
235 : * returning will just be ignored. Conversely, void_out and void_send
236 : * are needed so that "SELECT function_returning_void(...)" works.
237 : */
238 : Datum
239 26 : void_in(PG_FUNCTION_ARGS)
240 : {
241 26 : PG_RETURN_VOID(); /* you were expecting something different? */
242 : }
243 :
244 : Datum
245 6958 : void_out(PG_FUNCTION_ARGS)
246 : {
247 6958 : PG_RETURN_CSTRING(pstrdup(""));
248 : }
249 :
250 : Datum
251 0 : void_recv(PG_FUNCTION_ARGS)
252 : {
253 : /*
254 : * Note that since we consume no bytes, an attempt to send anything but an
255 : * empty string will result in an "invalid message format" error.
256 : */
257 0 : PG_RETURN_VOID();
258 : }
259 :
260 : Datum
261 0 : void_send(PG_FUNCTION_ARGS)
262 : {
263 : StringInfoData buf;
264 :
265 : /* send an empty string */
266 0 : pq_begintypsend(&buf);
267 0 : PG_RETURN_BYTEA_P(pq_endtypsend(&buf));
268 : }
269 :
270 : /*
271 : * shell
272 : *
273 : * shell_in and shell_out are entered in pg_type for "shell" types
274 : * (those not yet filled in). They should be unreachable, but we
275 : * set them up just in case some code path tries to do I/O without
276 : * having checked pg_type.typisdefined anywhere along the way.
277 : */
278 : Datum
279 0 : shell_in(PG_FUNCTION_ARGS)
280 : {
281 0 : ereport(ERROR,
282 : (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
283 : errmsg("cannot accept a value of a shell type")));
284 :
285 : PG_RETURN_VOID(); /* keep compiler quiet */
286 : }
287 :
288 : Datum
289 0 : shell_out(PG_FUNCTION_ARGS)
290 : {
291 0 : ereport(ERROR,
292 : (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
293 : errmsg("cannot display a value of a shell type")));
294 :
295 : PG_RETURN_VOID(); /* keep compiler quiet */
296 : }
297 :
298 :
299 : /*
300 : * pg_node_tree
301 : *
302 : * pg_node_tree isn't really a pseudotype --- it's real enough to be a table
303 : * column --- but it presently has no operations of its own, and disallows
304 : * input too, so its I/O functions seem to fit here as much as anywhere.
305 : *
306 : * We must disallow input of pg_node_tree values because the SQL functions
307 : * that operate on the type are not secure against malformed input.
308 : * We do want to allow output, though.
309 : */
310 0 : PSEUDOTYPE_DUMMY_INPUT_FUNC(pg_node_tree);
311 0 : PSEUDOTYPE_DUMMY_RECEIVE_FUNC(pg_node_tree);
312 :
313 : Datum
314 4184 : pg_node_tree_out(PG_FUNCTION_ARGS)
315 : {
316 4184 : return textout(fcinfo);
317 : }
318 :
319 : Datum
320 0 : pg_node_tree_send(PG_FUNCTION_ARGS)
321 : {
322 0 : return textsend(fcinfo);
323 : }
324 :
325 : /*
326 : * pg_ddl_command
327 : *
328 : * Like pg_node_tree, pg_ddl_command isn't really a pseudotype; it's here
329 : * for the same reasons as that one.
330 : *
331 : * We don't have any good way to output this type directly, so punt
332 : * for output as well as input.
333 : */
334 0 : PSEUDOTYPE_DUMMY_IO_FUNCS(pg_ddl_command);
335 0 : PSEUDOTYPE_DUMMY_BINARY_IO_FUNCS(pg_ddl_command);
336 :
337 :
338 : /*
339 : * Dummy I/O functions for various other pseudotypes.
340 : */
341 0 : PSEUDOTYPE_DUMMY_IO_FUNCS(any);
342 0 : PSEUDOTYPE_DUMMY_IO_FUNCS(trigger);
343 0 : PSEUDOTYPE_DUMMY_IO_FUNCS(event_trigger);
344 0 : PSEUDOTYPE_DUMMY_IO_FUNCS(language_handler);
345 0 : PSEUDOTYPE_DUMMY_IO_FUNCS(fdw_handler);
346 0 : PSEUDOTYPE_DUMMY_IO_FUNCS(table_am_handler);
347 0 : PSEUDOTYPE_DUMMY_IO_FUNCS(index_am_handler);
348 0 : PSEUDOTYPE_DUMMY_IO_FUNCS(tsm_handler);
349 0 : PSEUDOTYPE_DUMMY_IO_FUNCS(internal);
350 0 : PSEUDOTYPE_DUMMY_IO_FUNCS(anyelement);
351 0 : PSEUDOTYPE_DUMMY_IO_FUNCS(anynonarray);
352 0 : PSEUDOTYPE_DUMMY_IO_FUNCS(anycompatible);
353 0 : PSEUDOTYPE_DUMMY_IO_FUNCS(anycompatiblenonarray);
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