PostgreSQL Source Code  git master
fastpath.c
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1 /*-------------------------------------------------------------------------
2  *
3  * fastpath.c
4  * routines to handle function requests from the frontend
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/tcop/fastpath.c
12  *
13  * NOTES
14  * This cruft is the server side of PQfn.
15  *
16  *-------------------------------------------------------------------------
17  */
18 #include "postgres.h"
19 
20 #include "access/htup_details.h"
21 #include "access/xact.h"
22 #include "catalog/objectaccess.h"
23 #include "catalog/pg_proc.h"
24 #include "libpq/libpq.h"
25 #include "libpq/pqformat.h"
26 #include "mb/pg_wchar.h"
27 #include "miscadmin.h"
28 #include "port/pg_bswap.h"
29 #include "tcop/fastpath.h"
30 #include "tcop/tcopprot.h"
31 #include "utils/acl.h"
32 #include "utils/lsyscache.h"
33 #include "utils/snapmgr.h"
34 #include "utils/syscache.h"
35 
36 
37 /*
38  * Formerly, this code attempted to cache the function and type info
39  * looked up by fetch_fp_info, but only for the duration of a single
40  * transaction command (since in theory the info could change between
41  * commands). This was utterly useless, because postgres.c executes
42  * each fastpath call as a separate transaction command, and so the
43  * cached data could never actually have been reused. If it had worked
44  * as intended, it would have had problems anyway with dangling references
45  * in the FmgrInfo struct. So, forget about caching and just repeat the
46  * syscache fetches on each usage. They're not *that* expensive.
47  */
48 struct fp_info
49 {
51  FmgrInfo flinfo; /* function lookup info for funcid */
52  Oid namespace; /* other stuff from pg_proc */
53  Oid rettype;
55  char fname[NAMEDATALEN]; /* function name for logging */
56 };
57 
58 
59 static int16 parse_fcall_arguments(StringInfo msgBuf, struct fp_info *fip,
60  FunctionCallInfo fcinfo);
61 
62 /* ----------------
63  * SendFunctionResult
64  * ----------------
65  */
66 static void
68 {
70 
71  pq_beginmessage(&buf, 'V');
72 
73  if (isnull)
74  {
75  pq_sendint32(&buf, -1);
76  }
77  else
78  {
79  if (format == 0)
80  {
81  Oid typoutput;
82  bool typisvarlena;
83  char *outputstr;
84 
85  getTypeOutputInfo(rettype, &typoutput, &typisvarlena);
86  outputstr = OidOutputFunctionCall(typoutput, retval);
87  pq_sendcountedtext(&buf, outputstr, strlen(outputstr), false);
88  pfree(outputstr);
89  }
90  else if (format == 1)
91  {
92  Oid typsend;
93  bool typisvarlena;
94  bytea *outputbytes;
95 
96  getTypeBinaryOutputInfo(rettype, &typsend, &typisvarlena);
97  outputbytes = OidSendFunctionCall(typsend, retval);
98  pq_sendint32(&buf, VARSIZE(outputbytes) - VARHDRSZ);
99  pq_sendbytes(&buf, VARDATA(outputbytes),
100  VARSIZE(outputbytes) - VARHDRSZ);
101  pfree(outputbytes);
102  }
103  else
104  ereport(ERROR,
105  (errcode(ERRCODE_INVALID_PARAMETER_VALUE),
106  errmsg("unsupported format code: %d", format)));
107  }
108 
109  pq_endmessage(&buf);
110 }
111 
112 /*
113  * fetch_fp_info
114  *
115  * Performs catalog lookups to load a struct fp_info 'fip' for the
116  * function 'func_id'.
117  */
118 static void
119 fetch_fp_info(Oid func_id, struct fp_info *fip)
120 {
121  HeapTuple func_htp;
122  Form_pg_proc pp;
123 
124  Assert(fip != NULL);
125 
126  /*
127  * Since the validity of this structure is determined by whether the
128  * funcid is OK, we clear the funcid here. It must not be set to the
129  * correct value until we are about to return with a good struct fp_info,
130  * since we can be interrupted (i.e., with an ereport(ERROR, ...)) at any
131  * time. [No longer really an issue since we don't save the struct
132  * fp_info across transactions anymore, but keep it anyway.]
133  */
134  MemSet(fip, 0, sizeof(struct fp_info));
135  fip->funcid = InvalidOid;
136 
137  func_htp = SearchSysCache1(PROCOID, ObjectIdGetDatum(func_id));
138  if (!HeapTupleIsValid(func_htp))
139  ereport(ERROR,
140  (errcode(ERRCODE_UNDEFINED_FUNCTION),
141  errmsg("function with OID %u does not exist", func_id)));
142  pp = (Form_pg_proc) GETSTRUCT(func_htp);
143 
144  /* reject pg_proc entries that are unsafe to call via fastpath */
145  if (pp->prokind != PROKIND_FUNCTION || pp->proretset)
146  ereport(ERROR,
147  (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
148  errmsg("cannot call function \"%s\" via fastpath interface",
149  NameStr(pp->proname))));
150 
151  /* watch out for catalog entries with more than FUNC_MAX_ARGS args */
152  if (pp->pronargs > FUNC_MAX_ARGS)
153  elog(ERROR, "function %s has more than %d arguments",
154  NameStr(pp->proname), FUNC_MAX_ARGS);
155 
156  fip->namespace = pp->pronamespace;
157  fip->rettype = pp->prorettype;
158  memcpy(fip->argtypes, pp->proargtypes.values, pp->pronargs * sizeof(Oid));
159  strlcpy(fip->fname, NameStr(pp->proname), NAMEDATALEN);
160 
161  ReleaseSysCache(func_htp);
162 
163  fmgr_info(func_id, &fip->flinfo);
164 
165  /*
166  * This must be last!
167  */
168  fip->funcid = func_id;
169 }
170 
171 
172 /*
173  * HandleFunctionRequest
174  *
175  * Server side of PQfn (fastpath function calls from the frontend).
176  * This corresponds to the libpq protocol symbol "F".
177  *
178  * INPUT:
179  * postgres.c has already read the message body and will pass it in
180  * msgBuf.
181  *
182  * Note: palloc()s done here and in the called function do not need to be
183  * cleaned up explicitly. We are called from PostgresMain() in the
184  * MessageContext memory context, which will be automatically reset when
185  * control returns to PostgresMain.
186  */
187 void
189 {
190  LOCAL_FCINFO(fcinfo, FUNC_MAX_ARGS);
191  Oid fid;
192  AclResult aclresult;
193  int16 rformat;
194  Datum retval;
195  struct fp_info my_fp;
196  struct fp_info *fip;
197  bool callit;
198  bool was_logged = false;
199  char msec_str[32];
200 
201  /*
202  * We only accept COMMIT/ABORT if we are in an aborted transaction, and
203  * COMMIT/ABORT cannot be executed through the fastpath interface.
204  */
206  ereport(ERROR,
207  (errcode(ERRCODE_IN_FAILED_SQL_TRANSACTION),
208  errmsg("current transaction is aborted, "
209  "commands ignored until end of transaction block")));
210 
211  /*
212  * Now that we know we are in a valid transaction, set snapshot in case
213  * needed by function itself or one of the datatype I/O routines.
214  */
216 
217  /*
218  * Begin parsing the buffer contents.
219  */
220  fid = (Oid) pq_getmsgint(msgBuf, 4); /* function oid */
221 
222  /*
223  * There used to be a lame attempt at caching lookup info here. Now we
224  * just do the lookups on every call.
225  */
226  fip = &my_fp;
227  fetch_fp_info(fid, fip);
228 
229  /* Log as soon as we have the function OID and name */
230  if (log_statement == LOGSTMT_ALL)
231  {
232  ereport(LOG,
233  (errmsg("fastpath function call: \"%s\" (OID %u)",
234  fip->fname, fid)));
235  was_logged = true;
236  }
237 
238  /*
239  * Check permission to access and call function. Since we didn't go
240  * through a normal name lookup, we need to check schema usage too.
241  */
242  aclresult = pg_namespace_aclcheck(fip->namespace, GetUserId(), ACL_USAGE);
243  if (aclresult != ACLCHECK_OK)
244  aclcheck_error(aclresult, OBJECT_SCHEMA,
245  get_namespace_name(fip->namespace));
246  InvokeNamespaceSearchHook(fip->namespace, true);
247 
248  aclresult = pg_proc_aclcheck(fid, GetUserId(), ACL_EXECUTE);
249  if (aclresult != ACLCHECK_OK)
250  aclcheck_error(aclresult, OBJECT_FUNCTION,
251  get_func_name(fid));
253 
254  /*
255  * Prepare function call info block and insert arguments.
256  *
257  * Note: for now we pass collation = InvalidOid, so collation-sensitive
258  * functions can't be called this way. Perhaps we should pass
259  * DEFAULT_COLLATION_OID, instead?
260  */
261  InitFunctionCallInfoData(*fcinfo, &fip->flinfo, 0, InvalidOid, NULL, NULL);
262 
263  rformat = parse_fcall_arguments(msgBuf, fip, fcinfo);
264 
265  /* Verify we reached the end of the message where expected. */
266  pq_getmsgend(msgBuf);
267 
268  /*
269  * If func is strict, must not call it for null args.
270  */
271  callit = true;
272  if (fip->flinfo.fn_strict)
273  {
274  int i;
275 
276  for (i = 0; i < fcinfo->nargs; i++)
277  {
278  if (fcinfo->args[i].isnull)
279  {
280  callit = false;
281  break;
282  }
283  }
284  }
285 
286  if (callit)
287  {
288  /* Okay, do it ... */
289  retval = FunctionCallInvoke(fcinfo);
290  }
291  else
292  {
293  fcinfo->isnull = true;
294  retval = (Datum) 0;
295  }
296 
297  /* ensure we do at least one CHECK_FOR_INTERRUPTS per function call */
299 
300  SendFunctionResult(retval, fcinfo->isnull, fip->rettype, rformat);
301 
302  /* We no longer need the snapshot */
304 
305  /*
306  * Emit duration logging if appropriate.
307  */
308  switch (check_log_duration(msec_str, was_logged))
309  {
310  case 1:
311  ereport(LOG,
312  (errmsg("duration: %s ms", msec_str)));
313  break;
314  case 2:
315  ereport(LOG,
316  (errmsg("duration: %s ms fastpath function call: \"%s\" (OID %u)",
317  msec_str, fip->fname, fid)));
318  break;
319  }
320 }
321 
322 /*
323  * Parse function arguments in a 3.0 protocol message
324  *
325  * Argument values are loaded into *fcinfo, and the desired result format
326  * is returned.
327  */
328 static int16
330  FunctionCallInfo fcinfo)
331 {
332  int nargs;
333  int i;
334  int numAFormats;
335  int16 *aformats = NULL;
336  StringInfoData abuf;
337 
338  /* Get the argument format codes */
339  numAFormats = pq_getmsgint(msgBuf, 2);
340  if (numAFormats > 0)
341  {
342  aformats = (int16 *) palloc(numAFormats * sizeof(int16));
343  for (i = 0; i < numAFormats; i++)
344  aformats[i] = pq_getmsgint(msgBuf, 2);
345  }
346 
347  nargs = pq_getmsgint(msgBuf, 2); /* # of arguments */
348 
349  if (fip->flinfo.fn_nargs != nargs || nargs > FUNC_MAX_ARGS)
350  ereport(ERROR,
351  (errcode(ERRCODE_PROTOCOL_VIOLATION),
352  errmsg("function call message contains %d arguments but function requires %d",
353  nargs, fip->flinfo.fn_nargs)));
354 
355  fcinfo->nargs = nargs;
356 
357  if (numAFormats > 1 && numAFormats != nargs)
358  ereport(ERROR,
359  (errcode(ERRCODE_PROTOCOL_VIOLATION),
360  errmsg("function call message contains %d argument formats but %d arguments",
361  numAFormats, nargs)));
362 
363  initStringInfo(&abuf);
364 
365  /*
366  * Copy supplied arguments into arg vector.
367  */
368  for (i = 0; i < nargs; ++i)
369  {
370  int argsize;
371  int16 aformat;
372 
373  argsize = pq_getmsgint(msgBuf, 4);
374  if (argsize == -1)
375  {
376  fcinfo->args[i].isnull = true;
377  }
378  else
379  {
380  fcinfo->args[i].isnull = false;
381  if (argsize < 0)
382  ereport(ERROR,
383  (errcode(ERRCODE_PROTOCOL_VIOLATION),
384  errmsg("invalid argument size %d in function call message",
385  argsize)));
386 
387  /* Reset abuf to empty, and insert raw data into it */
388  resetStringInfo(&abuf);
390  pq_getmsgbytes(msgBuf, argsize),
391  argsize);
392  }
393 
394  if (numAFormats > 1)
395  aformat = aformats[i];
396  else if (numAFormats > 0)
397  aformat = aformats[0];
398  else
399  aformat = 0; /* default = text */
400 
401  if (aformat == 0)
402  {
403  Oid typinput;
404  Oid typioparam;
405  char *pstring;
406 
407  getTypeInputInfo(fip->argtypes[i], &typinput, &typioparam);
408 
409  /*
410  * Since stringinfo.c keeps a trailing null in place even for
411  * binary data, the contents of abuf are a valid C string. We
412  * have to do encoding conversion before calling the typinput
413  * routine, though.
414  */
415  if (argsize == -1)
416  pstring = NULL;
417  else
418  pstring = pg_client_to_server(abuf.data, argsize);
419 
420  fcinfo->args[i].value = OidInputFunctionCall(typinput, pstring,
421  typioparam, -1);
422  /* Free result of encoding conversion, if any */
423  if (pstring && pstring != abuf.data)
424  pfree(pstring);
425  }
426  else if (aformat == 1)
427  {
428  Oid typreceive;
429  Oid typioparam;
430  StringInfo bufptr;
431 
432  /* Call the argument type's binary input converter */
433  getTypeBinaryInputInfo(fip->argtypes[i], &typreceive, &typioparam);
434 
435  if (argsize == -1)
436  bufptr = NULL;
437  else
438  bufptr = &abuf;
439 
440  fcinfo->args[i].value = OidReceiveFunctionCall(typreceive, bufptr,
441  typioparam, -1);
442 
443  /* Trouble if it didn't eat the whole buffer */
444  if (argsize != -1 && abuf.cursor != abuf.len)
445  ereport(ERROR,
446  (errcode(ERRCODE_INVALID_BINARY_REPRESENTATION),
447  errmsg("incorrect binary data format in function argument %d",
448  i + 1)));
449  }
450  else
451  ereport(ERROR,
452  (errcode(ERRCODE_INVALID_PARAMETER_VALUE),
453  errmsg("unsupported format code: %d", aformat)));
454  }
455 
456  /* Return result format code */
457  return (int16) pq_getmsgint(msgBuf, 2);
458 }
signed short int16
Definition: c.h:428
Definition: fmgr.h:56
FmgrInfo flinfo
Definition: fastpath.c:51
short fn_nargs
Definition: fmgr.h:60
void getTypeOutputInfo(Oid type, Oid *typOutput, bool *typIsVarlena)
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Definition: postgres.h:315
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Definition: fastpath.c:55
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Definition: fmgr.c:126
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uintptr_t Datum
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Definition: syscache.c:1175
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FormData_pg_proc * Form_pg_proc
Definition: pg_proc.h:136
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