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parse_param.c
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1 /*-------------------------------------------------------------------------
2  *
3  * parse_param.c
4  * handle parameters in parser
5  *
6  * This code covers two cases that are used within the core backend:
7  * * a fixed list of parameters with known types
8  * * an expandable list of parameters whose types can optionally
9  * be determined from context
10  * In both cases, only explicit $n references (ParamRef nodes) are supported.
11  *
12  * Note that other approaches to parameters are possible using the parser
13  * hooks defined in ParseState.
14  *
15  * Portions Copyright (c) 1996-2017, PostgreSQL Global Development Group
16  * Portions Copyright (c) 1994, Regents of the University of California
17  *
18  *
19  * IDENTIFICATION
20  * src/backend/parser/parse_param.c
21  *
22  *-------------------------------------------------------------------------
23  */
24 
25 #include "postgres.h"
26 
27 #include <limits.h>
28 
29 #include "catalog/pg_type.h"
30 #include "nodes/nodeFuncs.h"
31 #include "parser/parse_param.h"
32 #include "utils/builtins.h"
33 #include "utils/lsyscache.h"
34 
35 
36 typedef struct FixedParamState
37 {
38  Oid *paramTypes; /* array of parameter type OIDs */
39  int numParams; /* number of array entries */
41 
42 /*
43  * In the varparams case, the caller-supplied OID array (if any) can be
44  * re-palloc'd larger at need. A zero array entry means that parameter number
45  * hasn't been seen, while UNKNOWNOID means the parameter has been used but
46  * its type is not yet known.
47  */
48 typedef struct VarParamState
49 {
50  Oid **paramTypes; /* array of parameter type OIDs */
51  int *numParams; /* number of array entries */
53 
54 static Node *fixed_paramref_hook(ParseState *pstate, ParamRef *pref);
55 static Node *variable_paramref_hook(ParseState *pstate, ParamRef *pref);
56 static Node *variable_coerce_param_hook(ParseState *pstate, Param *param,
57  Oid targetTypeId, int32 targetTypeMod,
58  int location);
59 static bool check_parameter_resolution_walker(Node *node, ParseState *pstate);
60 static bool query_contains_extern_params_walker(Node *node, void *context);
61 
62 
63 /*
64  * Set up to process a query containing references to fixed parameters.
65  */
66 void
68  Oid *paramTypes, int numParams)
69 {
70  FixedParamState *parstate = palloc(sizeof(FixedParamState));
71 
72  parstate->paramTypes = paramTypes;
73  parstate->numParams = numParams;
74  pstate->p_ref_hook_state = (void *) parstate;
76  /* no need to use p_coerce_param_hook */
77 }
78 
79 /*
80  * Set up to process a query containing references to variable parameters.
81  */
82 void
84  Oid **paramTypes, int *numParams)
85 {
86  VarParamState *parstate = palloc(sizeof(VarParamState));
87 
88  parstate->paramTypes = paramTypes;
89  parstate->numParams = numParams;
90  pstate->p_ref_hook_state = (void *) parstate;
93 }
94 
95 /*
96  * Transform a ParamRef using fixed parameter types.
97  */
98 static Node *
100 {
101  FixedParamState *parstate = (FixedParamState *) pstate->p_ref_hook_state;
102  int paramno = pref->number;
103  Param *param;
104 
105  /* Check parameter number is valid */
106  if (paramno <= 0 || paramno > parstate->numParams ||
107  !OidIsValid(parstate->paramTypes[paramno - 1]))
108  ereport(ERROR,
109  (errcode(ERRCODE_UNDEFINED_PARAMETER),
110  errmsg("there is no parameter $%d", paramno),
111  parser_errposition(pstate, pref->location)));
112 
113  param = makeNode(Param);
114  param->paramkind = PARAM_EXTERN;
115  param->paramid = paramno;
116  param->paramtype = parstate->paramTypes[paramno - 1];
117  param->paramtypmod = -1;
118  param->paramcollid = get_typcollation(param->paramtype);
119  param->location = pref->location;
120 
121  return (Node *) param;
122 }
123 
124 /*
125  * Transform a ParamRef using variable parameter types.
126  *
127  * The only difference here is we must enlarge the parameter type array
128  * as needed.
129  */
130 static Node *
132 {
133  VarParamState *parstate = (VarParamState *) pstate->p_ref_hook_state;
134  int paramno = pref->number;
135  Oid *pptype;
136  Param *param;
137 
138  /* Check parameter number is in range */
139  if (paramno <= 0 || paramno > INT_MAX / sizeof(Oid))
140  ereport(ERROR,
141  (errcode(ERRCODE_UNDEFINED_PARAMETER),
142  errmsg("there is no parameter $%d", paramno),
143  parser_errposition(pstate, pref->location)));
144  if (paramno > *parstate->numParams)
145  {
146  /* Need to enlarge param array */
147  if (*parstate->paramTypes)
148  *parstate->paramTypes = (Oid *) repalloc(*parstate->paramTypes,
149  paramno * sizeof(Oid));
150  else
151  *parstate->paramTypes = (Oid *) palloc(paramno * sizeof(Oid));
152  /* Zero out the previously-unreferenced slots */
153  MemSet(*parstate->paramTypes + *parstate->numParams,
154  0,
155  (paramno - *parstate->numParams) * sizeof(Oid));
156  *parstate->numParams = paramno;
157  }
158 
159  /* Locate param's slot in array */
160  pptype = &(*parstate->paramTypes)[paramno - 1];
161 
162  /* If not seen before, initialize to UNKNOWN type */
163  if (*pptype == InvalidOid)
164  *pptype = UNKNOWNOID;
165 
166  param = makeNode(Param);
167  param->paramkind = PARAM_EXTERN;
168  param->paramid = paramno;
169  param->paramtype = *pptype;
170  param->paramtypmod = -1;
171  param->paramcollid = get_typcollation(param->paramtype);
172  param->location = pref->location;
173 
174  return (Node *) param;
175 }
176 
177 /*
178  * Coerce a Param to a query-requested datatype, in the varparams case.
179  */
180 static Node *
182  Oid targetTypeId, int32 targetTypeMod,
183  int location)
184 {
185  if (param->paramkind == PARAM_EXTERN && param->paramtype == UNKNOWNOID)
186  {
187  /*
188  * Input is a Param of previously undetermined type, and we want to
189  * update our knowledge of the Param's type.
190  */
191  VarParamState *parstate = (VarParamState *) pstate->p_ref_hook_state;
192  Oid *paramTypes = *parstate->paramTypes;
193  int paramno = param->paramid;
194 
195  if (paramno <= 0 || /* shouldn't happen, but... */
196  paramno > *parstate->numParams)
197  ereport(ERROR,
198  (errcode(ERRCODE_UNDEFINED_PARAMETER),
199  errmsg("there is no parameter $%d", paramno),
200  parser_errposition(pstate, param->location)));
201 
202  if (paramTypes[paramno - 1] == UNKNOWNOID)
203  {
204  /* We've successfully resolved the type */
205  paramTypes[paramno - 1] = targetTypeId;
206  }
207  else if (paramTypes[paramno - 1] == targetTypeId)
208  {
209  /* We previously resolved the type, and it matches */
210  }
211  else
212  {
213  /* Oops */
214  ereport(ERROR,
215  (errcode(ERRCODE_AMBIGUOUS_PARAMETER),
216  errmsg("inconsistent types deduced for parameter $%d",
217  paramno),
218  errdetail("%s versus %s",
219  format_type_be(paramTypes[paramno - 1]),
220  format_type_be(targetTypeId)),
221  parser_errposition(pstate, param->location)));
222  }
223 
224  param->paramtype = targetTypeId;
225 
226  /*
227  * Note: it is tempting here to set the Param's paramtypmod to
228  * targetTypeMod, but that is probably unwise because we have no
229  * infrastructure that enforces that the value delivered for a Param
230  * will match any particular typmod. Leaving it -1 ensures that a
231  * run-time length check/coercion will occur if needed.
232  */
233  param->paramtypmod = -1;
234 
235  /*
236  * This module always sets a Param's collation to be the default for
237  * its datatype. If that's not what you want, you should be using the
238  * more general parser substitution hooks.
239  */
240  param->paramcollid = get_typcollation(param->paramtype);
241 
242  /* Use the leftmost of the param's and coercion's locations */
243  if (location >= 0 &&
244  (param->location < 0 || location < param->location))
245  param->location = location;
246 
247  return (Node *) param;
248  }
249 
250  /* Else signal to proceed with normal coercion */
251  return NULL;
252 }
253 
254 /*
255  * Check for consistent assignment of variable parameters after completion
256  * of parsing with parse_variable_parameters.
257  *
258  * Note: this code intentionally does not check that all parameter positions
259  * were used, nor that all got non-UNKNOWN types assigned. Caller of parser
260  * should enforce that if it's important.
261  */
262 void
264 {
265  VarParamState *parstate = (VarParamState *) pstate->p_ref_hook_state;
266 
267  /* If numParams is zero then no Params were generated, so no work */
268  if (*parstate->numParams > 0)
269  (void) query_tree_walker(query,
271  (void *) pstate, 0);
272 }
273 
274 /*
275  * Traverse a fully-analyzed tree to verify that parameter symbols
276  * match their types. We need this because some Params might still
277  * be UNKNOWN, if there wasn't anything to force their coercion,
278  * and yet other instances seen later might have gotten coerced.
279  */
280 static bool
282 {
283  if (node == NULL)
284  return false;
285  if (IsA(node, Param))
286  {
287  Param *param = (Param *) node;
288 
289  if (param->paramkind == PARAM_EXTERN)
290  {
291  VarParamState *parstate = (VarParamState *) pstate->p_ref_hook_state;
292  int paramno = param->paramid;
293 
294  if (paramno <= 0 || /* shouldn't happen, but... */
295  paramno > *parstate->numParams)
296  ereport(ERROR,
297  (errcode(ERRCODE_UNDEFINED_PARAMETER),
298  errmsg("there is no parameter $%d", paramno),
299  parser_errposition(pstate, param->location)));
300 
301  if (param->paramtype != (*parstate->paramTypes)[paramno - 1])
302  ereport(ERROR,
303  (errcode(ERRCODE_AMBIGUOUS_PARAMETER),
304  errmsg("could not determine data type of parameter $%d",
305  paramno),
306  parser_errposition(pstate, param->location)));
307  }
308  return false;
309  }
310  if (IsA(node, Query))
311  {
312  /* Recurse into RTE subquery or not-yet-planned sublink subquery */
313  return query_tree_walker((Query *) node,
315  (void *) pstate, 0);
316  }
318  (void *) pstate);
319 }
320 
321 /*
322  * Check to see if a fully-parsed query tree contains any PARAM_EXTERN Params.
323  */
324 bool
326 {
327  return query_tree_walker(query,
329  NULL, 0);
330 }
331 
332 static bool
334 {
335  if (node == NULL)
336  return false;
337  if (IsA(node, Param))
338  {
339  Param *param = (Param *) node;
340 
341  if (param->paramkind == PARAM_EXTERN)
342  return true;
343  return false;
344  }
345  if (IsA(node, Query))
346  {
347  /* Recurse into RTE subquery or not-yet-planned sublink subquery */
348  return query_tree_walker((Query *) node,
350  context, 0);
351  }
353  context);
354 }
Oid ** paramTypes
Definition: parse_param.c:50
bool query_tree_walker(Query *query, bool(*walker)(), void *context, int flags)
Definition: nodeFuncs.c:2257
static Node * variable_coerce_param_hook(ParseState *pstate, Param *param, Oid targetTypeId, int32 targetTypeMod, int location)
Definition: parse_param.c:181
#define IsA(nodeptr, _type_)
Definition: nodes.h:557
static bool query_contains_extern_params_walker(Node *node, void *context)
Definition: parse_param.c:333
static Node * fixed_paramref_hook(ParseState *pstate, ParamRef *pref)
Definition: parse_param.c:99
struct FixedParamState FixedParamState
struct VarParamState VarParamState
CoerceParamHook p_coerce_param_hook
Definition: parse_node.h:205
void parse_variable_parameters(ParseState *pstate, Oid **paramTypes, int *numParams)
Definition: parse_param.c:83
ParamKind paramkind
Definition: primnodes.h:244
Definition: nodes.h:506
int errcode(int sqlerrcode)
Definition: elog.c:575
#define MemSet(start, val, len)
Definition: c.h:857
char * format_type_be(Oid type_oid)
Definition: format_type.c:94
unsigned int Oid
Definition: postgres_ext.h:31
#define OidIsValid(objectId)
Definition: c.h:538
signed int int32
Definition: c.h:256
#define ERROR
Definition: elog.h:43
Oid paramcollid
Definition: primnodes.h:248
int location
Definition: primnodes.h:249
int * numParams
Definition: parse_param.c:51
ParseParamRefHook p_paramref_hook
Definition: parse_node.h:204
int errdetail(const char *fmt,...)
Definition: elog.c:873
#define ereport(elevel, rest)
Definition: elog.h:122
static Node * variable_paramref_hook(ParseState *pstate, ParamRef *pref)
Definition: parse_param.c:131
int number
Definition: parsenodes.h:236
static bool check_parameter_resolution_walker(Node *node, ParseState *pstate)
Definition: parse_param.c:281
#define InvalidOid
Definition: postgres_ext.h:36
Oid get_typcollation(Oid typid)
Definition: lsyscache.c:2749
int32 paramtypmod
Definition: primnodes.h:247
int location
Definition: parsenodes.h:237
#define makeNode(_type_)
Definition: nodes.h:554
#define NULL
Definition: c.h:229
void * p_ref_hook_state
Definition: parse_node.h:206
void parse_fixed_parameters(ParseState *pstate, Oid *paramTypes, int numParams)
Definition: parse_param.c:67
int paramid
Definition: primnodes.h:245
bool expression_tree_walker(Node *node, bool(*walker)(), void *context)
Definition: nodeFuncs.c:1855
int parser_errposition(ParseState *pstate, int location)
Definition: parse_node.c:109
void * repalloc(void *pointer, Size size)
Definition: mcxt.c:963
#define UNKNOWNOID
Definition: pg_type.h:427
bool query_contains_extern_params(Query *query)
Definition: parse_param.c:325
void * palloc(Size size)
Definition: mcxt.c:849
int errmsg(const char *fmt,...)
Definition: elog.c:797
void check_variable_parameters(ParseState *pstate, Query *query)
Definition: parse_param.c:263
Oid paramtype
Definition: primnodes.h:246