Line data Source code
1 : /* src/interfaces/ecpg/ecpglib/prepare.c */
2 :
3 : #define POSTGRES_ECPG_INTERNAL
4 : #include "postgres_fe.h"
5 :
6 : #include <ctype.h>
7 :
8 : #include "ecpgerrno.h"
9 : #include "ecpglib.h"
10 : #include "ecpglib_extern.h"
11 : #include "ecpgtype.h"
12 : #include "sqlca.h"
13 :
14 : #define STMTID_SIZE 32
15 :
16 : /*
17 : * The statement cache contains stmtCacheNBuckets hash buckets, each
18 : * having stmtCacheEntPerBucket entries, which we recycle as needed,
19 : * giving up the least-executed entry in the bucket.
20 : * stmtCacheEntries[0] is never used, so that zero can be a "not found"
21 : * indicator.
22 : */
23 : #define stmtCacheNBuckets 2039 /* should be a prime number */
24 : #define stmtCacheEntPerBucket 8
25 :
26 : #define stmtCacheArraySize (stmtCacheNBuckets * stmtCacheEntPerBucket + 1)
27 :
28 : typedef struct
29 : {
30 : int lineno;
31 : char stmtID[STMTID_SIZE];
32 : char *ecpgQuery;
33 : long execs; /* # of executions */
34 : const char *connection; /* connection for the statement */
35 : } stmtCacheEntry;
36 :
37 : static int nextStmtID = 1;
38 : static stmtCacheEntry *stmtCacheEntries = NULL;
39 :
40 : static bool deallocate_one(int lineno, enum COMPAT_MODE c, struct connection *con,
41 : struct prepared_statement *prev, struct prepared_statement *this);
42 :
43 : static bool
44 1654 : isvarchar(unsigned char c)
45 : {
46 1654 : if (isalnum(c))
47 6 : return true;
48 :
49 1648 : if (c == '_' || c == '>' || c == '-' || c == '.')
50 0 : return true;
51 :
52 1648 : if (c >= 128)
53 0 : return true;
54 :
55 1648 : return false;
56 : }
57 :
58 : bool
59 10 : ecpg_register_prepared_stmt(struct statement *stmt)
60 : {
61 : struct statement *prep_stmt;
62 : struct prepared_statement *this;
63 10 : struct connection *con = stmt->connection;
64 10 : struct prepared_statement *prev = NULL;
65 10 : int lineno = stmt->lineno;
66 :
67 : /* check if we already have prepared this statement */
68 10 : this = ecpg_find_prepared_statement(stmt->name, con, &prev);
69 10 : if (this && !deallocate_one(lineno, ECPG_COMPAT_PGSQL, con, prev, this))
70 0 : return false;
71 :
72 : /* allocate new statement */
73 10 : this = (struct prepared_statement *) ecpg_alloc(sizeof(struct prepared_statement), lineno);
74 10 : if (!this)
75 0 : return false;
76 :
77 10 : prep_stmt = (struct statement *) ecpg_alloc(sizeof(struct statement), lineno);
78 10 : if (!prep_stmt)
79 : {
80 0 : ecpg_free(this);
81 0 : return false;
82 : }
83 10 : memset(prep_stmt, 0, sizeof(struct statement));
84 :
85 : /* create statement */
86 10 : prep_stmt->lineno = lineno;
87 10 : prep_stmt->connection = con;
88 10 : prep_stmt->command = ecpg_strdup(stmt->command, lineno, NULL);
89 10 : if (!prep_stmt->command)
90 : {
91 0 : ecpg_free(prep_stmt);
92 0 : ecpg_free(this);
93 0 : return false;
94 : }
95 10 : prep_stmt->inlist = prep_stmt->outlist = NULL;
96 10 : this->name = ecpg_strdup(stmt->name, lineno, NULL);
97 10 : if (!this->name)
98 : {
99 0 : ecpg_free(prep_stmt->command);
100 0 : ecpg_free(prep_stmt);
101 0 : ecpg_free(this);
102 0 : return false;
103 : }
104 10 : this->stmt = prep_stmt;
105 10 : this->prepared = true;
106 :
107 10 : if (con->prep_stmts == NULL)
108 0 : this->next = NULL;
109 : else
110 10 : this->next = con->prep_stmts;
111 :
112 10 : con->prep_stmts = this;
113 10 : return true;
114 : }
115 :
116 : static bool
117 1714 : replace_variables(char **text, int lineno)
118 : {
119 1714 : bool string = false;
120 1714 : int counter = 1,
121 1714 : ptr = 0;
122 :
123 48784 : for (; (*text)[ptr] != '\0'; ptr++)
124 : {
125 47070 : if ((*text)[ptr] == '\'')
126 4 : string = string ? false : true;
127 :
128 47070 : if (string || (((*text)[ptr] != ':') && ((*text)[ptr] != '?')))
129 45410 : continue;
130 :
131 1660 : if (((*text)[ptr] == ':') && ((*text)[ptr + 1] == ':'))
132 4 : ptr += 2; /* skip '::' */
133 : else
134 : {
135 : /* a rough guess of the size we need: */
136 1656 : int buffersize = sizeof(int) * CHAR_BIT * 10 / 3;
137 : int len;
138 : char *buffer,
139 : *newcopy;
140 :
141 1656 : if (!(buffer = ecpg_alloc(buffersize, lineno)))
142 0 : return false;
143 :
144 1656 : snprintf(buffer, buffersize, "$%d", counter++);
145 :
146 1662 : for (len = 1; (*text)[ptr + len] && isvarchar((*text)[ptr + len]); len++)
147 : /* skip */ ;
148 1656 : if (!(newcopy = ecpg_alloc(strlen(*text) - len + strlen(buffer) + 1, lineno)))
149 : {
150 0 : ecpg_free(buffer);
151 0 : return false;
152 : }
153 :
154 1656 : memcpy(newcopy, *text, ptr);
155 1656 : strcpy(newcopy + ptr, buffer);
156 1656 : strcat(newcopy, (*text) +ptr + len);
157 :
158 1656 : ecpg_free(*text);
159 1656 : ecpg_free(buffer);
160 :
161 1656 : *text = newcopy;
162 :
163 1656 : if ((*text)[ptr] == '\0') /* we reached the end */
164 0 : ptr--; /* since we will (*text)[ptr]++ in the top
165 : * level for loop */
166 : }
167 : }
168 1714 : return true;
169 : }
170 :
171 : static bool
172 1714 : prepare_common(int lineno, struct connection *con, const char *name, const char *variable)
173 : {
174 : struct statement *stmt;
175 : struct prepared_statement *this;
176 : PGresult *query;
177 :
178 : /* allocate new statement */
179 1714 : this = (struct prepared_statement *) ecpg_alloc(sizeof(struct prepared_statement), lineno);
180 1714 : if (!this)
181 0 : return false;
182 :
183 1714 : stmt = (struct statement *) ecpg_alloc(sizeof(struct statement), lineno);
184 1714 : if (!stmt)
185 : {
186 0 : ecpg_free(this);
187 0 : return false;
188 : }
189 :
190 : /* create statement */
191 1714 : stmt->lineno = lineno;
192 1714 : stmt->connection = con;
193 1714 : stmt->command = ecpg_strdup(variable, lineno, NULL);
194 1714 : if (!stmt->command)
195 : {
196 0 : ecpg_free(stmt);
197 0 : ecpg_free(this);
198 0 : return false;
199 : }
200 1714 : stmt->inlist = stmt->outlist = NULL;
201 :
202 : /* if we have C variables in our statement replace them with '?' */
203 1714 : if (!replace_variables(&(stmt->command), lineno))
204 : {
205 0 : ecpg_free(stmt->command);
206 0 : ecpg_free(stmt);
207 0 : ecpg_free(this);
208 0 : return false;
209 : }
210 :
211 : /* add prepared statement to our list */
212 1714 : this->name = ecpg_strdup(name, lineno, NULL);
213 1714 : if (!this->name)
214 : {
215 0 : ecpg_free(stmt->command);
216 0 : ecpg_free(stmt);
217 0 : ecpg_free(this);
218 0 : return false;
219 : }
220 1714 : this->stmt = stmt;
221 :
222 : /* and finally really prepare the statement */
223 1714 : query = PQprepare(stmt->connection->connection, name, stmt->command, 0, NULL);
224 1714 : if (!ecpg_check_PQresult(query, stmt->lineno, stmt->connection->connection, stmt->compat))
225 : {
226 0 : ecpg_free(stmt->command);
227 0 : ecpg_free(this->name);
228 0 : ecpg_free(this);
229 0 : ecpg_free(stmt);
230 0 : return false;
231 : }
232 :
233 1714 : ecpg_log("prepare_common on line %d: name %s; query: \"%s\"\n", stmt->lineno, name, stmt->command);
234 1714 : PQclear(query);
235 1714 : this->prepared = true;
236 :
237 1714 : if (con->prep_stmts == NULL)
238 1662 : this->next = NULL;
239 : else
240 52 : this->next = con->prep_stmts;
241 :
242 1714 : con->prep_stmts = this;
243 1714 : return true;
244 : }
245 :
246 : /* handle the EXEC SQL PREPARE statement */
247 : /* questionmarks is not needed but remains in there for the time being to not change the API */
248 : bool
249 1710 : ECPGprepare(int lineno, const char *connection_name, const bool questionmarks,
250 : const char *name, const char *variable)
251 : {
252 : struct connection *con;
253 : struct prepared_statement *this,
254 : *prev;
255 :
256 : (void) questionmarks; /* quiet the compiler */
257 :
258 1710 : con = ecpg_get_connection(connection_name);
259 1710 : if (!ecpg_init(con, connection_name, lineno))
260 2 : return false;
261 :
262 : /* check if we already have prepared this statement */
263 1708 : this = ecpg_find_prepared_statement(name, con, &prev);
264 1708 : if (this && !deallocate_one(lineno, ECPG_COMPAT_PGSQL, con, prev, this))
265 0 : return false;
266 :
267 1708 : return prepare_common(lineno, con, name, variable);
268 : }
269 :
270 : struct prepared_statement *
271 3588 : ecpg_find_prepared_statement(const char *name,
272 : struct connection *con, struct prepared_statement **prev_)
273 : {
274 : struct prepared_statement *this,
275 : *prev;
276 :
277 3588 : for (this = con->prep_stmts, prev = NULL;
278 3722 : this != NULL;
279 134 : prev = this, this = this->next)
280 : {
281 3570 : if (strcmp(this->name, name) == 0)
282 : {
283 3436 : if (prev_)
284 1680 : *prev_ = prev;
285 3436 : return this;
286 : }
287 : }
288 152 : return NULL;
289 : }
290 :
291 : static bool
292 1720 : deallocate_one(int lineno, enum COMPAT_MODE c, struct connection *con,
293 : struct prepared_statement *prev, struct prepared_statement *this)
294 : {
295 1720 : bool r = false;
296 :
297 1720 : ecpg_log("deallocate_one on line %d: name %s\n", lineno, this->name);
298 :
299 : /* first deallocate the statement in the backend */
300 1720 : if (this->prepared)
301 : {
302 : char *text;
303 : PGresult *query;
304 :
305 1720 : text = ecpg_alloc(strlen("deallocate \"\" ") + strlen(this->name), this->stmt->lineno);
306 :
307 1720 : if (text)
308 : {
309 1720 : sprintf(text, "deallocate \"%s\"", this->name);
310 1720 : query = PQexec(this->stmt->connection->connection, text);
311 1720 : ecpg_free(text);
312 1720 : if (ecpg_check_PQresult(query, lineno,
313 1720 : this->stmt->connection->connection,
314 1720 : this->stmt->compat))
315 : {
316 1720 : PQclear(query);
317 1720 : r = true;
318 : }
319 : }
320 : }
321 :
322 : /*
323 : * Just ignore all errors since we do not know the list of cursors we are
324 : * allowed to free. We have to trust the software.
325 : */
326 1720 : if (!r && !INFORMIX_MODE(c))
327 : {
328 0 : ecpg_raise(lineno, ECPG_INVALID_STMT, ECPG_SQLSTATE_INVALID_SQL_STATEMENT_NAME, this->name);
329 0 : return false;
330 : }
331 :
332 : /* okay, free all the resources */
333 1720 : ecpg_free(this->stmt->command);
334 1720 : ecpg_free(this->stmt);
335 1720 : ecpg_free(this->name);
336 1720 : if (prev != NULL)
337 6 : prev->next = this->next;
338 : else
339 1714 : con->prep_stmts = this->next;
340 :
341 1720 : ecpg_free(this);
342 1720 : return true;
343 : }
344 :
345 : /* handle the EXEC SQL DEALLOCATE PREPARE statement */
346 : bool
347 108 : ECPGdeallocate(int lineno, int c, const char *connection_name, const char *name)
348 : {
349 : struct connection *con;
350 : struct prepared_statement *this,
351 : *prev;
352 :
353 108 : con = ecpg_get_connection(connection_name);
354 108 : if (!ecpg_init(con, connection_name, lineno))
355 0 : return false;
356 :
357 108 : this = ecpg_find_prepared_statement(name, con, &prev);
358 108 : if (this)
359 106 : return deallocate_one(lineno, c, con, prev, this);
360 :
361 : /* prepared statement is not found */
362 2 : if (INFORMIX_MODE(c))
363 0 : return true;
364 2 : ecpg_raise(lineno, ECPG_INVALID_STMT, ECPG_SQLSTATE_INVALID_SQL_STATEMENT_NAME, name);
365 2 : return false;
366 : }
367 :
368 : bool
369 262 : ecpg_deallocate_all_conn(int lineno, enum COMPAT_MODE c, struct connection *con)
370 : {
371 : /* deallocate all prepared statements */
372 302 : while (con->prep_stmts)
373 : {
374 40 : if (!deallocate_one(lineno, c, con, NULL, con->prep_stmts))
375 0 : return false;
376 : }
377 :
378 262 : return true;
379 : }
380 :
381 : bool
382 6 : ECPGdeallocate_all(int lineno, int compat, const char *connection_name)
383 : {
384 6 : struct connection *con = ecpg_get_connection(connection_name);
385 :
386 6 : if (!ecpg_init(con, connection_name, lineno))
387 4 : return false;
388 :
389 2 : return ecpg_deallocate_all_conn(lineno, compat, con);
390 : }
391 :
392 : char *
393 1710 : ecpg_prepared(const char *name, struct connection *con)
394 : {
395 : struct prepared_statement *this;
396 :
397 1710 : this = ecpg_find_prepared_statement(name, con, NULL);
398 1710 : return this ? this->stmt->command : NULL;
399 : }
400 :
401 : /* return the prepared statement */
402 : char *
403 44 : ECPGprepared_statement(const char *connection_name, const char *name, int lineno)
404 : {
405 44 : struct connection *con = ecpg_get_connection(connection_name);
406 :
407 44 : if (!ecpg_init(con, connection_name, lineno))
408 2 : return NULL;
409 :
410 42 : return ecpg_prepared(name, con);
411 : }
412 :
413 : /*
414 : * hash a SQL statement - returns entry # of first entry in the bucket
415 : */
416 : static int
417 20 : HashStmt(const char *ecpgQuery)
418 : {
419 : int stmtIx,
420 : bucketNo,
421 : hashLeng,
422 : stmtLeng;
423 : uint64 hashVal,
424 : rotVal;
425 :
426 20 : stmtLeng = strlen(ecpgQuery);
427 20 : hashLeng = 50; /* use 1st 50 characters of statement */
428 20 : if (hashLeng > stmtLeng) /* if the statement isn't that long */
429 20 : hashLeng = stmtLeng; /* use its actual length */
430 :
431 20 : hashVal = 0;
432 742 : for (stmtIx = 0; stmtIx < hashLeng; ++stmtIx)
433 : {
434 722 : hashVal = hashVal + (unsigned char) ecpgQuery[stmtIx];
435 : /* rotate 32-bit hash value left 13 bits */
436 722 : hashVal = hashVal << 13;
437 722 : rotVal = (hashVal & UINT64CONST(0x1fff00000000)) >> 32;
438 722 : hashVal = (hashVal & UINT64CONST(0xffffffff)) | rotVal;
439 : }
440 :
441 20 : bucketNo = hashVal % stmtCacheNBuckets;
442 :
443 : /* Add 1 so that array entry 0 is never used */
444 20 : return bucketNo * stmtCacheEntPerBucket + 1;
445 : }
446 :
447 : /*
448 : * search the statement cache - search for entry with matching ECPG-format query
449 : * Returns entry # in cache if found
450 : * OR zero if not present (zero'th entry isn't used)
451 : */
452 : static int
453 16 : SearchStmtCache(const char *ecpgQuery)
454 : {
455 : int entNo,
456 : entIx;
457 :
458 : /* quick failure if cache not set up */
459 16 : if (stmtCacheEntries == NULL)
460 2 : return 0;
461 :
462 : /* hash the statement */
463 14 : entNo = HashStmt(ecpgQuery);
464 :
465 : /* search the cache */
466 46 : for (entIx = 0; entIx < stmtCacheEntPerBucket; ++entIx)
467 : {
468 42 : if (stmtCacheEntries[entNo].stmtID[0]) /* check if entry is in use */
469 : {
470 10 : if (strcmp(ecpgQuery, stmtCacheEntries[entNo].ecpgQuery) == 0)
471 10 : break; /* found it */
472 : }
473 32 : ++entNo; /* incr entry # */
474 : }
475 :
476 : /* if entry wasn't found - set entry # to zero */
477 14 : if (entIx >= stmtCacheEntPerBucket)
478 4 : entNo = 0;
479 :
480 14 : return entNo;
481 : }
482 :
483 : /*
484 : * free an entry in the statement cache
485 : * Returns entry # in cache used
486 : * OR negative error code
487 : */
488 : static int
489 6 : ecpg_freeStmtCacheEntry(int lineno, int compat,
490 : int entNo) /* entry # to free */
491 : {
492 : stmtCacheEntry *entry;
493 : struct connection *con;
494 : struct prepared_statement *this,
495 : *prev;
496 :
497 : /* fail if cache isn't set up */
498 6 : if (stmtCacheEntries == NULL)
499 0 : return -1;
500 :
501 6 : entry = &stmtCacheEntries[entNo];
502 6 : if (!entry->stmtID[0]) /* return if the entry isn't in use */
503 6 : return 0;
504 :
505 0 : con = ecpg_get_connection(entry->connection);
506 :
507 : /*
508 : * If the connection is gone, the prepared_statement list it owned is
509 : * already unreachable, so just skip that cleanup. We must still clear
510 : * the cache slot below so it can be reused.
511 : */
512 0 : if (con)
513 : {
514 : /* free the 'prepared_statement' list entry */
515 0 : this = ecpg_find_prepared_statement(entry->stmtID, con, &prev);
516 0 : if (this && !deallocate_one(lineno, compat, con, prev, this))
517 0 : return -1;
518 : }
519 :
520 0 : entry->stmtID[0] = '\0';
521 :
522 : /* free the memory used by the cache entry */
523 0 : if (entry->ecpgQuery)
524 : {
525 0 : ecpg_free(entry->ecpgQuery);
526 0 : entry->ecpgQuery = NULL;
527 : }
528 :
529 0 : return entNo;
530 : }
531 :
532 : /*
533 : * add an entry to the statement cache
534 : * returns entry # in cache used OR negative error code
535 : */
536 : static int
537 6 : AddStmtToCache(int lineno, /* line # of statement */
538 : const char *stmtID, /* statement ID */
539 : const char *connection, /* connection */
540 : int compat, /* compatibility level */
541 : const char *ecpgQuery) /* query */
542 : {
543 : int ix,
544 : initEntNo,
545 : luEntNo,
546 : entNo;
547 : stmtCacheEntry *entry;
548 :
549 : /* allocate and zero cache array if we haven't already */
550 6 : if (stmtCacheEntries == NULL)
551 : {
552 2 : stmtCacheEntries = (stmtCacheEntry *)
553 2 : ecpg_alloc(sizeof(stmtCacheEntry) * stmtCacheArraySize, lineno);
554 2 : if (stmtCacheEntries == NULL)
555 0 : return -1;
556 : }
557 :
558 : /* hash the statement */
559 6 : initEntNo = HashStmt(ecpgQuery);
560 :
561 : /* search for an unused entry */
562 6 : entNo = initEntNo; /* start with the initial entry # for the
563 : * bucket */
564 6 : luEntNo = initEntNo; /* use it as the initial 'least used' entry */
565 6 : for (ix = 0; ix < stmtCacheEntPerBucket; ++ix)
566 : {
567 6 : entry = &stmtCacheEntries[entNo];
568 6 : if (!entry->stmtID[0]) /* unused entry - use it */
569 6 : break;
570 0 : if (entry->execs < stmtCacheEntries[luEntNo].execs)
571 0 : luEntNo = entNo; /* save new 'least used' entry */
572 0 : ++entNo; /* increment entry # */
573 : }
574 :
575 : /*
576 : * if no unused entries were found, re-use the 'least used' entry found in
577 : * the bucket
578 : */
579 6 : if (ix >= stmtCacheEntPerBucket)
580 0 : entNo = luEntNo;
581 :
582 : /* 'entNo' is the entry to use - make sure its free */
583 6 : if (ecpg_freeStmtCacheEntry(lineno, compat, entNo) < 0)
584 0 : return -1;
585 :
586 : /* add the query to the entry */
587 6 : entry = &stmtCacheEntries[entNo];
588 6 : entry->lineno = lineno;
589 6 : entry->ecpgQuery = ecpg_strdup(ecpgQuery, lineno, NULL);
590 6 : if (!entry->ecpgQuery)
591 0 : return -1;
592 6 : entry->connection = connection;
593 6 : entry->execs = 0;
594 6 : memcpy(entry->stmtID, stmtID, sizeof(entry->stmtID));
595 :
596 6 : return entNo;
597 : }
598 :
599 : /* handle cache and preparation of statements in auto-prepare mode */
600 : bool
601 16 : ecpg_auto_prepare(int lineno, const char *connection_name, const int compat, char **name, const char *query)
602 : {
603 : int entNo;
604 :
605 : /* search the statement cache for this statement */
606 16 : entNo = SearchStmtCache(query);
607 :
608 : /* if not found - add the statement to the cache */
609 16 : if (entNo)
610 : {
611 : char *stmtID;
612 : struct connection *con;
613 : struct prepared_statement *prep;
614 :
615 10 : ecpg_log("ecpg_auto_prepare on line %d: statement found in cache; entry %d\n", lineno, entNo);
616 :
617 10 : stmtID = stmtCacheEntries[entNo].stmtID;
618 10 : *name = ecpg_strdup(stmtID, lineno, NULL);
619 10 : if (*name == NULL)
620 0 : return false;
621 :
622 10 : con = ecpg_get_connection(connection_name);
623 10 : prep = ecpg_find_prepared_statement(stmtID, con, NULL);
624 : /* This prepared name doesn't exist on this connection. */
625 10 : if (!prep && !prepare_common(lineno, con, stmtID, query))
626 : {
627 0 : ecpg_free(*name);
628 0 : return false;
629 : }
630 :
631 : }
632 : else
633 : {
634 : char stmtID[STMTID_SIZE];
635 :
636 6 : ecpg_log("ecpg_auto_prepare on line %d: statement not in cache; inserting\n", lineno);
637 :
638 : /* generate a statement ID */
639 6 : sprintf(stmtID, "ecpg%d", nextStmtID++);
640 6 : *name = ecpg_strdup(stmtID, lineno, NULL);
641 6 : if (*name == NULL)
642 0 : return false;
643 :
644 6 : if (!ECPGprepare(lineno, connection_name, 0, stmtID, query))
645 : {
646 0 : ecpg_free(*name);
647 0 : return false;
648 : }
649 :
650 6 : entNo = AddStmtToCache(lineno, stmtID, connection_name, compat, query);
651 6 : if (entNo < 0)
652 : {
653 0 : ecpg_free(*name);
654 0 : return false;
655 : }
656 : }
657 :
658 : /* increase usage counter */
659 16 : stmtCacheEntries[entNo].execs++;
660 :
661 16 : return true;
662 : }
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