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postgresql.scm @ 14759

Revision 14759, 32.5 KB (checked in by sjamaan, 16 months ago)
Add query-map and query-fold-right to the high-level procedures

Line
1	;;; Bindings to the PostgreSQL C library
2	;;
3	;; Copyright (C) 2008-2009 Peter Bex
4	;; Copyright (C) 2004 Johannes Grødem <johs@copyleft.no>
5	;; Redistribution and use in source and binary forms, with or without
6	;; modification, is permitted.
7	;;
8	;; THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS
9	;; OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
10	;; WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
11	;; ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE
12	;; LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
13	;; CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT
14	;; OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR
15	;; BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
16	;; LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
17	;; (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE
18	;; USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH
19	;; DAMAGE.
20
21	(module postgresql
22	(update-type-parsers! default-type-parsers
23	char-parser bool-parser bytea-parser numeric-parser
24	update-type-unparsers! default-type-unparsers
25	bool-unparser
26
27	connect reset-connection disconnect connection?
28
29	exec-simple-queries exec-query
30
31	result? clear-result! result-row-count result-column-count
32	result-column-index result-column result-column-format
33	result-column-type result-column-type-modifier result-columns
34	result-table-oid result-table-column-index
35	result-value result-values result-alist result-affected-rows
36	result-inserted-oid invalid-oid
37
38	escape-string escape-bytea unescape-bytea
39
40	query-fold query-fold* query-fold-right query-fold-right*
41	query-for-each query-for-each* query-map query-map*)
42
43	(import chicken scheme foreign)
44
45	(require-extension srfi-1 srfi-4 srfi-13 srfi-18 srfi-69
46	extras data-structures sql-null)
47
48	(foreign-declare "#include <libpq-fe.h>")
49
50	(define-foreign-type pg-polling-status (enum "PostgresPollingStatusType"))
51	(define-foreign-variable PGRES_POLLING_FAILED pg-polling-status)
52	(define-foreign-variable PGRES_POLLING_READING pg-polling-status)
53	(define-foreign-variable PGRES_POLLING_WRITING pg-polling-status)
54	(define-foreign-variable PGRES_POLLING_OK pg-polling-status)
55
56	(define-foreign-type pg-exec-status (enum "ExecStatusType"))
57	(define-foreign-variable PGRES_EMPTY_QUERY pg-exec-status)
58	(define-foreign-variable PGRES_COMMAND_OK pg-exec-status)
59	(define-foreign-variable PGRES_TUPLES_OK pg-exec-status)
60	(define-foreign-variable PGRES_COPY_OUT pg-exec-status)
61	(define-foreign-variable PGRES_COPY_IN pg-exec-status)
62	(define-foreign-variable PGRES_BAD_RESPONSE pg-exec-status)
63	(define-foreign-variable PGRES_NONFATAL_ERROR pg-exec-status)
64	(define-foreign-variable PGRES_FATAL_ERROR pg-exec-status)
65
66	;(define-foreign-type pgconn* (c-pointer "PGconn"))
67	(define-foreign-type pgconn* c-pointer)
68
69	(define PQconnectStart (foreign-lambda pgconn* PQconnectStart (const c-string)))
70	(define PQconnectPoll (foreign-lambda pg-polling-status PQconnectPoll pgconn*))
71	(define PQresetStart (foreign-lambda bool PQresetStart pgconn*))
72	(define PQresetPoll (foreign-lambda pg-polling-status PQresetPoll pgconn*))
73	(define PQfinish (foreign-lambda void PQfinish pgconn*))
74	(define PQstatus (foreign-lambda (enum "ConnStatusType") PQstatus (const pgconn*)))
75	(define PQerrorMessage (foreign-lambda c-string PQerrorMessage (const pgconn*)))
76
77	;(define-foreign-type oid "Oid")
78	(define-foreign-type oid unsigned-int)
79
80	(define invalid-oid (foreign-value "InvalidOid" oid))
81
82	(define PQisBusy (foreign-lambda bool PQisBusy pgconn*))
83	(define PQconsumeInput (foreign-lambda bool PQconsumeInput pgconn*))
84
85	(define-foreign-type pgresult* (c-pointer "PGresult"))
86
87	(define PQgetResult (foreign-lambda pgresult* PQgetResult pgconn*))
88	(define PQresultStatus (foreign-lambda pg-exec-status PQresultStatus (const pgresult*)))
89	(define PQresultErrorMessage (foreign-lambda c-string PQresultErrorMessage (const pgresult*)))
90	(define PQresultErrorField (foreign-lambda c-string PQresultErrorField (const pgresult*) int))
91
92	(define PQclear (foreign-lambda void PQclear pgresult*))
93	(define PQntuples (foreign-lambda int PQntuples (const pgresult*)))
94	(define PQnfields (foreign-lambda int PQnfields (const pgresult*)))
95	(define PQfname (foreign-lambda c-string PQfname (const pgresult*) int))
96	(define PQfnumber (foreign-lambda int PQfnumber (const pgresult*) (const c-string)))
97	(define PQftable (foreign-lambda oid PQftable (const pgresult*) int))
98	(define PQftablecol (foreign-lambda int PQftablecol (const pgresult*) int))
99	(define PQfformat (foreign-lambda int PQfformat (const pgresult*) int))
100	(define PQftype (foreign-lambda oid PQftype (const pgresult*) int))
101	(define PQfmod (foreign-lambda int PQfmod (const pgresult*) int))
102	(define PQgetisnull (foreign-lambda bool PQgetisnull (const pgresult*) int int))
103	(define PQcmdTuples (foreign-lambda nonnull-c-string PQcmdTuples pgresult*))
104	(define PQoidValue (foreign-lambda oid PQoidValue pgresult*))
105
106	;; TODO: Create a real callback system?
107	(foreign-declare "static void nullNoticeReceiver(void arg, const PGresult res){ }")
108
109	(define-syntax define-foreign-int
110	(er-macro-transformer
111	(lambda (e r c)
112	;; cannot rename define-foreign-variable; it's a really special form
113	`(define-foreign-variable ,(cadr e) int ,(conc "(int) " (cadr e))))))
114
115	(define-foreign-int PG_DIAG_SEVERITY)
116	(define-foreign-int PG_DIAG_SQLSTATE)
117	(define-foreign-int PG_DIAG_MESSAGE_PRIMARY)
118	(define-foreign-int PG_DIAG_MESSAGE_DETAIL)
119	(define-foreign-int PG_DIAG_MESSAGE_HINT)
120	(define-foreign-int PG_DIAG_STATEMENT_POSITION)
121	(define-foreign-int PG_DIAG_CONTEXT)
122	(define-foreign-int PG_DIAG_SOURCE_FILE)
123	(define-foreign-int PG_DIAG_SOURCE_LINE)
124	(define-foreign-int PG_DIAG_SOURCE_FUNCTION)
125
126	(define (postgresql-error loc message . args)
127	(signal (make-pg-condition loc message args: args)))
128
129	(define (make-pg-condition loc message #!key (args '()) severity
130	error-class error-code message-detail
131	message-hint statement-position context
132	source-file source-line
133	source-function)
134	(make-composite-condition
135	(make-property-condition
136	'exn 'location loc 'message message 'arguments args)
137	(make-property-condition
138	'postgresql 'severity severity 'error-class error-class
139	'error-code error-code 'message-detail message-detail
140	'message-hint message-hint 'statement-position statement-position
141	'context context 'source-file source-file 'source-line source-line
142	;; Might break not-terribly-old versions of postgresql
143	;;'internal-position internal-position 'internal-query internal-query
144	'source-function source-function)))
145
146	;;;;;;;;;;;;;;;;;;;;;;;;
147	;;;; Type parsers
148	;;;;;;;;;;;;;;;;;;;;;;;;
149
150	(define (char-parser str) (string-ref str 0))
151
152	(define (bool-parser str) (string=? str "t"))
153
154	(define (abstime-parser str) str)
155
156	(define (reltime-parser str) str)
157
158	(define (parse-format-string s)
159	(let-syntax ((push! (syntax-rules ()
160	((_ value place)
161	(set! place (cons value place))))))
162	(do ([i 0 (+ i 1)]
163	[ranges (list)]
164	[cur-range (list)]
165	[len (string-length s)])
166	([= i len]
167	(when (not (null? cur-range))
168	(push! (cons (- i (length cur-range)) i)
169	ranges))
170	(reverse! ranges))
171	(let ([char (string-ref s i)])
172	(cond ([and (or (null? cur-range)
173	(char=? char (car cur-range)))
174	(char-alphabetic? char)]
175	(push! char cur-range))
176	([and (not (null? cur-range))
177	(not (char=? char (car cur-range)))]
178	(push! (cons (- i (length cur-range)) i)
179	ranges)
180	(set! cur-range
181	(if (char-alphabetic? char)
182	(list char)
183	(list)))))))))
184
185	(define-syntax define-time-parser
186	(syntax-rules ()
187	((_ name format-string)
188	(define name
189	(let ((format-ranges (parse-format-string format-string)))
190	(lambda (str)
191	(apply
192	vector
193	(map (lambda (range)
194	(if (> (cdr range) (string-length str))
195	0
196	(string->number
197	(substring str (car range) (cdr range)))))
198	format-ranges))))))))
199
200	(define-time-parser date-parser "YYYY-MM-DD")
201	(define-time-parser timestamp-parser "YYYY-MM-DD hh:mm:ss.ssssss")
202	(define-time-parser timestamp/tz-parser "YYYY-MM-DD hh:mm:ss.sssssszzz")
203	(define-time-parser time-parser "hh:mm:ss.ssssss")
204
205	(define (numeric-parser str)
206	(or (string->number str)
207	(postgresql-error 'numeric-parser "Unable to parse number" str)))
208
209	(define (bytea-parser str)
210	(blob->u8vector/shared (string->blob (unescape-bytea str))))
211
212	(define default-type-parsers
213	(make-parameter
214	`(("text" . ,identity)
215	("bytea" . ,bytea-parser)
216	("char" . ,char-parser)
217	("bpchar" . ,identity)
218	("bool" . ,bool-parser)
219	("int8" . ,numeric-parser)
220	("int4" . ,numeric-parser)
221	("int2" . ,numeric-parser)
222	("float4" . ,numeric-parser)
223	("float8" . ,numeric-parser)
224	("abstime" . ,abstime-parser)
225	("reltime" . ,reltime-parser)
226	("date" . ,date-parser)
227	("time" . ,time-parser)
228	("timestamp" . ,timestamp-parser)
229	("timestamptz" . ,timestamp/tz-parser)
230	("numeric" . ,numeric-parser)
231	("oid" . ,numeric-parser))))
232
233	;;;;;;;;;;;;;;;;;;;;;;;
234	;;;; Type unparsers
235	;;;;;;;;;;;;;;;;;;;;;;;
236
237	(define (bool-unparser b)
238	(if b "TRUE" "FALSE"))
239
240	(define default-type-unparsers
241	(make-parameter
242	`((,string? . ,identity)
243	(,u8vector? . ,u8vector->blob/shared)
244	(,char? . ,string)
245	(,boolean? . ,bool-unparser)
246	(,number? . ,number->string)
247	#;(,vector? . ,vector-unparser))))
248
249	;; Retrieve type-oids from PostgreSQL:
250	(define (update-type-parsers! conn #!optional new-type-parsers)
251	(let ((type-parsers (or new-type-parsers (pg-connection-type-parsers conn)))
252	(ht (make-hash-table))
253	(result '()))
254	;; Set the parsers now, so that we will be retrieving raw data
255	(pg-connection-oid-parsers-set! conn ht)
256	(pg-connection-type-parsers-set! conn type-parsers)
257	(unless (null? type-parsers) ; empty IN () clause is not allowed
258	(query-for-each*
259	(lambda (oid typname)
260	(and-let* ((procedure (assoc typname type-parsers)))
261	(hash-table-set! ht (string->number oid) (cdr procedure))))
262	conn
263	(conc "SELECT oid, typname FROM pg_type WHERE typname IN "
264	"('" (string-intersperse
265	(map (lambda (p) (escape-string conn (car p)))
266	type-parsers) "', '") "')")))))
267
268	(define (update-type-unparsers! conn new-type-unparsers)
269	(pg-connection-type-unparsers-set! conn new-type-unparsers))
270
271	;;;;;;;;;;;;;;;;;;;;
272	;;;; Connections
273	;;;;;;;;;;;;;;;;;;;;
274
275	(define-record pg-connection ptr type-parsers oid-parsers type-unparsers)
276	(define connection? pg-connection?)
277
278	(define (pgsql-connection->fd conn)
279	((foreign-lambda int PQsocket pgconn*) (pg-connection-ptr conn)))
280
281	;; TODO: Add timeout code
282	(define (wait-for-connection! conn poll-function)
283	(let ((conn-fd (pgsql-connection->fd conn))
284	(conn-ptr (pg-connection-ptr conn)))
285	(let loop ((result (poll-function conn-ptr)))
286	(cond ((= result PGRES_POLLING_OK) (void))
287	((= result PGRES_POLLING_FAILED)
288	(let ((error-message (PQerrorMessage conn-ptr)))
289	(disconnect conn)
290	(postgresql-error 'connect
291	(conc "Polling Postgres database failed. "
292	error-message))))
293	((member result (list PGRES_POLLING_WRITING PGRES_POLLING_READING))
294	(thread-wait-for-i/o! conn-fd (if (= PGRES_POLLING_READING result)
295	#:output
296	#:input))
297	(loop (poll-function conn-ptr)))
298	(else
299	(postgresql-error 'connect (conc "Unknown status code!")))))))
300
301	(define (alist->connection-spec alist)
302	(string-join
303	(map (lambda (subspec)
304	(sprintf "~A='~A'"
305	(car subspec) ;; this had better not contain [ =\']
306	(string-translate* (->string (cdr subspec))
307	'(("\\" . "\\\\") ("'" . "\\'")))))
308	alist)))
309
310	(define (connect connection-spec
311	#!optional
312	(type-parsers (default-type-parsers))
313	(type-unparsers (default-type-unparsers)))
314	(let* ((connection-spec (if (string? connection-spec)
315	connection-spec
316	(alist->connection-spec connection-spec)))
317	(conn-ptr (PQconnectStart connection-spec)))
318	(cond
319	((not conn-ptr)
320	(postgresql-error 'connect
321	"Unable to allocate a Postgres connection structure."
322	connection-spec))
323	((= (foreign-value "CONNECTION_BAD" int) (PQstatus conn-ptr))
324	(let ((error-message (PQerrorMessage conn-ptr)))
325	(PQfinish conn-ptr)
326	(postgresql-error 'connect
327	(conc "Connection to Postgres database failed: "
328	error-message)
329	connection-spec)))
330	(else
331	(let ((conn (make-pg-connection conn-ptr type-parsers
332	(make-hash-table) type-unparsers)))
333	;; We don't want libpq to piss in our stderr stream
334	((foreign-lambda* void ((pgconn* conn))
335	"PQsetNoticeReceiver(conn, nullNoticeReceiver, NULL);") conn-ptr)
336	(wait-for-connection! conn PQconnectPoll)
337	(set-finalizer! conn disconnect)
338	;; Retrieve type-information from PostgreSQL metadata for use by
339	;; the various value-parsers.
340	(update-type-parsers! conn)
341	conn)))))
342
343	(define (reset-connection connection)
344	(let ((conn-ptr (pg-connection-ptr connection)))
345	(if (PQresetStart conn-ptr) ;; Update oid-parsers?
346	(wait-for-connection! connection PQresetPoll)
347	(let ((error-message (PQerrorMessage conn-ptr)))
348	(disconnect connection)
349	(postgresql-error 'reset-connection
350	(conc "Reset of connection failed " error-message)
351	connection)))))
352
353	(define (disconnect connection)
354	(and-let* ((conn-ptr (pg-connection-ptr connection)))
355	(pg-connection-ptr-set! connection #f)
356	(pg-connection-type-parsers-set! connection #f)
357	(pg-connection-oid-parsers-set! connection #f)
358	(PQfinish conn-ptr))
359	(void))
360
361	;;;;;;;;;;;;;;;
362	;;;; Results
363	;;;;;;;;;;;;;;;
364
365	(define-record pg-result ptr value-parsers)
366	(define result? pg-result?)
367
368	(define (clear-result! result)
369	(and-let* ((result-ptr (pg-result-ptr result)))
370	(pg-result-ptr-set! result #f)
371	(PQclear result-ptr)))
372
373	(define (result-row-count result)
374	(PQntuples (pg-result-ptr result)))
375
376	(define (result-column-count result)
377	(PQnfields (pg-result-ptr result)))
378
379	;; Helper procedures for bounds checking; so we can distinguish between
380	;; out of bounds and nonexistant columns, and signal it.
381	(define (check-result-column-index! result index location)
382	(when (>= index (result-column-count result))
383	(postgresql-error
384	location (sprintf "Result column ~A out of bounds" index) result index)))
385
386	(define (check-result-row-index! result index location)
387	(when (>= index (result-row-count result))
388	(postgresql-error
389	location (sprintf "Result row ~A out of bounds" index) result index)))
390
391	(define (result-column result index)
392	(check-result-column-index! result index 'result-column)
393	(string->symbol (PQfname (pg-result-ptr result) index)))
394
395	(define (result-columns result)
396	(let loop ((ptr (pg-result-ptr result))
397	(row '())
398	(idx (result-column-count result)))
399	(if (= idx 0)
400	row
401	(loop ptr (cons (string->symbol
402	(PQfname ptr (sub1 idx))) row) (sub1 idx)))))
403
404	(define (result-column-index result name)
405	(let ((idx (PQfnumber (pg-result-ptr result) (symbol->string name))))
406	(and (>= idx 0) idx)))
407
408	(define (result-table-oid result index)
409	(check-result-column-index! result index 'result-table-oid)
410	(let ((oid (PQftable (pg-result-ptr result) index)))
411	(and (not (= oid invalid-oid)) oid)))
412
413	;; Fixes the off-by-1 unexpectedness in libpq/the protocol to make it more
414	;; consistent with the rest of Scheme. However, this is inconsistent with
415	;; almost all other PostgreSQL interfaces...
416	(define (result-table-column-index result index)
417	(check-result-column-index! result index 'result-table-column-index)
418	(let ((idx (PQftablecol (pg-result-ptr result) index)))
419	(and (> idx 0) (sub1 idx))))
420
421	(define format-table
422	'((0 . text) (1 . binary)))
423
424	(define (format->symbol format)
425	(or (alist-ref format format-table eq?)
426	(postgresql-error 'format->symbol "Unknown format" format)))
427
428	(define (symbol->format symbol)
429	(or (and-let* ((res (rassoc symbol format-table eq?)))
430	(car res))
431	(postgresql-error 'format->symbol "Unknown format" symbol)))
432
433	(define (result-column-format result index)
434	(check-result-column-index! result index 'result-column-format)
435	(format->symbol (PQfformat (pg-result-ptr result) index)))
436
437	(define (result-column-type result index)
438	(check-result-column-index! result index 'result-column-type)
439	(PQftype (pg-result-ptr result) index))
440
441	;; This is really not super-useful as it requires intimate knowledge
442	;; about the internal implementations of types in PostgreSQL.
443	(define (result-column-type-modifier result index)
444	(check-result-column-index! result index 'result-column-type)
445	(let ((mod (PQfmod (pg-result-ptr result) index)))
446	(and (>= mod 0) mod)))
447
448	;; Unchecked version, for speed
449	(define (result-value* result row column #!key raw)
450	(if (PQgetisnull (pg-result-ptr result) row column)
451	(sql-null)
452	(let ((value ((foreign-safe-lambda*
453	scheme-object ((c-pointer res) (int row) (int col))
454	"C_word fin, str; char val; int len;"
455	"len = PQgetlength(res, row, col);"
456	"str = C_alloc(C_bytestowords(len + sizeof(C_header)));"
457	"val = PQgetvalue(res, row, col);"
458	"fin = C_string(&str, len, val);"
459	"if (PQfformat(res, col) == 1) /* binary? */"
460	" C_string_to_bytevector(fin);"
461	"C_return(fin);")
462	(pg-result-ptr result) row column)))
463	(if (or raw (blob? value))
464	value
465	((vector-ref (pg-result-value-parsers result) column) value)))))
466
467	(define (result-value result row column #!key raw)
468	(check-result-row-index! result row 'result-value)
469	(check-result-column-index! result column 'result-value)
470	(result-value* result row column raw: raw))
471
472	(define (result-values result row #!key raw)
473	(check-result-row-index! result row 'result-list)
474	(let loop ((list '())
475	(column (result-column-count result)))
476	(if (= column 0)
477	list
478	(loop (cons (result-value* result row (sub1 column) raw: raw) list)
479	(sub1 column)))))
480
481	;; (define (result-alist result row)
482	;; (map cons (result-columns result row) (result-values result row)))
483	(define (result-alist result row)
484	(check-result-row-index! result row 'result-alist)
485	(let loop ((alist '())
486	(column (result-column-count result)))
487	(if (= column 0)
488	alist
489	(loop (cons (cons (PQfname (pg-result-ptr result) column)
490	(result-value* result row (sub1 column))) alist)
491	(sub1 column)))))
492
493	;;; TODO: Do we want/need PQnparams and PQparamtype bindings?
494
495	(define (result-affected-rows result)
496	(string->number (PQcmdTuples (pg-result-ptr result))))
497
498	(define (result-inserted-oid result)
499	(let ((oid (PQoidValue (pg-result-ptr result))))
500	(and (not (= oid invalid-oid)) oid)))
501
502
503	;;;;;;;;;;;;;;;;;;;;;;;;
504	;;;; Query procedures
505	;;;;;;;;;;;;;;;;;;;;;;;;
506
507	;; Buffer all available input, yielding if nothing is available:
508	(define (buffer-available-input! conn)
509	(let ((conn-ptr (pg-connection-ptr conn))
510	(conn-fd (pgsql-connection->fd conn)))
511	(let loop ()
512	(if (PQconsumeInput conn-ptr)
513	(when (PQisBusy conn-ptr)
514	(thread-wait-for-i/o! conn-fd #:input)
515	(loop))
516	(postgresql-error 'buffer-available-input!
517	(conc "Error reading reply from server. "
518	(PQerrorMessage conn-ptr))
519	conn-ptr)))))
520
521	(define (make-value-parsers conn pqresult)
522	(let ((nfields (PQnfields pqresult)))
523	(do ([col 0 (+ col 1)]
524	[parsers (make-vector nfields)])
525	([= col nfields] parsers)
526	(vector-set! parsers col
527	(hash-table-ref (pg-connection-oid-parsers conn)
528	(PQftype pqresult col)
529	(lambda () identity))))))
530
531	;; Collect the result pointers from the last query.
532	;;
533	;; A pgresult represents an entire resultset and is always read into memory
534	;; all at once.
535	(define (collect-results conn)
536	(buffer-available-input! conn)
537	(let loop ((results (list)))
538	(let* ((conn-ptr (pg-connection-ptr conn))
539	(result (PQgetResult conn-ptr)))
540	(if result
541	(cond
542	((member (PQresultStatus result) (list PGRES_BAD_RESPONSE
543	PGRES_FATAL_ERROR))
544	(let* ((msg (string-trim-right (PQresultErrorMessage result)))
545	(get-error-field (lambda (diag)
546	(PQresultErrorField result diag)))
547	(sqlstate (get-error-field PG_DIAG_SQLSTATE))
548	(maybe-severity (get-error-field PG_DIAG_SEVERITY))
549	(maybe-statement-position
550	(get-error-field PG_DIAG_STATEMENT_POSITION))
551	(condition
552	(make-pg-condition
553	'collect-results
554	(conc "PQgetResult: " msg)
555	args: (list conn)
556	severity: (and maybe-severity
557	(string->symbol
558	(string-downcase maybe-severity)))
559	error-class: (and sqlstate (string-take sqlstate 2))
560	error-code: sqlstate
561	message-detail: (get-error-field PG_DIAG_MESSAGE_DETAIL)
562	message-hint: (get-error-field PG_DIAG_MESSAGE_HINT)
563	statement-position: (and maybe-statement-position
564	(string->number
565	maybe-statement-position))
566	context: (get-error-field PG_DIAG_CONTEXT)
567	source-file: (get-error-field PG_DIAG_SOURCE_FILE)
568	source-line: (get-error-field PG_DIAG_SOURCE_LINE)
569	source-function: (get-error-field PG_DIAG_SOURCE_FUNCTION))))
570	;; Read out all remaining results (including the current one).
571	;; TODO: Is this really needed? libpq does it (in pqExecFinish),
572	;; but ostensibly only to concatenate the error messages for
573	;; each query. OTOH, maybe we want to do that, too.
574	(let clean-results! ((result result))
575	(when result
576	(PQclear result)
577	(clean-results! (PQgetResult (pg-connection-ptr conn)))))
578	(signal condition)))
579	(else
580	(let ((result-obj (make-pg-result result
581	(make-value-parsers conn result))))
582	(set-finalizer! result-obj clear-result!)
583	(loop (cons result-obj results)))))
584	(reverse! results)))))
585
586	(define (exec-simple-queries conn query)
587	(if ((foreign-lambda bool PQsendQuery pgconn* (const c-string))
588	(pg-connection-ptr conn) query)
589	(collect-results conn)
590	(postgresql-error 'exec-simple-queries
591	(conc "Unable to send query to server. "
592	(PQerrorMessage (pg-connection-ptr conn)))
593	conn query)))
594
595	(define (exec-query conn query #!optional (params '()) #!key (format 'text) raw)
596	(let* ((unparsers (pg-connection-type-unparsers conn))
597	(unparse (lambda (x)
598	(cond ((find (lambda (parse?)
599	((car parse?) x))
600	unparsers) => (lambda (parse)
601	((cdr parse) x)))
602	(else x))))
603	(params ;; Check all params and ensure they are proper pairs
604	(map ;; See if this can be moved into C
605	(lambda (p)
606	(let ((obj (if raw p (unparse p))))
607	(when (and (not (string? obj))
608	(not (blob? obj))
609	(not (sql-null? obj)))
610	(postgresql-error
611	'exec-query
612	(sprintf "Param value is not a string, sql-null or blob: ~S" p)
613	conn query params format))
614	(if (sql-null? obj) #f obj))) params))
615	(send-query
616	(foreign-lambda*
617	bool ((pgconn* conn) (nonnull-c-string query)
618	(int num) (scheme-object params) (int resfmt))
619	"int res = 0, i = 0, *lens = NULL;"
620	"char **vals = NULL;"
621	"int *fmts = NULL;"
622	"C_word obj, cons;"
623	"if (num > 0) {"
624	" vals = C_malloc(num * sizeof(char *));"
625	" lens = C_malloc(num * sizeof(int));"
626	" fmts = C_malloc(num * sizeof(int));"
627	"}"
628	"for (i=0,cons=params; i < num; ++i,cons=C_u_i_cdr(cons)) {"
629	" obj = C_u_i_car(cons);"
630	" if (obj == C_SCHEME_FALSE) {"
631	" fmts[i] = 0; /* don't care */"
632	" lens[i] = 0;"
633	" vals[i] = NULL;"
634	" } else if (C_header_bits(obj) == C_BYTEVECTOR_TYPE) {"
635	" fmts[i] = 1; /* binary */"
636	" lens[i] = C_header_size(obj);"
637	" vals[i] = C_c_string(obj);"
638	" } else {"
639	" /* text needs to be copied; it expects ASCIIZ */"
640	" fmts[i] = 0; /* text */"
641	" lens[i] = C_header_size(obj);"
642	" vals[i] = malloc(lens[i] + 1);"
643	" memcpy(vals[i], C_c_string(obj), lens[i]);"
644	" vals[i][lens[i]] = '\\0';"
645	" }"
646	"}"
647	"res = PQsendQueryParams(conn, query, num, NULL,"
648	" vals, lens, fmts, resfmt);"
649	"for (i=0,cons=params; i < num; ++i,cons=C_u_i_cdr(cons)) {"
650	" obj = C_u_i_car(cons);"
651	" if (!C_immediatep(obj) && C_header_bits(obj) == C_STRING_TYPE)"
652	" free(vals[i]); /* Clear copied strings only */"
653	"}"
654	"if (num > 0) {"
655	" free(fmts);"
656	" free(lens);"
657	" free(vals);"
658	"}"
659	"C_return(res);")))
660	(if (send-query (pg-connection-ptr conn) query
661	(length params) params (symbol->format format))
662	(car (collect-results conn)) ;; assumed to always return one result...
663	(postgresql-error 'exec-query
664	(conc "Unable to send query to server. "
665	(PQerrorMessage (pg-connection-ptr conn)))
666	conn query params format))))
667
668	;;;;;;;;;;;;;;;;;;;;;;
669	;;;; Value escaping
670	;;;;;;;;;;;;;;;;;;;;;;
671
672	(define (escape-string conn str)
673	(define %escape-string-conn
674	;; This could be more efficient by copying straight into a Scheme object.
675	;; Now it's being copied by PQescapeStringConn, and Chicken copies it again.
676	;; This can allocate up to twice as much memory than the string actually
677	;; uses; in extreme cases this could be a problem.
678	(foreign-lambda* c-string* ((pointer conn) (c-string from) (int fromlen))
679	"int err = 0; char *to;"
680	"to = malloc(sizeof(char) * (fromlen * 2 + 1));"
681	"PQescapeStringConn(conn, to, from, fromlen, &err);"
682	"if (err) {"
683	" free(to);"
684	" C_return(NULL);"
685	"}"
686	"C_return(to);"
687	))
688	(or (%escape-string-conn conn str (string-length str))
689	(postgresql-error 'escape-string
690	(conc "String escaping failed. "
691	(PQerrorMessage conn)) conn str)))
692
693	(define (escape-bytea conn str)
694	(define %escape-bytea-conn
695	;; This must copy because libpq returns a malloced ptr...
696	(foreign-safe-lambda* scheme-object ((pointer conn)
697	;; not copied/NUL interpreted:
698	((const unsigned-c-string*) from)
699	(int fromlen))
700	"size_t tolen=0; C_word res, fin; unsigned char esc;"
701	"esc = PQescapeByteaConn(conn, from, (size_t)fromlen, &tolen);"
702	"if (esc == NULL)"
703	" C_return(C_SCHEME_FALSE);"
704	"fin = C_alloc(C_bytestowords(tolen + sizeof(C_header)));"
705	"/* tolen includes the resulting NUL byte */"
706	"res = C_string(&fin, tolen - 1, (char *)esc);"
707	"PQfreemem(esc);"
708	"C_return(res);"
709	))
710	(or (%escape-bytea-conn conn str (string-length str))
711	(postgresql-error 'escape-bytea
712	(conc "Byte array escaping failed. "
713	(PQerrorMessage conn)) conn str)))
714
715	(define (unescape-bytea str)
716	(define %unescape-bytea
717	;; This must copy because libpq returns a malloced ptr...
718	(foreign-safe-lambda* scheme-object (((const unsigned-c-string*) from))
719	"size_t tolen=0; C_word res, fin; unsigned char unesc;"
720	"unesc = PQunescapeBytea(from, &tolen);"
721	"if (unesc == NULL)"
722	" C_return(C_SCHEME_FALSE);"
723	"fin = C_alloc(C_bytestowords(tolen + sizeof(C_header)));"
724	"res = C_string(&fin, tolen, (char *)unesc);"
725	"PQfreemem(unesc);"
726	"C_return(res);"
727	))
728	(or (%unescape-bytea str)
729	(postgresql-error 'unescape-bytea
730	"Byte array unescaping failed (out of memory?)" str)))
731
732
733	;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
734	;;;; High-level interface
735	;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
736
737	(define (query-fold kons knil conn query #!optional (params '()))
738	(let* ((result (exec-query conn query params))
739	(rows (result-row-count result)))
740	(let loop ((seed knil)
741	(row 0))
742	(if (= row rows)
743	seed
744	(loop (kons (result-values result row) seed) (add1 row))))))
745
746	(define (query-fold-right kons knil conn query #!optional (params '()))
747	(let* ((result (exec-query conn query params))
748	(rows (result-row-count result)))
749	(let loop ((seed knil)
750	(row 0))
751	(if (= row rows)
752	seed
753	(kons (result-values result row) (loop seed (add1 row)))))))
754
755	(define (query-fold* kons knil conn query #!optional (params '()))
756	(query-fold (lambda (values seed) (apply kons (append values (list seed))))
757	knil conn query params))
758	(define (query-fold-right* kons knil conn query #!optional (params '()))
759	(query-fold-right (lambda (val seed) (apply kons (append val (list seed))))
760	knil conn query params))
761
762	(define (query-for-each proc conn query #!optional (params '()))
763	(query-fold (lambda (values seed) (proc values)) #f conn query params)
764	(void))
765
766	(define (query-for-each* proc conn query #!optional (params '()))
767	(query-fold (lambda (values seed) (apply proc values)) #f conn query params)
768	(void))
769
770	;; Like regular Scheme map, the order in which the procedure is applied is
771	;; undefined. We make good use of that by traversing the resultset from
772	;; the end back to the beginning, thereby avoiding a reverse! on the result.
773	(define (query-map proc conn query #!optional (params '()))
774	(let ((result (exec-query conn query params)))
775	(let loop ((output '())
776	(row (result-row-count result)))
777	(if (= row 0)
778	output
779	(loop (cons (proc (result-values result (sub1 row))) output)
780	(sub1 row))))))
781
782	(define (query-map* proc conn query #!optional (params '()))
783	(query-map (lambda (values seed) (apply proc values)) #f conn query params))
784
785	)

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