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Commit8fb0ac8

Browse files
author
Bryan Henderson
committed
Make error messages more explicit, PQtrace() output more readable.
1 parente2da92f commit8fb0ac8

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2 files changed

+186
-138
lines changed

2 files changed

+186
-138
lines changed

‎src/interfaces/libpq/fe-exec.c

Lines changed: 171 additions & 129 deletions
Original file line numberDiff line numberDiff line change
@@ -7,7 +7,7 @@
77
*
88
*
99
* IDENTIFICATION
10-
* $Header: /cvsroot/pgsql/src/interfaces/libpq/fe-exec.c,v 1.25 1996/12/28 01:57:13 momjian Exp $
10+
* $Header: /cvsroot/pgsql/src/interfaces/libpq/fe-exec.c,v 1.26 1996/12/31 07:29:15 bryanh Exp $
1111
*
1212
*-------------------------------------------------------------------------
1313
*/
@@ -348,6 +348,170 @@ makePGresult(PGconn* conn, char* pname)
348348
}
349349

350350

351+
/*
352+
* Assuming that we just sent a query to the backend, read the backend's
353+
* response from stream <pfin> and respond accordingly.
354+
*
355+
* If <pfdebug> is non-null, write to that stream whatever we receive
356+
* (it's a debugging trace).
357+
*
358+
* Return as <result> a pointer to a proper final PGresult structure,
359+
* newly allocated, for the query based on the response we get. If the
360+
* response we get indicates that the query didn't execute, return a
361+
* null pointer and don't allocate any space, but also place a text
362+
* string explaining the problem at <*reason>.
363+
*/
364+
365+
staticvoid
366+
process_response_from_backend(FILE*pfin,FILE*pfout,FILE*pfdebug,
367+
PGconn*conn,
368+
PGresult**result_p,char*constreason) {
369+
370+
charid;
371+
/* The protocol character received from the backend. The protocol
372+
character is the first character in the backend's response to our
373+
query. It defines the nature of the response.
374+
*/
375+
PGnotify*newNotify;
376+
booldone;
377+
/* We're all done with the query and ready to return the result. */
378+
intemptiesSent;
379+
/* Number of empty queries we have sent in order to flush out multiple
380+
responses, less the number of corresponding responses we have
381+
received.
382+
*/
383+
charcmdStatus[MAX_MESSAGE_LEN];
384+
charpname[MAX_MESSAGE_LEN];/* portal name */
385+
386+
/* loop because multiple messages, especially NOTICES,
387+
can come back from the backend. NOTICES are output directly to stderr
388+
*/
389+
390+
emptiesSent=0;/* No empty queries sent yet */
391+
pname[0]='\0';
392+
393+
done= false;/* initial value */
394+
while (!done) {
395+
/* read the result id */
396+
id=pqGetc(pfin,pfdebug);
397+
if (id==EOF) {
398+
/* hmm, no response from the backend-end, that's bad */
399+
(void)sprintf(reason,
400+
"PQexec() -- Request was sent to backend, but backend "
401+
"closed the channel before "
402+
"responding. This probably means the backend "
403+
"terminated abnormally before or while processing "
404+
"the request.\n");
405+
conn->status=CONNECTION_BAD;/* No more connection to backend */
406+
*result_p= (PGresult*)NULL;
407+
done= true;
408+
}else {
409+
switch (id) {
410+
case'A':
411+
newNotify= (PGnotify*)malloc(sizeof(PGnotify));
412+
pqGetInt(&(newNotify->be_pid),4,pfin,pfdebug);
413+
pqGets(newNotify->relname,NAMEDATALEN,pfin,pfdebug);
414+
DLAddTail(conn->notifyList,DLNewElem(newNotify));
415+
/* async messages are piggy'ed back on other messages,
416+
so we stay in the while loop for other messages */
417+
break;
418+
case'C':/* portal query command, no rows returned */
419+
if (pqGets(cmdStatus,MAX_MESSAGE_LEN,pfin,pfdebug)==1) {
420+
sprintf(reason,
421+
"PQexec() -- query command completed, "
422+
"but return message from backend cannot be read.");
423+
*result_p= (PGresult*)NULL;
424+
done= true;
425+
}else {
426+
/*
427+
// since backend may produce more than one result for some
428+
// commands need to poll until clear
429+
// send an empty query down, and keep reading out of the pipe
430+
// until an 'I' is received.
431+
*/
432+
pqPuts("Q ",pfout,pfdebug);/* send an empty query */
433+
/*
434+
* Increment a flag and process messages in the usual way because
435+
* there may be async notifications pending. DZ - 31-8-1996
436+
*/
437+
emptiesSent++;
438+
}
439+
break;
440+
case'E':/* error return */
441+
if (pqGets(conn->errorMessage,ERROR_MSG_LENGTH,pfin,pfdebug)==1) {
442+
(void)sprintf(reason,
443+
"PQexec() -- error return detected from backend, "
444+
"but attempt to read the error message failed.");
445+
}
446+
*result_p= (PGresult*)NULL;
447+
done= true;
448+
break;
449+
case'I': {/* empty query */
450+
/* read and throw away the closing '\0' */
451+
intc;
452+
if ((c=pqGetc(pfin,pfdebug))!='\0') {
453+
fprintf(stderr,"error!, unexpected character %c following 'I'\n",c);
454+
}
455+
if (emptiesSent) {
456+
if (--emptiesSent==0) {/* is this the last one? */
457+
/*
458+
* If this is the result of a portal query command set the
459+
* command status and message accordingly. DZ - 31-8-1996
460+
*/
461+
*result_p=makeEmptyPGresult(conn,PGRES_COMMAND_OK);
462+
strncpy((*result_p)->cmdStatus,cmdStatus,CMDSTATUS_LEN-1);
463+
done= true;
464+
}
465+
}
466+
else {
467+
*result_p=makeEmptyPGresult(conn,PGRES_EMPTY_QUERY);
468+
done= true;
469+
}
470+
}
471+
break;
472+
case'N':/* notices from the backend */
473+
if (pqGets(reason,ERROR_MSG_LENGTH,pfin,pfdebug)==1) {
474+
sprintf(reason,
475+
"PQexec() -- Notice detected from backend, "
476+
"but attempt to read the notice failed.");
477+
*result_p= (PGresult*)NULL;
478+
done= true;
479+
}else
480+
/* Should we really be doing this? These notices are not important
481+
enough for us to presume to put them on stderr. Maybe the caller
482+
should decide whether to put them on stderr or not. BJH 96.12.27
483+
*/
484+
fprintf(stderr,"%s",reason);
485+
break;
486+
case'P':/* synchronous (normal) portal */
487+
pqGets(pname,MAX_MESSAGE_LEN,pfin,pfdebug);/* read in portal name*/
488+
break;
489+
case'T':/* actual row results: */
490+
*result_p=makePGresult(conn,pname);
491+
done= true;
492+
break;
493+
case'D':/* copy command began successfully */
494+
*result_p=makeEmptyPGresult(conn,PGRES_COPY_IN);
495+
done= true;
496+
break;
497+
case'B':/* copy command began successfully */
498+
*result_p=makeEmptyPGresult(conn,PGRES_COPY_OUT);
499+
done= true;
500+
break;
501+
default:
502+
sprintf(reason,
503+
"unknown protocol character '%c' read from backend. "
504+
"(The protocol character is the first character the "
505+
"backend sends in response to a query it receives).\n",
506+
id);
507+
*result_p= (PGresult*)NULL;
508+
done= true;
509+
}/* switch on protocol character */
510+
}/* if character was received */
511+
}/* while not done */
512+
}
513+
514+
351515

352516
/*
353517
* PQexec
@@ -364,27 +528,14 @@ PGresult*
364528
PQexec(PGconn*conn,constchar*query)
365529
{
366530
PGresult*result;
367-
intid;
368531
charbuffer[MAX_MESSAGE_LEN];
369-
charcmdStatus[MAX_MESSAGE_LEN];
370-
charpname[MAX_MESSAGE_LEN];/* portal name */
371-
PGnotify*newNotify;
372-
FILE*pfin,*pfout,*pfdebug;
373-
staticintemptiesPending=0;
374-
boolemptySent= false;
375-
376-
pname[0]='\0';
377532

378533
if (!conn)returnNULL;
379534
if (!query) {
380535
sprintf(conn->errorMessage,"PQexec() -- query pointer is null.");
381536
returnNULL;
382537
}
383538

384-
pfin=conn->Pfin;
385-
pfout=conn->Pfout;
386-
pfdebug=conn->Pfdebug;
387-
388539
/*clear the error string */
389540
conn->errorMessage[0]='\0';
390541

@@ -406,129 +557,20 @@ PQexec(PGconn* conn, const char* query)
406557
sprintf(buffer,"Q%s",query);
407558

408559
/* send the query to the backend; */
409-
if (pqPuts(buffer,pfout,pfdebug)==1) {
560+
if (pqPuts(buffer,conn->Pfout,conn->Pfdebug)==1) {
410561
(void)sprintf(conn->errorMessage,
411562
"PQexec() -- while sending query: %s\n"
412563
"-- fprintf to Pfout failed: errno=%d\n%s\n",
413-
query,errno,strerror(errno));
564+
query,errno,strerror(errno));
414565
returnNULL;
415566
}
416567

417-
/* loop forever because multiple messages, especially NOTICES,
418-
can come back from the backend
419-
NOTICES are output directly to stderr
420-
*/
421-
422-
while (1) {
568+
process_response_from_backend(conn->Pfin,conn->Pfout,conn->Pfdebug,conn,
569+
&result,conn->errorMessage);
570+
return(result);
571+
}
423572

424-
/* read the result id */
425-
id=pqGetc(pfin,pfdebug);
426-
if (id==EOF) {
427-
/* hmm, no response from the backend-end, that's bad */
428-
(void)sprintf(conn->errorMessage,
429-
"PQexec() -- Request was sent to backend, but backend "
430-
"closed the channel before "
431-
"responding. This probably means the backend "
432-
"terminated abnormally before or while processing "
433-
"the request.\n");
434-
conn->status=CONNECTION_BAD;/* No more connection to backend */
435-
return (PGresult*)NULL;
436-
}
437573

438-
switch (id) {
439-
case'A':
440-
newNotify= (PGnotify*)malloc(sizeof(PGnotify));
441-
pqGetInt(&(newNotify->be_pid),4,pfin,pfdebug);
442-
pqGets(newNotify->relname,NAMEDATALEN,pfin,pfdebug);
443-
DLAddTail(conn->notifyList,DLNewElem(newNotify));
444-
/* async messages are piggy'ed back on other messages,
445-
so we stay in the while loop for other messages */
446-
break;
447-
case'C':/* portal query command, no rows returned */
448-
if (pqGets(cmdStatus,MAX_MESSAGE_LEN,pfin,pfdebug)==1) {
449-
sprintf(conn->errorMessage,
450-
"PQexec() -- query command completed, "
451-
"but return message from backend cannot be read.");
452-
return (PGresult*)NULL;
453-
}
454-
else {
455-
/*
456-
// since backend may produce more than one result for some commands
457-
// need to poll until clear
458-
// send an empty query down, and keep reading out of the pipe
459-
// until an 'I' is received.
460-
*/
461-
pqPuts("Q",pfout,pfdebug);/* send an empty query */
462-
/*
463-
* Increment a flag and process messages in the usual way because
464-
* there may be async notifications pending. DZ - 31-8-1996
465-
*/
466-
emptiesPending++;
467-
emptySent= true;
468-
}
469-
break;
470-
case'E':/* error return */
471-
if (pqGets(conn->errorMessage,ERROR_MSG_LENGTH,pfin,pfdebug)==1) {
472-
(void)sprintf(conn->errorMessage,
473-
"PQexec() -- error return detected from backend, "
474-
"but attempt to read the error message failed.");
475-
}
476-
return (PGresult*)NULL;
477-
break;
478-
case'I':/* empty query */
479-
/* read the throw away the closing '\0' */
480-
{
481-
intc;
482-
if ((c=pqGetc(pfin,pfdebug))!='\0') {
483-
fprintf(stderr,"error!, unexpected character %c following 'I'\n",c);
484-
}
485-
if (emptiesPending) {
486-
if (--emptiesPending==0&&emptySent) {/* is this the last one? */
487-
/*
488-
* If this is the result of a portal query command set the
489-
* command status and message accordingly. DZ - 31-8-1996
490-
*/
491-
result=makeEmptyPGresult(conn,PGRES_COMMAND_OK);
492-
strncpy(result->cmdStatus,cmdStatus,CMDSTATUS_LEN-1);
493-
returnresult;
494-
}
495-
}
496-
else {
497-
result=makeEmptyPGresult(conn,PGRES_EMPTY_QUERY);
498-
returnresult;
499-
}
500-
}
501-
break;
502-
case'N':/* notices from the backend */
503-
if (pqGets(conn->errorMessage,ERROR_MSG_LENGTH,pfin,pfdebug)==1) {
504-
sprintf(conn->errorMessage,
505-
"PQexec() -- Notice detected from backend, "
506-
"but attempt to read the notice failed.");
507-
return (PGresult*)NULL;
508-
}
509-
else
510-
fprintf(stderr,"%s",conn->errorMessage);
511-
break;
512-
case'P':/* synchronous (normal) portal */
513-
pqGets(pname,MAX_MESSAGE_LEN,pfin,pfdebug);/* read in portal name*/
514-
break;
515-
case'T':/* actual row results: */
516-
returnmakePGresult(conn,pname);
517-
break;
518-
case'D':/* copy command began successfully */
519-
returnmakeEmptyPGresult(conn,PGRES_COPY_IN);
520-
break;
521-
case'B':/* copy command began successfully */
522-
returnmakeEmptyPGresult(conn,PGRES_COPY_OUT);
523-
break;
524-
default:
525-
sprintf(conn->errorMessage,
526-
"unknown protocol character %c read from backend\n",
527-
id);
528-
return (PGresult*)NULL;
529-
}/* switch */
530-
}/* while (1)*/
531-
}
532574

533575
/*
534576
* PQnotifies

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