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Revise syntax-error reporting behavior to give pleasant results for
errors in internally-generated queries, such as those submitted by plpgsql functions. Per recent discussions with Fabien Coelho.
1 parent bee3b2a commit f938c2b

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25 files changed

+672
-125
lines changed

25 files changed

+672
-125
lines changed

‎doc/src/sgml/libpq.sgml

Lines changed: 28 additions & 4 deletions
Original file line numberDiff line numberDiff line change
@@ -1,5 +1,5 @@
11
<!--
2-
$PostgreSQL: pgsql/doc/src/sgml/libpq.sgml,v 1.147 2004/03/11 02:39:10 momjian Exp $
2+
$PostgreSQL: pgsql/doc/src/sgml/libpq.sgml,v 1.148 2004/03/21 22:29:10 tgl Exp $
33
-->
44

55
<chapter id="libpq">
@@ -1390,13 +1390,37 @@ bytes.
13901390
</listitem>
13911391
</varlistentry>
13921392

1393+
<varlistentry>
1394+
<term><symbol>PG_DIAG_INTERNAL_POSITION</></term>
1395+
<listitem>
1396+
<para>
1397+
This is defined the same as the <symbol>PG_DIAG_STATEMENT_POSITION</>
1398+
field, but it is used when the cursor position refers to an internally
1399+
generated command rather than the one submitted by the client.
1400+
The <symbol>PG_DIAG_INTERNAL_QUERY</> field will always appear when this field
1401+
appears.
1402+
</para>
1403+
</listitem>
1404+
</varlistentry>
1405+
1406+
<varlistentry>
1407+
<term><symbol>PG_DIAG_INTERNAL_QUERY</></term>
1408+
<listitem>
1409+
<para>
1410+
The text of a failed internally-generated command.
1411+
This could be, for example, a SQL query issued by a PL/pgSQL function.
1412+
</para>
1413+
</listitem>
1414+
</varlistentry>
1415+
13931416
<varlistentry>
13941417
<term><symbol>PG_DIAG_CONTEXT</></term>
13951418
<listitem>
13961419
<para>
1397-
An indication of the context in which the error occurred. Presently
1398-
this includes a call stack traceback of active PL functions. The
1399-
trace is one entry per line, most recent first.
1420+
An indication of the context in which the error occurred.
1421+
Presently this includes a call stack traceback of active
1422+
procedural language functions and internally-generated queries.
1423+
The trace is one entry per line, most recent first.
14001424
</para>
14011425
</listitem>
14021426
</varlistentry>

‎doc/src/sgml/protocol.sgml

Lines changed: 30 additions & 4 deletions
Original file line numberDiff line numberDiff line change
@@ -1,4 +1,4 @@
1-
<!-- $PostgreSQL: pgsql/doc/src/sgml/protocol.sgml,v 1.50 2004/03/09 16:57:46 neilc Exp $ -->
1+
<!-- $PostgreSQL: pgsql/doc/src/sgml/protocol.sgml,v 1.51 2004/03/21 22:29:10 tgl Exp $ -->
22

33
<chapter id="protocol">
44
<title>Frontend/Backend Protocol</title>
@@ -3902,16 +3902,42 @@ message.
39023902
</ListItem>
39033903
</VarListEntry>
39043904

3905+
<VarListEntry>
3906+
<Term>
3907+
<literal>p</>
3908+
</Term>
3909+
<ListItem>
3910+
<Para>
3911+
Internal position: this is defined the same as the <literal>P</>
3912+
field, but it is used when the cursor position refers to an internally
3913+
generated command rather than the one submitted by the client.
3914+
The <literal>q</> field will always appear when this field appears.
3915+
</Para>
3916+
</ListItem>
3917+
</VarListEntry>
3918+
3919+
<VarListEntry>
3920+
<Term>
3921+
<literal>q</>
3922+
</Term>
3923+
<ListItem>
3924+
<Para>
3925+
Internal query: the text of a failed internally-generated command.
3926+
This could be, for example, a SQL query issued by a PL/pgSQL function.
3927+
</Para>
3928+
</ListItem>
3929+
</VarListEntry>
3930+
39053931
<VarListEntry>
39063932
<Term>
39073933
<literal>W</>
39083934
</Term>
39093935
<ListItem>
39103936
<Para>
39113937
Where: an indication of the context in which the error occurred.
3912-
Presently this includes a call stack traceback of active
3913-
procedural language functions. The trace is one entry per line,
3914-
most recent first.
3938+
Presently this includes a call stack traceback of active
3939+
procedural language functions and internally-generated queries.
3940+
The trace is one entry per line, most recent first.
39153941
</Para>
39163942
</ListItem>
39173943
</VarListEntry>

‎src/backend/catalog/pg_proc.c

Lines changed: 200 additions & 15 deletions
Original file line numberDiff line numberDiff line change
@@ -8,7 +8,7 @@
88
*
99
*
1010
* IDENTIFICATION
11-
* $PostgreSQL: pgsql/src/backend/catalog/pg_proc.c,v 1.112 2004/03/14 01:58:41 tgl Exp $
11+
* $PostgreSQL: pgsql/src/backend/catalog/pg_proc.c,v 1.113 2004/03/21 22:29:10 tgl Exp $
1212
*
1313
*-------------------------------------------------------------------------
1414
*/
@@ -23,9 +23,11 @@
2323
#include "executor/executor.h"
2424
#include "fmgr.h"
2525
#include "miscadmin.h"
26+
#include "mb/pg_wchar.h"
2627
#include "parser/parse_coerce.h"
2728
#include "parser/parse_expr.h"
2829
#include "parser/parse_type.h"
30+
#include "tcop/pquery.h"
2931
#include "tcop/tcopprot.h"
3032
#include "utils/acl.h"
3133
#include "utils/builtins.h"
@@ -45,6 +47,10 @@ Datum fmgr_sql_validator(PG_FUNCTION_ARGS);
4547
static Datum create_parameternames_array(int parameterCount,
4648
const char *parameterNames[]);
4749
static void sql_function_parse_error_callback(void *arg);
50+
static int match_prosrc_to_query(const char *prosrc, const char *queryText,
51+
int cursorpos);
52+
static bool match_prosrc_to_literal(const char *prosrc, const char *literal,
53+
int cursorpos, int *newcursorpos);
4854

4955

5056
/* ----------------------------------------------------------------
@@ -763,12 +769,10 @@ fmgr_sql_validator(PG_FUNCTION_ARGS)
763769
prosrc = DatumGetCString(DirectFunctionCall1(textout, tmp));
764770

765771
/*
766-
* Setup error traceback support for ereport(). This is mostly
767-
* so we can add context info that shows that a syntax-error
768-
* location is inside the function body, not out in CREATE FUNCTION.
772+
* Setup error traceback support for ereport().
769773
*/
770774
sqlerrcontext.callback = sql_function_parse_error_callback;
771-
sqlerrcontext.arg = proc;
775+
sqlerrcontext.arg = tuple;
772776
sqlerrcontext.previous = error_context_stack;
773777
error_context_stack = &sqlerrcontext;
774778

@@ -800,22 +804,203 @@ fmgr_sql_validator(PG_FUNCTION_ARGS)
800804
}
801805

802806
/*
803-
* error context callback to let us supply a context marker
807+
* Error context callback for handling errors in SQL function definitions
804808
*/
805809
static void
806810
sql_function_parse_error_callback(void *arg)
807811
{
808-
Form_pg_proc proc = (Form_pg_proc) arg;
812+
HeapTuple tuple = (HeapTuple) arg;
813+
Form_pg_proc proc = (Form_pg_proc) GETSTRUCT(tuple);
814+
bool isnull;
815+
Datum tmp;
816+
char *prosrc;
817+
818+
/* See if it's a syntax error; if so, transpose to CREATE FUNCTION */
819+
tmp = SysCacheGetAttr(PROCOID, tuple, Anum_pg_proc_prosrc, &isnull);
820+
if (isnull)
821+
elog(ERROR, "null prosrc");
822+
prosrc = DatumGetCString(DirectFunctionCall1(textout, tmp));
823+
824+
if (!function_parse_error_transpose(prosrc))
825+
{
826+
/* If it's not a syntax error, push info onto context stack */
827+
errcontext("SQL function \"%s\"", NameStr(proc->proname));
828+
}
829+
830+
pfree(prosrc);
831+
}
832+
833+
/*
834+
* Adjust a syntax error occurring inside the function body of a CREATE
835+
* FUNCTION command. This can be used by any function validator, not only
836+
* for SQL-language functions. It is assumed that the syntax error position
837+
* is initially relative to the function body string (as passed in). If
838+
* possible, we adjust the position to reference the original CREATE command;
839+
* if we can't manage that, we set up an "internal query" syntax error instead.
840+
*
841+
* Returns true if a syntax error was processed, false if not.
842+
*/
843+
bool
844+
function_parse_error_transpose(const char *prosrc)
845+
{
846+
int origerrposition;
847+
int newerrposition;
848+
const char *queryText;
849+
850+
/*
851+
* Nothing to do unless we are dealing with a syntax error that has
852+
* a cursor position.
853+
*
854+
* Some PLs may prefer to report the error position as an internal
855+
* error to begin with, so check that too.
856+
*/
857+
origerrposition = geterrposition();
858+
if (origerrposition <= 0)
859+
{
860+
origerrposition = getinternalerrposition();
861+
if (origerrposition <= 0)
862+
return false;
863+
}
864+
865+
/* We can get the original query text from the active portal (hack...) */
866+
Assert(ActivePortal && ActivePortal->portalActive);
867+
queryText = ActivePortal->sourceText;
868+
869+
/* Try to locate the prosrc in the original text */
870+
newerrposition = match_prosrc_to_query(prosrc, queryText, origerrposition);
871+
872+
if (newerrposition > 0)
873+
{
874+
/* Successful, so fix error position to reference original query */
875+
errposition(newerrposition);
876+
/* Get rid of any report of the error as an "internal query" */
877+
internalerrposition(0);
878+
internalerrquery(NULL);
879+
}
880+
else
881+
{
882+
/*
883+
* If unsuccessful, convert the position to an internal position
884+
* marker and give the function text as the internal query.
885+
*/
886+
errposition(0);
887+
internalerrposition(origerrposition);
888+
internalerrquery(prosrc);
889+
}
890+
891+
return true;
892+
}
809893

894+
/*
895+
* Try to locate the string literal containing the function body in the
896+
* given text of the CREATE FUNCTION command. If successful, return the
897+
* character (not byte) index within the command corresponding to the
898+
* given character index within the literal. If not successful, return 0.
899+
*/
900+
static int
901+
match_prosrc_to_query(const char *prosrc, const char *queryText,
902+
int cursorpos)
903+
{
810904
/*
811-
* XXX it'd be really nice to adjust the syntax error position to
812-
* account for the offset from the start of the statement to the
813-
* function body string, not to mention any quoting characters in
814-
* the string, but I can't see any decent way to do that...
905+
* Rather than fully parsing the CREATE FUNCTION command, we just scan
906+
* the command looking for $prosrc$ or 'prosrc'. This could be fooled
907+
* (though not in any very probable scenarios), so fail if we find
908+
* more than one match.
909+
*/
910+
int prosrclen = strlen(prosrc);
911+
int querylen = strlen(queryText);
912+
int matchpos = 0;
913+
int curpos;
914+
int newcursorpos;
915+
916+
for (curpos = 0; curpos < querylen-prosrclen; curpos++)
917+
{
918+
if (queryText[curpos] == '$' &&
919+
strncmp(prosrc, &queryText[curpos+1], prosrclen) == 0 &&
920+
queryText[curpos+1+prosrclen] == '$')
921+
{
922+
/*
923+
* Found a $foo$ match. Since there are no embedded quoting
924+
* characters in a dollar-quoted literal, we don't have to do
925+
* any fancy arithmetic; just offset by the starting position.
926+
*/
927+
if (matchpos)
928+
return 0; /* multiple matches, fail */
929+
matchpos = pg_mbstrlen_with_len(queryText, curpos+1)
930+
+ cursorpos;
931+
}
932+
else if (queryText[curpos] == '\'' &&
933+
match_prosrc_to_literal(prosrc, &queryText[curpos+1],
934+
cursorpos, &newcursorpos))
935+
{
936+
/*
937+
* Found a 'foo' match. match_prosrc_to_literal() has adjusted
938+
* for any quotes or backslashes embedded in the literal.
939+
*/
940+
if (matchpos)
941+
return 0; /* multiple matches, fail */
942+
matchpos = pg_mbstrlen_with_len(queryText, curpos+1)
943+
+ newcursorpos;
944+
}
945+
}
946+
947+
return matchpos;
948+
}
949+
950+
/*
951+
* Try to match the given source text to a single-quoted literal.
952+
* If successful, adjust newcursorpos to correspond to the character
953+
* (not byte) index corresponding to cursorpos in the source text.
954+
*
955+
* At entry, literal points just past a ' character. We must check for the
956+
* trailing quote.
957+
*/
958+
static bool
959+
match_prosrc_to_literal(const char *prosrc, const char *literal,
960+
int cursorpos, int *newcursorpos)
961+
{
962+
int newcp = cursorpos;
963+
int chlen;
964+
965+
/*
966+
* This implementation handles backslashes and doubled quotes in the
967+
* string literal. It does not handle the SQL syntax for literals
968+
* continued across line boundaries.
815969
*
816-
* In the meantime, put in a CONTEXT entry that can cue clients
817-
* not to trust the syntax error position completely.
970+
* We do the comparison a character at a time, not a byte at a time,
971+
* so that we can do the correct cursorpos math.
818972
*/
819-
errcontext("SQL function \"%s\"",
820-
NameStr(proc->proname));
973+
while (*prosrc)
974+
{
975+
cursorpos--; /* characters left before cursor */
976+
/*
977+
* Check for backslashes and doubled quotes in the literal; adjust
978+
* newcp when one is found before the cursor.
979+
*/
980+
if (*literal == '\\')
981+
{
982+
literal++;
983+
if (cursorpos > 0)
984+
newcp++;
985+
}
986+
else if (*literal == '\'')
987+
{
988+
if (literal[1] != '\'')
989+
return false;
990+
literal++;
991+
if (cursorpos > 0)
992+
newcp++;
993+
}
994+
chlen = pg_mblen(prosrc);
995+
if (strncmp(prosrc, literal, chlen) != 0)
996+
return false;
997+
prosrc += chlen;
998+
literal += chlen;
999+
}
1000+
1001+
*newcursorpos = newcp;
1002+
1003+
if (*literal == '\'' && literal[1] != '\'')
1004+
return true;
1005+
return false;
8211006
}

‎src/backend/commands/portalcmds.c

Lines changed: 5 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -14,7 +14,7 @@
1414
*
1515
*
1616
* IDENTIFICATION
17-
* $PostgreSQL: pgsql/src/backend/commands/portalcmds.c,v 1.25 2003/11/29 19:51:47 pgsql Exp $
17+
* $PostgreSQL: pgsql/src/backend/commands/portalcmds.c,v 1.26 2004/03/21 22:29:10 tgl Exp $
1818
*
1919
*-------------------------------------------------------------------------
2020
*/
@@ -270,6 +270,7 @@ void
270270
PersistHoldablePortal(Portal portal)
271271
{
272272
QueryDesc *queryDesc = PortalGetQueryDesc(portal);
273+
Portal saveActivePortal;
273274
MemoryContext savePortalContext;
274275
MemoryContext saveQueryContext;
275276
MemoryContext oldcxt;
@@ -311,6 +312,8 @@ PersistHoldablePortal(Portal portal)
311312
/*
312313
* Set global portal context pointers.
313314
*/
315+
saveActivePortal = ActivePortal;
316+
ActivePortal = portal;
314317
savePortalContext = PortalContext;
315318
PortalContext = PortalGetHeapMemory(portal);
316319
saveQueryContext = QueryContext;
@@ -342,6 +345,7 @@ PersistHoldablePortal(Portal portal)
342345
/* Mark portal not active */
343346
portal->portalActive = false;
344347

348+
ActivePortal = saveActivePortal;
345349
PortalContext = savePortalContext;
346350
QueryContext = saveQueryContext;
347351

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