1 /*
2 * contrib/spi/autoinc.c
3 */
4 #include "postgres.h"
5
6 #include "access/htup_details.h"
7 #include "catalog/pg_type.h"
8 #include "commands/sequence.h"
9 #include "commands/trigger.h"
10 #include "executor/spi.h"
11 #include "utils/builtins.h"
12 #include "utils/rel.h"
13
14 PG_MODULE_MAGIC;
15
16 PG_FUNCTION_INFO_V1(autoinc);
17
18 Datum
autoinc(PG_FUNCTION_ARGS)19 autoinc(PG_FUNCTION_ARGS)
20 {
21 TriggerData *trigdata = (TriggerData *) fcinfo->context;
22 Trigger *trigger; /* to get trigger name */
23 int nargs; /* # of arguments */
24 int *chattrs; /* attnums of attributes to change */
25 int chnattrs = 0; /* # of above */
26 Datum *newvals; /* vals of above */
27 bool *newnulls; /* null flags for above */
28 char **args; /* arguments */
29 char *relname; /* triggered relation name */
30 Relation rel; /* triggered relation */
31 HeapTuple rettuple = NULL;
32 TupleDesc tupdesc; /* tuple description */
33 bool isnull;
34 int i;
35
36 if (!CALLED_AS_TRIGGER(fcinfo))
37 /* internal error */
38 elog(ERROR, "not fired by trigger manager");
39 if (!TRIGGER_FIRED_FOR_ROW(trigdata->tg_event))
40 /* internal error */
41 elog(ERROR, "must be fired for row");
42 if (!TRIGGER_FIRED_BEFORE(trigdata->tg_event))
43 /* internal error */
44 elog(ERROR, "must be fired before event");
45
46 if (TRIGGER_FIRED_BY_INSERT(trigdata->tg_event))
47 rettuple = trigdata->tg_trigtuple;
48 else if (TRIGGER_FIRED_BY_UPDATE(trigdata->tg_event))
49 rettuple = trigdata->tg_newtuple;
50 else
51 /* internal error */
52 elog(ERROR, "cannot process DELETE events");
53
54 rel = trigdata->tg_relation;
55 relname = SPI_getrelname(rel);
56
57 trigger = trigdata->tg_trigger;
58
59 nargs = trigger->tgnargs;
60 if (nargs <= 0 || nargs % 2 != 0)
61 /* internal error */
62 elog(ERROR, "autoinc (%s): even number gt 0 of arguments was expected", relname);
63
64 args = trigger->tgargs;
65 tupdesc = rel->rd_att;
66
67 chattrs = (int *) palloc(nargs / 2 * sizeof(int));
68 newvals = (Datum *) palloc(nargs / 2 * sizeof(Datum));
69 newnulls = (bool *) palloc(nargs / 2 * sizeof(bool));
70
71 for (i = 0; i < nargs;)
72 {
73 int attnum = SPI_fnumber(tupdesc, args[i]);
74 int32 val;
75 Datum seqname;
76
77 if (attnum <= 0)
78 ereport(ERROR,
79 (errcode(ERRCODE_TRIGGERED_ACTION_EXCEPTION),
80 errmsg("\"%s\" has no attribute \"%s\"",
81 relname, args[i])));
82
83 if (SPI_gettypeid(tupdesc, attnum) != INT4OID)
84 ereport(ERROR,
85 (errcode(ERRCODE_TRIGGERED_ACTION_EXCEPTION),
86 errmsg("attribute \"%s\" of \"%s\" must be type INT4",
87 args[i], relname)));
88
89 val = DatumGetInt32(SPI_getbinval(rettuple, tupdesc, attnum, &isnull));
90
91 if (!isnull && val != 0)
92 {
93 i += 2;
94 continue;
95 }
96
97 i++;
98 chattrs[chnattrs] = attnum;
99 seqname = CStringGetTextDatum(args[i]);
100 newvals[chnattrs] = DirectFunctionCall1(nextval, seqname);
101 /* nextval now returns int64; coerce down to int32 */
102 newvals[chnattrs] = Int32GetDatum((int32) DatumGetInt64(newvals[chnattrs]));
103 if (DatumGetInt32(newvals[chnattrs]) == 0)
104 {
105 newvals[chnattrs] = DirectFunctionCall1(nextval, seqname);
106 newvals[chnattrs] = Int32GetDatum((int32) DatumGetInt64(newvals[chnattrs]));
107 }
108 newnulls[chnattrs] = false;
109 pfree(DatumGetTextPP(seqname));
110 chnattrs++;
111 i++;
112 }
113
114 if (chnattrs > 0)
115 {
116 rettuple = heap_modify_tuple_by_cols(rettuple, tupdesc,
117 chnattrs, chattrs,
118 newvals, newnulls);
119 }
120
121 pfree(relname);
122 pfree(chattrs);
123 pfree(newvals);
124 pfree(newnulls);
125
126 return PointerGetDatum(rettuple);
127 }
128