Age Owner TLA Line data Source code
1 : /*
2 : * PostgreSQL definitions for managed Large Objects.
3 : *
4 : * contrib/lo/lo.c
5 : *
6 : */
7 :
8 : #include "postgres.h"
9 :
10 : #include "commands/trigger.h"
11 : #include "executor/spi.h"
12 : #include "utils/builtins.h"
13 : #include "utils/rel.h"
14 :
6158 tgl 15 CBC 1 : PG_MODULE_MAGIC;
16 :
17 :
18 : /*
19 : * This is the trigger that protects us from orphaned large objects
20 : */
8175 21 2 : PG_FUNCTION_INFO_V1(lo_manage);
22 :
23 : Datum
8350 24 3 : lo_manage(PG_FUNCTION_ARGS)
25 : {
26 3 : TriggerData *trigdata = (TriggerData *) fcinfo->context;
27 : int attnum; /* attribute number to monitor */
28 : char **args; /* Args containing attr name */
29 : TupleDesc tupdesc; /* Tuple Descriptor */
30 : HeapTuple rettuple; /* Tuple to be returned */
31 : bool isdelete; /* are we deleting? */
32 : HeapTuple newtuple; /* The new value for tuple */
33 : HeapTuple trigtuple; /* The original value of tuple */
34 :
2118 35 3 : if (!CALLED_AS_TRIGGER(fcinfo)) /* internal error */
1101 tgl 36 UBC 0 : elog(ERROR, "lo_manage: not fired by trigger manager");
37 :
2118 tgl 38 CBC 3 : if (!TRIGGER_FIRED_FOR_ROW(trigdata->tg_event)) /* internal error */
3424 tgl 39 UBC 0 : elog(ERROR, "%s: must be fired for row",
40 : trigdata->tg_trigger->tgname);
41 :
42 : /*
43 : * Fetch some values from trigdata
44 : */
8350 tgl 45 CBC 3 : newtuple = trigdata->tg_newtuple;
46 3 : trigtuple = trigdata->tg_trigtuple;
47 3 : tupdesc = trigdata->tg_relation->rd_att;
48 3 : args = trigdata->tg_trigger->tgargs;
49 :
3424 50 3 : if (args == NULL) /* internal error */
3424 tgl 51 UBC 0 : elog(ERROR, "%s: no column name provided in the trigger definition",
52 : trigdata->tg_trigger->tgname);
53 :
54 : /* tuple to return to Executor */
8350 tgl 55 CBC 3 : if (TRIGGER_FIRED_BY_UPDATE(trigdata->tg_event))
8720 bruce 56 2 : rettuple = newtuple;
57 : else
58 1 : rettuple = trigtuple;
59 :
60 : /* Are we deleting the row? */
8350 tgl 61 3 : isdelete = TRIGGER_FIRED_BY_DELETE(trigdata->tg_event);
62 :
63 : /* Get the column we're interested in */
8720 bruce 64 3 : attnum = SPI_fnumber(tupdesc, args[0]);
65 :
6499 tgl 66 3 : if (attnum <= 0)
3424 tgl 67 UBC 0 : elog(ERROR, "%s: column \"%s\" does not exist",
68 : trigdata->tg_trigger->tgname, args[0]);
69 :
70 : /*
71 : * Handle updates
72 : *
73 : * Here, if the value of the monitored attribute changes, then the large
74 : * object associated with the original value is unlinked.
75 : */
1126 peter 76 CBC 5 : if (newtuple != NULL &&
77 2 : bms_is_member(attnum - FirstLowInvalidHeapAttributeNumber, trigdata->tg_updatedcols))
78 : {
8720 bruce 79 1 : char *orig = SPI_getvalue(trigtuple, tupdesc, attnum);
80 1 : char *newv = SPI_getvalue(newtuple, tupdesc, attnum);
81 :
6499 tgl 82 1 : if (orig != NULL && (newv == NULL || strcmp(orig, newv) != 0))
2294 peter_e 83 1 : DirectFunctionCall1(be_lo_unlink,
84 : ObjectIdGetDatum(atooid(orig)));
85 :
8720 bruce 86 1 : if (newv)
87 1 : pfree(newv);
88 1 : if (orig)
89 1 : pfree(orig);
90 : }
91 :
92 : /*
93 : * Handle deleting of rows
94 : *
95 : * Here, we unlink the large object associated with the managed attribute
96 : */
97 3 : if (isdelete)
98 : {
99 1 : char *orig = SPI_getvalue(trigtuple, tupdesc, attnum);
100 :
101 1 : if (orig != NULL)
102 : {
2294 peter_e 103 1 : DirectFunctionCall1(be_lo_unlink,
104 : ObjectIdGetDatum(atooid(orig)));
105 :
8720 bruce 106 1 : pfree(orig);
107 : }
108 : }
109 :
8350 tgl 110 3 : return PointerGetDatum(rettuple);
111 : }
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