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0c3c5c3b06
The idea is to encourage more the use of these new routines across the
tree, as these offer stronger type safety guarantees than palloc().
The following paths are included in this batch, treating all the areas
proposed by the author for the most trivial changes, except src/backend
(by far the largest batch):
src/bin/
src/common/
src/fe_utils/
src/include/
src/pl/
src/test/
src/tutorial/
Similar work has been done in 31d3847a37.
The code compiles the same before and after this commit, with the
following exceptions due to changes in line numbers because some of the
new allocation formulas are shorter:
blkreftable.c
pgfnames.c
pl_exec.c
Author: David Geier <geidav.pg@gmail.com>
Discussion: https://postgr.es/m/ad0748d4-3080-436e-b0bc-ac8f86a3466a@gmail.com
147 lines
3.5 KiB
C
147 lines
3.5 KiB
C
/* src/tutorial/funcs.c */
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/******************************************************************************
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These are user-defined functions that can be bound to a Postgres backend
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and called by Postgres to execute SQL functions of the same name.
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The calling format for these functions is defined by the CREATE FUNCTION
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SQL statement that binds them to the backend.
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*****************************************************************************/
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#include "postgres.h" /* general Postgres declarations */
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#include "executor/executor.h" /* for GetAttributeByName() */
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#include "utils/fmgrprotos.h" /* for text_starts_with() */
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#include "utils/geo_decls.h" /* for point type */
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#include "varatt.h" /* for VARDATA/VARSIZE macros */
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PG_MODULE_MAGIC;
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/* By Value */
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PG_FUNCTION_INFO_V1(add_one);
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Datum
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add_one(PG_FUNCTION_ARGS)
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{
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int32 arg = PG_GETARG_INT32(0);
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PG_RETURN_INT32(arg + 1);
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}
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/* By Reference, Fixed Length */
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PG_FUNCTION_INFO_V1(add_one_float8);
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Datum
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add_one_float8(PG_FUNCTION_ARGS)
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{
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/* The macros for FLOAT8 hide its pass-by-reference nature */
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float8 arg = PG_GETARG_FLOAT8(0);
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PG_RETURN_FLOAT8(arg + 1.0);
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}
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PG_FUNCTION_INFO_V1(makepoint);
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Datum
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makepoint(PG_FUNCTION_ARGS)
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{
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Point *pointx = PG_GETARG_POINT_P(0);
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Point *pointy = PG_GETARG_POINT_P(1);
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Point *new_point = palloc_object(Point);
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new_point->x = pointx->x;
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new_point->y = pointy->y;
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PG_RETURN_POINT_P(new_point);
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}
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/* By Reference, Variable Length */
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PG_FUNCTION_INFO_V1(copytext);
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Datum
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copytext(PG_FUNCTION_ARGS)
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{
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text *t = PG_GETARG_TEXT_PP(0);
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/*
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* VARSIZE_ANY_EXHDR is the size of the struct in bytes, minus the
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* VARHDRSZ or VARHDRSZ_SHORT of its header. Construct the copy with a
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* full-length header.
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*/
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text *new_t = (text *) palloc(VARSIZE_ANY_EXHDR(t) + VARHDRSZ);
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SET_VARSIZE(new_t, VARSIZE_ANY_EXHDR(t) + VARHDRSZ);
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/*
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* VARDATA is a pointer to the data region of the new struct. The source
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* could be a short datum, so retrieve its data through VARDATA_ANY.
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*/
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memcpy(VARDATA(new_t), /* destination */
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VARDATA_ANY(t), /* source */
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VARSIZE_ANY_EXHDR(t)); /* how many bytes */
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PG_RETURN_TEXT_P(new_t);
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}
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PG_FUNCTION_INFO_V1(concat_text);
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Datum
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concat_text(PG_FUNCTION_ARGS)
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{
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text *arg1 = PG_GETARG_TEXT_PP(0);
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text *arg2 = PG_GETARG_TEXT_PP(1);
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int32 arg1_size = VARSIZE_ANY_EXHDR(arg1);
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int32 arg2_size = VARSIZE_ANY_EXHDR(arg2);
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int32 new_text_size = arg1_size + arg2_size + VARHDRSZ;
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text *new_text = (text *) palloc(new_text_size);
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SET_VARSIZE(new_text, new_text_size);
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memcpy(VARDATA(new_text), VARDATA_ANY(arg1), arg1_size);
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memcpy(VARDATA(new_text) + arg1_size, VARDATA_ANY(arg2), arg2_size);
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PG_RETURN_TEXT_P(new_text);
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}
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/* A wrapper around starts_with(text, text) */
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PG_FUNCTION_INFO_V1(t_starts_with);
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Datum
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t_starts_with(PG_FUNCTION_ARGS)
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{
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text *t1 = PG_GETARG_TEXT_PP(0);
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text *t2 = PG_GETARG_TEXT_PP(1);
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Oid collid = PG_GET_COLLATION();
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bool result;
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result = DatumGetBool(DirectFunctionCall2Coll(text_starts_with,
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collid,
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PointerGetDatum(t1),
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PointerGetDatum(t2)));
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PG_RETURN_BOOL(result);
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}
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/* Composite types */
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PG_FUNCTION_INFO_V1(c_overpaid);
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Datum
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c_overpaid(PG_FUNCTION_ARGS)
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{
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HeapTupleHeader t = PG_GETARG_HEAPTUPLEHEADER(0);
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int32 limit = PG_GETARG_INT32(1);
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bool isnull;
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int32 salary;
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salary = DatumGetInt32(GetAttributeByName(t, "salary", &isnull));
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if (isnull)
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PG_RETURN_BOOL(false);
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/*
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* Alternatively, we might prefer to do PG_RETURN_NULL() for null salary
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*/
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PG_RETURN_BOOL(salary > limit);
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}
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