Обсуждение: pgsql: Avoid premature free of pass-by-reference CALL arguments.
Avoid premature free of pass-by-reference CALL arguments. Prematurely freeing the EState used to evaluate CALL arguments led, in some cases, to passing dangling pointers to the procedure. This was masked in trivial cases because the argument pointers would point to Const nodes in the original expression tree, and in some other cases because the result value would end up in the standalone ExprContext rather than in memory belonging to the EState --- but that wasn't exactly high quality programming either, because the standalone ExprContext was never explicitly freed, breaking assorted API contracts. In addition, using a separate EState for each argument was just silly. So let's use just one EState, and one ExprContext, and make the latter belong to the former rather than be standalone, and clean up the EState (and hence the ExprContext) post-call. While at it, improve the function's commentary a bit. Discussion: https://postgr.es/m/29173.1518282748@sss.pgh.pa.us Branch ------ master Details ------- https://git.postgresql.org/pg/commitdiff/d02d4a6d4f27c223f48b03a5e651a22c8460b3c4 Modified Files -------------- src/backend/commands/functioncmds.c | 28 ++++++++++++++++++++------ src/test/regress/expected/create_procedure.out | 12 +++++++---- src/test/regress/sql/create_procedure.sql | 4 +++- 3 files changed, 33 insertions(+), 11 deletions(-)
On 2018-02-10 18:37:17 +0000, Tom Lane wrote: > Avoid premature free of pass-by-reference CALL arguments. > src/test/regress/expected/create_procedure.out | 12 +++++++---- > src/test/regress/sql/create_procedure.sql | 4 +++- > 3 files changed, 33 insertions(+), 11 deletions(-) There's a recent llvm buildfarm animal failure related to this: https://buildfarm.postgresql.org/cgi-bin/show_log.pl?nm=pogona&dt=2018-03-24%2020%3A10%3A01 *** /home/bf/build/buildfarm-pogona/HEAD/pgsql.build/../pgsql/src/test/regress/expected/create_procedure.out 2018-03-2308:10:44.326010286 +0100 --- /home/bf/build/buildfarm-pogona/HEAD/pgsql.build/src/test/regress/results/create_procedure.out 2018-03-24 21:15:28.749352165+0100 *************** *** 44,50 **** SELECT * FROM cp_test ORDER BY b COLLATE "C"; a | b ---+------- ! 1 | 0 1 | a 1 | xyzzy (3 rows) --- 44,50 ---- SELECT * FROM cp_test ORDER BY b COLLATE "C"; a | b ---+------- ! 1 | 9 1 | a 1 | xyzzy (3 rows) With the differening output created by: CREATE PROCEDURE ptest1(x text) LANGUAGE SQL AS $$ INSERT INTO cp_test VALUES (1, x); $$; CALL ptest1(substring(random()::text, 1, 1)); -- ok, volatile arg At first I was gosh darned confused, this really didn't seem likely to be an LLVM induced failure. And it turns out it isn't. If the value returned by random() is very small, the text representation switches to scientific notation like 8.26204195618629e-05. So, perhaps we should choose a different volatile function here? Greetings, Andres Freund
On 2018-02-10 18:37:17 +0000, Tom Lane wrote: > Avoid premature free of pass-by-reference CALL arguments. > src/test/regress/expected/create_procedure.out | 12 +++++++---- > src/test/regress/sql/create_procedure.sql | 4 +++- > 3 files changed, 33 insertions(+), 11 deletions(-) There's a recent llvm buildfarm animal failure related to this: https://buildfarm.postgresql.org/cgi-bin/show_log.pl?nm=pogona&dt=2018-03-24%2020%3A10%3A01 *** /home/bf/build/buildfarm-pogona/HEAD/pgsql.build/../pgsql/src/test/regress/expected/create_procedure.out 2018-03-2308:10:44.326010286 +0100 --- /home/bf/build/buildfarm-pogona/HEAD/pgsql.build/src/test/regress/results/create_procedure.out 2018-03-24 21:15:28.749352165+0100 *************** *** 44,50 **** SELECT * FROM cp_test ORDER BY b COLLATE "C"; a | b ---+------- ! 1 | 0 1 | a 1 | xyzzy (3 rows) --- 44,50 ---- SELECT * FROM cp_test ORDER BY b COLLATE "C"; a | b ---+------- ! 1 | 9 1 | a 1 | xyzzy (3 rows) With the differening output created by: CREATE PROCEDURE ptest1(x text) LANGUAGE SQL AS $$ INSERT INTO cp_test VALUES (1, x); $$; CALL ptest1(substring(random()::text, 1, 1)); -- ok, volatile arg At first I was gosh darned confused, this really didn't seem likely to be an LLVM induced failure. And it turns out it isn't. If the value returned by random() is very small, the text representation switches to scientific notation like 8.26204195618629e-05. So, perhaps we should choose a different volatile function here? Greetings, Andres Freund
Andres Freund <andres@anarazel.de> writes:
> On 2018-02-10 18:37:17 +0000, Tom Lane wrote:
> CALL ptest1(substring(random()::text, 1, 1)); -- ok, volatile arg
> At first I was gosh darned confused, this really didn't seem likely to
> be an LLVM induced failure. And it turns out it isn't. If the value
> returned by random() is very small, the text representation switches to
> scientific notation like 8.26204195618629e-05.
Ooops. I'll do something about that tomorrow.
regards, tom lane
Andres Freund <andres@anarazel.de> writes:
> On 2018-02-10 18:37:17 +0000, Tom Lane wrote:
> CALL ptest1(substring(random()::text, 1, 1)); -- ok, volatile arg
> At first I was gosh darned confused, this really didn't seem likely to
> be an LLVM induced failure. And it turns out it isn't. If the value
> returned by random() is very small, the text representation switches to
> scientific notation like 8.26204195618629e-05.
Ooops. I'll do something about that tomorrow.
regards, tom lane