From 4424cbd218c3ff968d1273edf40ffc3689cc1f5d Mon Sep 17 00:00:00 2001 From: Craig Ringer Date: Wed, 9 Sep 2020 12:55:29 +0800 Subject: [PATCH v999 3/3] Add guards to detect return from between PG_TRY() and PG_END_TRY() These don't work because of the issue mentioned earlier where llvm's scan-build loses track of a pointer escape when the containing struct pointer is cleared from a global then restored to the global again. --- src/backend/utils/error/elog.c | 7 +++++++ src/include/utils/elog.h | 10 ++++++++++ 2 files changed, 17 insertions(+) diff --git a/src/backend/utils/error/elog.c b/src/backend/utils/error/elog.c index 9af7155171..c1fb3d4785 100644 --- a/src/backend/utils/error/elog.c +++ b/src/backend/utils/error/elog.c @@ -93,6 +93,9 @@ ErrorContextCallback *error_context_stack = NULL; PG_sigjmp_buf *PG_exception_stack = NULL; +/* HACK for scan-build testing */ +const PG_try_guard_entry * pg_try_guard = NULL; + extern bool redirection_done; /* @@ -580,6 +583,10 @@ errfinish(const char *filename, int lineno, const char *funcname) if (elevel >= PANIC) { + /* trick clang into thinking we actually use pg_try_guard, hopefully... */ + if (pg_try_guard) + abort(); + /* * Serious crash time. Postmaster will observe SIGABRT process exit * status and kill the other backends too. diff --git a/src/include/utils/elog.h b/src/include/utils/elog.h index fe82225dbe..bf40ca632c 100644 --- a/src/include/utils/elog.h +++ b/src/include/utils/elog.h @@ -299,12 +299,21 @@ typedef struct PG_sigjmp_buf sigjmp_buf buf; } PG_sigjmp_buf; +/* HACK to show that scan-build does detect escapes from PG_CATCH() */ +typedef struct PG_try_guard_entry +{ + const struct PG_try_guard_entry * const previous; +} PG_try_guard_entry; +extern const PG_try_guard_entry * pg_try_guard; + #define PG_TRY() \ do { \ PG_sigjmp_buf *_save_exception_stack = PG_exception_stack; \ ErrorContextCallback *_save_context_stack = error_context_stack; \ PG_sigjmp_buf _local_sigjmp_buf; \ bool _do_rethrow = false; \ + const PG_try_guard_entry _this_pg_try_guard = { pg_try_guard }; \ + pg_try_guard = &_this_pg_try_guard; \ if (sigsetjmp(_local_sigjmp_buf.buf, 0) == 0) \ { \ PG_exception_stack = &_local_sigjmp_buf @@ -326,6 +335,7 @@ typedef struct PG_sigjmp_buf #define PG_END_TRY() \ } \ + pg_try_guard = _this_pg_try_guard.previous; \ if (_do_rethrow) \ PG_RE_THROW(); \ PG_exception_stack = _save_exception_stack; \ -- 2.26.2