[PATCH v2] stdlib: Describe __cxa_finalize usage in function comment
Florian Weimer
fweimer@redhat.com
Fri May 31 12:53:55 GMT 2024
---
v2: Typo fixes from Joe & Jonathan.
stdlib/cxa_finalize.c | 17 ++++++++++++++++-
1 file changed, 16 insertions(+), 1 deletion(-)
diff --git a/stdlib/cxa_finalize.c b/stdlib/cxa_finalize.c
index 258fa56ce5..496141d802 100644
--- a/stdlib/cxa_finalize.c
+++ b/stdlib/cxa_finalize.c
@@ -24,7 +24,22 @@
/* If D is non-NULL, call all functions registered with `__cxa_atexit'
with the same dso handle. Otherwise, if D is NULL, call all of the
- registered handlers. */
+ registered handlers.
+
+ A __cxa_finalize function is declared in the libstdc++ <cxxabi.h>
+ header, and the libstdc++ implementation calls this function. GCC
+ calls the glibc variant directly from its CRT files, from an ELF
+ destructor. this call always passes a non-null D argument. In the
+ current implementation, the GCC-provided __cxa_finalize call is
+ responsible for removing the registered __cxa_atexit (C++)
+ destructors of an object that is undergoing dlclose. Note that
+ this is specific to dlclose. During process termination, glibc
+ invokes the __run_exit_handlers, which calls registered
+ __cxa_atexit (C++) destructors in reverse registration order,
+ across all objects. The subsequent GCC-provided __cxa_finalize
+ calls (which are ordered according to ELF object dependencies, not
+ __cxa_atexit call order, and group destructor calls per object
+ during dlclose) do not result in further destructor invocations. */
void
__cxa_finalize (void *d)
{
base-commit: 46b5e98ef6f1b9f4b53851f152ecb8209064b26c
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