From e325a5b67453fd8cfe06d3d0d6c7c5ab7e4ad772 Mon Sep 17 00:00:00 2001 From: Volker Lendecke Date: Fri, 24 Sep 2010 19:20:06 +0200 Subject: talloc: Add a warning about talloc_autofree_context() and dlclose() --- lib/talloc/talloc.h | 9 +++++++++ lib/talloc/talloc_guide.txt | 13 +++++++++++++ 2 files changed, 22 insertions(+) (limited to 'lib') diff --git a/lib/talloc/talloc.h b/lib/talloc/talloc.h index 187d7e7816..8b9ade202e 100644 --- a/lib/talloc/talloc.h +++ b/lib/talloc/talloc.h @@ -972,6 +972,15 @@ int talloc_unlink(const void *context, void *ptr); * which will be automatically freed on program exit. This can be used * to reduce the noise in memory leak reports. * + * Never use this in code that might be used in objects loaded with + * dlopen and unloaded with dlclose. talloc_autofree_context() + * internally uses atexit(3). Some platforms like modern Linux handles + * this fine, but for example FreeBSD does not deal well with dlopen() + * and atexit() used simultaneously: dlclose() does not clean up the + * list of atexit-handlers, so when the program exits the code that + * was registered from within talloc_autofree_context() is gone, the + * program crashes at exit. + * * @return A talloc context, NULL on error. */ void *talloc_autofree_context(void); diff --git a/lib/talloc/talloc_guide.txt b/lib/talloc/talloc_guide.txt index a79fd03a83..f29b1d699a 100644 --- a/lib/talloc/talloc_guide.txt +++ b/lib/talloc/talloc_guide.txt @@ -74,6 +74,19 @@ without proper synchronization ; shouldn't be used by several threads simultaneously without synchronization. +talloc and shared objects +------------------------- + +talloc can be used in shared objects. Special care needs to be taken +to never use talloc_autofree_context() in code that might be loaded +with dlopen() and unloaded with dlclose(), as talloc_autofree_context() +internally uses atexit(3). Some platforms like modern Linux handles +this fine, but for example FreeBSD does not deal well with dlopen() +and atexit() used simultaneously: dlclose() does not clean up the list +of atexit-handlers, so when the program exits the code that was +registered from within talloc_autofree_context() is gone, the program +crashes at exit. + =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=- (type *)talloc(const void *context, type); -- cgit