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author | jdp <jdp@FreeBSD.org> | 1996-01-15 17:53:25 +0000 |
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committer | jdp <jdp@FreeBSD.org> | 1996-01-15 17:53:25 +0000 |
commit | 83a650d90c7424446b3b768820ba6def8b151593 (patch) | |
tree | aaf9386dd73c53d4496e061a04769e110b4e26b3 /lib/csu | |
parent | ad0d6ac8dbc83a7e965ca6a28eb4ae8e5822cec9 (diff) | |
download | FreeBSD-src-83a650d90c7424446b3b768820ba6def8b151593.zip FreeBSD-src-83a650d90c7424446b3b768820ba6def8b151593.tar.gz |
Check the count in the first word of __CTOR_LIST__ before executing
the loop that invokes the static constructors. That makes it safe
to link c++rt0.o into any shared library, even one that does not
have any static constructors. Formerly, doing that would cause a
bus error. If the library has no static constructors, __CTOR_LIST__
comes out as a simple 4-byte COMMON region, and it does not have
the usual NULL word that terminates the list of constructors. This
caused the old code to "call" a garbage address via the non-existent
entry __CTOR_LIST__[1].
The analogous code that invokes the static destructors was already safe.
This change is fully backward-compatible.
Reviewed by: dfr@render.com (Doug Rabson)
Diffstat (limited to 'lib/csu')
-rw-r--r-- | lib/csu/i386/c++rt0.c | 16 |
1 files changed, 12 insertions, 4 deletions
diff --git a/lib/csu/i386/c++rt0.c b/lib/csu/i386/c++rt0.c index aa28109..40cc5fa 100644 --- a/lib/csu/i386/c++rt0.c +++ b/lib/csu/i386/c++rt0.c @@ -27,7 +27,7 @@ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. * - * $Id: c++rt0.c,v 1.2 1995/05/30 05:39:36 rgrimes Exp $ + * $Id: c++rt0.c,v 1.3 1995/06/27 09:53:24 dfr Exp $ */ /* @@ -54,10 +54,18 @@ __dtors(void) static void __ctors(void) { - void (**p)(void) = __CTOR_LIST__ + 1; + /* + * If the shared library doesn't have any static constructors in it, + * then __CTOR_LIST__ will come out as a simple COMMON region of + * 4 bytes. That is why we have to check the count in the first + * word. + */ + if ((unsigned long) __CTOR_LIST__[0] > 0) { + void (**p)(void) = __CTOR_LIST__ + 1; - while (*p) - (**p++)(); + while (*p) + (**p++)(); + } } extern void __init() asm(".init"); |