Re: can't catch exceptions from inside dynamically loaded object

["Paul Forgey" <paulf at aphrodite dot com>]

I, too can reproduce this, at least on sparc-sun-solaris2.6, with
egcs-2.91.60

Unlike Shigeru, I am in _desperate_ need of a response, and will probably be
here all night trying to track this down, as this is causing a crisis point
for our project.


-----Original Message-----
From: sgk@happysize.co.jp <sgk@happysize.co.jp>
To: egcs-bugs@cygnus.com <egcs-bugs@cygnus.com>
Date: Wednesday, January 27, 1999 5:13 AM
Subject: can't catch exceptions from inside dynamically loaded object


>I am not sure that this is an egcs bug or not.
>I do not ask you to respond to this email.
>I hope this helps.
>
>Shigeru Kanemoto
>HappySize, Inc.
>
>---------------------------------------------------------
>problem:
>
>I could not catch exceptions (in main executable) thrown from inside
>dynamically loaded shared object (with dlopen()). This happens on
>i586-pc-linux-gnu platform (redhat linux 5.1) with many versions of egcs
>and binutils including one listed below. I have not yet fully tested,
>but it seems that the same problem happens on i586-sun-solaris2.6
>platform (Solaris 2.6 for Intel). However, sparc-sun-solaris2.5.1 and 2.
>6 are good.
>
>platform: i586-pc-linux-gnu (redhat linux 5.1)
>libc version: glibc 2.0.7
>egcs version: 1.1.1
>binutils version: 2.9.1.0.19a
>
>---
>The "static struct object* objects" of "egcs/gcc/frame.c" exists both in
>the main executable and the shared object. On the *bad* platform, each
>EH FRAME of each binary files will be registered to each "static struct
>object* objects" of each binaries. On the *good* platform, all EH FRAME
>will be registered to "static struct object* objects" of the main
>executable.
>
>I think this may be a problem of ld.so or even my command line of
>compiling shared object. But I can not determine.
>
>---
>Example:
>
>With the following code, executing "./a" produces output like:
>    % ./a
>    I am B.
>    Abort (core dumped)
>    %
>on i586-pc-linux-gnu (the "Abort" is by default terminate()).
>And,
>    % ./a
>    I am B.
>    caught int
>    %
>on sparc-sun-solaris2.5.1.
>
>===a.cpp===
>#include <iostream>
>#include <cstdlib>
>#include <dlfcn.h>
>
>main()
>{
>    void *handle = dlopen("./b.so", RTLD_LAZY);
>    void (*thrower)() = (void(*)())dlsym(handle, "thrower");
>    try {
>        (*thrower)();
>    }
>    catch (int&) {
>        cerr << "caught int" << endl;
>        exit(1);
>    }
>    catch (...) {
>        cerr << "caught unknown" << endl;
>        exit(2);
>    }
>    exit(0);
>}
>
>===b.cpp===
>#include <iostream>
>
>extern "C" void
>thrower()
>{
>    cerr << "I am B." << endl;
>    throw int(1);
>}
>
>===Makefile===
>all: a b.so
>a: a.cpp
>        g++ -o a a.cpp -ldl
>b.so : b.cpp
>        g++ -shared -fPIC -o b.so b.cpp
>