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Re: Undefined reference to atexit (FAQ).


On Thu, 25 Oct 2001, Tiago de Paula Peixoto uttered the following:
> gcc -o test     test.c  -lssl -lcrypto 
> /lib/libdl.so.2: undefined reference to `atexit'
> collect2: ld returned 1 exit status
> 
> I know this is a FAQ and all, but libc_nonshared.a is in the right place
> and I don't know why the linker isn't getting to it. 
> 
> /usr/lib/libc.so reads:
> 
> /* GNU ld script
>    Use the shared library, but some functions are only in
>    the static library, so try that secondarily.  */
> GROUP ( /lib/libc.so.6 /usr/lib/libc_nonshared.a )
> 
> I'm using glibc-2.2.4, compiled with gcc-2.95.3.

Recompile glibc with gcc-2.94pre from CVS with this patch applied to
GCC, and a recent binutils, and it should work properly. (Unless you
have an alpha; the non-buggy-on-alpha version was posted on the
libc-alpha mailing list shortly after this one, but I foolishly didn't
grab it.)

--- gcc-2.95.x/gcc/config/alpha/crtbegin.asm.jj     Wed Dec 16 22:00:53 1998
+++ gcc-2.95.x/gcc/config/alpha/crtbegin.asm        Wed Jun 13 12:41:28 2001
@@ -97,6 +97,31 @@ __EH_FRAME_BEGIN__:
  # Support recursive calls to exit.
 $ptr:  .quad   __DTOR_LIST__

+/* A globally unique widget for c++ local destructors to hang off.
+
+   This has a unique value in every dso; in the main program its
+   value is zero.  The object should be protected.  This means the
+   instance in any dso or the main program is not used in any other
+   dso.  The dynamic linker takes care of this.  */
+
+       .global __dso_handle
+       .type __dso_handle,@object
+       .size __dso_handle,8
+#ifdef SHARED
+.section .data
+       .align 3
+__dso_handle:
+       .quad   __dso_handle
+#else
+.section .bss
+       .align 3
+__dso_handle:
+       .zero 8
+#endif
+#ifdef HAVE_GAS_HIDDEN
+       .hidden __dso_handle
+#endif
+
 .text

        .align 3
============================================================
Index: gcc/crtstuff.c
--- gcc-2.95.x/gcc/crtstuff.c	2001/04/03 10:34:32	1.18.4.1
+++ gcc-2.95.x/gcc/crtstuff.c	2001/08/09 06:56:33
@@ -55,6 +55,7 @@ Boston, MA 02111-1307, USA.  */
 #include "defaults.h"
 #include <stddef.h>
 #include "frame.h"
+#include "auto-host.h"
 
 /* We do not want to add the weak attribute to the declarations of these
    routines in frame.h because that will cause the definition of these
@@ -134,7 +135,29 @@ typedef void (*func_ptr) (void);
 #ifdef INIT_SECTION_ASM_OP
 
 #ifdef OBJECT_FORMAT_ELF
+/* Declare the __dso_handle variable.  It should have a unique value
+   in every shared-object; in a main program its value is zero.  The
+   object should in any case be protected.  This means the instance
+   in one DSO or the main program is not used in another object.  The
+   dynamic linker takes care of this.  */
+
+/* XXX Ideally the following should be implemented using
+   __attribute__ ((__visibility__ ("hidden")))
+   but the __attribute__ support is not yet there.  */
+#ifdef HAVE_GAS_HIDDEN
+asm (".hidden\t__dso_handle");
+#endif
+
+#ifdef CRTSTUFFS_O
+void *__dso_handle = &__dso_handle;
+#else
+void *__dso_handle = 0;
+#endif
 
+/* The __cxa_finalize function may not be available so we use only a
+   weak declaration.  */
+extern void __cxa_finalize (void *) TARGET_ATTRIBUTE_WEAK;
+
 /* Run all the global destructors on exit from the program.  */
  
 /* Some systems place the number of pointers in the first word of the
@@ -164,6 +187,11 @@ __do_global_dtors_aux (void)
 
   if (completed)
     return;
+
+#ifdef CRTSTUFFS_O
+  if (__cxa_finalize)
+    __cxa_finalize (__dso_handle);
+#endif
 
   while (*p)
     {
--- gcc-2.95.x/gcc/configure.in.jj  Wed Oct 13 09:58:02 1999
+++ gcc-2.95.x/gcc/configure.in     Wed Jun 13 12:44:34 2001
@@ -4053,6 +4053,21 @@ EOF
 fi
 AC_MSG_RESULT($gcc_cv_as_subsections)

+AC_MSG_CHECKING(assembler hidden support)
+gcc_cv_as_hidden=
+if test x$gcc_cv_as != x; then
+       # Check if we have .hidden
+       echo "  .hidden foobar" > conftest.s
+       echo "foobar:" >> conftest.s
+       if $gcc_cv_as -o conftest.o conftest.s > /dev/null 2>&1; then
+               AC_DEFINE(HAVE_GAS_HIDDEN, 1,
+                       [Define if your assembler supports .hidden.])
+               gcc_cv_as_hidden="yes"
+       fi
+       rm -f conftest.s conftest.o conftest.nm1 conftest.nm2
+fi
+AC_MSG_RESULT($gcc_cv_as_hidden)
+
 AC_MSG_CHECKING(assembler instructions)
 gcc_cv_as_instructions=
 if test x$gcc_cv_as != x; then
--- gcc-2.95.x/gcc/config.in.jj     Mon Oct 25 10:02:08 1999
+++ gcc-2.95.x/gcc/config.in        Wed Jun 13 12:45:56 2001
2 the beginning of your section */
 #undef HAVE_GAS_SUBSECTION_ORDERING

+/* Define if your assembler supports .hidden. */
+#undef HAVE_GAS_HIDDEN
+
 /* Define if your assembler uses the old HImode fild and fist notation.  */
 #undef HAVE_GAS_FILDS_FISTS


-- 
`You're the only person I know who can't tell the difference
 between a pair of trousers and a desk.' --- Kieran, to me


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