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Since I got no objections to this patch, and no one has offered any

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alternative, I present .. ta! da! .. the __error() hack.

This patch to the a.out dynamic loader provides old a.out binaries
with __error() if they are linked with an older libc that lacks it,
but are also linked against a library that needs it.

There is a smaller, tricker hack that takes advantage of the fact
that ld.so has __error() too, courtesy of the new libc, but this
hack is the straightforward version.
This commit is contained in:
Stephen McKay 1998-06-21 14:22:29 +00:00
parent 3006f10bdb
commit 1188f66af7
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=37092
1 changed files with 70 additions and 1 deletions
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71
libexec/rtld-aout/rtld.c
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@ -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: rtld.c,v 1.53 1998/05/26 20:12:51 sos Exp $
* $Id: rtld.c,v 1.54 1998/06/07 03:53:06 brian Exp $
*/
#include <sys/param.h>
@ -252,6 +252,7 @@ static struct nzlist *lookup_in_obj __P((char *, unsigned long,
static struct rt_symbol *enter_rts __P((char *, unsigned long, long, int,
caddr_t, long, struct so_map *));
static void *sym_addr __P((char *));
static struct nzlist * lookup_errno_hack(char *, struct so_map **, int);
static void die __P((void));
static void generror __P((char *, ...));
static int maphints __P((void));
@ -1502,6 +1503,13 @@ lookup(name, src_map, real_def_only)
return rtsp->rt_sp;
}
/*
* Just before giving up, check for the __error() hack.
*/
np = lookup_errno_hack(name, src_map, real_def_only);
if (np != NULL)
return np;
/* No definition was found for the symbol. */
return NULL;
}
@ -1596,6 +1604,67 @@ sym_addr(name)
return ((smp == NULL) ? NULL : smp->som_addr) + np->nz_value;
}
/*
* Help old a.out binaries that are broken by the new errno macro. They
* can be missing __error() through no fault of their own. In particular,
* old a.out binaries can link against an old libc that does not contain
* __error(), yet still require __error() because of other libraries that
* have been recompiled since the errno change. This locates the backward
* compatible work-alike we have hidden here in ld.so.
*/
static struct nzlist *
lookup_errno_hack(sym, src_map, real_def_only)
char *sym;
struct so_map **src_map;
int real_def_only;
{
struct so_map *smp;
struct nzlist *np;
if (strcmp(sym, "___error") != 0)
return NULL;
/*
* Specifically find the ld.so link map because most routines
* skip over it during normal operation.
*/
for (smp = link_map_head; ; smp = smp->som_next)
if (LM_PRIVATE(smp)->spd_flags & RTLD_RTLD)
break;
/*
* Actually, ld.so uses errno via the new macro, so it has a copy
* of __error() lying around. The really neat but obscure hack
* is to just use that one, but to be really clear about what
* is going on, we use an explicit __error() substitute.
*/
np = lookup("___error_unthreaded_hack", &smp, real_def_only);
if (np != NULL)
*src_map = smp;
#ifdef DEBUG
if (np == NULL)
xprintf(" HACK: %s fudge not found, oops\n", sym);
else
xprintf(" HACK: %s fudge in %s\n", sym, smp->som_path);
#endif
return np;
}
/*
* Just like __error_unthreaded(), but for those poor orphaned a.out
* binaries from way back that are bamboozled by the new errno macro.
*/
int *
__error_unthreaded_hack()
{
return &errno;
}
/*
* This routine is called from the jumptable to resolve
* procedure calls to shared objects.