Change ld.so to correctly load dependant libraries for dlopen and unload them

on dlclose.  Also correctly call constructors and destructors for libraries
linked with /usr/lib/c++rt0.o.
Change interpretation of dlopen manpage to call _init() rather than init()
for dlopened objects.
Change c++rt0.o to avoid using atexit to call destructors, allowing dlclose to
call destructors when an object is unloaded.
Change interface between crt0 and ld.so to allow crt0 to call a function on
exit to call destructors for shared libraries explicitly.

These changes are backwards compatible.  Old binaries will work with the new
ld.so and new binaries will work with the old ld.so.  A version number has
been introduced in the crt0-ld.so interface to allow for future changes.

Reviewed by:	GAWollman, Craig Struble <cstruble@singularity.bevc.blacksburg.va.us>

1 files changed, 234 insertions, 66 deletions

diff --git a/libexec/rtld-aout/rtld.c b/libexec/rtld-aout/rtld.c
index e0547af..dbbae89 100644
--- a/libexec/rtld-aout/rtld.c
+++ b/libexec/rtld-aout/rtld.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: rtld.c,v 1.23 1995/04/21 04:57:50 nate Exp $
+ *	$Id: rtld.c,v 1.24 1995/05/30 05:01:49 rgrimes Exp $
  */
 
 #include <sys/param.h>
@@ -83,6 +83,7 @@ struct somap_private {
 #define RTLD_MAIN	1
 #define RTLD_RTLD	2
 #define RTLD_DL		4
+#define RTLD_INIT	8
 	unsigned long	a_text;    /* text size, if known     */
 	unsigned long	a_data;    /* initialized data size   */
 	unsigned long	a_bss;     /* uninitialized data size */
@@ -159,9 +160,10 @@ static void		*__dlopen __P((char *, int));
 static int		__dlclose __P((void *));
 static void		*__dlsym __P((void *, char *));
 static char		*__dlerror __P((void));
+static void		__dlexit __P((void));
 
 static struct ld_entry	ld_entry = {
-	__dlopen, __dlclose, __dlsym, __dlerror
+	__dlopen, __dlclose, __dlsym, __dlerror, __dlexit
 };
 
        void		xprintf __P((char *, ...));
@@ -169,6 +171,9 @@ static void		load_objects __P((	struct crt_ldso *,
 						struct _dynamic *));
 static struct so_map	*map_object __P((struct sod *, struct so_map *));
 static int		unmap_object __P((struct so_map	*));
+static struct so_map	*load_object __P((struct sod *, struct so_map *,
+					  int, int));
+static int		unload_object __P((struct so_map	*));
 static struct so_map	*alloc_link_map __P((	char *, struct sod *,
 						struct so_map *, caddr_t,
 						struct _dynamic *));
@@ -177,7 +182,8 @@ static inline int	check_text_reloc __P((	struct relocation_info *,
 						caddr_t));
 static int		reloc_map __P((struct so_map *));
 static void		reloc_copy __P((struct so_map *));
-static void		init_map __P((struct so_map *, char *));
+static void		init_map __P((struct so_map *, char *, int));
+static void		call_map __P((struct so_map *, char *));
 static char		*rtfindlib __P((char *, int, int, int *));
 void			binder_entry __P((void));
 long			binder __P((jmpslot_t *));
@@ -289,7 +295,7 @@ struct _dynamic		*dp;
 	for (smp = link_map_head; smp; smp = smp->som_next) {
 		if (LM_PRIVATE(smp)->spd_flags & RTLD_RTLD)
 			continue;
-		init_map(smp, ".init");
+		init_map(smp, ".init", 0);
 	}
 
 	/* Fill in some field in main's __DYNAMIC structure */
@@ -323,7 +329,7 @@ struct _dynamic		*dp;
 	/* Close our file descriptor */
 	(void)close(crtp->crt_ldfd);
 	anon_close();
-	return 0;
+	return LDSO_VERSION_HAS_DLEXIT;
 }
 
 
@@ -459,6 +465,42 @@ alloc_link_map(path, sodp, parent, addr, dp)
 	return smp;
 }
 
+	static struct so_map *
+find_object(sodp, smp)
+	struct sod	*sodp;
+	struct so_map	*smp;
+{
+	char		*path, *name = (char *)(sodp->sod_name + LM_LDBASE(smp));
+	int		usehints = 0;
+	struct so_map	*p;
+
+	if (sodp->sod_library) {
+		usehints = 1;
+again:
+		path = rtfindlib(name, sodp->sod_major,
+				 sodp->sod_minor, &usehints);
+		if (path == NULL) {
+			generror ("Can't find shared library \"%s\"",
+				  name);
+			return NULL;
+		}
+	} else {
+		if (careful && *name != '/') {
+			generror ("Shared library path must start with \"/\" for \"%s\"",
+				  name);
+			return NULL;
+		}
+		path = name;
+	}
+
+	/* Check if already loaded */
+	for (p = link_map_head; p; p = p->som_next)
+		if (p->som_path && strcmp(p->som_path, path) == 0)
+			break;
+
+	return p;
+}
+
 /*
  * Map object identified by link object LOP which was found
  * in link map LMP.
@@ -612,8 +654,7 @@ unmap_object(smp)
 			return -1;
                     }
         }
-	free((caddr_t) smp->som_sod->sod_name);
-	free(smp->som_sod);
+	if (smp->som_path) free(smp->som_path);
 	free(smp);
         return 0;
 }
@@ -763,7 +804,42 @@ reloc_copy(smp)
 }
 
 static void
-init_map(smp, sym)
+init_map(smp, sym, dependants)
+	struct so_map		*smp;
+	char			*sym;
+	int			dependants;
+{
+	struct so_map		*src_map = smp;
+	struct nzlist		*np;
+
+	if (LM_PRIVATE(smp)->spd_flags & RTLD_INIT)
+	    	return;
+
+	LM_PRIVATE(smp)->spd_flags |= RTLD_INIT;
+
+	if (dependants) {
+	    struct sod	*sodp;
+	    struct so_map	*smp2;
+	    long		next;
+
+	    next = LD_NEED(smp->som_dynamic);
+
+	    while (next) {
+		sodp = (struct sod *)(LM_LDBASE(smp) + next);
+		smp2 = find_object(sodp, smp);
+		if (smp2)
+		    init_map(smp2, sym, dependants);
+		next = sodp->sod_next;
+	    }
+	}
+
+	np = lookup(sym, &src_map, 1);
+	if (np)
+		(*(void (*)())(src_map->som_addr + np->nz_value))();
+}
+
+static void
+call_map(smp, sym)
 	struct so_map		*smp;
 	char			*sym;
 {
@@ -776,6 +852,119 @@ init_map(smp, sym)
 }
 
 /*
+ * Load an object with all its dependant objects, recording the type of the
+ * object and optionally calling its init function.
+ */
+static struct so_map *
+load_object(sodp, parent, type, init)
+    struct sod	*sodp;
+    struct so_map	*parent;
+    int		type;
+    int		init;
+{
+    struct so_map* smp;
+
+    /*
+     * Find or map the object.
+     */
+    smp = map_object(sodp, parent);
+    if (smp == NULL) return NULL;
+
+    /*
+     * The first time the object is mapped, load it's dependant objects and
+     * relocate it.
+     */
+    if (LM_PRIVATE(smp)->spd_refcount++ == 0) {
+	struct sod	*sodp;
+	struct so_map	*smp2;
+	long		next;
+
+	next = LD_NEED(smp->som_dynamic);
+
+	/*
+	 * Load dependant objects but defer initialisation until later.
+	 * When all the dependants (and sub dependants, etc.) have been
+	 * loaded and relocated, it is safe to call the init functions,
+	 * using a recursive call to init_map.  This ensures that if init
+	 * code in the dependants calls code in the parent, it will work
+	 * as expected.
+	 */
+	while (next) {
+	    sodp = (struct sod *)(LM_LDBASE(smp) + next);
+	    /*
+	     * Dependant objects (of both dlopen and main) don't get a
+	     * specific type.
+	     */
+	    if ((smp2 = load_object(sodp, smp, 0, 0)) == NULL) {
+#ifdef DEBUG
+xprintf("ld.so: map_object failed on cascaded %s %s (%d.%d): %s\n",
+	smp->sod_library ? "library" : "file", smp->sod_name,
+	smp->sod_major, smp->sod_minor, strerror(errno));
+#endif
+		unload_object(smp);
+		return NULL;
+	    }
+	    next = sodp->sod_next;
+	}
+
+	LM_PRIVATE(smp)->spd_flags |= type;
+	if (reloc_map(smp) < 0) {
+	    unload_object(smp);
+	    return NULL;
+	}
+	reloc_copy(smp);
+	if (init) {
+	    init_map(smp, ".init", 1);
+	}
+    }
+
+    return smp;
+}
+
+/*
+ * Unload an object, recursively unloading dependant objects.
+ */
+static int
+unload_object(smp)
+    struct so_map *smp;
+{
+    struct so_map 	*smp2;
+    struct sod		*sodp;
+    long		next;
+
+    if (--LM_PRIVATE(smp)->spd_refcount != 0)
+	return -1;
+
+    /*
+     * Call destructors for the object (before unloading its dependants
+     * since destructors may use them.  Only call destructors if constructors
+     * have been called.
+     */
+    if (LM_PRIVATE(smp)->spd_flags & RTLD_INIT)
+	call_map(smp, ".fini");
+
+    /*
+     * Unmap any dependant objects first.
+     */
+    next = LD_NEED(smp->som_dynamic);
+    while (next) {
+	sodp = (struct sod *)(LM_LDBASE(smp) + next);
+	smp2 = find_object(sodp, smp);
+	if (smp2)
+	    unload_object(smp2);
+	next = sodp->sod_next;
+    }
+
+    /*
+     * Remove from address space.
+     */
+    if (unmap_object(smp) < 0)
+	return -1;
+
+    return 0;
+}
+
+/*
  * Run-time common symbol table.
  */
 
@@ -1262,6 +1451,7 @@ static struct so_map dlmap = {
 static char  dlerror_buf [DLERROR_BUF_SIZE];
 static char *dlerror_msg = NULL;
 
+
 	static void *
 __dlopen(name, mode)
 	char	*name;
@@ -1286,24 +1476,19 @@ __dlopen(name, mode)
 	sodp->sod_library = 0;
 	sodp->sod_major = sodp->sod_minor = 0;
 
-	if ((smp = map_object(sodp, &dlmap)) == NULL) {
+	if ((smp = load_object(sodp, &dlmap, RTLD_DL, 1)) == NULL) {
 #ifdef DEBUG
 		xprintf("%s: %s\n", name, dlerror_buf);
 #endif
 		return NULL;
 	}
 
-	if (dl_cascade(smp) == 0)
-		return NULL;
-
-	if (LM_PRIVATE(smp)->spd_refcount++ == 0) {
-		LM_PRIVATE(smp)->spd_flags |= RTLD_DL;
-		if (reloc_map(smp) < 0)
-			return NULL;
-		reloc_copy(smp);
-		init_map(smp, ".init");
-		init_map(smp, "_init");
-	}
+	/*
+	 * If this was newly loaded, call the _init() function in the 
+	 * object as per manpage.
+	 */
+	if (LM_PRIVATE(smp)->spd_refcount == 1)
+	    call_map(smp, "__init");
 
 	return smp;
 }
@@ -1318,13 +1503,25 @@ __dlclose(fd)
         xprintf("dlclose(%s): refcount = %d\n", smp->som_path,
                 LM_PRIVATE(smp)->spd_refcount);
 #endif
-	if (--LM_PRIVATE(smp)->spd_refcount != 0)
-		return 0;
 
-	/* Dismantle shared object map and descriptor */
-	init_map(smp, "_fini");
+	if (smp == NULL) {
+	    generror("NULL argument to dlclose");
+	    return -1;
+	}
+
+	if (LM_PRIVATE(smp)->spd_refcount > 1) {
+	    LM_PRIVATE(smp)->spd_refcount--;
+	    return 0;
+	}
+
+	/*
+	 * Call the function _fini() in the object as per manpage.
+	 */
+	call_map(smp, "__fini");
 
-        if (unmap_object(smp) < 0)
+	free((void*) smp->som_sod->sod_name);
+	free(smp->som_sod);
+        if (unload_object(smp) < 0)
 		return -1;
 
 	return 0;
@@ -1369,6 +1566,18 @@ __dlerror __P((void))
         return err;
 }
 
+	static void
+__dlexit __P((void))
+{
+	struct so_map *smp;
+
+	for (smp = link_map_head; smp; smp = smp->som_next) {
+		if (LM_PRIVATE(smp)->spd_flags & (RTLD_RTLD|RTLD_MAIN))
+			continue;
+		call_map(smp, ".fini");
+	}
+}
+
 /*
  * Generate an error message that can be later be retrieved via dlerror.
  */
@@ -1413,44 +1622,3 @@ char	*fmt;
 	va_end(ap);
 }
 
-static int
-dl_cascade(smp)
-	struct so_map	*smp;
-{
-	struct sod	*sodp;
-	struct so_map	*smp2;
-	long		next;
-
-	next = LD_NEED(smp->som_dynamic);
-
-	while (next) {
-		sodp = (struct sod *)(LM_LDBASE(smp) + next);
-		if ((smp2 = map_object(sodp, smp)) == NULL) {
-#ifdef DEBUG
-xprintf("ld.so: map_object failed on cascaded %s %s (%d.%d): %s\n",
-	smp->sod_library ? "library" : "file", smp->sod_name,
-	smp->sod_major, smp->sod_minor, strerror(errno));
-#endif
-			return 0;
-		}
-#if 0
-		/*
-		 * XXX - this doesn't work for some reason.  not
-		 * at all sure why.  -mrg
-		 */
-		if (dl_cascade(smp2) == 0)
-			return 0;
-#endif
-
-		if (LM_PRIVATE(smp2)->spd_refcount++ == 0) {
-			LM_PRIVATE(smp2)->spd_flags |= RTLD_DL;
-			reloc_map(smp2);
-			reloc_copy(smp2);
-			init_map(smp2, ".init");
-			init_map(smp2, "_init");
-		}
-
-		next = sodp->sod_next;
-	}
-	return 1;
-}