a.out ld.so fix for constructor order

Found this while compiling kde 3.1.
kpovmodeler works statically, but not dynamically.

Looking at the link graph,
kpovmodeler is linked against libkpovmodelerpart and libqt-mt and libkpovmodelerpart is linked against libqt-mt

The issue is that the linker resolves ctors sequentially, so libqt-mt ctors are called after libkpovmodelerpart... and some libkpovmodelerpart ctors are dependent on libqt-mt being initialized already.

Logically, ctors for a dependent library should be called *before* ctors for the library itself.

The following patch allows ld.so to build a full dependency tree of libraries it loads, and to resolve constructors in a better order: dependent libraries first, in sequential order, and then main library (there is a flag that forbids initializing a library twice).

I'm now running with this. Please test and comment.

Note: there is a possibility that this is the bug that cripples dynamic builds of mozilla, though I haven't checked yet...

Index: rtld.c

--- rtld.c	5 Jan 2003 09:04:10 -0000	1.33
+++ rtld.c	15 Jan 2003 18:31:55 -0000
@@ -97,11 +97,19 @@ struct somap_private {
 #define RTLD_MAIN	1
 #define RTLD_RTLD	2
 #define RTLD_DL		4
+#define RTLD_INITED	8
 	size_t		spd_size;
 
 #ifdef SUN_COMPAT
 	long		spd_offset;	/* Correction for Sun main programs */
 #endif


+	struct dep_node	*first_child;


+	struct dep_node	*last_child;


+};
+
+struct dep_node {


+	struct dep_node *next_sibling;


+	struct so_map *data;

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 #define LM_PRIVATE(smp) ((struct somap_private *)(smp)->som_spd) @@ -358,6 +366,23 @@ rtld(int version, struct crt_ldso *crtp,

         return 0;
 }  

+static void
+link_sub(struct so_map *dep, struct so_map *p)
+{


+	struct dep_node *n;


+	struct somap_private *pp;


+

+	n = xmalloc(sizeof *n);

+	n->data = dep;

+	n->next_sibling = NULL;

+	pp = LM_PRIVATE(p);

+	if (pp->first_child) {

+		pp->last_child->next_sibling = n;

+		pp->last_child = n;

+	} else {

+		pp->first_child = pp->last_child = n;

+	}

+}
 
 static int
 load_subs(struct so_map	*smp)
@@ -380,16 +405,35 @@ load_subs(struct so_map	*smp)
 
 			if ((newmap = map_object(sodp, smp)) == NULL) {
 				if (!ld_tracing) {
-					char *fmt = sodp->sod_library ?
-						"%s: lib%s.so.%d.%d" :
-						"%s: %s";
-					err(1, fmt, main_progname,

+				    if (smp != main_map)

+					if (sodp->sod_library)

+					    err(1, "%s(%s): lib%s.so.%d.%d",

+						main_progname,

+						smp->som_path,

+						sodp->sod_name+LM_LDBASE(smp),

+						sodp->sod_major,

+						sodp->sod_minor);

+					else

+					    err(1, "%s(%s): %s",

+						main_progname,

+						smp->som_path,

+						sodp->sod_name+LM_LDBASE(smp));

+				    else

+					if (sodp->sod_library)

+					    err(1, "%s: lib%s.so.%d.%d",


+						main_progname,


 						sodp->sod_name+LM_LDBASE(smp),
 						sodp->sod_major,
 						sodp->sod_minor);

+					else

+					    err(1, "%s: %s",

+						main_progname,


+						sodp->sod_name+LM_LDBASE(smp));


 				}
 				newmap = alloc_link_map(NULL, sodp, smp,
 				    0, 0, 0);


+			} else {


+				link_sub(newmap, smp);


 			}
 			LM_PRIVATE(newmap)->spd_refcount++;
 			next = sodp->sod_next;
@@ -511,6 +555,8 @@ alloc_link_map(char *path, struct sod *s
 	smpp->spd_flags = 0;
 	smpp->spd_parent = parent;
 	smpp->spd_size = size;


+	smpp->first_child = NULL;


+	smpp->last_child = NULL;


 
 #ifdef SUN_COMPAT
 	smpp->spd_offset =
@@ -690,6 +736,23 @@ unmap_object(struct so_map *smp)
 	(void)munmap(smp->som_addr, LM_PRIVATE(smp)->spd_size);

+void init_dependent_before_main(struct so_map *smp)
+{


+	struct dep_node *n;


+


+	LM_PRIVATE(smp)->spd_flags |= RTLD_INITED;


+

+	for (n = LM_PRIVATE(smp)->first_child; n; n = n->next_sibling) {

+		if (LM_PRIVATE(n->data)->spd_flags & RTLD_INITED)

+			continue;

+		init_dependent_before_main(n->data);
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+	}

+

+	call_map(smp, ".init");

+	call_map(smp, "__init");


+	call_map(smp, "__GLOBAL__DI");


+}
+
 void
 init_maps(struct so_map *head)
 {
@@ -713,9 +776,9 @@ init_maps(struct so_map *head)
 	for (smp = head; smp; smp = smp->som_next) {
 		if (LM_PRIVATE(smp)->spd_flags & RTLD_RTLD)
 			continue;
-		call_map(smp, ".init");
-		call_map(smp, "__init");
-		call_map(smp, "__GLOBAL__DI");

+		if (LM_PRIVATE(smp)->spd_flags & RTLD_INITED)

+			continue;


+		init_dependent_before_main(smp);


 	}