Fix the parsing of the .fini_array in the dynamic linker (it should happen in reverse order).
Also add a small design overview document for the linker. The latter contains details on
how the initialization/finalization is supposed to work.
diff --git a/linker/linker.c b/linker/linker.c
index bb3b8e7..5180ae0 100644
--- a/linker/linker.c
+++ b/linker/linker.c
@@ -1248,13 +1248,38 @@
return 0;
}
-static void call_array(unsigned *ctor, int count)
+
+/* Please read the "Initialization and Termination functions" functions.
+ * of the linker design note in bionic/linker/README.TXT to understand
+ * what the following code is doing.
+ *
+ * The important things to remember are:
+ *
+ * DT_PREINIT_ARRAY must be called first for executables, and should
+ * not appear in shared libraries.
+ *
+ * DT_INIT should be called before DT_INIT_ARRAY if both are present
+ *
+ * DT_FINI should be called after DT_FINI_ARRAY if both are present
+ *
+ * DT_FINI_ARRAY must be parsed in reverse order.
+ */
+
+static void call_array(unsigned *ctor, int count, int reverse)
{
- int n;
- for(n = count; n > 0; n--){
- TRACE("[ %5d Looking at ctor *0x%08x == 0x%08x ]\n", pid,
+ int n, inc = 1;
+
+ if (reverse) {
+ ctor += (count-1);
+ inc = -1;
+ }
+
+ for(n = count; n > 0; n--) {
+ TRACE("[ %5d Looking at %s *0x%08x == 0x%08x ]\n", pid,
+ reverse ? "dtor" : "ctor",
(unsigned)ctor, (unsigned)*ctor);
- void (*func)() = (void (*)()) *ctor++;
+ void (*func)() = (void (*)()) *ctor;
+ ctor += inc;
if(((int) func == 0) || ((int) func == -1)) continue;
TRACE("[ %5d Calling func @ 0x%08x ]\n", pid, (unsigned)func);
func();
@@ -1263,17 +1288,11 @@
static void call_constructors(soinfo *si)
{
- /* TODO: THE ORIGINAL CODE SEEMED TO CALL THE INIT FUNCS IN THE WRONG ORDER.
- * Old order: init, init_array, preinit_array..
- * Correct order: preinit_array, init, init_array.
- * Verify WHY.
- */
-
if (si->flags & FLAG_EXE) {
TRACE("[ %5d Calling preinit_array @ 0x%08x [%d] for '%s' ]\n",
pid, (unsigned)si->preinit_array, si->preinit_array_count,
si->name);
- call_array(si->preinit_array, si->preinit_array_count);
+ call_array(si->preinit_array, si->preinit_array_count, 0);
TRACE("[ %5d Done calling preinit_array for '%s' ]\n", pid, si->name);
} else {
if (si->preinit_array) {
@@ -1283,11 +1302,6 @@
}
}
- // If we have an init section, then we should call it now, to make sure
- // that all the funcs in the .ctors section get run.
- // Note: For ARM, we shouldn't have a .ctor section (should be empty)
- // when we have an (pre)init_array section, but let's be compatible with
- // old (non-eabi) binaries and try the _init (DT_INIT) anyway.
if (si->init_func) {
TRACE("[ %5d Calling init_func @ 0x%08x for '%s' ]\n", pid,
(unsigned)si->init_func, si->name);
@@ -1298,25 +1312,21 @@
if (si->init_array) {
TRACE("[ %5d Calling init_array @ 0x%08x [%d] for '%s' ]\n", pid,
(unsigned)si->init_array, si->init_array_count, si->name);
- call_array(si->init_array, si->init_array_count);
+ call_array(si->init_array, si->init_array_count, 0);
TRACE("[ %5d Done calling init_array for '%s' ]\n", pid, si->name);
}
}
+
static void call_destructors(soinfo *si)
{
if (si->fini_array) {
TRACE("[ %5d Calling fini_array @ 0x%08x [%d] for '%s' ]\n", pid,
(unsigned)si->fini_array, si->fini_array_count, si->name);
- call_array(si->fini_array, si->fini_array_count);
+ call_array(si->fini_array, si->fini_array_count, 1);
TRACE("[ %5d Done calling fini_array for '%s' ]\n", pid, si->name);
}
- // If we have an fini section, then we should call it now, to make sure
- // that all the funcs in the .dtors section get run.
- // Note: For ARM, we shouldn't have a .dtor section (should be empty)
- // when we have an fini_array section, but let's be compatible with
- // old (non-eabi) binaries and try the _fini (DT_FINI) anyway.
if (si->fini_func) {
TRACE("[ %5d Calling fini_func @ 0x%08x for '%s' ]\n", pid,
(unsigned)si->fini_func, si->name);