Add extra argument to substitute_hook_functions and interpose_imports for use with unhooking.

I think we'll need to explicitly record trampoline locations to avoid
the possibility of stomping on someone else's stuff if the function was
re-patched...

Also, document substitute_hook_functions.

2 files changed, 7 insertions, 2 deletions

diff --git a/lib/darwin/interpose.c b/lib/darwin/interpose.c
index dd267ac..c74f747 100644
--- a/lib/darwin/interpose.c
+++ b/lib/darwin/interpose.c
@@ -147,12 +147,17 @@ static void *off_to_addr(const struct interpose_state *st, uint32_t off) {
 EXPORT
 int substitute_interpose_imports(const struct substitute_image *image,
                                  const struct substitute_import_hook *hooks,
-                                 size_t nhooks, int options) {
+                                 size_t nhooks,
+                                 struct substitute_import_hook_record **recordp,
+                                 int options) {
     int ret = SUBSTITUTE_OK;
 
     if (options != 0)
         substitute_panic("%s: unrecognized options\n", __func__);
 
+    if (recordp)
+        *recordp = NULL;
+
     struct interpose_state st;
     st.slide = image->slide;
     st.nsegments = 0;
diff --git a/lib/darwin/substrate-compat.c b/lib/darwin/substrate-compat.c
index 3515e44..bb68366 100644
--- a/lib/darwin/substrate-compat.c
+++ b/lib/darwin/substrate-compat.c
@@ -43,7 +43,7 @@ EXPORT
 void SubHookFunction(void *symbol, void *replace, void **result) __asm__("SubHookFunction");
 void SubHookFunction(void *symbol, void *replace, void **result) {
     struct substitute_function_hook hook = {symbol, replace, result};
-    int ret = substitute_hook_functions(&hook, 1, SUBSTITUTE_NO_THREAD_SAFETY);
+    int ret = substitute_hook_functions(&hook, 1, NULL, SUBSTITUTE_NO_THREAD_SAFETY);
     if (ret) {
         substitute_panic("SubHookFunction: substitute_hook_functions returned %s\n",
                          substitute_strerror(ret));