From 887c53ed44b566e7894352da42b60f444b913e7f Mon Sep 17 00:00:00 2001
From: nganhkhoa <mail.nganhkhoa@gmail.com>
Date: Wed, 7 Jun 2023 10:49:59 +0700
Subject: [PATCH] add test for objc

---
 research/custom_loader/a.mm     |  8 ++++++++
 research/custom_loader/b.cc     | 20 ++++++++++++++++----
 research/custom_loader/build.sh | 21 ++++++++++++++++++++-
 3 files changed, 44 insertions(+), 5 deletions(-)
 create mode 100644 research/custom_loader/a.mm

diff --git a/research/custom_loader/a.mm b/research/custom_loader/a.mm
new file mode 100644
index 0000000..029b87e
--- /dev/null
+++ b/research/custom_loader/a.mm
@@ -0,0 +1,8 @@
+#import <Foundation/Foundation.h>
+
+int main(int argc, const char * argv[]) {
+    @autoreleasepool {
+        NSLog(@"Hello, World!");
+    }
+    return 0;
+}
diff --git a/research/custom_loader/b.cc b/research/custom_loader/b.cc
index fd80703..30c7b25 100644
--- a/research/custom_loader/b.cc
+++ b/research/custom_loader/b.cc
@@ -31,7 +31,6 @@ void set_cwd(const char *const *envp) {
   pwd = (char *)(*envp + 4);
   for (; pwd[pwd_len] != 0; pwd_len++)
     ;
-  printf("%s\n", pwd);
 }
 
 const uint32_t magic64 = 0xfeedfacf;
@@ -111,6 +110,7 @@ uint32_t calculate_libname_hash(const libcache *cache, const char *name) {
 // i don't know if dyld_stub_binder should be better
 // because if they are not familiar with dyld
 // they would not suspect dyld_stub_binder inside modern macho
+// Added iOS 6, macOS 10.8
 extern "C" uint32_t dyld_get_sdk_version(const mach_header *mh);
 void exported_from_c();
 
@@ -491,10 +491,17 @@ void bootstrap_libcache_item(struct libcache_item* item, const void* header, con
 }
 
 struct libcache_item* get_libcache_with_name(struct libcache* cache, const char* name) {
+  void* to_find = 0;
+  if (custom_strcmp(name, "main") == 0) {
+    to_find = cache->main;
+  } else if (custom_strcmp(name, "thislib") == 0) {
+    to_find = cache->thislib;
+  }
   uint32_t hash = calculate_libname_hash(cache, name);
   for (int i = 0; i < cache->size; i++) {
     struct libcache_item* cache_lib = &cache->libs[i];
-    if (cache_lib->hash == hash) {
+    // search by hash or by pointer for special case
+    if (cache_lib->hash == hash || cache_lib->header == to_find) {
       return cache_lib;
     }
   }
@@ -545,6 +552,7 @@ void test(struct libcache& cache);
 __attribute__((constructor)) static void
 bruh(int argc, const char *const argv[], const char *const envp[],
      const char *const apple[], const struct ProgramVars *vars) {
+  printf("=== manual symbol bind starts ===\n");
   set_cwd(envp);
 
   // ProgramVars contains pointer to main executable (mapped) file
@@ -572,6 +580,7 @@ bruh(int argc, const char *const argv[], const char *const envp[],
     free(cache.libs[i].segment);
   }
   free(cache.libs);
+  printf("=== manual symbol bind completes ===\n");
 }
 
 void build_cache(struct libcache& cache, void* main) {
@@ -708,7 +717,10 @@ void fix(struct libcache& cache) {
 #include "out/b.h"
   // think of a way to get what binary to fix
   // so we can iterate through them
-  struct libcache_item* libfixing = get_libcache_with_name(&cache, "./out/a");
+  if (nimports == 0) {
+    printf("there is no imports to fix\n");
+  }
+  struct libcache_item* libfixing = get_libcache_with_name(&cache, lib_to_resolve);
   // print_macho_summary(libfixing->header);
   for (int i = 0; i < nimports; i++) {
     struct imported_symbol symbol = imported_table[i];
@@ -742,7 +754,7 @@ void fix(struct libcache& cache) {
            symbol.name, fix_at);
     printf("  from=%s\n", symbol.lib);
     printf("  segment id=%d; offset=0x%llx;", symbol.segment_i, symbol.offset);
-    printf("  resolved=%p\n", resolved);
+    printf("  resolved=%llx(%p)\n", *(uint64_t*)fix_at, resolved);
   }
 
   for (int j = 0; j < npage_rw_fixed; j++) {
diff --git a/research/custom_loader/build.sh b/research/custom_loader/build.sh
index 442bf99..dd4018d 100755
--- a/research/custom_loader/build.sh
+++ b/research/custom_loader/build.sh
@@ -2,7 +2,7 @@
 
 VERSION=${1:-14}
 OUT=./out
-LOGIC=2
+LOGIC=3
 
 mkdir -p $OUT
 
@@ -48,6 +48,25 @@ clang++ -mmacosx-version-min=$VERSION -o $OUT/libb.dylib -shared -Wl,-reexport_l
 
 out/a
 
+elif [[ $LOGIC -eq 3 ]]
+then
+# remove imports test
+
+# libc to test reexport custom lib
+clang++ -mmacosx-version-min=$VERSION -o $OUT/libc.dylib -shared c.cc
+
+# create our dummy lib first
+clang++ -mmacosx-version-min=$VERSION -o $OUT/libb.dylib -shared -Wl,-reexport_library out/libc.dylib dummy.cc
+# build a references libb
+clang -fobjc-arc -ObjC -mmacosx-version-min=$VERSION -o $OUT/a -L"./out" -lb a.mm
+
+# extract symbols from a
+../../macho-go/bin/ios-wrapper remove-imports $OUT/a -o $OUT/a > $OUT/b.h
+# build libb with symbols extracted from a
+clang++ -mmacosx-version-min=$VERSION -o $OUT/libb.dylib -shared -Wl,-reexport_library out/libc.dylib b.cc
+
+out/a
+
 else
 
 # dummy test build