added arg check and improved error log

Author: Antibioticss

.clang-format

@@ -1,10 +1,6 @@
----
 # We'll use defaults from the LLVM style, but with 4 columns indentation.
 BasedOnStyle: LLVM
 IndentWidth: 4
----
-Language: Cpp
-# Force pointers to the type for C++.
 ColumnLimit: 120
 AlignConsecutiveMacros: AcrossEmptyLines
 AllowShortFunctionsOnASingleLine: false

.clangd

@@ -13,3 +13,6 @@ Diagnostics:
     Add: [bugprone-*, cert-*, modernize-*, performance-*]
     Remove: [bugprone-easily-swappable-parameters]
     FastCheckFilter: None
+
+Completion:
+  HeaderInsertion: Never

LICENSE

@@ -1,6 +1,6 @@
 MIT License
 
-Copyright (c) 2026 Antibiotics
+Copyright (c) 2024-2026 Antibiotics
 
 Permission is hereby granted, free of charge, to any person obtaining a copy
 of this software and associated documentation files (the "Software"), to deal

README.md

@@ -4,10 +4,10 @@
 
 ## Features
 
- - inline hook
- - symbol interposing
- - symbol resolving
- - objc runtime hook
+- inline hook
+- symbol interposing
+- symbol resolving
+- objc runtime hook
 
 ## Building
 
@@ -22,18 +22,20 @@ make
 ```
 
 Available targets:
- - `static` (default) build static library
- - `shared` build shared library
- - `all` build both static and shared libraries
- - `test` run tinyhook tests
+
+- `static` (default) build static library
+- `shared` build shared library
+- `all` build both static and shared libraries
+- `test` run tinyhook tests
 
 Available variables:
- - `ARCH` the arch to build: `arm64`, `arm64e`, `x86_64`
- - `TARGET` targeting os: `macosx`(default), `iphoneos`
- - `MIN_OSVER` minimum os version requirement
- - `DEBUG` generate debug infomation
- - `COMPACT` no error log output (not recommended!)
- - `NO_EXPORT` hide all symbols (don't use this for dynamic library)
+
+- `ARCH` the arch to build: `arm64`, `arm64e`, `x86_64`
+- `TARGET` targeting os: `macosx`(default), `iphoneos`
+- `MIN_OSVER` minimum os version requirement
+- `DEBUG` generate debug infomation
+- `COMPACT` no error log output (not recommended!)
+- `NO_EXPORT` hide all symbols (don't use this for dynamic library)
 
 For example, building shared library for iOS 18.0+ `arm64e` binary with `DEBUG` enabled
 

src/exhook.c

@@ -11,12 +11,16 @@ static int get_jump_size(const void *src, const void *dst) {
 }
 
 int tiny_hook_ex(th_bak_t *bak, void *function, void *destination, void **origin) {
+    ARG_CHECK(bak != NULL);
+    ARG_CHECK(function != NULL);
+    ARG_CHECK(destination != NULL);
     bak->address = function;
     bak->jump_size = get_jump_size(function, destination);
     read_mem(bak->head_bak, bak->address, bak->jump_size);
     return tiny_hook(function, destination, origin);
 }
 
 int tiny_unhook_ex(const th_bak_t *bak) {
+    ARG_CHECK(bak != 0);
     return write_mem(bak->address, bak->head_bak, bak->jump_size);
 }

src/interpose.c

@@ -11,6 +11,8 @@
 #endif
 
 int tiny_interpose(uint32_t image_index, const char *symbol_name, void *replacement, void **origin) {
+    ARG_CHECK(symbol_name != NULL);
+    ARG_CHECK(replacement != NULL);
     intptr_t image_slide = _dyld_get_image_vmaddr_slide(image_index);
     struct mach_header_64 *mh_header = (struct mach_header_64 *)_dyld_get_image_header(image_index);
     struct load_command *ld_command = (void *)mh_header + sizeof(struct mach_header_64);
@@ -52,7 +54,7 @@ int tiny_interpose(uint32_t image_index, const char *symbol_name, void *replacem
         ld_command = (void *)ld_command + ld_command->cmdsize;
     }
     if (linkedit_cmd == NULL || symtab_cmd == NULL || dysymtab_cmd == NULL) {
-        LOG_ERROR("tiny_interpose: bad mach-o structure!");
+        LOG_ERROR("tiny_interpose: bad mach-o structure for image_index %d!", image_index);
         return 1;
     }
     void *linkedit_base = (void *)image_slide + linkedit_cmd->vmaddr - linkedit_cmd->fileoff;
@@ -80,7 +82,7 @@ int tiny_interpose(uint32_t image_index, const char *symbol_name, void *replacem
                     err = mach_vm_protect(mach_task_self(), (mach_vm_address_t)sym_ptrs, sym_sec->size, FALSE,
                                           VM_PROT_READ | VM_PROT_WRITE | VM_PROT_COPY);
                     if (err != 0) {
-                        LOG_ERROR("mach_vm_protect: %s", mach_error_string(err));
+                        LOG_ERROR("mach_vm_protect failed for address %p: %s", sym_ptrs, mach_error_string(err));
                         break;
                     }
                 }
@@ -93,7 +95,7 @@ int tiny_interpose(uint32_t image_index, const char *symbol_name, void *replacem
 
     if (!found) {
         err = -1;
-        LOG_ERROR("tiny_interpose: no matching indirect symbol found!");
+        LOG_ERROR("tiny_interpose: symbol '%s' not found in image_index %d!", symbol_name, image_index);
     }
     return err;
 }

src/memory.c

@@ -39,35 +39,39 @@ static inline void copy_mem(void *destination, const void *source, size_t len) {
 }
 
 int read_mem(void *destination, const void *source, size_t len) {
+    ARG_CHECK(destination != NULL);
+    ARG_CHECK(source != NULL);
+    ARG_CHECK(len != 0);
     int kr = 0;
     vm_offset_t data;
     mach_msg_type_number_t dataCnt;
-    kr = mach_vm_read(mach_task_self(), (mach_vm_address_t)source, len, &data, &dataCnt);
+    mach_port_t task = mach_task_self();
+    kr = mach_vm_read(task, (mach_vm_address_t)source, len, &data, &dataCnt);
     if (kr != 0) {
-        LOG_ERROR("mach_vm_read: %s", mach_error_string(kr));
+        LOG_ERROR("mach_vm_read failed for address %p: %s", source, mach_error_string(kr));
         return kr;
     }
-    memcpy((void *)destination, (void *)data, dataCnt);
-    kr = mach_vm_deallocate(mach_task_self(), data, dataCnt);
+    memcpy(destination, (void *)data, dataCnt);
+    kr = mach_vm_deallocate(task, data, dataCnt);
     if (kr != 0) {
         LOG_ERROR("mach_vm_deallocate: %s", mach_error_string(kr));
     }
     return kr;
 }
 
 int write_mem(void *destination, const void *source, size_t len) {
-    int kr = 0;
-    kr = mach_vm_protect_trap(mach_task_self(), (mach_vm_address_t)destination, len, FALSE,
-                              VM_PROT_READ | VM_PROT_WRITE | VM_PROT_COPY);
+    ARG_CHECK(destination != NULL);
+    ARG_CHECK(source != NULL);
+    ARG_CHECK(len != 0);
+    mach_port_t task = mach_task_self();
+    mach_vm_address_t dst = (mach_vm_address_t)destination;
+    int kr = mach_vm_protect_trap(task, dst, len, FALSE, VM_PROT_READ | VM_PROT_WRITE | VM_PROT_COPY);
     if (kr != 0) {
-        LOG_ERROR("mach_vm_protect: %s", mach_error_string(kr));
+        LOG_ERROR("mach_vm_protect failed for address %p: %s", destination, mach_error_string(kr));
         return kr;
     }
     copy_mem(destination, source, len);
-    kr = mach_vm_protect_trap(mach_task_self(), (mach_vm_address_t)destination, len, FALSE,
-                              VM_PROT_READ | VM_PROT_EXECUTE);
-    if (kr != 0) {
-        LOG_ERROR("mach_vm_protect: %s", mach_error_string(kr));
-    }
-    return kr;
+    mach_vm_protect_trap(task, dst, len, FALSE, VM_PROT_READ | VM_PROT_EXECUTE);
+    // might fail when editing __DATA, but not a big deal
+    return 0;
 }

src/objcrt.c

@@ -4,6 +4,8 @@
 #include <objc/runtime.h> // objc_*, ...
 
 Method ocrt_method(char type, const char *cls, const char *sel) {
+    ARG_CHECK(cls != NULL);
+    ARG_CHECK(sel != NULL);
     Method oc_method = NULL;
     Class oc_class = objc_getClass(cls);
     SEL oc_selector = sel_registerName(sel);
@@ -22,6 +24,8 @@ Method ocrt_method(char type, const char *cls, const char *sel) {
 }
 
 void *ocrt_impl(char type, const char *cls, const char *sel) {
+    ARG_CHECK(cls != NULL);
+    ARG_CHECK(sel != NULL);
     return method_getImplementation(ocrt_method(type, cls, sel));
 }
 
@@ -31,7 +35,7 @@ static Method ensure_method(const char *cls, const char *sel) {
         oc_method = ocrt_method('-', cls, sel);
     }
     if (oc_method == NULL) {
-        LOG_ERROR("ensure_method: method not found!");
+        LOG_ERROR("ensure_method: method '[%s %s]' not found!", cls, sel);
     }
     return oc_method;
 }
@@ -47,6 +51,9 @@ int ocrt_swap(const char *cls1, const char *sel1, const char *cls2, const char *
 }
 
 int ocrt_hook(const char *cls, const char *sel, void *destination, void **origin) {
+    ARG_CHECK(cls != NULL);
+    ARG_CHECK(sel != NULL);
+    ARG_CHECK(destination != NULL);
     Method oc_method = ensure_method(cls, sel);
     if (oc_method == NULL) {
         return 1;

src/private.h

@@ -18,6 +18,7 @@
 
 #ifdef COMPACT
     #define LOG_ERROR(fmt, ...) ((void)0)
+    #define ARG_CHECK(x)        ((void)0)
 #else
     #if TARGET_OS_OSX
         #include <printf.h> // fprintf()
@@ -28,6 +29,11 @@
             os_log_with_type(OS_LOG_DEFAULT, OS_LOG_TYPE_ERROR, "ERROR [%s:%d]: " fmt "\n", __FILE__, __LINE__,        \
                              ##__VA_ARGS__)
     #endif
+    #define ARG_CHECK(x)                                                                                               \
+        if (!(x)) {                                                                                                    \
+            LOG_ERROR("ARG_CHECK '%s' failed", #x);                                                                    \
+            abort();                                                                                                   \
+        }
 #endif
 
 #define MB (1ll << 20)

src/symsolve/symexport.c

@@ -59,12 +59,13 @@ static void *trie_query(const uint8_t *export, const char *name) {
 }
 
 void *symexp_solve(uint32_t image_index, const char *symbol_name) {
+    ARG_CHECK(symbol_name != NULL);
     void *symbol_address = NULL;
     intptr_t image_slide = _dyld_get_image_vmaddr_slide(image_index);
     struct mach_header_64 *mh_header = (struct mach_header_64 *)_dyld_get_image_header(image_index);
     struct load_command *ld_command = (void *)mh_header + sizeof(struct mach_header_64);
     if (mh_header == NULL) {
-        LOG_ERROR("symexp_solve: image_index out of range!");
+        LOG_ERROR("symexp_solve: image_index %d out of range!", image_index);
     }
     struct dyld_info_command *dyldinfo_cmd = NULL;
     struct segment_command_64 *linkedit_cmd = NULL;
@@ -87,7 +88,7 @@ void *symexp_solve(uint32_t image_index, const char *symbol_name) {
         ld_command = (void *)ld_command + ld_command->cmdsize;
     }
     if (linkedit_cmd == NULL) {
-        LOG_ERROR("symexp_solve: __LINKEDIT segment not found!");
+        LOG_ERROR("symexp_solve: __LINKEDIT segment not found for image_index %d!", image_index);
         return NULL;
     }
     // stroff and strtbl are in the __LINKEDIT segment
@@ -99,7 +100,9 @@ void *symexp_solve(uint32_t image_index, const char *symbol_name) {
     else if (export_trie != NULL)
         export_offset = linkedit_base + export_trie->dataoff;
     else {
-        LOG_ERROR("symexp_solve: neither LC_DYLD_INFO_ONLY nor LC_DYLD_EXPORTS_TRIE load command found!");
+        LOG_ERROR(
+            "symexp_solve: neither LC_DYLD_INFO_ONLY nor LC_DYLD_EXPORTS_TRIE load command found for image_index %d!",
+            image_index);
         return NULL;
     }
     symbol_address = trie_query(export_offset, symbol_name);
@@ -108,7 +111,7 @@ void *symexp_solve(uint32_t image_index, const char *symbol_name) {
         symbol_address += (uint64_t)mh_header;
     }
     else {
-        LOG_ERROR("symexp_solve: symbol not found!");
+        LOG_ERROR("symexp_solve: symbol '%s' not found in image_index %d!", symbol_name, image_index);
     }
     return symbol_address;
 }