Enable to remove Mach-O symbols

Author: romainthomas

api/python/MachO/objects/pyBinary.cpp

@@ -394,6 +394,11 @@ void create<Binary>(py::module& m) {
         "" RST_CLASS_REF(lief.MachO.LOAD_COMMAND_TYPES) "",
         "type"_a)
 
+    .def("remove",
+        static_cast<bool (Binary::*)(const Symbol&)>(&Binary::remove),
+        "Remove the given " RST_CLASS_REF(lief.MachO.Symbol)"",
+        "symbol"_a)
+
     .def("remove_command",
         static_cast<bool (Binary::*)(size_t)>(&Binary::remove_command),
         "Remove the " RST_CLASS_REF(lief.MachO.LoadCommand) " at ``index``",
@@ -403,6 +408,21 @@ void create<Binary>(py::module& m) {
         static_cast<bool (Binary::*)(void)>(&Binary::remove_signature),
         "Remove the " RST_CLASS_REF(lief.MachO.CodeSignature) " (if any)")
 
+    .def("remove_symbol",
+        static_cast<bool (Binary::*)(const std::string&)>(&Binary::remove_symbol),
+        "Remove all symbol(s) with the given name",
+        "name"_a)
+
+    .def("unexport",
+        static_cast<bool (Binary::*)(const std::string&)>(&Binary::unexport),
+        "Remove the symbol from the export table",
+        "name"_a)
+
+    .def("unexport",
+        static_cast<bool (Binary::*)(const Symbol&)>(&Binary::unexport),
+        "Remove the symbol from the export table",
+        "symbol"_a)
+
     .def("extend",
         static_cast<bool (Binary::*)(const LoadCommand&, uint64_t)>(&Binary::extend),
         "Extend a " RST_CLASS_REF(lief.MachO.LoadCommand) " by ``size``",

include/LIEF/MachO/Binary.hpp

@@ -200,6 +200,18 @@ class LIEF_API Binary : public LIEF::Binary  {
   const SegmentCommand* get_segment(const std::string& name) const;
   SegmentCommand* get_segment(const std::string& name);
 
+  //! Remove symbol with the given name
+  bool remove_symbol(const std::string& name);
+
+  //! Remove the given symbol
+  bool remove(const Symbol& sym);
+
+  //! Remove the given symbol from the export table
+  bool unexport(const std::string& name);
+
+  //! Remove the given symbol from the export table
+  bool unexport(const Symbol& sym);
+
   // ======
   // Helper
   // ======

include/LIEF/MachO/DyldInfo.hpp

@@ -40,6 +40,7 @@ class BinaryParser;
 class LIEF_API DyldInfo : public LoadCommand {
 
   friend class BinaryParser;
+  friend class Binary;
   friend class Builder;
 
   public:

src/ELF/Binary.cpp

@@ -704,7 +704,6 @@ void Binary::remove_static_symbol(Symbol* symbol) {
   this->static_symbols_.erase(it_symbol);
 
   symbol = nullptr;
-
 }
 
 

src/MachO/Binary.cpp

@@ -1209,6 +1209,82 @@ LoadCommand& Binary::add(const SegmentCommand& segment) {
   return segment_added;
 }
 
+bool Binary::unexport(const std::string& name) {
+  if (not this->has_symbol(name)) {
+    return false;
+  }
+  const Symbol& s = this->get_symbol(name);
+  return this->unexport(s);
+}
+
+bool Binary::unexport(const Symbol& sym) {
+  if (not this->has_dyld_info()) {
+    return false;
+  }
+
+  DyldInfo& dyld = this->dyld_info();
+  auto&& it_export = std::find_if(
+      std::begin(dyld.export_info_),
+      std::end(dyld.export_info_),
+      [&sym] (const ExportInfo* info) {
+        return info->has_symbol() and info->symbol() == sym;
+      });
+
+  if (it_export != std::end(dyld.export_info_)) {
+    delete *it_export;
+    dyld.export_info_.erase(it_export);
+    return true;
+  }
+
+  return false;
+}
+
+bool Binary::remove(const Symbol& sym) {
+  /* bool export_removed = */ this->unexport(sym);
+
+  auto&& it_symbol = std::find_if(
+      std::begin(this->symbols_),
+      std::end(this->symbols_),
+      [&sym] (const Symbol* s) {
+        return s->name() == sym.name();
+      });
+
+  // No Symbol
+  if (it_symbol == std::end(this->symbols_)) {
+    return false;
+  }
+
+  Symbol* symbol_to_remove = *it_symbol;
+
+  // Remove from the symbol command
+  // ------------------------------
+  if (this->has_symbol_command()) {
+    SymbolCommand& sym_cmd = this->symbol_command();
+    sym_cmd.numberof_symbols(sym_cmd.numberof_symbols() - 1);
+  }
+
+
+  // Remove from symbol table
+  // ------------------------
+  delete symbol_to_remove;
+  this->symbols_.erase(it_symbol);
+  symbol_to_remove = nullptr;
+  return true;
+}
+
+bool Binary::remove_symbol(const std::string& name) {
+  bool removed = false;
+  while (this->has_symbol(name)) {
+    const Symbol& s = this->get_symbol(name);
+    if (not this->remove(s)) {
+      break;
+    }
+
+    removed = true;
+  }
+  return removed;
+}
+
 
 bool Binary::remove_signature(void) {
 

src/MachO/Builder.tcc

@@ -626,9 +626,19 @@ void Builder::build(SymbolCommand* symbol_command) {
     raw_symbol_names.push_back(0);
   }
 
+  // If the table is smaller than th original one, fill with 0
+  if (raw_symbol_names.size() < symbol_command->strings_size()) {
+    raw_symbol_names.insert(
+        std::end(raw_symbol_names),
+        symbol_command->strings_size() - raw_symbol_names.size() ,
+        0
+    );
+  }
+
   size_t padding = align(raw_symbol_names.size(), sizeof(uint)) - raw_symbol_names.size();
   raw_symbol_names.insert(std::end(raw_symbol_names), padding, 0);
 
+
   // To be removed later
   CHECK(raw_symbol_names.size() <= symbol_command->strings_size()) << std::hex << std::showbase << raw_symbol_names.size() << " vs " << symbol_command->strings_size();
 
@@ -696,9 +706,9 @@ void Builder::build(SymbolCommand* symbol_command) {
   //const uint32_t size_needed = sizeof(symtab_command) + nlist_table.size() + raw_symbol_names.size();
   symtab.cmd     = static_cast<uint32_t>(symbol_command->command());
   symtab.cmdsize = static_cast<uint32_t>(symbol_command->size());
-  symtab.symoff  = static_cast<uint32_t>(symbol_command->symbol_offset()); // After the header
+  symtab.symoff  = static_cast<uint32_t>(symbol_command->symbol_offset());    // **Usually** After the header
   symtab.nsyms   = static_cast<uint32_t>(symbol_command->numberof_symbols());
-  symtab.stroff  = static_cast<uint32_t>(symbol_command->strings_offset()); // After nlist table
+  symtab.stroff  = static_cast<uint32_t>(symbol_command->strings_offset());   // **Usually** After nlist table
   symtab.strsize = static_cast<uint32_t>(symbol_command->strings_size());
 
   symbol_command->originalData_.clear();
@@ -710,18 +720,6 @@ void Builder::build(SymbolCommand* symbol_command) {
       std::back_inserter(symbol_command->originalData_)
   );
 
-  //std::move(
-  //  std::begin(nlist_table),
-  //  std::end(nlist_table),
-  //  std::back_inserter(symbol_command->originalData_)
-  //);
-
-  //std::move(
-  //  std::begin(raw_symbol_names),
-  //  std::end(raw_symbol_names),
-  //  std::back_inserter(symbol_command->originalData_)
-  //);
-
 }