Shall we commit this and another V4 version of these patches?

On Sunday, January 19, 2020 at 8:17:39 PM UTC-5, Zhiting Zhu wrote:
>
> dlsym function doesn't seem to lookup symbol deep enough. This 
> patch includes a bfs version of collect dependencies. It 
> fixes test_dlsym_from_sofile_with_preload and 
> dlsym_with_dependencies. 
>
> Signed-off-by: Waldemar Kozaczuk <jwkoz...@gmail.com <javascript:>> 
> Signed-off-by: Zhiting Zhu <zhit...@cs.utexas.edu <javascript:>> 
> --- 
>  core/elf.cc        | 39 +++++++++++++++++++++++++++++++++++++++ 
>  include/osv/elf.hh |  2 ++ 
>  libc/dlfcn.cc      |  2 +- 
>  tests/tst-dlfcn.cc |  2 +- 
>  4 files changed, 43 insertions(+), 2 deletions(-) 
>
> diff --git a/core/elf.cc b/core/elf.cc 
> index 73834b19..a419ea6a 100644 
> --- a/core/elf.cc 
> +++ b/core/elf.cc 
> @@ -27,6 +27,7 @@ 
>  #include <sys/utsname.h> 
>  #include <osv/demangle.hh> 
>  #include <boost/version.hpp> 
> +#include <deque> 
>   
>  #include "arch.hh" 
>   
> @@ -950,6 +951,22 @@ Elf64_Sym* object::lookup_symbol(const char* name, 
> bool self_lookup) 
>      return sym; 
>  } 
>   
> +symbol_module object::lookup_symbol_deep(const char* name) 
> +{ 
> +    symbol_module sym = { lookup_symbol(name, false), this }; 
> +    if (!sym.symbol) { 
> +        auto deps = this->collect_dependencies_bfs(); 
> +        for (auto&& _obj : deps) { 
> +            auto symbol = _obj->lookup_symbol(name, false); 
> +            if (symbol) { 
> +                sym = { symbol, _obj }; 
> +                break; 
> +            } 
> +        } 
> +    } 
> +    return sym; 
> +} 
> + 
>  unsigned object::symtab_len() 
>  { 
>      if (dynamic_exists(DT_HASH)) { 
> @@ -1089,6 +1106,28 @@ void 
> object::collect_dependencies(std::unordered_set<elf::object*>& ds) 
>      } 
>  } 
>   
> +std::deque<elf::object*> object::collect_dependencies_bfs() 
> +{ 
> +    std::unordered_set<object*> deps_set; 
> +    std::deque<object*> operate_queue; 
> +    std::deque<object*> deps; 
> +    operate_queue.push_back(this); 
> +    deps_set.insert(this); 
> + 
> +    while (!operate_queue.empty()) { 
> +        object* obj = operate_queue.front(); 
> +        operate_queue.pop_front(); 
> +        deps.push_back(obj); 
> +        for (auto&& d : obj->_needed) { 
> +            if (!deps_set.count(d.get())) { 
> +                deps_set.insert(d.get()); 
> +                operate_queue.push_back(d.get()); 
> +            } 
> +        } 
> +    } 
> +    return deps; 
> +} 
> + 
>  std::string object::soname() 
>  { 
>      return dynamic_exists(DT_SONAME) ? dynamic_str(DT_SONAME) : 
> std::string(); 
> diff --git a/include/osv/elf.hh b/include/osv/elf.hh 
> index 1dac6c08..c942ac61 100644 
> --- a/include/osv/elf.hh 
> +++ b/include/osv/elf.hh 
> @@ -347,6 +347,7 @@ public: 
>      void* base() const; 
>      void* end() const; 
>      Elf64_Sym* lookup_symbol(const char* name, bool self_lookup); 
> +    symbol_module lookup_symbol_deep(const char* name); 
>      void load_segments(); 
>      void process_headers(); 
>      void unload_segments(); 
> @@ -405,6 +406,7 @@ private: 
>      void relocate_pltgot(); 
>      unsigned symtab_len(); 
>      void collect_dependencies(std::unordered_set<elf::object*>& ds); 
> +    std::deque<elf::object*> collect_dependencies_bfs(); 
>      void prepare_initial_tls(void* buffer, size_t size, 
> std::vector<ptrdiff_t>& offsets); 
>      void prepare_local_tls(std::vector<ptrdiff_t>& offsets); 
>      void alloc_static_tls(); 
> diff --git a/libc/dlfcn.cc b/libc/dlfcn.cc 
> index 346cf195..e3a4a577 100644 
> --- a/libc/dlfcn.cc 
> +++ b/libc/dlfcn.cc 
> @@ -74,7 +74,7 @@ void* dlsym(void* handle, const char* name) 
>          abort(); 
>      } else { 
>          auto obj = 
> *reinterpret_cast<std::shared_ptr<elf::object>*>(handle); 
> -        sym = { obj->lookup_symbol(name, false), obj.get() }; 
> +        sym = obj->lookup_symbol_deep(name); 
>      } 
>      if (!sym.obj || !sym.symbol) { 
>          dlerror_fmt("dlsym: symbol %s not found", name); 
> diff --git a/tests/tst-dlfcn.cc b/tests/tst-dlfcn.cc 
> index 5258256a..6d91fb93 100644 
> --- a/tests/tst-dlfcn.cc 
> +++ b/tests/tst-dlfcn.cc 
> @@ -13,7 +13,7 @@ 
>  namespace utf = boost::unit_test; 
>   
>  const bool rtld_next = false; 
> -const bool deep_lookup = false; 
> +const bool deep_lookup = true; 
>   
>  static bool called = false; 
>  extern "C" void DlSymTestFunction() 
> -- 
> 2.17.1 
>
>

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