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wrap_elf: Provide accessors to global variables exported from ELFs
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cmake/wrap_elf.cmake
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cmake/wrap_elf.cmake
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src/libelfloader/wrapgen/wrapgen.cpp
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src/libelfloader/wrapgen/wrapgen.cpp
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// TODO: use wrapgen32 to generate 32-bit wrappers.
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void parse_elf(const char* elf, std::string& soname_out, std::set<std::string>& symbols_out);
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void parse_elf(const char* elf, std::string& soname_out, std::set<std::string>& functions_out, std::set<std::string>& vars_out);
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void generate_wrapper(std::ofstream& output, const char* soname, const std::set<std::string>& symbols);
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void generate_var_wrappers(std::ofstream& output, std::ofstream& outputHeader, const std::set<std::string>& vars);
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int main(int argc, const char** argv)
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{
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std::string elfLibrary;
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std::set<std::string> symbols;
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std::set<std::string> functions, vars;
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std::string soname;
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std::ofstream output;
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if (argc != 3)
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if (argc != 4)
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{
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std::cerr << "Usage: " << argv[0] << " <library-name> <output-file>\n";
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std::cerr << "Usage: " << argv[0] << " <library-name> <output-file> <var-access-header>\n";
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return 1;
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}
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···
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dlclose(handle);
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}
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parse_elf(elfLibrary.c_str(), soname, symbols);
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generate_wrapper(output, soname.c_str(), symbols);
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parse_elf(elfLibrary.c_str(), soname, functions, vars);
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generate_wrapper(output, soname.c_str(), functions);
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if (!vars.empty())
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{
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std::ofstream outputHeader(argv[3]);
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if (!outputHeader.is_open())
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throw std::runtime_error("Cannot open output macro header file");
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generate_var_wrappers(output, outputHeader, vars);
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}
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}
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catch (const std::exception& e)
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{
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return 0;
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}
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void parse_elf(const char* elf, std::string& soname, std::set<std::string>& symbols)
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void parse_elf(const char* elf, std::string& soname, std::set<std::string>& symbols, std::set<std::string>& vars)
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{
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int fd;
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const Elf64_Ehdr* ehdr;
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if (ELF64_ST_VISIBILITY(sym->st_other) != STV_DEFAULT)
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continue;
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symbols.insert(strings + sym->st_name);
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if (ELF64_ST_TYPE(sym->st_info) == STT_FUNC)
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symbols.insert(strings + sym->st_name);
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else
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vars.insert(strings + sym->st_name);
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}
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break;
···
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"___elfname: .asciz \\\"" << soname << "\\\"\");\n";
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}
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void generate_var_wrappers(std::ofstream& output, std::ofstream& outputHeader, const std::set<std::string>& vars)
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{
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outputHeader << "#pragma once\n\n";
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outputHeader << "#ifdef __cplusplus\n"
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"extern \"C\" {\n"
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"#endif\n\n";
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for (const std::string& sym : vars)
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{
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output << "void* __elf_get_" << sym << "(void) {\n"
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"\treturn _elfcalls->dlsym_fatal(lib_handle, \"" << sym << "\");\n"
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"}\n\n";
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outputHeader << "extern __typeof(" << sym << ")* __elf_get_" << sym << "(void);\n"
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"#define " << sym << "(*__elf_get_" << sym << "())\n\n";
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}
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outputHeader << "\n\n#ifdef __cplusplus\n"
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"}\n"
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"#endif\n\n";
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}