Link everything in main.cpp

.gitignore

@@ -1,2 +1,3 @@
 build
 test.o
+test

src/main.cpp

@@ -22,8 +22,8 @@
 
 void llvm_hello_world();
 
-std::string read_file(std::string& filepath) {
-    std::ifstream input{ filepath };
+std::string read_file(std::string_view filepath) {
+    std::ifstream input{ std::string{filepath} };
     if (!input) {
         std::cerr << "Failed to read " << filepath << std::endl;
         return {};
@@ -41,8 +41,8 @@ std::string read_file(std::string& filepath) {
     return out;
 }
 
-int write_file(std::string& filepath, std::string& content) {
-    std::ofstream output{ filepath };
+int write_file(std::string_view filepath, std::string& content) {
+    std::ofstream output{ std::string{filepath} };
     if (!output) {
         std::cerr << "Failed to open " << filepath << " for reading" << std::endl;
         return 1;
@@ -57,12 +57,12 @@ struct CompileOutput {
     std::string obj_string;
 };
 
-std::optional<CompileOutput> compile(std::string& in_filename) {
+std::optional<CompileOutput> compile(std::string_view in_filename) {
     std::string out{ read_file(in_filename) };
 
     std::cout << out << std::endl;
 
-    auto tokens = token::tokenize(out, in_filename);
+    auto tokens = token::tokenize(out, std::string{ in_filename });
     for (token::Token token : tokens) {
         std::cout << token << std::endl;
     }
@@ -154,15 +154,59 @@ std::optional<CompileOutput> compile(std::string& in_filename) {
     };
 }
 
+std::string exec(const char* cmd) {
+    std::array<char, 128> buffer;
+    std::string result;
+    std::unique_ptr<FILE, decltype(&pclose)> pipe(popen(cmd, "r"), pclose);
+    if (!pipe) {
+        throw std::runtime_error("popen() failed!");
+    }
+    while (fgets(buffer.data(), static_cast<int>(buffer.size()), pipe.get()) != nullptr) {
+        result += buffer.data();
+    }
+    return result;
+}
+
+/// @brief Discovers the path of a given library using POSIX-util "whereis"
+/// @param libname 
+/// @return path to the library, empty string if nothing was found
+std::string find_lib(std::string libname) {
+    std::string cmd = "whereis " + libname;
+    auto output = exec(cmd.c_str());
+    output.erase(0, libname.size() + 2);
+    auto path = output.substr(0, output.find('\n'));
+    path = path.substr(0, path.find(' '));
+
+    return path;
+}
+
 int main() {
 
     std::string in_filename{ "test.c" };
     std::string out_filename{ "test.o" };
+    std::string exec_filename{ "test" };
 
     auto out = compile(in_filename);
     if (out) {
+        // Print LLVM IR, produce Obj-file
         std::cout << out->llvm_ir_string << std::endl;
         write_file(out_filename, out->obj_string);
+
+        // Find necessary libraries
+
+        std::string command = "ld";
+        auto linker = find_lib("ld-linux-x86-64.so.2");
+        auto crt1 = find_lib("crt1.o");
+        auto crti = find_lib("crti.o");
+        auto crtn = find_lib("crtn.o");
+
+
+        // Link everything together and produce a file with exec_filename
+        std::string cmd = command + " -dynamic-linker " + linker + " -lc "
+            + crt1 + " " + crti + " " + crtn + " "
+            + out_filename + " -o " + exec_filename;
+        std::cout << cmd << std::endl;
+        std::cout << exec(cmd.c_str()) << std::endl;
     }
 
     return 0;