[clang] Verify ssp buffer size is a valid integer

[alextsao1999]

Summary

This patch adds to verify whether the ssp buffer size is a legal integer and a new diagnostic driver kind has been added.

[compnerd]

clang/lib/Driver/ToolChains/Clang.cpp

3205–3210

I really am not a fan of the 16 here. Why not just use split and split on =? Or use [constexpr] strlen?

3210

Please consistently use the braces (either applied to both or on neither).

[alextsao1999]

update

[alextsao1999]

clang/lib/Driver/ToolChains/Clang.cpp

3210

Thanks, fixed. Are there any other issues?

clang/include/clang/Basic/DiagnosticDriverKinds.td

 def err_drv_preamble_format : Error<
     "incorrect format for -preamble-bytes=N,END">;
 def warn_invalid_ios_deployment_target : Warning<
   "invalid iOS deployment version '%0', iOS 10 is the maximum deployment "
   "target for 32-bit targets">, InGroup<InvalidIOSDeploymentTarget>,
   DefaultError;
 def err_invalid_macos_32bit_deployment_target : Error<
   "32-bit targets are not supported when building for Mac Catalyst">;
+def err_invalid_ssp_buffer_size : Error<
+  "ssp buffer size is not valid">;
 def err_drv_invalid_os_in_arg : Error<"invalid OS value '%0' in '%1'">;
 def err_drv_conflicting_deployment_targets : Error<
   "conflicting deployment targets, both '%0' and '%1' are present in environment">;
 def err_arc_unsupported_on_runtime : Error<
   "-fobjc-arc is not supported on platforms using the legacy runtime">;
 def err_arc_unsupported_on_toolchain : Error< // feel free to generalize this
   "-fobjc-arc is not supported on versions of OS X prior to 10.6">;
 def err_objc_weak_with_gc : Error<

clang/lib/Driver/ToolChains/Clang.cpp

if (Arg *A = Args.getLastArg(options::OPT_fno_stack_protector,
     StackProtectorLevel = DefaultStackProtectorLevel;
   }
 
   if (StackProtectorLevel) {
     CmdArgs.push_back("-stack-protector");
     CmdArgs.push_back(Args.MakeArgString(Twine(StackProtectorLevel)));
   }
 
+  auto IsInteger = [](StringRef Str) -> bool {
+    if (Str.empty())
+      return false;
+    for (auto &Chr : Str)
+      if (Chr < '0' || Chr > '9')
+        return false;
+    return true;
+  };
+
   // --param ssp-buffer-size=
   for (const Arg *A : Args.filtered(options::OPT__param)) {
     StringRef Str(A->getValue());
-    if (Str.startswith("ssp-buffer-size=")) {
+    auto StrSplit = Str.split('=');
+    if (StrSplit.first.equals("ssp-buffer-size")) {
       if (StackProtectorLevel) {
+        if (IsInteger(StrSplit.second)) {
           CmdArgs.push_back("-stack-protector-buffer-size");
-        // FIXME: Verify the argument is a valid integer.
-        CmdArgs.push_back(Args.MakeArgString(Str.drop_front(16)));
+          CmdArgs.push_back(Args.MakeArgString(StrSplit.second));
+        } else {
+          D.Diag(clang::diag::err_invalid_ssp_buffer_size);
+        }
       }
       A->claim();
     }
   }
 
   const std::string &TripleStr = EffectiveTriple.getTriple();
   if (Arg *A = Args.getLastArg(options::OPT_mstack_protector_guard_EQ)) {
     StringRef Value = A->getValue();