HACK-WIP

src/exec.jl

@@ -1,10 +1,28 @@
 # Replacement for the GAP kernel function ExecuteProcess
 const use_orig_ExecuteProcess = Ref{Bool}(false)
-function GAP_ExecuteProcess(dir::GapObj, prg::GapObj, in::Int, out::Int, args::GapObj)
-    if use_orig_ExecuteProcess[]
-        return GAP.Globals._ORIG_ExecuteProcess(dir, prg, in, out, args)
+function GAP_Error(args...)
+    gapargs = [Obj(x) for x in args]
+    GAP.Globals.Error(gapargs...)
+end
+
+function GAP_ExecuteProcess(dir::Any, prg::Any, in::Any, out::Any, args::Any)
+    (dir isa GapObj && Wrappers.IsString(dir)) || GAP_Error("ExecuteProcess: <dir> must be a string (not the value '", dir, "')")
+    (prg isa GapObj && Wrappers.IsString(prg)) || GAP_Error("ExecuteProcess: <prg> must be a string (not the value '", prg, "')")
+    in isa Int || GAP_Error("ExecuteProcess: <in> must be a small integer (not the value '", in, "')")
+    out isa Int || GAP_Error("ExecuteProcess: <out> must be a small integer (not the value '", out, "')")
+    (args isa GapObj && Wrappers.IsList(args)) || GAP_Error("ExecuteProcess: <args> must be a small list (not the value '", args, "')")
+    all(Wrappers.IsString, args) || GAP_Error("ExecuteProcess: <args> must be a list of strings")
+
+    # convert Julia errors to GAP errors
+    # TODO: we should probably do this in general
+    try
+        if use_orig_ExecuteProcess[]
+            return GAP.Globals._ORIG_ExecuteProcess(dir, prg, in, out, args)
+        end
+        return GAP_ExecuteProcess(String(dir), String(prg), in::Int, out::Int, Vector{String}(args))
+    catch
+        GAP_Error("a julia exception was raised")
     end
-    return GAP_ExecuteProcess(String(dir), String(prg), in, out, Vector{String}(args))
 end
 
 function GAP_ExecuteProcess(dir::String, prg::String, fin::Int, fout::Int, args::Vector{String})
@@ -30,6 +48,9 @@ function GAP_ExecuteProcess(dir::String, prg::String, fin::Int, fout::Int, args:
         fout = RawFD(fout)
     end
 
+# TODO: this hangs
+#    ExecuteProcess("","",0,0,[]);
+
     # TODO: verify `dir` is a valid dir?
     cd(dir) do
         res = run(pipeline(ignorestatus(`$prg $args`), stdin=fin, stdout=fout))