Improve error reporting between kernel<->user

kernel/src/scheduler.cpp

@@ -10,6 +10,7 @@
 #include <optional.hpp>
 #include <string.hpp>
 #include <lock_guard.hpp>
+#include <errors.hpp>
 
 #include "scheduler.hpp"
 #include "paging.hpp"
@@ -532,7 +533,7 @@ int64_t scheduler::exec(const std::string& file){
             k_print_line("Not a file");
         }
 
-        return -1;
+        return -std::ERROR_NOT_EXISTS;
     }
 
     if(!elf::is_valid(content)){
@@ -540,7 +541,7 @@ int64_t scheduler::exec(const std::string& file){
             k_print_line("Not a valid file");
         }
 
-        return -2;
+        return -std::ERROR_NOT_EXECUTABLE;
     }
 
     auto buffer = content.c_str();
@@ -552,7 +553,7 @@ int64_t scheduler::exec(const std::string& file){
             k_print_line("Impossible to create paging");
         }
 
-        return -3;
+        return -std::ERROR_FAILED_EXECUTION;
     }
 
     process.brk_start = program_break;

programs/tsh/src/main.cpp

@@ -9,6 +9,7 @@
 #include <system.hpp>
 #include <string.hpp>
 #include <algorithms.hpp>
+#include <errors.hpp>
 
 namespace {
 
@@ -99,15 +100,7 @@ int main(){
 
                     if(!result.valid()){
                         print("error: ");
-
-                        auto err = result.error();
-                        if(err == 1){
-                            print_line("The file does not exist");
-                        } else if(err == 2){
-                            print_line("The file is not an executable");
-                        } else if(err == 3){
-                            print_line("Failed to execute the file");
-                        }
+                        print_line(std::error_message(result.error()));
                     }
                 }
             }

tstl/include/errors.hpp

@@ -0,0 +1,32 @@
+//=======================================================================
+// Copyright Baptiste Wicht 2013-2014.
+// Distributed under the Boost Software License, Version 1.0.
+// (See accompanying file LICENSE_1_0.txt or copy at
+//  http://www.boost.org/LICENSE_1_0.txt)
+//=======================================================================
+
+#ifndef ERRORS_H
+#define ERRORS_H
+
+namespace std {
+
+constexpr const size_t ERROR_NOT_EXISTS = 1;
+constexpr const size_t ERROR_NOT_EXECUTABLE = 2;
+constexpr const size_t ERROR_FAILED_EXECUTION = 3;
+
+inline const char* error_message(size_t error){
+    switch(error){
+        case ERROR_NOT_EXISTS:
+            return "The file does not exist";
+        case ERROR_NOT_EXECUTABLE:
+            return "The file is not an executable";
+        case ERROR_FAILED_EXECUTION:
+            return "Execution failed";
+        default:
+            return "Unknonwn error";
+    }
+}
+
+}
+
+#endif