test262-runner: Use names for the different exit codes

These are not used by test-test262 but can be used to quickly
distinguish the type of problem if the runner fails when running
manually.

Tests/LibJS/test262-runner.cpp

@@ -566,6 +566,11 @@ extern "C" __attribute__((__noreturn__)) void __assert_fail(char const* assertio
 }
 #endif
 
+constexpr int exit_wrong_arguments = 2;
+constexpr int exit_stdout_setup_failed = 1;
+constexpr int exit_setup_input_failure = 7;
+constexpr int exit_read_file_failure = 3;
+
 int main(int argc, char** argv)
 {
     int timeout = 10;
@@ -585,7 +590,7 @@ int main(int argc, char** argv)
 #ifndef AK_OS_MACOS
     if (disable_core_dumping && prctl(PR_SET_DUMPABLE, 0, 0) < 0) {
         perror("prctl(PR_SET_DUMPABLE)");
-        return 2;
+        return exit_wrong_arguments;
     }
 #endif
 
@@ -597,7 +602,7 @@ int main(int argc, char** argv)
 
     if (timeout <= 0) {
         warnln("timeout must be at least 1");
-        return 2;
+        return exit_wrong_arguments;
     }
 
     AK::set_debug_enabled(enable_debug_printing);
@@ -609,19 +614,19 @@ int main(int argc, char** argv)
     auto saved_stdout = dup(STDOUT_FILENO);
     if (saved_stdout < 0) {
         perror("dup");
-        return 1;
+        return exit_stdout_setup_failed;
     }
 
     saved_stdout_fd = fdopen(saved_stdout, "w");
     if (!saved_stdout_fd) {
         perror("fdopen");
-        return 1;
+        return exit_stdout_setup_failed;
     }
 
     int stdout_pipe[2];
     if (pipe(stdout_pipe) < 0) {
         perror("pipe");
-        return 1;
+        return exit_stdout_setup_failed;
     }
 
     auto flags = fcntl(stdout_pipe[0], F_GETFL);
@@ -634,12 +639,12 @@ int main(int argc, char** argv)
 
     if (dup2(stdout_pipe[1], STDOUT_FILENO) < 0) {
         perror("dup2");
-        return 1;
+        return exit_stdout_setup_failed;
     }
 
     if (close(stdout_pipe[1]) < 0) {
         perror("close");
-        return 1;
+        return exit_stdout_setup_failed;
     }
 
     auto collect_output = [&] {
@@ -665,12 +670,12 @@ int main(int argc, char** argv)
 
     auto standard_input_or_error = Core::Stream::File::standard_input();
     if (standard_input_or_error.is_error())
-        return 7;
+        return exit_setup_input_failure;
 
     Array<u8, 1024> input_buffer {};
     auto buffered_standard_input_or_error = Core::Stream::BufferedFile::create(standard_input_or_error.release_value());
     if (buffered_standard_input_or_error.is_error())
-        return 7;
+        return exit_setup_input_failure;
 
     auto& buffered_input_stream = buffered_standard_input_or_error.value();
 
@@ -687,7 +692,7 @@ int main(int argc, char** argv)
 
         if (s_automatic_harness_detection_mode) {
             if (!extract_harness_directory(path))
-                return 4;
+                return exit_read_file_failure;
             s_automatic_harness_detection_mode = false;
             VERIFY(!s_harness_file_directory.is_empty());
         }
@@ -695,7 +700,7 @@ int main(int argc, char** argv)
         auto file_or_error = Core::Stream::File::open(path, Core::Stream::OpenMode::Read);
         if (file_or_error.is_error()) {
             warnln("Could not open file: {}", path);
-            return 3;
+            return exit_read_file_failure;
         }
         auto& file = file_or_error.value();
 
@@ -709,7 +714,7 @@ int main(int argc, char** argv)
             auto contents_or_error = file->read_all();
             if (contents_or_error.is_error()) {
                 warnln("Could not read contents of file: {}", path);
-                return 3;
+                return exit_read_file_failure;
             }
             auto& contents = contents_or_error.value();
             StringBuilder builder { contents.size() + strict_length };