HackStudio: Use Core::System APIs where possible

Userland/DevTools/HackStudio/Editor.cpp

@@ -480,11 +480,12 @@ void Editor::set_document(GUI::TextDocument& doc)
         // Otherwise, if the file has already been opened before in some Editor instance, it should exist in the LanguageServer's
         // FileDB, and the LanguageServer should already have its up-to-date content.
         // So it's OK to just pass an fd here (rather than the TextDocument's content).
-        int fd = open(code_document.file_path().characters(), O_RDONLY | O_NOCTTY);
-        if (fd < 0) {
-            perror("open");
+        auto maybe_fd = Core::System::open(code_document.file_path(), O_RDONLY | O_NOCTTY);
+        if (maybe_fd.is_error()) {
+            warnln("Failed to open `{}`: {}", code_document.file_path(), maybe_fd.release_error());
             return;
         }
+        auto fd = maybe_fd.release_value();
         m_language_client->open_file(code_document.file_path(), fd);
         close(fd);
     } else {

Userland/DevTools/HackStudio/HackStudioWidget.cpp

@@ -239,8 +239,8 @@ void HackStudioWidget::open_project(ByteString const& root_path)
 {
     if (warn_unsaved_changes("There are unsaved changes, do you want to save before closing current project?") == ContinueDecision::No)
         return;
-    if (chdir(root_path.characters()) < 0) {
-        perror("chdir");
+    if (auto result = Core::System::chdir(root_path); result.is_error()) {
+        warnln("Failed to open project: {}", result.release_error());
         exit(1);
     }
     if (m_project) {
@@ -1024,7 +1024,7 @@ ErrorOr<NonnullRefPtr<GUI::Action>> HackStudioWidget::create_debug_action()
         // The debugger calls wait() on the debuggee, so the TerminalWrapper can't do that.
         auto ptm_res = m_terminal_wrapper->setup_master_pseudoterminal(TerminalWrapper::WaitForChildOnExit::No);
         if (ptm_res.is_error()) {
-            perror("setup_master_pseudoterminal");
+            warnln("Failed to set up master pseudoterminal: {}", ptm_res.release_error());
             return;
         }
 

Userland/DevTools/HackStudio/LanguageServers/ConnectionFromClient.cpp

@@ -29,12 +29,12 @@ void ConnectionFromClient::die()
 void ConnectionFromClient::greet(ByteString const& project_root)
 {
     m_filedb.set_project_root(project_root);
-    if (unveil(project_root.characters(), "r") < 0) {
-        perror("unveil");
+    if (auto result = Core::System::unveil(project_root, "r"sv); result.is_error()) {
+        warnln("Failed to unveil `{}`: {}", project_root, result.error());
         exit(1);
     }
-    if (unveil(nullptr, nullptr) < 0) {
-        perror("unveil");
+    if (auto result = Core::System::unveil(nullptr, nullptr); result.is_error()) {
+        warnln("Failed to lock the veil: {}", result.error());
         exit(1);
     }
 }

Userland/DevTools/HackStudio/main.cpp

@@ -93,18 +93,25 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
 
 static bool make_is_available()
 {
-    pid_t pid;
     char const* argv[] = { "make", "--version", nullptr };
     posix_spawn_file_actions_t action;
     posix_spawn_file_actions_init(&action);
     posix_spawn_file_actions_addopen(&action, STDOUT_FILENO, "/dev/null", O_WRONLY, 0);
 
-    if ((errno = posix_spawnp(&pid, "make", &action, nullptr, const_cast<char**>(argv), environ))) {
-        perror("posix_spawn");
+    auto maybe_pid = Core::System::posix_spawnp("make"sv, &action, nullptr, const_cast<char**>(argv), environ);
+    if (maybe_pid.is_error()) {
+        warnln("Failed to posix_spawn make: {}", maybe_pid.release_error());
         return false;
     }
-    int wstatus;
-    waitpid(pid, &wstatus, 0);
+    pid_t pid = maybe_pid.release_value();
+
+    auto waitpid_result = Core::System::waitpid(pid, 0);
+    if (waitpid_result.is_error()) {
+        warnln("Failed to waitpid for make: {}", waitpid_result.release_error());
+        return false;
+    }
+
+    int wstatus = waitpid_result.value().status;
     posix_spawn_file_actions_destroy(&action);
     return WEXITSTATUS(wstatus) == 0;
 }