fix: last RV11 gaps - bench enum args, theme NUL paths, Zig error names

Resolves the 3 remaining gaps in docs/rewrite/notes/review-rv11-codex.md
(final-Z14.md):
- ghostty-bench validates every occurrence of enum options in order
  (Args::take_enum; empty value resets) like cli/args.zig, so
  `--mode=bad --mode=noop` fails as in Zig.
- Theme paths with an interior NUL open the prefix like Zig's C-string
  path handling (verified against /usr/bin/ghostty).
- Filesystem diagnostics print Zig's error names (error.FileNotFound,
  NotDir, AccessDenied, IsDir, NameTooLong, SymLinkLoop, ...) via a
  shared ghostty_os::zig_error mapping used by theme/path/config-file/
  file_load/edit-config/list-themes; messages match the oracle.

Test Plan:
- cargo test --workspace --no-fail-fast
- just check-macos (both), just check-windows, just check-wasm

crates/ghostty-bench/src/args.rs

@@ -122,6 +122,27 @@ impl Args {
         })
     }
 
+    /// Take an enum value (`parseIntoField` on an enum): every occurrence is
+    /// validated against `variants` in order (a bad value is an error even if
+    /// a later one is fine); an empty value resets to `default`.
+    pub fn take_enum<T: Copy>(
+        &mut self,
+        key: &str,
+        default: T,
+        variants: &[(&str, T)],
+    ) -> Result<T, String> {
+        self.apply(key, default, |v| {
+            let v = v.ok_or_else(|| format!("option --{key} requires a value"))?;
+            let bad = || format!("invalid value for --{key}: {}", v.to_string_lossy());
+            let v = v.to_str().ok_or_else(bad)?;
+            variants
+                .iter()
+                .find(|(n, _)| *n == v)
+                .map(|(_, t)| *t)
+                .ok_or_else(bad)
+        })
+    }
+
     /// Take a file path value (any bytes are allowed).
     pub fn take_opt_path(&mut self, key: &str) -> Result<Option<PathBuf>, String> {
         self.apply(key, None, |v| {
@@ -197,6 +218,21 @@ mod tests {
         assert!(a.take("n", 0u16).is_err());
     }
 
+    #[test]
+    fn take_enum_validates_every_occurrence() {
+        let t = |v: &[&str]| {
+            Args::parse(v.iter().map(OsString::from))
+                .unwrap()
+                .take_enum("mode", 0u8, &[("noop", 0), ("table", 1)])
+        };
+        assert!(t(&["--mode=bad", "--mode=noop"]).is_err());
+        assert!(t(&["--mode=noop", "--mode=bad"]).is_err());
+        assert!(t(&["--mode=bad", "--mode="]).is_err());
+        assert_eq!(t(&["--mode=table", "--mode="]).unwrap(), 0);
+        assert_eq!(t(&["--mode=noop", "--mode=table"]).unwrap(), 1);
+        assert_eq!(t(&[]).unwrap(), 0);
+    }
+
     #[test]
     fn duplicates_apply_in_order_and_first_error_wins() {
         let a = |v: &[&str]| Args::parse(v.iter().map(OsString::from)).unwrap();

crates/ghostty-bench/src/benches.rs

@@ -104,11 +104,7 @@ impl TerminalStream {
         let rows = args.take("terminal-rows", 80u16)?;
         let cols = args.take("terminal-cols", 120u16)?;
         let data = args.take_opt_path("data")?;
-        let full = match args.take_opt_string("handler")?.as_deref() {
+        let full = args.take_enum("handler", false, &[("print", false), ("full", true)])?;
-            None | Some("print") => false,
-            Some("full") => true,
-            Some(m) => return Err(format!("invalid value for --handler: {m}")),
-        };
         let t = Terminal::new(TermOptions::new(cols, rows)).map_err(|e| format!("{e:?}"))?;
         Ok(TerminalStream {
             data: Data::new(data),
@@ -259,13 +255,16 @@ pub struct CodepointWidth {
 
 impl CodepointWidth {
     pub fn create(args: &mut Args) -> std::result::Result<Self, String> {
-        let mode = match args.take_opt_string("mode")?.as_deref() {
+        let mode = args.take_enum(
-            None | Some("noop") => WidthMode::Noop,
+            "mode",
-            Some("wcwidth") => WidthMode::Wcwidth,
+            WidthMode::Noop,
-            Some("simd") => WidthMode::Simd,
+            &[
-            Some("table") => WidthMode::Table,
+                ("noop", WidthMode::Noop),
-            Some(m) => return Err(format!("invalid value for --mode: {m}")),
+                ("wcwidth", WidthMode::Wcwidth),
-        };
+                ("simd", WidthMode::Simd),
+                ("table", WidthMode::Table),
+            ],
+        )?;
         Ok(CodepointWidth {
             data: Data::new(args.take_opt_path("data")?),
             mode,
@@ -384,11 +383,7 @@ pub struct GraphemeBreak {
 
 impl GraphemeBreak {
     pub fn create(args: &mut Args) -> std::result::Result<Self, String> {
-        let noop = match args.take_opt_string("mode")?.as_deref() {
+        let noop = args.take_enum("mode", false, &[("noop", true), ("table", false)])?;
-            None | Some("table") => false,
-            Some("noop") => true,
-            Some(m) => return Err(format!("invalid value for --mode: {m}")),
-        };
         Ok(GraphemeBreak {
             data: Data::new(args.take_opt_path("data")?),
             noop,
@@ -473,11 +468,11 @@ pub fn is_symbol_computed(cp: u32) -> bool {
 
 impl IsSymbol {
     pub fn create(args: &mut Args) -> std::result::Result<Self, String> {
-        let mode = match args.take_opt_string("mode")?.as_deref() {
+        let mode = args.take_enum(
-            None | Some("uucode") => SymbolMode::Uucode,
+            "mode",
-            Some("table") => SymbolMode::Table,
+            SymbolMode::Uucode,
-            Some(m) => return Err(format!("invalid value for --mode: {m}")),
+            &[("uucode", SymbolMode::Uucode), ("table", SymbolMode::Table)],
-        };
+        )?;
         Ok(IsSymbol {
             data: Data::new(args.take_opt_path("data")?),
             mode,
@@ -536,12 +531,15 @@ pub struct ScreenClone {
 
 impl ScreenClone {
     pub fn create(args: &mut Args) -> std::result::Result<Self, String> {
-        let mode = match args.take_opt_string("mode")?.as_deref() {
+        let mode = args.take_enum(
-            None | Some("clone") => CloneMode::Clone,
+            "mode",
-            Some("noop") => CloneMode::Noop,
+            CloneMode::Clone,
-            Some("render") => CloneMode::Render,
+            &[
-            Some(m) => return Err(format!("invalid value for --mode: {m}")),
+                ("clone", CloneMode::Clone),
-        };
+                ("noop", CloneMode::Noop),
+                ("render", CloneMode::Render),
+            ],
+        )?;
         let rows = args.take("terminal-rows", 80u16)?;
         let cols = args.take("terminal-cols", 120u16)?;
         let data = args.take_opt_path("data")?;
@@ -718,6 +716,20 @@ mod tests {
         let _ = std::fs::remove_file(p);
     }
 
+    #[test]
+    fn duplicate_bad_enum_modes_fail() {
+        let mk = |v: &[&str]| Args::parse(v.iter().map(|s| (*s).to_owned())).unwrap();
+        for v in [
+            &["--mode=bad", "--mode=noop"][..],
+            &["--mode=bad", "--mode="][..],
+        ] {
+            assert!(CodepointWidth::create(&mut mk(v)).is_err());
+            assert!(GraphemeBreak::create(&mut mk(v)).is_err());
+            assert!(IsSymbol::create(&mut mk(v)).is_err());
+            assert!(ScreenClone::create(&mut mk(v)).is_err());
+        }
+    }
+
     #[test]
     fn is_symbol_modes_run() {
         let p = sample_file("sym");

crates/ghostty-bench/src/bin/ghostty-synthetic.rs

@@ -40,11 +40,14 @@ fn run() -> Result<(), String> {
         }
         "osc" => {
             let p_valid = args.take("p-valid", 0.5f64)?;
-            let style = match args.take_opt_string("style")?.as_deref() {
+            let style = args.take_enum(
-                None | Some("streaming") => OscStyle::Streaming,
+                "style",
-                Some("parser") => OscStyle::Parser,
+                OscStyle::Streaming,
-                Some(s) => return Err(format!("invalid value for --style: {s}")),
+                &[
-            };
+                    ("streaming", OscStyle::Streaming),
+                    ("parser", OscStyle::Parser),
+                ],
+            )?;
             args.finish()?;
             run_osc(&mut out, &mut rng, p_valid, style)
         }

crates/ghostty-cli/src/edit_config.rs

@@ -122,11 +122,7 @@ fn exec_editor(stderr: &mut dyn Write, path: &EncodedOs) -> Result<u8, Error> {
         .exec();
 
     // If we reached this point then exec failed.
-    let err = match err.kind() {
+    let err = ghostty_os::zig_error::io_error_name(&err);
-        std::io::ErrorKind::NotFound => "error.FileNotFound".to_string(),
-        std::io::ErrorKind::PermissionDenied => "error.AccessDenied".to_string(),
-        _ => err.to_string(),
-    };
     let msg = format!(
         "Failed to execute the editor. Error code={err}.\n\
          \n\

crates/ghostty-cli/src/list_themes/preview.rs

@@ -1396,11 +1396,9 @@ impl Preview {
 fn error_name(e: &ghostty_config::config::Error) -> String {
     use ghostty_config::config::Error;
     match e {
-        Error::Io(io) => match io.kind() {
+        Error::Io(io) => ghostty_os::zig_error::io_error_name(io)
-            std::io::ErrorKind::NotFound => "FileNotFound".to_string(),
+            .trim_start_matches("error.")
-            std::io::ErrorKind::PermissionDenied => "AccessDenied".to_string(),
+            .to_owned(),
-            _ => io.to_string(),
-        },
         e => e.to_string(),
     }
 }

crates/ghostty-config/src/config.rs

@@ -3752,7 +3752,7 @@ crate::config_struct! {
 /// Errors from loading configuration.
 #[derive(Debug, thiserror::Error)]
 pub enum Error {
-    #[error("{0}")]
+    #[error("{}", ghostty_os::zig_error::io_error_name(.0))]
     Io(#[from] std::io::Error),
     #[error("{0}")]
     Arg(#[from] ArgError),
@@ -4273,7 +4273,7 @@ impl Config {
                             message: format!(
                                 "error opening config-file {}: {}",
                                 path.as_encoded(),
-                                zig_io_error_name(&err)
+                                ghostty_os::zig_error::io_error_name(&err)
                             ),
                             ..Diagnostic::default()
                         };
@@ -4806,40 +4806,6 @@ impl Iterator for ChangeIterator<'_> {
     }
 }
 
-/// Name of an IO error like Zig's `{}` formatting of an error value
-/// (`error.FileNotFound`), used in user-visible diagnostics.
-fn zig_io_error_name(err: &std::io::Error) -> String {
-    use std::io::ErrorKind;
-    #[cfg(unix)]
-    if let Some(errno) = err.raw_os_error() {
-        let name = match errno {
-            2 => Some("FileNotFound"),
-            13 => Some("AccessDenied"),
-            1 => Some("PermissionDenied"),
-            21 => Some("IsDir"),
-            20 => Some("NotDir"),
-            40 => Some("SymLinkLoop"),
-            36 => Some("NameTooLong"),
-            24 => Some("ProcessFdQuotaExceeded"),
-            23 => Some("SystemFdQuotaExceeded"),
-            12 => Some("SystemResources"),
-            19 => Some("NoDevice"),
-            16 => Some("DeviceBusy"),
-            26 => Some("FileBusy"),
-            30 => Some("ReadOnlyFileSystem"),
-            _ => None,
-        };
-        if let Some(name) = name {
-            return format!("error.{name}");
-        }
-    }
-    match err.kind() {
-        ErrorKind::NotFound => "error.FileNotFound".to_string(),
-        ErrorKind::PermissionDenied => "error.AccessDenied".to_string(),
-        _ => "error.Unexpected".to_string(),
-    }
-}
-
 fn file_kind_name(meta: &std::fs::Metadata) -> &'static str {
     let ft = meta.file_type();
     if ft.is_dir() {

crates/ghostty-config/src/file_load.rs

@@ -170,15 +170,20 @@ pub fn open(path: &EncodedOs) -> Result<File, OpenFileError> {
             OpenFileError::FileNotFound
         } else {
             log::warn!(
-                "unexpected file open error path={} err={err}",
+                "unexpected file open error path={} err={}",
-                real.display()
+                real.display(),
+                ghostty_os::zig_error::io_error_name(&err)
             );
             OpenFileError::FileOpenFailed
         }
     })?;
 
     let meta = file.metadata().map_err(|err| {
-        log::warn!("error getting file stat path={} err={err}", real.display());
+        log::warn!(
+            "error getting file stat path={} err={}",
+            real.display(),
+            ghostty_os::zig_error::io_error_name(&err)
+        );
         OpenFileError::FileOpenFailed
     })?;
     if !meta.is_file() {

crates/ghostty-config/src/path.rs

@@ -164,7 +164,11 @@ impl Path {
             }
             Err(err) => {
                 diags.append(Diagnostic {
-                    message: format!("error resolving file path {}: {err}", path.as_encoded()),
+                    message: format!(
+                        "error resolving file path {}: {}",
+                        path.as_encoded(),
+                        ghostty_os::zig_error::io_error_name(&err)
+                    ),
                     ..Diagnostic::default()
                 });
 

crates/ghostty-config/src/theme.rs

@@ -128,7 +128,13 @@ pub(crate) fn special_kind_name(_: std::fs::FileType) -> &'static str {
 fn check_regular(file: &File, theme: &str, diags: &mut DiagnosticList) -> bool {
     match file.metadata() {
         Err(err) => {
-            diag(diags, format!("not reading theme from \"{theme}\": {err}"));
+            diag(
+                diags,
+                format!(
+                    "not reading theme from \"{theme}\": {}",
+                    ghostty_os::zig_error::io_error_name(&err)
+                ),
+            );
             false
         }
         Ok(m) if !m.is_file() => {
@@ -197,7 +203,7 @@ pub fn open(
     let mut it = LocationIterator::new(resources_dir);
     while let Some((_, dir)) = it.next_location() {
         let path = EncodedOs::from_path(&dir.to_path().ok()?.join(&theme_path));
-        match path.to_path().and_then(File::open) {
+        match path.to_syscall_path().and_then(File::open) {
             Ok(file) => {
                 if !check_regular(&file, theme_text, diags) {
                     return None;
@@ -211,8 +217,9 @@ pub fn open(
                 diag(
                     diags,
                     format!(
-                        "failed to load theme \"{theme_text}\" from the file \"{}\": {err}",
+                        "failed to load theme \"{theme_text}\" from the file \"{}\": {}",
-                        path.as_encoded()
+                        path.as_encoded(),
+                        ghostty_os::zig_error::io_error_name(&err)
                     ),
                 );
                 return None;
@@ -241,7 +248,7 @@ pub fn open(
 /// then messages will be appended to the given error list and None is
 /// returned.
 pub fn open_absolute(theme: &EncodedOs, diags: &mut DiagnosticList) -> Option<File> {
-    let path = theme.to_path();
+    let path = theme.to_syscall_path();
     let theme = theme.as_encoded();
     match path.and_then(File::open) {
         Ok(f) => Some(f),
@@ -254,7 +261,10 @@ pub fn open_absolute(theme: &EncodedOs, diags: &mut DiagnosticList) -> Option<Fi
             } else {
                 diag(
                     diags,
-                    format!("failed to load theme from the path \"{theme}\": {err}"),
+                    format!(
+                        "failed to load theme from the path \"{theme}\": {}",
+                        ghostty_os::zig_error::io_error_name(&err)
+                    ),
                 );
             }
             None
@@ -282,6 +292,33 @@ mod tests {
         );
     }
 
+    #[cfg(unix)]
+    #[test]
+    fn theme_path_errors_use_zig_names() {
+        let mut d = DiagnosticList::default();
+        assert!(open(&e("/etc/passwd/x"), None, &mut d).is_none());
+        assert_eq!(
+            d.items()[0].message,
+            "failed to load theme from the path \"/etc/passwd/x\": error.NotDir"
+        );
+    }
+
+    #[cfg(unix)]
+    #[test]
+    fn theme_absolute_interior_nul_opens_prefix() {
+        let dir = std::env::temp_dir().join(format!("gtheme-nul-{}", std::process::id()));
+        let _ = std::fs::create_dir_all(&dir);
+        let f = dir.join("t");
+        std::fs::write(&f, "background = #112233\n").unwrap();
+        let mut bytes = f.as_os_str().as_encoded_bytes().to_vec();
+        bytes.extend_from_slice(b"\0tail");
+        let t = EncodedOs::from_bytes(&bytes);
+        let mut d = DiagnosticList::default();
+        assert!(open(&t, None, &mut d).is_some());
+        assert_eq!(d.items().len(), 0);
+        let _ = std::fs::remove_dir_all(&dir);
+    }
+
     #[test]
     fn theme_absolute_missing_and_dir() {
         let mut d = DiagnosticList::default();

crates/ghostty-os/src/lib.rs

@@ -123,6 +123,7 @@ pub use unsupported::homedir::expand_home;
 pub use unsupported::{ResourcesDir, homedir, is_flatpak, passwd, resources_dir, xdg};
 #[cfg(not(target_arch = "wasm32"))]
 pub mod xdg;
+pub mod zig_error;
 
 #[cfg(test)]
 pub(crate) mod testutil;

crates/ghostty-os/src/zig_error.rs

@@ -0,0 +1,63 @@
+//! `std::io::Error` -> Zig error name (`{}` of an error value, e.g.
+//! `error.FileNotFound`), following Zig std's posix errno mapping for the
+//! calls Ghostty makes (`openat`, `fstat`, `realpath`, `execve`, ...).
+
+/// Zig error name (without the `error.` prefix) for a Linux errno.
+#[must_use]
+pub fn errno_name(errno: i32) -> &'static str {
+    match errno {
+        1 => "PermissionDenied",        // EPERM
+        2 => "FileNotFound",            // ENOENT
+        3 => "ProcessNotFound",         // ESRCH
+        6 | 19 => "NoDevice",           // ENXIO, ENODEV
+        11 => "WouldBlock",             // EAGAIN
+        12 => "SystemResources",        // ENOMEM
+        13 => "AccessDenied",           // EACCES
+        16 => "DeviceBusy",             // EBUSY
+        17 => "PathAlreadyExists",      // EEXIST
+        20 => "NotDir",                 // ENOTDIR
+        21 => "IsDir",                  // EISDIR
+        23 => "SystemFdQuotaExceeded",  // ENFILE
+        24 => "ProcessFdQuotaExceeded", // EMFILE
+        26 => "FileBusy",               // ETXTBSY
+        27 | 75 => "FileTooBig",        // EFBIG, EOVERFLOW
+        28 => "NoSpaceLeft",            // ENOSPC
+        30 => "ReadOnlyFileSystem",     // EROFS
+        36 => "NameTooLong",            // ENAMETOOLONG
+        40 => "SymLinkLoop",            // ELOOP
+        84 => "InvalidWtf8",            // EILSEQ
+        95 => "FileLocksNotSupported",  // EOPNOTSUPP
+        _ => "Unexpected",
+    }
+}
+
+/// `error.Name` text for an I/O error.
+#[must_use]
+pub fn io_error_name(err: &std::io::Error) -> String {
+    if let Some(errno) = err.raw_os_error() {
+        return format!("error.{}", errno_name(errno));
+    }
+    match err.kind() {
+        std::io::ErrorKind::NotFound => "error.FileNotFound".into(),
+        std::io::ErrorKind::PermissionDenied => "error.AccessDenied".into(),
+        std::io::ErrorKind::InvalidInput => "error.BadPathName".into(),
+        _ => "error.Unexpected".into(),
+    }
+}
+
+#[cfg(all(test, unix))]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn names() {
+        let n = |e| io_error_name(&std::io::Error::from_raw_os_error(e));
+        assert_eq!(n(2), "error.FileNotFound");
+        assert_eq!(n(20), "error.NotDir");
+        assert_eq!(n(13), "error.AccessDenied");
+        assert_eq!(n(21), "error.IsDir");
+        assert_eq!(n(36), "error.NameTooLong");
+        assert_eq!(n(40), "error.SymLinkLoop");
+        assert_eq!(n(9999), "error.Unexpected");
+    }
+}

docs/rewrite/notes/final-Z14.md

@@ -0,0 +1,5 @@
+# Z14 (RV11 gaps)
+
+1. ghostty-bench: `Args::take_enum` validates every occurrence of an enum option in order (empty value resets to default), used by codepoint-width, grapheme-break, is-symbol, screen-clone, terminal-stream `--handler` and synthetic `+osc --style`. Tests in args.rs / benches.rs.
+2. Theme open (named and absolute) uses `to_syscall_path` so an interior NUL truncates the path like Zig's C string. Test `theme_absolute_interior_nul_opens_prefix`; checked against /usr/bin/ghostty (no diagnostics, loads).
+3. New `ghostty_os::zig_error::{errno_name, io_error_name}` (Zig std posix errno mapping). Used by theme.rs, path.rs, config.rs (config-file open, `config::Error::Io` Display), file_load.rs logs, edit_config.rs, list_themes preview. Verified identical to oracle for FileNotFound, NotDir, AccessDenied, IsDir ("it is a directory" path), NameTooLong, SymLinkLoop.