A script whose interpreter is not there is told apart from a missing shell, and Tty refuses it up front

Tty's up-front check found the script and let it through, so the pane was made, its exec failed ENOENT, and the log read new, msg shell: shell not found, del, then the err. The check now reads a script's #! line and refuses it, interpreter /no/such/interp not found, and an exec that fails ENOENT on a file that is there says the same.

Co-Authored-By: Claude Opus 5.5 <[email protected]>

1 files changed, 24 insertions, 10 deletions

diff --git a/src/pardes.zig b/src/pardes.zig
index d9c69921..d2fd795b 100644
--- a/src/pardes.zig
+++ b/src/pardes.zig
@@ -5338,16 +5338,7 @@ pub const Pardes = struct {
         const pane = p.panes[id] orelse return;
         pane.shell_failed = true;
         ctlfs.pty.shellGone(p, pane, false);
-        if (err == error.FileNotFound or err == error.NotDir)
-            p.reportFailure(id, "shell: directory missing (no such directory)")
-        else
-            p.reportError(id, "shell", err);
-        // A 9P write that asked for the shell (pty/ctl's exec), waiting on
-        // it, fails with what was said, as a failed Save's does.
-        const said = pane.msg[0..pane.msg_len];
-        const kept = @import("Messages.zig").clip(said, p.fs.late_failure.len);
-        @memcpy(p.fs.late_failure[0..kept.len], kept);
-        p.fs.late_failure_len = @intCast(kept.len);
+        p.sayShellFailure(id, err);
         // A command that never started ended: `exit 127`, as a shell says of
         // a command it could not run, so a follower waiting on its exit
         // hears one, its tag stops saying it runs, and Kill finds nothing.
@@ -5362,6 +5353,29 @@ pub const Pardes = struct {
         }
     }
 
+    fn sayShellFailure(p: *Pardes, id: u8, err: anyerror) void {
+        const pane = p.panes[id] orelse return;
+        if (err == error.FileNotFound or err == error.NotDir) {
+            p.reportFailure(id, "shell: directory missing (no such directory)");
+        } else if (err == error.InterpreterNotFound) {
+            // The script is there; the program its `#!` names is not.
+            var said: [320]u8 = undefined;
+            var interp: [256]u8 = undefined;
+            var buf: [std.fs.max_path_bytes]u8 = undefined;
+            const Shell = if (comptime hosted) @import("host_io.zig").Shell else void;
+            const name: ?[]const u8 = if (comptime hosted) (if (Shell.find(pane.shell orelse p.shellBin(), &buf)) |f| Shell.missingInterpreter(f, &interp) else null) else null;
+            p.reportFailure(id, if (name) |n| std.fmt.bufPrint(&said, "shell: interpreter {s} not found", .{n}) catch "shell: interpreter not found" else "shell: interpreter not found");
+        } else {
+            p.reportError(id, "shell", err);
+        }
+        // A 9P write that asked for the shell (pty/ctl's exec), waiting on
+        // it, fails with what was said, as a failed Save's does.
+        const said = pane.msg[0..pane.msg_len];
+        const kept = @import("Messages.zig").clip(said, p.fs.late_failure.len);
+        @memcpy(p.fs.late_failure[0..kept.len], kept);
+        p.fs.late_failure_len = @intCast(kept.len);
+    }
+
     pub fn saveFailed(p: *Pardes, id: u8, path: []const u8, err: anyerror) void {
         if (p.panes[id]) |pane| if (pane.file) |*f| {
             // The `-%` spelling fs.zig already uses for "make this dirty".