Tty or Shell naming a file that is there but not executable says so

It said no shell "x", not found, as for a name that is nowhere. A file that exists without its execute bit now says not a shell: x is not executable.

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

1 files changed, 5 insertions, 0 deletions

diff --git a/src/host_io.zig b/src/host_io.zig
index 85ba94f4..072f3100 100644
--- a/src/host_io.zig
+++ b/src/host_io.zig
@@ -872,6 +872,8 @@ pub const Shell = struct {
             @memcpy(buf[0..bin.len], bin);
             buf[bin.len] = 0;
             if (isDirectory(@ptrCast(&buf))) return std.fmt.bufPrint(said, "not a shell: {s} is a directory", .{bin}) catch "not a shell: a directory";
+            // There, but no program: said so, not "not found".
+            if (libc.access(@ptrCast(&buf), 0) == 0) return std.fmt.bufPrint(said, "not a shell: {s} is not executable", .{bin}) catch "not a shell: not executable";
         }
         // "not found": the words a mount reads as ENOENT.
         return std.fmt.bufPrint(said, "no shell \"{s}\", not found (a name on the usual paths, or a path to one)", .{bin}) catch "no such shell";
@@ -912,6 +914,9 @@ pub const Shell = struct {
         try std.testing.expectEqualStrings("interpreter /no/such/interp not found", refusal(try std.fmt.bufPrint(&path, "{s}/bad", .{dir}), &said).?);
         try std.testing.expect(refusal(try std.fmt.bufPrint(&path, "{s}/good", .{dir}), &said) == null);
         try std.testing.expect(std.mem.startsWith(u8, refusal(try std.fmt.bufPrint(&path, "{s}/none", .{dir}), &said).?, "no shell "));
+        try tmp.dir.writeFile(std.testing.io, .{ .sub_path = "plain", .data = "echo\n" });
+        const plain = try std.fmt.bufPrint(&path, "{s}/plain", .{dir});
+        try std.testing.expect(std.mem.endsWith(u8, refusal(plain, &said).?, "plain is not executable"));
     }
 
     fn fallback(buf: *[std.fs.max_path_bytes]u8) [*:0]const u8 {