Forwarding pardes @pN for a pane the session has not is refused, "this session has no such pane", exit 1 and no pane made; one it has is looked at

@p999:1 was taken as a new file's name, so a pane named <cwd>/@p999 was
made and the launch succeeded; an @pN the session did have was the same
stray pane. A pane address is now checked against the session: one it
has is a look at it, one it has not is refused with the reason and exit
1, as a refused name is.

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

2 files changed, 25 insertions, 2 deletions

diff --git a/src/main.zig b/src/main.zig
index 6c5eaba1..3218fef1 100644
--- a/src/main.zig
+++ b/src/main.zig
@@ -106,6 +106,8 @@ fn forwardWords(err: anyerror, buf: []u8) []const u8 {
         error.NotOneLine => "a file name is one line, and this one holds a newline",
         error.NotAFileName => "names a directory, not a file",
         error.NoWorkingDirectory => "this shell's working directory is gone",
+        error.NotAPaneAddress => "not a pane address: @p and a pane's number",
+        error.NoSuchPane => "this session has no such pane",
         else => if (pardes.Messages.dialReason(err)) |why| why else words: {
             var n: usize = 0;
             for (@errorName(err), 0..) |c, i| {
@@ -450,6 +452,20 @@ fn nativeMain(init: std.process.Init) !void {
         var home_buf: [4096]u8 = undefined;
         const word = pardes.filesystem.expandHome(typed_word, &home_buf);
         const target = @import("look.zig").parsePathLine(word);
+        // `@pN[:addr]` addresses a pane of this session: one it has is
+        // looked at, one it has not is refused, never a file of that name.
+        if (std.mem.startsWith(u8, target.path, pardes.config.pane_addr)) {
+            const digits = word[pardes.config.pane_addr.len .. std.mem.indexOfScalar(u8, word, ':') orelse word.len];
+            const serial = std.fmt.parseInt(u32, digits, 10) catch Refuse.with(init.io, word, error.NotAPaneAddress);
+            var name_buf: [64]u8 = undefined;
+            const name = try std.fmt.bufPrint(&name_buf, "/pane/{d}/name", .{serial});
+            const named = ninep_io.Client.read(arena, parent.dial, name, name) catch Refuse.with(init.io, word, error.NoSuchPane);
+            arena.free(named);
+            var command_buf: [4200]u8 = undefined;
+            const command = std.fmt.bufPrint(&command_buf, "{s}\n", .{word}) catch |err| Refuse.with(init.io, word, err);
+            ninep_io.Client.write(arena, parent.dial, look, command) catch |err| Refuse.with(init.io, word, err);
+            return;
+        }
         var realbuf: [4096]u8 = undefined;
         var newbuf: [4096]u8 = undefined;
         const found_path: ?[]const u8 = if (pardes.filesystem.isVirtual(target.path)) target.path else if (pardes.filesystem.resolveOs(target.path, &realbuf)) |r| r.path else null;
diff --git a/test/fs.py b/test/fs.py
index eba5a5fa..7061c61f 100644
--- a/test/fs.py
+++ b/test/fs.py
@@ -1391,14 +1391,21 @@ def test(binary, quic=False):
             assert refused.returncode == 1, refused
             assert b'bad character in file name' in refused.stderr, refused.stderr
             assert serials() == before, (serials(), before)
-            # A name with a newline is said in words, not an error's name.
-            for word, said in (('two\nlines.txt', b'a file name is one line'),):
+            # A pane address the session has not is refused in words, exit
+            # 1, no pane made for a file of that name; one it has is looked
+            # at. A name with a newline is said in words, not an error name.
+            for word, said in (('@p999:1', b'pardes: @p999:1: this session has no such pane'),
+                               ('two\nlines.txt', b'a file name is one line')):
                 refused = subprocess.run([binary, word], cwd=root, env=env,
                                          stdout=subprocess.PIPE, stderr=subprocess.PIPE, timeout=10)
                 assert refused.returncode == 1, refused
                 assert said in refused.stderr, refused.stderr
                 assert b'NotOneLine' not in refused.stderr and b'NoSuchPane' not in refused.stderr
                 assert serials() == before, (serials(), before)
+            looked = subprocess.run([binary, '@p1:1'], cwd=root, env=env,
+                                    stdout=subprocess.PIPE, stderr=subprocess.PIPE, timeout=10)
+            assert looked.returncode == 0, looked.stderr
+            assert serials() == before, (serials(), before)
             orphan = launch('--wait')
             assert orphan.poll() is None
         assert orphan.wait(timeout=5) == 1