log stats 0, and pardes re-pins cloud9 whose 9ns opens such a file direct and nonseekable: fs.md's follow recipe with cat works through a mount

The log stated the length an open would freeze, a length a mount's
kernel could take as its end, and a splicing cat read it from the
kernel's offset. log now stats 0, as the other streams and generated
views do, and the re-pinned cloud9's 9ns opens any file stating 0
FOPEN_DIRECT_IO | FOPEN_NONSEEKABLE. A look at such a file (the mounted
index) reads a regular file that will not seek as a stream rather than
refusing it as a pipe. selfmount runs the recipe, exec 3<>log; echo
follow >&3; cat <&3, through the mount and hears a record made after it
started.

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

1 files changed, 11 insertions, 1 deletions

diff --git a/src/ninep/tree.zig b/src/ninep/tree.zig
index be03e8f0..8c536c51 100644
--- a/src/ninep/tree.zig
+++ b/src/ninep/tree.zig
@@ -646,7 +646,9 @@ fn topSize(p: *Pardes, f: TopFile) u64 {
         .README => fs.help.len,
         .status => ctl.statusLen(p),
         .look, .exec, .tagexec => ctl.resultsLen(p),
-        .log => events.logLen(&p.fs.log),
+        // A stream: a length would read as its end to a kernel that caches
+        // one (a 9ns mount's splice), and a follower's reads go past it.
+        .log => 0,
         .ctl => ctl.rootLen(p),
         .commands => ctl.commandsLen(),
         .focus => focus: {
@@ -1335,6 +1337,14 @@ test "filesystem inspection preserves pending and displayed Look hover" {
     try testing.expect(!p.raw_hover_intent);
 }
 
+test "log stats 0 however much it holds, a stream as acme's generated files are" {
+    const p = try th.withFile(testing.allocator, "x\n");
+    defer p.deinit();
+    _ = th.wr(p, Node.of(th.serialOf(p), .exec), "Msg a record for the log\n");
+    try testing.expect(th.logHas(p, "a record for the log"));
+    try testing.expectEqual(@as(u64, 0), call(p, .{ .tag = 1, .op = .getattr, .node = @intFromEnum(TopFile.log) }).reply.attr.size);
+}
+
 test "filesystem pane creation and truncation cancel Look hover" {
     const requests = [_]Req{
         // Opening `new` is what makes a pane now; walking to it makes none,