DumpDir refuses a relative directory and one that may not be written, up front, and a Dump that could not make its directory says permission denied

A relative DumpDir was resolved from wherever pardes started, and one
under a directory that may not be written was taken, the Dump failing
later as `no such directory`. DumpDir now takes an absolute or `~` path
whose nearest directory there may be written, and refuses any other with
what it takes; a Dump refused by a directory above says permission
denied (fs.deniedAbove), as a Save does.

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

1 files changed, 16 insertions, 2 deletions

diff --git a/src/ninep/ctl.zig b/src/ninep/ctl.zig
index 89c2e5dd..d4d09e0b 100644
--- a/src/ninep/ctl.zig
+++ b/src/ninep/ctl.zig
@@ -2332,8 +2332,9 @@ test "a Restore of a file that is no dump fails the write before any warning, an
     try testing.expect(p.panes[0].?.discard_warned == null);
 
     p.fs.late_failure_len = 0;
-    p.dumpFailed("/nowhere/pardes.dump.zon", error.FileNotFound);
-    try testing.expectEqualStrings("Dump /nowhere/pardes.dump.zon: no such directory", p.fs.late_failure[0..p.fs.late_failure_len]);
+    // (Under /tmp: under / a user's Dump is refused permission, not missing.)
+    p.dumpFailed("/tmp/pardes-nowhere-zz/pardes.dump.zon", error.FileNotFound);
+    try testing.expectEqualStrings("Dump /tmp/pardes-nowhere-zz/pardes.dump.zon: no such directory", p.fs.late_failure[0..p.fs.late_failure_len]);
     // A DumpDir that is there but no directory says that.
     p.fs.late_failure_len = 0;
     p.dumpFailed("/dev/null/pardes.dump.zon", error.NotDir);
@@ -4357,3 +4358,16 @@ test "a ctl line over 1 MiB is refused once, EINVAL, and its tail is not run as
     try testing.expectEqualStrings("", pane_files.fileOf(p.panes[0].?).?.content);
     _ = call(p, .{ .tag = 4, .op = .release, .node = node, .handle = h });
 }
+
+test "DumpDir refuses a relative directory and one that may not be written, up front; a Dump there says permission denied" {
+    if (comptime !pardes.hosted) return;
+    const p = try withFile(testing.allocator, "x\n");
+    defer p.deinit();
+    const root_ctl = @intFromEnum(tree.TopFile.ctl);
+    try testing.expectEqual(E.INVAL, wr(p, root_ctl, "DumpDir dumps\n").errno());
+    try testing.expectEqual(E.INVAL, wr(p, root_ctl, "DumpDir /proc/1/root/dumps\n").errno());
+    try testing.expectEqual(Status.ok, wr(p, root_ctl, "DumpDir /tmp/pardes-dumps-test\n").reply.status);
+    p.fs.late_failure_len = 0;
+    p.dumpFailed("/proc/1/root/x/pardes.dump.zon", error.FileNotFound);
+    try testing.expect(std.mem.endsWith(u8, p.fs.late_failure[0..p.fs.late_failure_len], ": permission denied"));
+}