A Dump into a DumpDir that is no directory says so; the doc says a missing last directory is made

DumpDir /dev/null said no such directory though it is there, and the doc claimed a missing DumpDir always fails, where its last component is made at the Dump.

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

3 files changed, 21 insertions, 7 deletions

diff --git a/src/exec.zig b/src/exec.zig
index fdb9bdb7..683b2f04 100644
--- a/src/exec.zig
+++ b/src/exec.zig
@@ -397,12 +397,18 @@ pub fn isDirectory(path: []const u8) bool {
 
 /// Whether `path` is a plain file on this host, the turn out while it asks.
 pub fn isFile(path: []const u8) bool {
+    return kindOf(path) == .file;
+}
+
+/// What `path` is on this host, null when it is not there; the turn out
+/// while it asks.
+pub fn kindOf(path: []const u8) ?std.Io.File.Kind {
     var buf: [4096]u8 = undefined;
-    const z = std.fmt.bufPrintSentinel(&buf, "{s}", .{path}, 0) catch return false;
+    const z = std.fmt.bufPrintSentinel(&buf, "{s}", .{path}, 0) catch return null;
     pardes.turn.yield();
     defer pardes.turn.back();
-    const stat = std.Io.Dir.cwd().statFile(std.Io.Threaded.global_single_threaded.io(), z, .{}) catch return false;
-    return stat.kind == .file;
+    const stat = std.Io.Dir.cwd().statFile(std.Io.Threaded.global_single_threaded.io(), z, .{}) catch return null;
+    return stat.kind;
 }
 
 /// With `BootShell replace`, a doc landing in `col` closes a lone pristine
diff --git a/src/ninep/ctl.zig b/src/ninep/ctl.zig
index dc2d9a84..ea0a0bc6 100644
--- a/src/ninep/ctl.zig
+++ b/src/ninep/ctl.zig
@@ -1667,6 +1667,10 @@ test "a Restore of a file that is no dump fails the write before any warning, an
     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]);
+    // 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);
+    try testing.expectEqualStrings("Dump /dev/null/pardes.dump.zon: /dev/null is not a directory", p.fs.late_failure[0..p.fs.late_failure_len]);
 }
 
 test "a setting this frontend cannot show says GUI-only, and DumpDir reads back the directory in effect" {
diff --git a/src/pardes.zig b/src/pardes.zig
index 2bf594c4..f6032ac5 100644
--- a/src/pardes.zig
+++ b/src/pardes.zig
@@ -5425,11 +5425,15 @@ pub const Pardes = struct {
     pub fn dumpFailed(p: *Pardes, path: []const u8, err: anyerror) void {
         var what: [limits.host_path_cap + 8]u8 = undefined;
         const operation = std.fmt.bufPrint(&what, "Dump {s}", .{path}) catch "Dump";
-        // Into a DumpDir that is not there: said so, ENOENT, as a Save is.
+        // Into a DumpDir that is not there: said so, ENOENT, as a Save is;
+        // one that is there but no directory (`/dev/null`) says that.
         const parent = std.fs.path.dirname(path) orelse "/";
-        const no_dir = err == error.FileNotFound or err == error.NotDir or
-            (if (comptime hosted) (if (filesystem.localPath(parent)) |local| !exec.isDirectory(local) else false) else false);
-        if (no_dir) {
+        const kind: ?std.Io.File.Kind = if (comptime hosted) (if (filesystem.localPath(parent)) |local| exec.kindOf(local) else .directory) else .directory;
+        const no_dir = err == error.FileNotFound or err == error.NotDir or kind != .directory;
+        if (kind != null and kind != .directory) {
+            var said: [limits.host_path_cap + 48]u8 = undefined;
+            p.reportFailure(p.active, std.fmt.bufPrint(&said, "{s}: {s} is not a directory", .{ operation, parent }) catch "Dump: not a directory");
+        } else if (no_dir) {
             var said: [limits.host_path_cap + 48]u8 = undefined;
             p.reportFailure(p.active, std.fmt.bufPrint(&said, "{s}: no such directory", .{operation}) catch "Dump: no such directory");
         } else p.reportError(p.active, operation, err);