1 files changed, 57 insertions, 0 deletions
diff --git a/src/fs.zig b/src/fs.zig
index 14b6a76a..50b56f76 100644
--- a/src/fs.zig
+++ b/src/fs.zig
@@ -1200,6 +1200,63 @@ pub fn readFile(gpa: std.mem.Allocator, path: []const u8) ![]u8 {
     return readFileLimit(gpa, path, limits.max_file_bytes);
 }
 
+/// Restore first tries a relative argument under the default dump directory,
+/// then preserves the ordinary file lookup. Absolute paths remain verbatim.
+pub fn readRestore(gpa: std.mem.Allocator, path: []const u8) ![]u8 {
+    var dir_buf: [4096]u8 = undefined;
+    const dir = @import("dump.zig").defaultDirectory(&dir_buf);
+    return readRestoreIn(gpa, path, dir);
+}
+
+fn readRestoreIn(gpa: std.mem.Allocator, path: []const u8, dir: ?[]const u8) ![]u8 {
+    if (!std.fs.path.isAbsolute(path)) {
+        if (dir) |base| {
+            var buf: [4096]u8 = undefined;
+            if (std.fmt.bufPrint(&buf, "{s}/{s}", .{ base, path })) |candidate| {
+                if (readFile(gpa, candidate)) |bytes| return bytes else |err| switch (err) {
+                    error.FileNotFound => {},
+                    else => return err,
+                }
+            } else |_| {}
+        }
+    }
+    return readFile(gpa, path);
+}
+
+test "Restore prefers default directory then falls back to original path" {
+    if (!platform_has_fs) return error.SkipZigTest;
+    const gpa = std.testing.allocator;
+    var tmp = std.testing.tmpDir(.{});
+    defer tmp.cleanup();
+    const relative = try std.fmt.allocPrint(gpa, ".zig-cache/tmp/{s}/a.dump", .{tmp.sub_path});
+    defer gpa.free(relative);
+    const base = try std.fmt.allocPrint(gpa, ".zig-cache/tmp/{s}/dumps", .{tmp.sub_path});
+    defer gpa.free(base);
+    const nested = try std.fmt.allocPrint(gpa, "dumps/.zig-cache/tmp/{s}", .{tmp.sub_path});
+    defer gpa.free(nested);
+    try tmp.dir.createDirPath(std.testing.io, nested);
+    try tmp.dir.writeFile(std.testing.io, .{ .sub_path = "dumps/a.dump", .data = "short name" });
+    const short = try readRestoreIn(gpa, "a.dump", base);
+    defer gpa.free(short);
+    try std.testing.expectEqualStrings("short name", short);
+    try tmp.dir.writeFile(std.testing.io, .{ .sub_path = "a.dump", .data = "original" });
+    const fallback = try readRestoreIn(gpa, relative, base);
+    defer gpa.free(fallback);
+    try std.testing.expectEqualStrings("original", fallback);
+    const candidate = try std.fmt.allocPrint(gpa, "{s}/{s}", .{ base, relative });
+    defer gpa.free(candidate);
+    try writeFile(candidate, "default");
+    const preferred = try readRestoreIn(gpa, relative, base);
+    defer gpa.free(preferred);
+    try std.testing.expectEqualStrings("default", preferred);
+    const absolute = try tmp.dir.realPathFileAlloc(std.testing.io, "a.dump", gpa);
+    defer gpa.free(absolute);
+    const direct = try readRestoreIn(gpa, absolute, base);
+    defer gpa.free(direct);
+    try std.testing.expectEqualStrings("original", direct);
+    try std.testing.expectError(error.FileNotFound, readRestoreIn(gpa, "missing-restore-test.dump", base));
+}
+
 fn readFileLimit(gpa: std.mem.Allocator, path: []const u8, limit: usize) ![]u8 {
     if (std.mem.indexOfScalar(u8, path, 0) != null) return error.OpenFailed;
     if (!platform_has_fs or std.mem.startsWith(u8, path, "/virtual/")) {