Add tempdir support

crates/lb/Cargo.toml

@@ -9,7 +9,7 @@ repository.workspace = true
 
 [features]
 task = ["tokio/rt", "tokio/time"]
-fs = ["tokio/fs", "dep:walkdir", "dep:globset"]
+fs = ["tokio/fs", "dep:walkdir", "dep:globset", "dep:tempfile"]
 net = ["tokio/net"]
 
 [dependencies]
@@ -18,6 +18,7 @@ globset = { version = "0.4.16", optional = true }
 luaffi = { path = "../luaffi" }
 luajit = { path = "../luajit" }
 sysexits = "0.9.0"
+tempfile = { version = "3.20.0", optional = true }
 thiserror = "2.0.12"
 tokio = { version = "1.45.1" }
 walkdir = { version = "2.5.0", optional = true }

crates/lb/src/fs.rs

@@ -98,6 +98,14 @@ impl lb_fslib {
             prefix,
         })
     }
+
+    pub extern "Lua-C" fn temp_dir(&self) -> Result<lb_temp_dir> {
+        Ok(tempfile::tempdir()?.into())
+    }
+
+    pub extern "Lua-C" fn temp_dir_in(&self, path: &str) -> Result<lb_temp_dir> {
+        Ok(tempfile::tempdir_in(path)?.into())
+    }
 }
 
 /// Iterator over the entries in a directory.
@@ -401,3 +409,20 @@ impl lb_glob_dir {
         Ok(None)
     }
 }
+
+/// Directory in the filesystem that is automatically deleted when it is garbage-collected.
+#[derive(Debug, From)]
+#[cdef]
+pub struct lb_temp_dir(#[opaque] tempfile::TempDir);
+
+#[metatype]
+impl lb_temp_dir {
+    pub extern "Lua-C" fn path(&self) -> String {
+        self.0.path().to_string_lossy().into()
+    }
+
+    #[tostring]
+    pub extern "Lua" fn tostring(&self) -> String {
+        self.path()
+    }
+}

crates/lb/tests/fs.lua

@@ -0,0 +1,17 @@
+local ok, fs = pcall(require, "lb:fs")
+if not ok then return end
+
+describe("temp files", function()
+  test("temp_dir cleans itself", function()
+    local path
+    do
+      local dir = fs:temp_dir()
+      path = dir:path()
+      assert(path and path ~= "")
+      fs:write(path .. "/test.txt", "test file")
+      assert(fs:read(path .. "/test.txt") == "test file")
+    end
+    collectgarbage()
+    assert(not pcall(fs.read, fs, path .. "/test.txt"))
+  end)
+end)