Remove dependency on tempfile

This broke the MSRV build, and was bringing in the whole
of rand, wasi, and a ton of other stuff.  All so we could
have a temporary directory during a few tests.  6 crates for
generating randomness just for that!

This accounted for 10% of the size of Cargo.lock alone.

rustls-mio/Cargo.toml

@@ -27,8 +27,8 @@ mio = { version = "0.7", features = ["os-poll", "tcp"] }
 regex = "1.0"
 serde = "1.0"
 serde_derive = "1.0"
-tempfile = "3.0"
 webpki-roots = "0.19"
+ring = "0.16.0"
 
 [[example]]
 name = "tlsclient"

rustls-mio/tests/common/mod.rs

@@ -11,7 +11,25 @@ use std::time;
 
 use regex;
 use self::regex::Regex;
-use tempfile;
+
+use ring::rand::SecureRandom;
+
+pub struct DeleteFilesOnDrop {
+    path: PathBuf,
+}
+
+impl DeleteFilesOnDrop {
+    pub fn path(&self) -> &PathBuf {
+        &self.path
+    }
+}
+
+impl Drop for DeleteFilesOnDrop {
+    fn drop(&mut self) {
+        fs::remove_dir_all(&self.path)
+            .unwrap();
+    }
+}
 
 macro_rules! embed_files {
     (
@@ -33,18 +51,30 @@ macro_rules! embed_files {
             }
         }
 
-        pub fn new_test_ca() -> tempfile::TempDir {
-            let dir = tempfile::TempDir::new().unwrap();
+        pub fn new_test_ca() -> DeleteFilesOnDrop {
+            let mut rand = [0u8; 4];
+            ring::rand::SystemRandom::new()
+                .fill(&mut rand)
+                .unwrap();
 
-            fs::create_dir(dir.path().join("ecdsa")).unwrap();
-            fs::create_dir(dir.path().join("rsa")).unwrap();
+            let dir = env::temp_dir()
+                .join(format!("rustls-{:02x}{:02x}{:02x}{:02x}",
+                              rand[0], rand[1], rand[2], rand[3]));
+            let deleter = DeleteFilesOnDrop {
+                path: dir,
+            };
+
+            fs::create_dir(&deleter.path).unwrap();
+            fs::create_dir(deleter.path.join("ecdsa")).unwrap();
+            fs::create_dir(deleter.path.join("rsa")).unwrap();
 
             $(
-                let mut f = File::create(dir.path().join($keytype).join($path)).unwrap();
+                let filename = deleter.path.join($keytype).join($path);
+                let mut f = File::create(&filename).unwrap();
                 f.write($name).unwrap();
             )+
 
-            dir
+            deleter
         }
     }
 }

rustls/Cargo.toml

@@ -27,7 +27,6 @@ quic = []
 [dev-dependencies]
 env_logger = "0.7.1"
 log = "0.4.4"
-tempfile = "3.0"
 webpki-roots = "0.19.0"
 criterion = "0.3.0"
 

rustls/tests/common/mod.rs

@@ -1,9 +1,5 @@
-use std::fs::{self, File};
-use std::str;
-use tempfile;
-
 use std::sync::Arc;
-use std::io::{self, Write};
+use std::io;
 
 use rustls;
 
@@ -47,20 +43,6 @@ macro_rules! embed_files {
                 _ => panic!("unknown keytype {} with path {}", keytype, path),
             }
         }
-
-        pub fn new_test_ca() -> tempfile::TempDir {
-            let dir = tempfile::TempDir::new().unwrap();
-
-            fs::create_dir(dir.path().join("ecdsa")).unwrap();
-            fs::create_dir(dir.path().join("rsa")).unwrap();
-
-            $(
-                let mut f = File::create(dir.path().join($keytype).join($path)).unwrap();
-                f.write($name).unwrap();
-            )+
-
-            dir
-        }
     }
 }