remove rand crate

the few uses of rand::thread_rng() have been replaced with either
prngs or reads from /dev/urandom. the implementations are under
the `rand_ish` minicrate.

`protoc-rust` depends on `tempdir`, which relies on rand, so
`tempdir` has been patched with a rewritten version that does not
have rand as a dependency.

BUG=chromium:921795
TEST=cargo test --features plugin

Change-Id: I6f1c7d7a1aeef4dd55ac71e58294d16c291b8871
Reviewed-on: https://chromium-review.googlesource.com/1409705
Commit-Ready: Daniel Prilik <prilik@google.com>
Tested-by: kokoro <noreply+kokoro@google.com>
Reviewed-by: Zach Reizner <zachr@chromium.org>

2 files changed, 61 insertions, 0 deletions

diff --git a/tempdir/Cargo.toml b/tempdir/Cargo.toml
new file mode 100644
index 0000000..9a3bed9
--- /dev/null
+++ b/tempdir/Cargo.toml
@@ -0,0 +1,7 @@
+[package]
+name = "tempdir"
+version = "0.3.5"
+authors = ["The Chromium OS Authors"]
+
+[dependencies]
+rand_ish = { path = "../rand_ish" }
diff --git a/tempdir/src/lib.rs b/tempdir/src/lib.rs
new file mode 100644
index 0000000..ab0bb8a
--- /dev/null
+++ b/tempdir/src/lib.rs
@@ -0,0 +1,54 @@
+// Copyright 2019 The Chromium OS Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+//! Simplified tempdir which doesn't depend on the `rand` crate, instead using
+//! /dev/urandom as a source of entropy
+
+extern crate rand_ish;
+
+use std::env;
+use std::fs;
+use std::io::{self, Error, ErrorKind};
+use std::path::{Path, PathBuf};
+use rand_ish::urandom_str;
+
+pub struct TempDir {
+    path: PathBuf,
+}
+
+const NUM_RETRIES: u32 = 4;
+
+impl TempDir {
+    /// Tries to make a tempdir inside of `env::temp_dir()` with a specified
+    /// prefix. The directory and it's content is destroyed when TempDir is
+    /// dropped.
+    /// If the directory can not be created, `Err` is returned.
+    pub fn new(prefix: &str) -> io::Result<TempDir> {
+        for _ in 0..NUM_RETRIES {
+            let suffix = urandom_str(12)?;
+            let path = env::temp_dir().join(format!("{}.{}", prefix, suffix));
+
+            match fs::create_dir(&path) {
+                Ok(_) => return Ok(TempDir { path }),
+                Err(ref e) if e.kind() == ErrorKind::AlreadyExists => {}
+                Err(e) => return Err(e),
+            }
+        }
+
+        Err(Error::new(ErrorKind::AlreadyExists, "too many tempdirs exist"))
+    }
+
+    /// Accesses the tempdir's [`Path`].
+    ///
+    /// [`Path`]: http://doc.rust-lang.org/std/path/struct.Path.html
+    pub fn path(&self) -> &Path {
+        self.path.as_ref()
+    }
+}
+
+impl Drop for TempDir {
+    fn drop(&mut self) {
+        let _ = fs::remove_dir_all(&self.path);
+    }
+}