From abd38194dcdbd22fb94da3591873d5ebe3988b5d Mon Sep 17 00:00:00 2001
From: akashfortanix <akash.anand@fortanix.com>
Date: Wed, 12 Dec 2018 14:07:20 +0530
Subject: [PATCH] Add support for x86_64-fortanix-unknown-sgx target

---
 Cargo.toml  |  3 +++
 src/rand.rs | 23 ++++++++++++++++++++++-
 2 files changed, 25 insertions(+), 1 deletion(-)

diff --git a/Cargo.toml b/Cargo.toml
index d192eb236a..5e50bb8966 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -286,6 +286,9 @@ libc = { version = "0.2.34" }
 [target.'cfg(any(target_os = "redox", all(unix, not(any(target_os = "macos", target_os = "ios")))))'.dependencies]
 lazy_static = "1.2"
 
+[target.'cfg(target_env = "sgx")'.dependencies]
+rdrand = "0.3.0"
+
 # Keep this in sync with `[dependencies]` in pregenerate_asm/Cargo.toml.
 [build-dependencies]
 # we do not use the gcc parallel feature because we do the
diff --git a/src/rand.rs b/src/rand.rs
index 3cf6aece8a..2bcd34a401 100644
--- a/src/rand.rs
+++ b/src/rand.rs
@@ -93,7 +93,7 @@ impl SecureRandom for SystemRandom {
 
 impl private::Sealed for SystemRandom {}
 
-#[cfg(not(any(target_os = "linux", target_os = "macos", target_os = "ios", windows)))]
+#[cfg(not(any(target_os = "linux", target_os = "macos", target_os = "ios", windows, target_env = "sgx")))]
 use self::urandom::fill as fill_impl;
 
 #[cfg(any(
@@ -107,6 +107,9 @@ use self::sysrand_or_urandom::fill as fill_impl;
 
 #[cfg(any(target_os = "macos", target_os = "ios"))]
 use self::darwin::fill as fill_impl;
+
+#[cfg(target_env = "sgx")]
+use self::rdrandom::fill as fill_impl;
 use crate::private;
 
 #[cfg(target_os = "linux")]
@@ -275,6 +278,24 @@ mod darwin {
     }
 }
 
+#[cfg(target_env = "sgx")]
+mod rdrandom {
+    use rdrand::RdRand;
+    use crate::error;
+    use crate::endian::LittleEndian;
+
+    pub fn fill(dest: &mut [u8]) -> Result<(), error::Unspecified> {
+        let rng = RdRand::new().map_err(|_| error::Unspecified)?;
+        for dst_chunk in dest.chunks_mut(8) {
+            let src_num = rng.try_next_u64().ok_or(error::Unspecified)?;
+            let temp = LittleEndian::from(src_num);
+            let src_chunk = temp.as_ref();
+            dst_chunk.copy_from_slice(&src_chunk[..dst_chunk.len()]);
+        }
+        Ok(())
+    }
+}
+
 #[cfg(test)]
 mod tests {
     use crate::rand::{self, SecureRandom};