From 0106165088d13635cd2ead04b1d20375546e376a Mon Sep 17 00:00:00 2001
From: Wiktor Kwapisiewicz <wiktor@metacode.biz>
Date: Thu, 10 Nov 2022 10:33:31 +0100
Subject: [PATCH] Expose `num` parameter of the cipher

---
 openssl-sys/src/evp.rs             |  5 +++++
 openssl-sys/src/handwritten/evp.rs |  3 +++
 openssl/src/cipher_ctx.rs          | 16 ++++++++++++++++
 3 files changed, 24 insertions(+)

diff --git a/openssl-sys/src/evp.rs b/openssl-sys/src/evp.rs
index 1e1a4dd93d..fc3003f7bd 100644
--- a/openssl-sys/src/evp.rs
+++ b/openssl-sys/src/evp.rs
@@ -97,6 +97,11 @@ cfg_if! {
         pub unsafe fn EVP_CIPHER_CTX_iv_length(ctx: *const EVP_CIPHER_CTX) -> c_int {
             EVP_CIPHER_CTX_get_iv_length(ctx)
         }
+
+        #[inline]
+        pub unsafe fn EVP_CIPHER_CTX_num(ctx: *const EVP_CIPHER_CTX) -> c_int {
+            EVP_CIPHER_CTX_get_num(ctx)
+        }
     } else {
         pub unsafe fn EVP_MD_CTX_size(ctx: *const EVP_MD_CTX) -> c_int {
             EVP_MD_size(EVP_MD_CTX_md(ctx))
diff --git a/openssl-sys/src/handwritten/evp.rs b/openssl-sys/src/handwritten/evp.rs
index ffb0a0819d..a85d628ade 100644
--- a/openssl-sys/src/handwritten/evp.rs
+++ b/openssl-sys/src/handwritten/evp.rs
@@ -26,6 +26,7 @@ cfg_if! {
             pub fn EVP_CIPHER_CTX_get_key_length(ctx: *const EVP_CIPHER_CTX) -> c_int;
             pub fn EVP_CIPHER_CTX_get_iv_length(ctx: *const EVP_CIPHER_CTX) -> c_int;
             pub fn EVP_CIPHER_CTX_get_tag_length(ctx: *const EVP_CIPHER_CTX) -> c_int;
+            pub fn EVP_CIPHER_CTX_get_num(ctx: *const EVP_CIPHER_CTX) -> c_int;
         }
     } else {
         extern "C" {
@@ -44,6 +45,8 @@ cfg_if! {
             pub fn EVP_CIPHER_CTX_block_size(ctx: *const EVP_CIPHER_CTX) -> c_int;
             pub fn EVP_CIPHER_CTX_key_length(ctx: *const EVP_CIPHER_CTX) -> c_int;
             pub fn EVP_CIPHER_CTX_iv_length(ctx: *const EVP_CIPHER_CTX) -> c_int;
+            #[cfg(ossl110)]
+            pub fn EVP_CIPHER_CTX_num(ctx: *const EVP_CIPHER_CTX) -> c_int;
         }
     }
 }
diff --git a/openssl/src/cipher_ctx.rs b/openssl/src/cipher_ctx.rs
index 8e017115b1..a4d1c461c5 100644
--- a/openssl/src/cipher_ctx.rs
+++ b/openssl/src/cipher_ctx.rs
@@ -363,6 +363,22 @@ impl CipherCtxRef {
         unsafe { ffi::EVP_CIPHER_CTX_iv_length(self.as_ptr()) as usize }
     }
 
+    /// Returns the `num` parameter of the cipher.
+    ///
+    /// Built-in ciphers typically use this to track how much of the
+    /// current underlying block has been "used" already.
+    ///
+    /// # Panics
+    ///
+    /// Panics if the context has not been initialized with a cipher.
+    #[corresponds(EVP_CIPHER_CTX_num)]
+    #[cfg(ossl110)]
+    pub fn num(&self) -> usize {
+        self.assert_cipher();
+
+        unsafe { ffi::EVP_CIPHER_CTX_num(self.as_ptr()) as usize }
+    }
+
     /// Sets the length of the IV expected by this context.
     ///
     /// Only some ciphers support configurable IV lengths.