rust/pv*: Move u8_to_hexstring to pv_core

Move pvapconfig::helper::u8_to_hexstring to pv_core::utils::encode_hex.
Discard pvapconfig::helper::hexstring_to_u8 in favor of
pv_core::utils::decode_hex.

Signed-off-by: Jakob Naucke <naucke@linux.ibm.com>
Reviewed-by: Steffen Eiden <seiden@linux.ibm.com>
Signed-off-by: Jan Höppner <hoeppner@linux.ibm.com>

rust/pv_core/src/lib.rs

@@ -21,8 +21,9 @@ pub mod attest {
 pub mod misc {
     pub use crate::utils::pv_guest_bit_set;
     pub use crate::utils::{create_file, open_file, read_exact_file, read_file, write_file};
-    pub use crate::utils::{decode_hex, parse_hex, to_u16, to_u32, try_parse_u128, try_parse_u64};
+    pub use crate::utils::{decode_hex, encode_hex, parse_hex};
     pub use crate::utils::{read, write};
+    pub use crate::utils::{to_u16, to_u32, try_parse_u128, try_parse_u64};
     pub use crate::utils::{Flags, Lsb0Flags64, Msb0Flags64};
 }
 

rust/pv_core/src/utils.rs

@@ -355,6 +355,15 @@ usize_to_ui! {
 #[doc = r"u16"]
 => u16, to_u16}
 
+/// Converts the u8 slice into (lowercase) hexstring
+pub fn encode_hex<S: AsRef<[u8]>>(s: S) -> String {
+    let slice = s.as_ref();
+    let string = String::with_capacity(2 * slice.len());
+    slice
+        .iter()
+        .fold(string, |acc, e| acc + &format!("{e:02x}"))
+}
+
 /// Converts the hexstring into a byte vector.
 ///
 /// # Errors
@@ -504,6 +513,14 @@ mod tests {
     fn lsb_flags_unset_panic() {
         Lsb0Flags64::default().unset_bit(64)
     }
+
+    #[test]
+    fn encode_hex() {
+        let arr = [0x12, 0x34, 0x56, 0xac, 0xbe, 0xf0];
+        let exp = "123456acbef0";
+        assert_eq!(super::encode_hex(arr), exp);
+    }
+
     #[test]
     fn parse_hex() {
         let s = "123456acbef0";