tcti: Adds support for libtpms backend

This is useful for running tests without having to spawn a simulator in
another process.

Signed-off-by: Arthur Gautier <[email protected]>

Author: baloo

tss-esapi/src/tcti_ldr.rs

@@ -21,6 +21,7 @@ const DEVICE: &str = "device";
 const MSSIM: &str = "mssim";
 const SWTPM: &str = "swtpm";
 const TABRMD: &str = "tabrmd";
+const LIBTPMS: &str = "libtpms";
 
 /// TCTI Context created via a TCTI Loader Library.
 /// Wrapper around the TSS2_TCTI_CONTEXT structure.
@@ -139,6 +140,8 @@ pub enum TctiNameConf {
     ///
     /// For more information about configuration, see [this page](https://www.mankier.com/3/Tss2_Tcti_Mssim_Init)
     Swtpm(TpmSimulatorConfig),
+    /// Connect to a TPM (simulator) available as a library
+    LibTpms,
     /// Connect to a TPM through an Access Broker/Resource Manager daemon
     ///
     /// For more information about configuration, see [this page](https://www.mankier.com/3/Tss2_Tcti_Tabrmd_Init)
@@ -174,6 +177,7 @@ impl TryFrom<TctiNameConf> for CString {
             TctiNameConf::Mssim(..) => MSSIM,
             TctiNameConf::Swtpm(..) => SWTPM,
             TctiNameConf::Tabrmd(..) => TABRMD,
+            TctiNameConf::LibTpms => LIBTPMS,
         };
 
         let tcti_conf = match tcti {
@@ -204,6 +208,7 @@ impl TryFrom<TctiNameConf> for CString {
             TctiNameConf::Tabrmd(config) => {
                 format!("bus_name={},bus_type={}", config.bus_name, config.bus_type)
             }
+            TctiNameConf::LibTpms => String::new(),
         };
 
         if tcti_conf.is_empty() {
@@ -247,6 +252,11 @@ impl FromStr for TctiNameConf {
             )?));
         }
 
+        let libtpms_pattern = Regex::new(r"^libtpms$").unwrap(); //should not fail
+        if let Some(_captures) = libtpms_pattern.captures(config_str) {
+            return Ok(TctiNameConf::LibTpms);
+        }
+
         Err(Error::WrapperError(WrapperErrorKind::InvalidParam))
     }
 }