feat: add reading and writing PSBT files

Author: rustaceanrob

bdk-ffi/src/bitcoin.rs

@@ -32,6 +32,8 @@ use bdk_wallet::miniscript::psbt::PsbtExt;
 use bdk_wallet::serde_json;
 
 use std::fmt::Display;
+use std::fs::File;
+use std::io::{BufReader, BufWriter};
 use std::ops::Deref;
 use std::str::FromStr;
 use std::sync::{Arc, Mutex};
@@ -495,6 +497,15 @@ impl Psbt {
         Ok(Arc::new(Psbt(Mutex::new(psbt))))
     }
 
+    /// Create a new `Psbt` from a `.psbt` file.
+    #[uniffi::constructor]
+    pub(crate) fn from_file(path: String) -> Result<Self, PsbtError> {
+        let file = File::open(path)?;
+        let mut buf_read = BufReader::new(file);
+        let psbt: BdkPsbt = BdkPsbt::deserialize_from_reader(&mut buf_read)?;
+        Ok(Psbt(Mutex::new(psbt)))
+    }
+
     /// Serialize the PSBT into a base64-encoded string.
     pub(crate) fn serialize(&self) -> String {
         let psbt = self.0.lock().unwrap().clone();
@@ -566,6 +577,15 @@ impl Psbt {
         }
     }
 
+    /// Write the `Psbt` to a file. Note that the file must not yet exist.
+    pub(crate) fn write_to_file(&self, path: String) -> Result<(), PsbtError> {
+        let file = File::create_new(path)?;
+        let mut writer = BufWriter::new(file);
+        let psbt = self.0.lock().unwrap();
+        psbt.serialize_to_writer(&mut writer)?;
+        Ok(())
+    }
+
     /// Serializes the PSBT into a JSON string representation.
     pub(crate) fn json_serialize(&self) -> String {
         let psbt = self.0.lock().unwrap();

bdk-ffi/src/error.rs

@@ -1438,6 +1438,22 @@ impl From<BdkPsbtParseError> for PsbtParseError {
     }
 }
 
+impl From<std::io::Error> for PsbtError {
+    fn from(error: std::io::Error) -> Self {
+        PsbtError::Io {
+            error_message: error.to_string(),
+        }
+    }
+}
+
+impl From<bdk_wallet::bitcoin::io::Error> for PsbtError {
+    fn from(error: bdk_wallet::bitcoin::io::Error) -> Self {
+        PsbtError::Io {
+            error_message: error.to_string(),
+        }
+    }
+}
+
 impl From<BdkPsbtFinalizeError> for PsbtFinalizeError {
     fn from(value: BdkPsbtFinalizeError) -> Self {
         match value {