Add writing support for strings and StrProperty

src/common.rs

@@ -1,4 +1,4 @@
-use binrw::BinRead;
+use binrw::{BinRead, BinWrite};
 use binrw::BinResult;
 
 pub(crate) fn read_bool_from<T: From<u8> + PartialEq>(x: T) -> bool {
@@ -25,6 +25,26 @@ pub(crate) fn read_string_with_length() -> BinResult<String> {
     }))
 }
 
+#[binrw::writer(writer, endian)]
+pub(crate) fn write_string_with_length(string: &String) -> BinResult<()> {
+    if string.is_empty() {
+        let length = 0u32;
+        length.write_le(writer)?;
+        return Ok(());
+    }
+    // + 1 for the null terminator
+    let length = string.len() as u32 + 1;
+    length.write_le(writer)?;
+    for char in string.chars() {
+        let byte = char as u8;
+        byte.write_le(writer)?;
+    }
+    let null_terminator = 0u8;
+    null_terminator.write_le(writer)?;
+    Ok(())
+}
+
+
 #[cfg(test)]
 mod tests {
     use super::*;

src/str_property.rs

@@ -1,29 +1,30 @@
-use crate::common::read_string_with_length;
+use crate::common::{read_string_with_length, write_string_with_length};
 use binrw::binrw;
 
 #[binrw]
 #[derive(Debug)]
 pub struct StrProperty {
-    #[br(pad_after = 5)]
+    #[brw(pad_after = 5)]
+    // Only add + 1 for the null terminator if the string *isn't* empty.
+    #[bw(calc = value.len() as u32 + 4 + if value.is_empty() { 0 } else { 1})]
     pub size_in_bytes: u32,
 
     #[br(parse_with = read_string_with_length)]
-    #[bw(ignore)]
+    #[bw(write_with = write_string_with_length)]
     pub value: String,
 }
 
 #[cfg(test)]
 mod tests {
     use super::*;
-    use binrw::BinRead;
+    use binrw::{BinRead, BinWrite};
     use std::io::Cursor;
 
     #[test]
-    fn empty_string() {
+    fn read_empty_string() {
         // From Slot.sav
         let data = [
-            0x04, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x0b,
-            0x00, 0x00, 0x00, 0x4c, 0x6f, 0x61, 0x64, 0x4f, 0x70, 0x74, 0x69, 0x6f, 0x6e, 0x00,
+            0x04, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
         ];
         let mut cursor = Cursor::new(data);
         let decoded = StrProperty::read_le(&mut cursor).unwrap();
@@ -31,7 +32,25 @@ mod tests {
     }
 
     #[test]
-    fn regular_string() {
+    fn write_empty_string() {
+        let expected_data: [u8; 13] = [
+            0x04, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+        ];
+        let property = StrProperty {
+            value: "".to_string(),
+        };
+
+        let mut buffer: Vec<u8> = Vec::new();
+        {
+            let mut cursor = Cursor::new(&mut buffer);
+            property.write_le(&mut cursor).unwrap();
+        }
+
+        assert_eq!(expected_data, &buffer[..]);
+    }
+
+    #[test]
+    fn read_regular_string() {
         // From Slot.sav
         let data = [
             0x1e, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x1a, 0x00, 0x00, 0x00, 0x41,
@@ -42,4 +61,24 @@ mod tests {
         let decoded = StrProperty::read_le(&mut cursor).unwrap();
         assert_eq!(decoded.value, "AR0XJGFWA6HNIQ1AAUJ9UR828");
     }
+
+    #[test]
+    fn write_regular_string() {
+        let expected_data: [u8; 39] = [
+            0x1e, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x1a, 0x00, 0x00, 0x00, 0x41,
+            0x52, 0x30, 0x58, 0x4a, 0x47, 0x46, 0x57, 0x41, 0x36, 0x48, 0x4e, 0x49, 0x51, 0x31,
+            0x41, 0x41, 0x55, 0x4a, 0x39, 0x55, 0x52, 0x38, 0x32, 0x38, 0x00,
+        ];
+        let property = StrProperty {
+            value: "AR0XJGFWA6HNIQ1AAUJ9UR828".to_string(),
+        };
+
+        let mut buffer: Vec<u8> = Vec::new();
+        {
+            let mut cursor = Cursor::new(&mut buffer);
+            property.write_le(&mut cursor).unwrap();
+        }
+
+        assert_eq!(expected_data, &buffer[..]);
+    }
 }