feat: Error 'w' command if overwriting other file

src/cmd/io_commands/file.rs

@@ -160,12 +160,15 @@ pub fn write_to_file(
   };
 
   // If not wq, parse path
-  let (q, path) = if in_path != "q" {
-    (false, parse_path(in_path).unwrap_or(Path::File(&state.file)))
+  let (q, path, overwrite) = if in_path != "q" {
+    match parse_path(in_path) {
+      Some(p) => (false, p, false),
+      None => (false, Path::File(&state.file), true),
+    }
   }
   // If wq, use current file path
   else {
-    (true, (Path::File(&state.file)))
+    (true, Path::File(&state.file), true)
   };
   // If the 'q' flag is set the whole buffer must be selected
   if q && sel.is_some() { return Err(EdError::UnsavedChanges); }
@@ -177,10 +180,18 @@ pub fn write_to_file(
   // Write into command or file, print nr of bytes written
   match path {
     Path::File(file) => {
-      let append = command == 'W';
+      let wtype = if command == 'W' {
+        WriteType::Append
+      } else {
+        if overwrite {
+          WriteType::Overwrite
+        } else {
+          WriteType::Create
+        }
+      };
       let written = state.io.write_file(
         file,
-        append,
+        wtype,
         data,
       )?;
       ui.print_message(&format!(

src/cmd/mod.rs

@@ -1,4 +1,4 @@
-use crate::{Ed, Substitution, Line, Clipboard, Buffer};
+use crate::{Ed, Substitution, Line, Clipboard, Buffer, WriteType};
 use crate::ui::{UI, ScriptedUI};
 use crate::error::*;
 use crate::messages::*;

src/io/dummy_io.rs

@@ -1,5 +1,8 @@
 use crate::{
-  io::IO,
+  io::{
+    IO,
+    WriteType,
+  },
   ui::UILock,
   buffer::iters::LinesIter,
 };
@@ -42,7 +45,7 @@ impl IO for DummyIO {
   }
   fn write_file(&mut self,
     _path: &str,
-    _append: bool,
+    _type: WriteType,
     _data: LinesIter,
   ) -> Result<usize> {
     unimplemented!()

src/io/fake_io.rs

@@ -1,5 +1,8 @@
 use crate::{
-  io::IO,
+  io::{
+    IO,
+    WriteType,
+  },
   ui::UILock,
   buffer::iters::LinesIter,
 };
@@ -9,13 +12,15 @@ use super::Result;
 pub enum FakeIOError {
   ChildExitError,
   NotFound,
+  Overwrite,
 }
 impl std::fmt::Display for FakeIOError {
   fn fmt(&self, f: &mut std::fmt::Formatter) -> std::fmt::Result {
-    use FakeIOError::*;
+    use FakeIOError as FIE;
     match self {
-      ChildExitError => write!(f,"Child process returned error after running."),
-      NotFound => write!(f,"Could not open file. Not found or invalid path."),
+      FIE::ChildExitError => write!(f,"Child process returned error after running."),
+      FIE::NotFound => write!(f,"Could not open file. Not found or invalid path."),
+      FIE::Overwrite => write!(f,"Will not overwrite existing file.")
     }
   }
 }
@@ -103,16 +108,13 @@ impl IO for FakeIO {
   }
   fn write_file(&mut self,
     path: &str,
-    append: bool,
+    wtype: WriteType,
     data: LinesIter,
   ) -> Result<usize> {
-    let base_data = if append {
-      match self.fake_fs.get(path) {
-        Some(x) => x.clone(),
-        None => String::new(),
-      }
-    } else {
-      String::new()
+    let base_data = match self.fake_fs.get(path) {
+      Some(x) if wtype == WriteType::Append => x.clone(),
+      Some(_) if wtype != WriteType::Overwrite => { return Err(FakeIOError::Overwrite.into()); },
+      _ => String::new(),
     };
     let data = data.fold(base_data, |mut s, x|{s.push_str(x); s});
     let datalen = data.len();

src/io/local_io/mod.rs

@@ -6,7 +6,7 @@ use std::process::{
   Command,
   Stdio,
 };
-use crate::IO;
+use crate::{IO, WriteType};
 use super::LinesIter;
 use crate::UILock;
 use super::Result;
@@ -48,17 +48,23 @@ impl LocalIO {
   }
   fn write_internal<'a>(
     path: &str,
-    append: bool,
+    wtype: WriteType,
     data: impl Iterator<Item = &'a str>,
   ) -> std::io::Result<usize> {
     use std::io::Write;
-    let mut file = std::fs::OpenOptions::new()
-      .write(true)
-      .append(append)
-      .truncate(!append)
-      .create(true)
-      .open(path)
-    ?;
+    let mut options = std::fs::OpenOptions::new();
+    match wtype {
+      WriteType::Create => options
+        .write(true)
+        .create_new(true),
+      WriteType::Append => options
+        .append(true),
+      WriteType::Overwrite => options
+        .create(true) // May, but is not required to, create new file
+        .write(true)
+        .truncate(true),
+    };
+    let mut file = options.open(path)?;
     let mut written = 0;
     for line in data {
       written += line.len();
@@ -187,11 +193,11 @@ impl IO for LocalIO {
 
   fn write_file(&mut self,
     path: &str,
-    append: bool,
+    wtype: WriteType,
     data: LinesIter,
   ) -> Result<usize> {
     if path.len() == 0 { return Err(LocalIOError::NoPath.into()); }
-    Self::write_internal(path, append, data)
+    Self::write_internal(path, wtype, data)
       .map_err(|e| LocalIOError::file_error(path, e).into())
   }
   fn read_file(&mut self,

src/io/local_io/test.rs

@@ -20,7 +20,7 @@ fn test_file_io() {
   // Create new file
   io.write_file(
     path,
-    false, // don't append
+    WriteType::Create,
     Box::new("1\n2\n".split_inclusive('\n')).into(),
   ).unwrap();
   let read = std::fs::read_to_string(path).unwrap();
@@ -33,7 +33,7 @@ fn test_file_io() {
   // File path must not be empty for writing
   let ret = io.write_file(
     "",
-    false,
+    WriteType::Create,
     Box::new("data\n".split_inclusive('\n')).into(),
   );
   assert!(
@@ -43,7 +43,7 @@ fn test_file_io() {
   // Overwrite the file
   io.write_file(
     path,
-    false, // don't append
+    WriteType::Overwrite,
     Box::new("1\n2\n".split_inclusive('\n')).into(),
   ).unwrap();
   let read = std::fs::read_to_string(path).unwrap();
@@ -56,7 +56,7 @@ fn test_file_io() {
   // Append to the file
   io.write_file(
     path,
-    true, // Append
+    WriteType::Append,
     Box::new("1\n2\n".split_inclusive('\n')).into(),
   ).unwrap();
   let read = std::fs::read_to_string(path).unwrap();

src/io/mod.rs

@@ -15,6 +15,17 @@ pub mod local_io;
 #[cfg(feature = "local_io")]
 pub use local_io::LocalIO;
 
+/// Simple enum only used for the IO trait's write_file method
+#[derive(PartialEq, Debug)]
+pub enum WriteType {
+  /// Used for 'w' interactions with an explicit path, prohibits overwriting
+  Create,
+  /// Used for all 'W' interactions
+  Append,
+  /// Only used for 'w' when writing to current file
+  Overwrite,
+}
+
 /// Trait that abstracts file interactions and running shell commands
 ///
 /// Intended to allow modifying how and where system interactions occur.
@@ -97,8 +108,8 @@ pub trait IO {
   fn write_file(&mut self,
     // Path to file as give by user. Not checked beyond shell escape parsing
     path: &str,
-    // If appending
-    append: bool,
+    // Write type, see above
+    wtype: WriteType,
     // Data to write to file
     data: LinesIter,
   ) -> Result<usize>;

src/lib.rs

@@ -57,7 +57,7 @@ mod cmd;
 pub mod ui;
 use ui::{UI, UILock, ScriptedUI};
 pub mod io;
-use io::IO;
+use io::{IO, WriteType};
 
 mod history;
 pub use history::History;