subplotlib: Add open_write() to Datadir impl

Signed-off-by: Daniel Silverstone <dsilvers@digital-scurf.org>

1 files changed, 12 insertions, 0 deletions

diff --git a/subplotlib/src/steplibrary/datadir.rs b/subplotlib/src/steplibrary/datadir.rs
index 69f79cf..1ef485e 100644
--- a/subplotlib/src/steplibrary/datadir.rs
+++ b/subplotlib/src/steplibrary/datadir.rs
@@ -5,6 +5,7 @@
 //! If you want to create files, run commands, etc. from your scenarios, you
 //! will likely be using them from within the datadir.
 
+use std::fs::{File, OpenOptions};
 use std::path::{Component, Path, PathBuf};
 
 pub use crate::prelude::*;
@@ -83,6 +84,17 @@ impl Datadir {
         }
         ret
     }
+
+    /// Open a file for writing
+    #[throws(StepError)]
+    pub fn open_write<S: AsRef<Path>>(&self, subpath: S) -> File {
+        let full_path = self.canonicalise_filename(subpath)?;
+        OpenOptions::new()
+            .create(true)
+            .write(true)
+            .truncate(true)
+            .open(full_path)?
+    }
 }
 
 /// A simple check for enough disk space in the data dir