feat: set max output size to writable virtual drives

Currently, the max size is hard coded to 1 GiB, but that can be made
user-configurable later.

Sponsored-by: author

1 files changed, 19 insertions, 2 deletions

diff --git a/src/qemu.rs b/src/qemu.rs
index c0aa1b1..98254bf 100644
--- a/src/qemu.rs
+++ b/src/qemu.rs
@@ -8,6 +8,7 @@ use std::{
     process::{Command, Stdio},
 };
 
+const MAX_OUTPUT_SIZE: u64 = 1024 * 1024 * 1024;
 const OVMF_FD: &str = "/usr/share/ovmf/OVMF.fd";
 
 /// A QEMU runner.
@@ -57,8 +58,10 @@ impl Qemu {
         copy(&self.image, &image).map_err(|e| QemuError::Copy(self.image.clone(), e))?;
         copy(OVMF_FD, &vars).map_err(|e| QemuError::Copy(OVMF_FD.into(), e))?;
 
-        let output_drive = Self::create_tar(tmp.path().join("output"), empty.path())?;
-        let cache_drive = Self::create_tar(tmp.path().join("cache"), empty.path())?;
+        let output_drive =
+            Self::create_tar_with_size(tmp.path().join("output"), empty.path(), MAX_OUTPUT_SIZE)?;
+        let cache_drive =
+            Self::create_tar_with_size(tmp.path().join("cache"), empty.path(), MAX_OUTPUT_SIZE)?;
         let deps_drive = Self::create_tar(tmp.path().join("deps"), empty.path())?;
 
         if let Some(shell) = &self.shell {
@@ -121,6 +124,20 @@ impl Qemu {
             .map_err(|e| QemuError::Tar(dirname.into(), e))?;
         Ok(tar)
     }
+
+    fn create_tar_with_size(
+        tar_filename: PathBuf,
+        dirname: &Path,
+        size: u64,
+    ) -> Result<VirtualDrive, QemuError> {
+        let tar = VirtualDriveBuilder::default()
+            .filename(&tar_filename)
+            .root_directory(dirname)
+            .size(size)
+            .create()
+            .map_err(|e| QemuError::Tar(dirname.into(), e))?;
+        Ok(tar)
+    }
 }
 
 #[derive(Debug, Default)]