bwrap: Pass mutability flag, not unified core

We have two `bool` values here and that's a code smell.  I was
going to add another option and we definitely don't want three
bools.

We already have an enum here related to what's going on,
so change things to use it.

rust/src/bwrap.rs

@@ -473,19 +473,14 @@ pub(crate) fn bubblewrap_run_sync(
     rootfs_dfd: i32,
     args: &Vec<String>,
     capture_stdout: bool,
-    unified_core: bool,
+    mutability: BubblewrapMutability,
 ) -> CxxResult<Vec<u8>> {
     let rootfs_dfd = unsafe { &crate::ffiutil::ffi_dirfd(rootfs_dfd)? };
     let tempetc = crate::core::prepare_tempetc_guard(rootfs_dfd.as_raw_fd())?;
-    let mutability = if unified_core {
-        BubblewrapMutability::RoFiles
-    } else {
-        BubblewrapMutability::MutateFreely
-    };
     let mut bwrap = Bubblewrap::new_with_mutability(rootfs_dfd, mutability)?;
 
-    if unified_core {
-        bwrap.bind_read("var", "/var");
+    if mutability != BubblewrapMutability::MutateFreely {
+        bwrap.bind_read("var", "/var")
     } else {
         bwrap.bind_readwrite("var", "/var")
     }

rust/src/composepost.rs

@@ -506,8 +506,12 @@ fn compose_postprocess_scripts(
         )?;
         println!("Executing `postprocess` inline script '{}'", i);
         let child_argv = vec![binpath.to_string()];
-        let _ =
-            bwrap::bubblewrap_run_sync(rootfs_dfd.as_raw_fd(), &child_argv, false, unified_core)?;
+        let _ = bwrap::bubblewrap_run_sync(
+            rootfs_dfd.as_raw_fd(),
+            &child_argv,
+            false,
+            BubblewrapMutability::for_unified_core(unified_core),
+        )?;
         rootfs_dfd.remove_file(target_binpath)?;
     }
 
@@ -531,7 +535,7 @@ fn compose_postprocess_scripts(
             rootfs_dfd.as_raw_fd(),
             child_argv,
             false,
-            unified_core,
+            BubblewrapMutability::for_unified_core(unified_core),
         )
         .context("Executing postprocessing script")?;
 

rust/src/core.rs

@@ -97,7 +97,12 @@ pub(crate) fn run_depmod(rootfs_dfd: i32, kver: &str, unified_core: bool) -> Cxx
         .into_iter()
         .map(|s| s.to_string())
         .collect();
-    let _ = crate::bwrap::bubblewrap_run_sync(rootfs_dfd, &args, false, unified_core)?;
+    let _ = crate::bwrap::bubblewrap_run_sync(
+        rootfs_dfd,
+        &args,
+        false,
+        crate::ffi::BubblewrapMutability::for_unified_core(unified_core),
+    )?;
     Ok(())
 }
 

rust/src/lib.rs

@@ -20,6 +20,7 @@ mod cxxrsutil;
 mod ffiutil;
 pub(crate) mod ffiwrappers;
 pub(crate) use cxxrsutil::*;
+use ffi::BubblewrapMutability;
 
 /// APIs defined here are automatically bridged between Rust and C++ using https://cxx.rs/
 ///
@@ -123,7 +124,7 @@ pub mod ffi {
             rootfs_dfd: i32,
             args: &Vec<String>,
             capture_stdout: bool,
-            unified_core: bool,
+            mutability: BubblewrapMutability,
         ) -> Result<Vec<u8>>;
 
         fn bubblewrap_new(rootfs_fd: i32) -> Result<Box<Bubblewrap>>;
@@ -927,6 +928,16 @@ pub mod ffi {
     }
 }
 
+impl BubblewrapMutability {
+    pub(crate) fn for_unified_core(unified_core: bool) -> Self {
+        if unified_core {
+            Self::RoFiles
+        } else {
+            Self::MutateFreely
+        }
+    }
+}
+
 pub mod builtins;
 pub(crate) use crate::builtins::apply_live::*;
 pub(crate) use crate::builtins::compose::commit::*;