blockdev: Use /sysroot as fallback in get_devices() if

`/boot` is not mounted

Inspired by #855 (comment)
If `/boot` is not mounted, the parent devices of `/sysroot` will
be used as a fallback.

Author: HuijingHei

src/blockdev.rs

@@ -1,24 +1,38 @@
 use camino::Utf8Path;
 use std::path::Path;
 
-use anyhow::{bail, Context, Result};
+use anyhow::{Context, Result};
 use bootc_blockdev::PartitionTable;
 use fn_error_context::context;
 
-#[context("get parent devices from mount point boot")]
+#[context("get parent devices from mount point boot or sysroot")]
 pub fn get_devices<P: AsRef<Path>>(target_root: P) -> Result<Vec<String>> {
     let target_root = target_root.as_ref();
-    let bootdir = target_root.join("boot");
-    if !bootdir.exists() {
-        bail!("{} does not exist", bootdir.display());
+    let mut source = None;
+
+    for path in ["boot", "sysroot"] {
+        let target_path = target_root.join(path);
+        if !target_path.exists() {
+            continue;
+        }
+
+        let target_dir = openat::Dir::open(&target_path)
+            .with_context(|| format!("Opening {}", target_path.display()))?;
+        if let Ok(fsinfo) = crate::filesystem::inspect_filesystem(&target_dir, ".") {
+            source = Some(fsinfo.source);
+            break;
+        }
     }
-    let bootdir = openat::Dir::open(&bootdir)?;
-    // Run findmnt to get the source path of mount point boot
-    let fsinfo = crate::filesystem::inspect_filesystem(&bootdir, ".")?;
+
+    let source = match source {
+        Some(s) => s,
+        None => anyhow::bail!("Failed to inspect filesystem from boot or sysroot"),
+    };
+
     // Find the parent devices of the source path
-    let parent_devices = bootc_blockdev::find_parent_devices(&fsinfo.source)
-        .with_context(|| format!("while looking for backing devices of {}", fsinfo.source))?;
-    log::debug!("Find parent devices: {parent_devices:?}");
+    let parent_devices = bootc_blockdev::find_parent_devices(&source)
+        .with_context(|| format!("While looking for backing devices of {}", source))?;
+    log::debug!("Found parent devices: {parent_devices:?}");
     Ok(parent_devices)
 }
 

src/util.rs

@@ -5,20 +5,6 @@ use std::process::Command;
 use anyhow::{bail, Context, Result};
 use openat_ext::OpenatDirExt;
 
-pub(crate) trait CommandRunExt {
-    fn run(&mut self) -> Result<()>;
-}
-
-impl CommandRunExt for Command {
-    fn run(&mut self) -> Result<()> {
-        let r = self.status()?;
-        if !r.success() {
-            bail!("Child [{:?}] exited: {}", self, r);
-        }
-        Ok(())
-    }
-}
-
 /// Parse an environment variable as UTF-8
 #[allow(dead_code)]
 pub(crate) fn getenv_utf8(n: &str) -> Result<Option<String>> {