From 5b34ba3a9e005492e1a7f598c7adf232aa40f666 Mon Sep 17 00:00:00 2001
From: Allison Karlitskaya <allison.karlitskaya@redhat.com>
Date: Tue, 8 Oct 2024 13:35:52 +0200
Subject: [PATCH] teach gc about composefs-info objects

---
 src/repository.rs | 24 +++++++++++++++++++++++-
 1 file changed, 23 insertions(+), 1 deletion(-)

diff --git a/src/repository.rs b/src/repository.rs
index 6856bc4..ed222ba 100644
--- a/src/repository.rs
+++ b/src/repository.rs
@@ -12,6 +12,7 @@ use std::{
         Path,
         PathBuf,
     },
+    process::Command,
 };
 
 use anyhow::{
@@ -324,7 +325,28 @@ impl Repository {
             println!("{} lives as an image", hex::encode(object));
             objects.insert(object);
 
-            // TODO: composefs-info objects
+            // composefs-info mmaps the file, so pipes aren't normally OK but we pass the
+            // underlying file directly, which works.
+            let output = Command::new("composefs-info")
+                .stdin(File::from(self.open_object(object)?))
+                .args(["objects", "/proc/self/fd/0"])
+                .output()?
+                .stdout;
+
+            if output.len() % 66 != 0 {
+                bail!("composefs-info gave invalid output (wrong size)");
+            }
+
+            for line in output.chunks_exact(66) {
+                if line[2] != b'/' || line[65] != b'\n' {
+                    bail!("composefs-info gave invalid output");
+                }
+                let mut value = Sha256HashValue::EMPTY;
+                hex::decode_to_slice(&line[0..2], &mut value[0..1])?;
+                hex::decode_to_slice(&line[3..65], &mut value[1..32])?;
+                println!("    with {}", hex::encode(&value));
+                objects.insert(value);
+            }
         }
 
         for object in self.gc_category("streams")? {