From 923549e843816ba928ec3ac7dca29cba93096d69 Mon Sep 17 00:00:00 2001
From: trivernis <trivernis@protonmail.com>
Date: Sat, 29 Oct 2022 22:20:23 +0200
Subject: [PATCH] Fix missing file link and resolv.conf in chroot

---
 configs/crystal/install-base/up.nu |  5 ---
 src/error.rs                       |  3 ++
 src/task/chrooting/mapping.rs      | 55 ++++++++++++++++++++++++++++++
 3 files changed, 58 insertions(+), 5 deletions(-)

diff --git a/configs/crystal/install-base/up.nu b/configs/crystal/install-base/up.nu
index ad03156..ebe9889 100644
--- a/configs/crystal/install-base/up.nu
+++ b/configs/crystal/install-base/up.nu
@@ -2,9 +2,4 @@ let REQUIRES_CHROOT = true;
 # Applies all system changes of `install-base`
 def main [cfg] {
     echo "Executing up task `install-base` with config" $cfg
-    ls /etc
-    cat /etc/mtab
-    pacman -S --noconfirm neofetch
-    neofetch
-    exit 1
 }
diff --git a/src/error.rs b/src/error.rs
index 6246400..e4dd2d8 100644
--- a/src/error.rs
+++ b/src/error.rs
@@ -105,6 +105,9 @@ pub enum ChrootError {
     #[error("Failed to remove symlink in chroot: {0}")]
     Unlink(io::Error),
 
+    #[error("Failed to copy file {0} to chroot: {1}")]
+    Copy(PathBuf, io::Error),
+
     #[error("Failed to change process working directory: {0}")]
     ChDir(io::Error),
 }
diff --git a/src/task/chrooting/mapping.rs b/src/task/chrooting/mapping.rs
index 1f71ebf..75090bc 100644
--- a/src/task/chrooting/mapping.rs
+++ b/src/task/chrooting/mapping.rs
@@ -9,6 +9,8 @@ pub enum Mapping {
     Device(PathBuf),
     Dir(PathBuf, DirOpts),
     Special(PathBuf, PathBuf, DirOpts),
+    Link(PathBuf, PathBuf),
+    Copy(PathBuf, PathBuf),
 }
 
 #[derive(Default)]
@@ -47,6 +49,18 @@ impl DirOpts {
 
 pub enum MappingHandle {
     Mount(UnmountDrop<Mount>),
+    Link(LinkDrop),
+    None,
+}
+
+pub struct LinkDrop {
+    path: PathBuf,
+}
+
+impl Drop for LinkDrop {
+    fn drop(&mut self) {
+        std::fs::remove_file(&self.path).unwrap();
+    }
 }
 
 impl Mapping {
@@ -62,11 +76,21 @@ impl Mapping {
         Self::Special(src.into(), dst.into(), opt)
     }
 
+    fn link<P1: Into<PathBuf>, P2: Into<PathBuf>>(src: P1, dst: P2) -> Self {
+        Self::Link(src.into(), dst.into())
+    }
+
+    fn copy<P1: Into<PathBuf>, P2: Into<PathBuf>>(src: P1, dst: P2) -> Self {
+        Self::Copy(src.into(), dst.into())
+    }
+
     pub async fn create_mapping(&self, root_path: &Path) -> Result<MappingHandle, ChrootError> {
         match &self {
             Mapping::Device(d) => self.map_dev(d, &root_path.join(d)).await,
             Mapping::Dir(d, opt) => self.map_dir(d, &root_path.join(d), opt).await,
             Mapping::Special(src, dst, opt) => self.map_dir(src, &root_path.join(dst), opt).await,
+            Mapping::Link(src, dst) => self.map_link(src, &root_path.join(dst)).await,
+            Mapping::Copy(src, dst) => self.copy_file(src, &root_path.join(dst)).await,
         }
     }
 
@@ -112,6 +136,32 @@ impl Mapping {
 
         Ok(MappingHandle::Mount(mount))
     }
+
+    async fn map_link(&self, src: &Path, dst: &Path) -> Result<MappingHandle, ChrootError> {
+        if dst.exists() && dst.is_symlink() {
+            fs::remove_file(dst).await.map_err(ChrootError::Unlink)?;
+        }
+        fs::symlink(src, dst)
+            .await
+            .map_err(|e| ChrootError::Link(dst.to_owned(), e))?;
+        Ok(MappingHandle::Link(LinkDrop {
+            path: dst.to_owned(),
+        }))
+    }
+
+    async fn copy_file(&self, src: &Path, dst: &Path) -> Result<MappingHandle, ChrootError> {
+        if dst.exists() && dst.is_file() {
+            fs::remove_file(dst)
+                .await
+                .map_err(|e| ChrootError::Copy(dst.to_owned(), e))?;
+        }
+
+        fs::copy(src, dst)
+            .await
+            .map_err(|e| ChrootError::Copy(dst.to_owned(), e))?;
+
+        Ok(MappingHandle::None)
+    }
 }
 
 pub fn default_mappings() -> Vec<Mapping> {
@@ -162,6 +212,11 @@ pub fn default_mappings() -> Vec<Mapping> {
         Mapping::dev("/dev/tty"),
         Mapping::dev("/dev/urandom"),
         Mapping::dev("/dev/zero"),
+        Mapping::link("/proc/self/fd", "dev/fd"),
+        Mapping::link("/proc/self/fd/0", "dev/stdin"),
+        Mapping::link("/proc/self/fd/1", "dev/stdout"),
+        Mapping::link("/proc/self/fd/2", "dev/stderr"),
+        Mapping::copy("/etc/resolv.conf", "etc/resolv.conf"),
         Mapping::dir(
             "/run",
             DirOpts::default().fs_type("tmpfs").flags(NOSUID | NODEV),