From a78c9f94779a0aaf0184953f92b62d06ea4a0667 Mon Sep 17 00:00:00 2001
From: Colin Walters <walters@verbum.org>
Date: Fri, 29 Sep 2023 16:50:20 -0400
Subject: [PATCH] install: Give better error if not run in a podman container

(We should probably detect docker and error out nicely there
 too, or of course support docker too)

Signed-off-by: Colin Walters <walters@verbum.org>
---
 lib/src/containerenv.rs | 20 ++++++++++++--------
 lib/src/install.rs      |  5 ++++-
 2 files changed, 16 insertions(+), 9 deletions(-)

diff --git a/lib/src/containerenv.rs b/lib/src/containerenv.rs
index 485bd0aa0..a79583a2b 100644
--- a/lib/src/containerenv.rs
+++ b/lib/src/containerenv.rs
@@ -1,12 +1,13 @@
 //! Helpers for parsing the `/run/.containerenv` file generated by podman.
 
-use std::fs::File;
 use std::io::{BufRead, BufReader};
 
-use anyhow::{Context, Result};
+use anyhow::Result;
+use cap_std_ext::cap_std::fs::Dir;
+use cap_std_ext::prelude::CapStdExtDirExt;
 use fn_error_context::context;
 
-const PATH: &str = "/run/.containerenv";
+const PATH: &str = "run/.containerenv";
 
 #[derive(Debug, Default)]
 pub(crate) struct ContainerExecutionInfo {
@@ -18,11 +19,14 @@ pub(crate) struct ContainerExecutionInfo {
 }
 
 /// Load and parse the `/run/.containerenv` file.
-#[context("Parsing {PATH}")]
-pub(crate) fn get_container_execution_info() -> Result<ContainerExecutionInfo> {
-    let f = File::open(PATH)
-        .with_context(|| format!("Opening {PATH}"))
-        .map(BufReader::new)?;
+#[context("Querying container")]
+pub(crate) fn get_container_execution_info(rootfs: &Dir) -> Result<ContainerExecutionInfo> {
+    let f = match rootfs.open_optional(PATH)? {
+        Some(f) => BufReader::new(f),
+        None => {
+            anyhow::bail!("This command must be executed inside a podman container (missing {PATH}")
+        }
+    };
     let mut r = ContainerExecutionInfo::default();
     for line in f.lines() {
         let line = line?;
diff --git a/lib/src/install.rs b/lib/src/install.rs
index bfa1299e2..7ee652f31 100644
--- a/lib/src/install.rs
+++ b/lib/src/install.rs
@@ -770,8 +770,11 @@ async fn prepare_install(
     crate::cli::require_root()?;
     require_systemd_pid1()?;
 
+    let rootfs = cap_std::fs::Dir::open_ambient_dir("/", cap_std::ambient_authority())
+        .context("Opening /")?;
+
     // This command currently *must* be run inside a privileged container.
-    let container_info = crate::containerenv::get_container_execution_info()?;
+    let container_info = crate::containerenv::get_container_execution_info(&rootfs)?;
     let source = SourceInfo::from_container(&container_info)?;
 
     ensure_var()?;