feat(brew): use sudo if Homebrew owned by another user on Linux (#904)

feat(brew): use sudo if Homebrew owned by another user

On Linux, run "brew update" with sudo if the Homebrew installation directory
is owned by a different user. This is typically the user who installed
Homebrew, but can also be a dedicated user account. This change ensures that
Homebrew updates can proceed smoothly even when its directory ownership does
not match the current user's UID. Proper sudo configuration is assumed for
this to work properly.

src/steps/os/unix.rs

@@ -13,6 +13,8 @@ use color_eyre::eyre::Context;
 use color_eyre::eyre::Result;
 use home;
 use ini::Ini;
+#[cfg(target_os = "linux")]
+use nix::unistd::Uid;
 use semver::Version;
 use tracing::debug;
 
@@ -270,6 +272,23 @@ pub fn upgrade_gnome_extensions(ctx: &ExecutionContext) -> Result<()> {
         .status_checked()
 }
 
+#[cfg(target_os = "linux")]
+pub fn brew_linux_sudo_uid() -> Option<u32> {
+    let linuxbrew_directory = "/home/linuxbrew/.linuxbrew";
+    if let Ok(metadata) = std::fs::metadata(linuxbrew_directory) {
+        let owner_id = metadata.uid();
+        let current_id = Uid::effective();
+        // print debug these two values
+        debug!("linuxbrew_directory owner_id: {}, current_id: {}", owner_id, current_id);
+        return if owner_id == current_id.as_raw() {
+            None // no need for sudo if linuxbrew is owned by the current user
+        } else {
+            Some(owner_id) // otherwise use sudo to run brew as the owner
+        };
+    }
+    None
+}
+
 #[cfg(any(target_os = "linux", target_os = "macos"))]
 pub fn run_brew_formula(ctx: &ExecutionContext, variant: BrewVariant) -> Result<()> {
     #[allow(unused_variables)]
@@ -282,6 +301,30 @@ pub fn run_brew_formula(ctx: &ExecutionContext, variant: BrewVariant) -> Result<
         }
     }
 
+    #[cfg(target_os = "linux")]
+    {
+        let sudo_uid = brew_linux_sudo_uid();
+        // if brew is owned by another user, execute "sudo -Hu <uid> brew update"
+        if let Some(user_id) = sudo_uid {
+            let uid = nix::unistd::Uid::from_raw(user_id);
+            let user = nix::unistd::User::from_uid(uid)
+                .expect("failed to call getpwuid()")
+                .expect("this user should exist");
+            print_separator(format!("{} (sudo as user '{}')", variant.step_title(), user.name));
+            let sudo = crate::utils::require_option(ctx.sudo().as_ref(), "sudo is needed to run the update".into())?;
+            ctx.run_type()
+                .execute(sudo)
+                .current_dir("/tmp") // brew needs a writable current directory
+                .args([
+                    "--set-home",
+                    &format!("--user={}", user.name),
+                    &format!("{}", binary_name.to_string_lossy()),
+                    "update",
+                ])
+                .status_checked()?;
+            return Ok(());
+        }
+    }
     print_separator(variant.step_title());
     let run_type = ctx.run_type();