Rename remove_dir_if_exists to ensure_empty_dir and create the dir in this function

This avoids removing the directory, which may conflict with sandbox
systems like Landlock.

build_system/build_sysroot.rs

@@ -6,7 +6,7 @@
 use crate::prepare::apply_patches;
 use crate::rustc_info::{get_default_sysroot, get_file_name};
 use crate::utils::{
-    remove_dir_if_exists, spawn_and_wait, try_hard_link, CargoProject, Compiler, LogGroup,
+    ensure_empty_dir, spawn_and_wait, try_hard_link, CargoProject, Compiler, LogGroup,
 };
 use crate::{config, CodegenBackend, SysrootKind};
 
@@ -24,8 +24,7 @@ pub(crate) fn build_sysroot(
 
     let dist_dir = RelPath::DIST.to_path(dirs);
 
-    remove_dir_if_exists(&dist_dir);
-    fs::create_dir_all(&dist_dir).unwrap();
+    ensure_empty_dir(&dist_dir);
     fs::create_dir_all(dist_dir.join("bin")).unwrap();
     fs::create_dir_all(dist_dir.join("lib")).unwrap();
 
@@ -223,7 +222,7 @@ fn build_clif_sysroot_for_triple(
     if !config::get_bool("keep_sysroot") {
         // Cleanup the deps dir, but keep build scripts and the incremental cache for faster
         // recompilation as they are not affected by changes in cg_clif.
-        remove_dir_if_exists(&build_dir.join("deps"));
+        ensure_empty_dir(&build_dir.join("deps"));
     }
 
     // Build sysroot

build_system/path.rs

@@ -1,7 +1,7 @@
 use std::fs;
 use std::path::PathBuf;
 
-use crate::utils::remove_dir_if_exists;
+use crate::utils::ensure_empty_dir;
 
 #[derive(Debug, Clone)]
 pub(crate) struct Dirs {
@@ -64,7 +64,6 @@ pub(crate) fn ensure_exists(&self, dirs: &Dirs) {
 
     pub(crate) fn ensure_fresh(&self, dirs: &Dirs) {
         let path = self.to_path(dirs);
-        remove_dir_if_exists(&path);
-        fs::create_dir_all(path).unwrap();
+        ensure_empty_dir(&path);
     }
 }

build_system/prepare.rs

@@ -5,7 +5,7 @@
 use std::process::Command;
 
 use crate::path::{Dirs, RelPath};
-use crate::utils::{copy_dir_recursively, remove_dir_if_exists, spawn_and_wait};
+use crate::utils::{copy_dir_recursively, ensure_empty_dir, spawn_and_wait};
 
 pub(crate) fn prepare(dirs: &Dirs) {
     RelPath::DOWNLOAD.ensure_exists(dirs);
@@ -202,8 +202,7 @@ pub(crate) fn apply_patches(dirs: &Dirs, crate_name: &str, source_dir: &Path, ta
 
     eprintln!("[COPY] {crate_name} source");
 
-    remove_dir_if_exists(target_dir);
-    fs::create_dir_all(target_dir).unwrap();
+    ensure_empty_dir(target_dir);
     copy_dir_recursively(source_dir, target_dir);
 
     init_git_repo(target_dir);

build_system/utils.rs

@@ -172,11 +172,33 @@ pub(crate) fn spawn_and_wait(mut cmd: Command) {
     }
 }
 
-pub(crate) fn remove_dir_if_exists(path: &Path) {
-    match fs::remove_dir_all(&path) {
+/// Create the specified directory if it doesn't exist yet and delete all contents.
+pub(crate) fn ensure_empty_dir(path: &Path) {
+    fs::create_dir_all(path).unwrap();
+    let read_dir = match fs::read_dir(&path) {
+        Ok(read_dir) => read_dir,
+        Err(err) if err.kind() == io::ErrorKind::NotFound => {
+            return;
+        }
+        Err(err) => {
+            panic!("Failed to read contents of {path}: {err}", path = path.display())
+        }
+    };
+    for entry in read_dir {
+        let entry = entry.unwrap();
+        if entry.file_type().unwrap().is_dir() {
+            match fs::remove_dir_all(entry.path()) {
                 Ok(()) => {}
                 Err(err) if err.kind() == io::ErrorKind::NotFound => {}
-        Err(err) => panic!("Failed to remove {path}: {err}", path = path.display()),
+                Err(err) => panic!("Failed to remove {path}: {err}", path = entry.path().display()),
+            }
+        } else {
+            match fs::remove_file(entry.path()) {
+                Ok(()) => {}
+                Err(err) if err.kind() == io::ErrorKind::NotFound => {}
+                Err(err) => panic!("Failed to remove {path}: {err}", path = entry.path().display()),
+            }
+        }
     }
 }