esp: Find shim and grub in newer fcos images

From fcos 43, shim and grub are not longer located in /usr/lib/bootupd..
but in /usr/lib/efi/..

This commit adds some changes to be able to find shim and grub binaries
both under the old and new image fs hierarchy.

Note that as for the kernel images, the first found shim and grub are
returned.

Signed-off-by: Beñat Gartzia Arruabarrena <bgartzia@redhat.com>

Author: bgartzi

lib/src/esp.rs

@@ -4,6 +4,7 @@
 // SPDX-License-Identifier: MIT
 
 use crate::pefile;
+use glob::glob;
 use std::fs;
 use std::io;
 use std::path::{Path, PathBuf};
@@ -14,35 +15,32 @@ pub struct Esp {
     grub: PathBuf,
 }
 
-const ESP_VENDOR_NAMES: [&str; 2] = ["redhat", "fedora"];
+fn find_efi_bin(root_path: &Path, bin_name: &str) -> io::Result<PathBuf> {
+    let glob_path = root_path.join(Path::new("**/EFI/*/").join(bin_name));
+    let glob_pattern = glob_path.to_str().ok_or_else(|| {
+        io::Error::new(
+            io::ErrorKind::InvalidInput,
+            "Invalid efi bin search pattern",
+        )
+    })?;
 
-fn esp_vendor_path(esp_root_path: &Path) -> io::Result<PathBuf> {
-    for vendor in ESP_VENDOR_NAMES {
-        let vendor_path = esp_root_path.join(format!("EFI/{vendor}"));
-        match fs::metadata(&vendor_path) {
-            Err(_) => {}
-            Ok(metadata) => {
-                if metadata.is_dir() {
-                    return Ok(vendor_path);
-                }
-            }
+    let search_results = match glob(glob_pattern) {
+        Ok(results) => results,
+        Err(_) => {
+            return Err(io::Error::new(
+                io::ErrorKind::InvalidInput,
+                "Invalid efi bin search pattern",
+            ));
         }
+    };
+    if let Some(path) = search_results.filter_map(Result::ok).next() {
+        // Assume there's just one of them; return the first one
+        return Ok(path);
     }
-    Err(io::Error::new(
-        io::ErrorKind::NotFound,
-        String::from("Unknown ESP tree format"),
-    ))
-}
 
-fn bin_path_from_esp_vendor(esp_vendor_path: &Path, bin_name: &str) -> io::Result<PathBuf> {
-    let bin_path = esp_vendor_path.join(bin_name);
-    let metadata = fs::metadata(&bin_path)?;
-    if metadata.is_file() {
-        return Ok(bin_path);
-    }
     Err(io::Error::new(
-        io::ErrorKind::IsADirectory,
-        bin_path.to_string_lossy(),
+        io::ErrorKind::NotFound,
+        format!("{bin_name} not found"),
     ))
 }
 
@@ -53,11 +51,9 @@ impl Esp {
             return Err(io::Error::new(io::ErrorKind::NotADirectory, path));
         }
 
-        let esp_vendor_path = esp_vendor_path(&path_pb)?;
-
         Ok(Esp {
-            grub: bin_path_from_esp_vendor(&esp_vendor_path, "grubx64.efi")?,
-            shim: bin_path_from_esp_vendor(&esp_vendor_path, "shimx64.efi")?,
+            grub: find_efi_bin(&path_pb, "grubx64.efi")?,
+            shim: find_efi_bin(&path_pb, "shimx64.efi")?,
         })
     }
 

lib/src/rootfs.rs

@@ -3,22 +3,33 @@
 //
 // SPDX-License-Identifier: MIT
 
+use std::fs;
 use std::io;
 use std::path;
 
 const RELATIVE_KERNELS_PATH: &str = "usr/lib/modules/";
-const RELATIVE_ESP_PATH: &str = "usr/lib/bootupd/updates/";
+const RELATIVE_ESP_OLD: &str = "usr/lib/bootupd/updates/";
+// From fcos-43 on shim/grub are stored in different directories
+const RELATIVE_ESP_NEW: &str = "usr/lib/efi";
 
 pub struct RootFSTree {
     esp_path: String,
     kernels_path: String,
 }
 
+fn esp_path_absolute(rootfs_path: &path::Path) -> io::Result<path::PathBuf> {
+    let temptative = rootfs_path.join(RELATIVE_ESP_NEW);
+    match fs::exists(&temptative)? {
+        true => Ok(temptative),
+        false => Ok(rootfs_path.join(RELATIVE_ESP_OLD)),
+    }
+}
+
 impl RootFSTree {
     pub fn new(rootfs_path: &str) -> io::Result<RootFSTree> {
         let rootfs_path = path::absolute(rootfs_path)?;
         let kernels_path = rootfs_path.join(RELATIVE_KERNELS_PATH);
-        let esp_path = rootfs_path.join(RELATIVE_ESP_PATH);
+        let esp_path = esp_path_absolute(&rootfs_path)?;
         Ok(RootFSTree {
             esp_path: esp_path.to_str().unwrap().into(),
             kernels_path: kernels_path.to_str().unwrap().into(),