Libguestfs - Nov 2016 - [PATCH 1/2] kernel: refactor build_kernel & find_kernel

Move the handling of the SUPERMIN_* envvars, and the kernel copy/symlink
out of find_kernel to build_kernel: this way find_kernel does only the
search.  Also, the modules path search is done in by find_kernel as
well.

This is mostly code motion, with no behaviour changes.
---
 src/kernel.ml | 89 +++++++++++++++++++++++++++++------------------------------
 1 file changed, 44 insertions(+), 45 deletions(-)

diff --git a/src/kernel.ml b/src/kernel.ml
index 9b0e8a2..2e061d8 100644
--- a/src/kernel.ml
+++ b/src/kernel.ml
@@ -40,28 +40,7 @@ let patt_of_cpu host_cpu  
 let rec build_kernel debug host_cpu dtb_wildcard copy_kernel kernel dtb    (*
Locate the kernel. *)
-  let kernel_name, kernel_version -    find_kernel debug host_cpu copy_kernel
kernel in
-
-  (* If the user passed --dtb option, locate dtb. *)
-  (match dtb_wildcard with
-  | None -> ()
-  | Some wildcard ->
-    find_dtb debug copy_kernel kernel_name wildcard dtb
-  );
-
-  (* Get the kernel modules. *)
-  let modpath = find_modpath debug kernel_version in
-
-  if debug >= 1 then (
-    printf "supermin: kernel: kernel_version %s\n" kernel_version;
-    printf "supermin: kernel: modules %s\n%!" modpath;
-  );
-
-  (kernel_version, modpath)
-
-and find_kernel debug host_cpu copy_kernel kernel -  let kernel_file,
kernel_name, kernel_version +  let kernel_file, kernel_name, kernel_version,
modpath      try
       let kernel_env = getenv "SUPERMIN_KERNEL" in
       if debug >= 1 then
@@ -78,38 +57,58 @@ and find_kernel debug host_cpu copy_kernel kernel         
printf "supermin: kernel: SUPERMIN_KERNEL version %s\n%!"
           kernel_version;
       let kernel_name = Filename.basename kernel_env in
-      kernel_env, kernel_name, kernel_version
+      let modpath = find_modpath debug kernel_version in
+      kernel_env, kernel_name, kernel_version, modpath
     with Not_found ->
-      let is_arm -        String.length host_cpu >= 3 &&
-        host_cpu.[0] = 'a' && host_cpu.[1] = 'r'
&& host_cpu.[2] = 'm' in
+      find_kernel debug host_cpu kernel in
 
-      let all_files = Sys.readdir "/boot" in
-      let all_files = Array.to_list all_files in
+  (* If the user passed --dtb option, locate dtb. *)
+  (match dtb_wildcard with
+  | None -> ()
+  | Some wildcard ->
+    find_dtb debug copy_kernel kernel_name wildcard dtb
+  );
 
-      (* In original: ls -1dvr /boot/vmlinuz-*.$arch* 2>/dev/null | grep -v
xen *)
-      let patterns = patt_of_cpu host_cpu in
-      let files = kernel_filter patterns is_arm all_files in
+  if debug >= 1 then (
+    printf "supermin: kernel: kernel_version %s\n" kernel_version;
+    printf "supermin: kernel: modules %s\n%!" modpath;
+  );
 
-      let files -        if files <> [] then files
-        else
-          (* In original: ls -1dvr /boot/vmlinuz-* 2>/dev/null | grep -v xen
*)
-          kernel_filter ["vmlinu?-*"] is_arm all_files in
+  copy_or_symlink_file copy_kernel kernel_file kernel;
 
-      if files = [] then no_kernels host_cpu;
+  (kernel_version, modpath)
 
-      let files = List.sort (fun a b -> compare_version b a) files in
-      let kernel_name = List.hd files in
-      let kernel_version = get_kernel_version kernel_name in
+and find_kernel debug host_cpu kernel +  let is_arm +    String.length host_cpu
>= 3 &&
+    host_cpu.[0] = 'a' && host_cpu.[1] = 'r' &&
host_cpu.[2] = 'm' in
 
-      if debug >= 1 then
-        printf "supermin: kernel: picked kernel %s\n%!" kernel_name;
+  let all_files = Sys.readdir "/boot" in
+  let all_files = Array.to_list all_files in
 
-      ("/boot" // kernel_name), kernel_name, kernel_version in
+  (* In original: ls -1dvr /boot/vmlinuz-*.$arch* 2>/dev/null | grep -v xen
*)
+  let patterns = patt_of_cpu host_cpu in
+  let files = kernel_filter patterns is_arm all_files in
 
-  copy_or_symlink_file copy_kernel kernel_file kernel;
-  kernel_name, kernel_version
+  let files +    if files <> [] then files
+    else
+      (* In original: ls -1dvr /boot/vmlinuz-* 2>/dev/null | grep -v xen *)
+      kernel_filter ["vmlinu?-*"] is_arm all_files in
+
+  if files = [] then no_kernels host_cpu;
+
+  let files = List.sort (fun a b -> compare_version b a) files in
+  let kernel_name = List.hd files in
+  let kernel_version = get_kernel_version kernel_name in
+
+  if debug >= 1 then
+    printf "supermin: kernel: picked kernel %s\n%!" kernel_name;
+
+  (* Get the kernel modules. *)
+  let modpath = find_modpath debug kernel_version in
+
+  ("/boot" // kernel_name), kernel_name, kernel_version, modpath
 
 and kernel_filter patterns is_arm all_files    let files -- 
2.7.4

Newer kernel packages e.g. in Fedora place the kernel image named
"vmlinuz" directly within the modules path of that kernel.
Find these images first, not looking for kernels in /boot if any is
found under modules paths.
---
 src/kernel.ml | 24 +++++++++++++++++++++++-
 1 file changed, 23 insertions(+), 1 deletion(-)

diff --git a/src/kernel.ml b/src/kernel.ml
index 2e061d8..b4e89da 100644
--- a/src/kernel.ml
+++ b/src/kernel.ml
@@ -22,6 +22,7 @@ open Printf
 open Utils
 open Ext2fs
 open Fnmatch
+open Glob
 
 let patt_of_cpu host_cpu    let models @@ -60,7 +61,28 @@ let rec build_kernel
debug host_cpu dtb_wildcard copy_kernel kernel dtb        let modpath =
find_modpath debug kernel_version in
       kernel_env, kernel_name, kernel_version, modpath
     with Not_found ->
-      find_kernel debug host_cpu kernel in
+      let kernels +        let files = glob "/lib/modules/*/vmlinuz"
[GLOB_NOSORT; GLOB_NOESCAPE] in
+        let files = Array.to_list files in
+        let kernels +          List.map (
+            fun f ->
+              let modpath = Filename.dirname f in
+              f, Filename.basename f, Filename.basename modpath, modpath
+          ) files in
+        List.sort (
+          fun (_, _, a, _) (_, _, b, _) -> compare_version b a
+        ) kernels in
+
+      if kernels <> [] then (
+        let kernel = List.hd kernels in
+        if debug >= 1 then (
+          let kernel_file, _, _, _ = kernel in
+          printf "supermin: kernel: picked vmlinuz %s\n%!"
kernel_file;
+        );
+        kernel
+      ) else
+        find_kernel debug host_cpu kernel in
 
   (* If the user passed --dtb option, locate dtb. *)
   (match dtb_wildcard with
-- 
2.7.4

The changes seem OK, so ACK.

This code gives me a headache ...  We don't have any module interface
kernel.mli defined, and it passes around tuples instead of
well-defined structs.

Rich.

-- 
Richard Jones, Virtualization Group, Red Hat http://people.redhat.com/~rjones
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