Libguestfs - Sep 2016 - [PATCH 2/2] v2v: ilnux: detect name of grub2-mkconfig

On Debian family of OSes Grub2 tools are prefixed with 'grub-', not with
'grub2-'. We have to detect the correct name of the tool to use it.

Signed-off-by: Tomáš Golembiovský <tgolembi@redhat.com>
---
 v2v/linux_bootloaders.ml | 20 ++++++++++++++++++--
 1 file changed, 18 insertions(+), 2 deletions(-)

diff --git a/v2v/linux_bootloaders.ml b/v2v/linux_bootloaders.ml
index a5e4c8d..0729f17 100644
--- a/v2v/linux_bootloaders.ml
+++ b/v2v/linux_bootloaders.ml
@@ -189,6 +189,22 @@ class bootloader_grub2 (g : G.guestfs) grub_config  object
(self)
   inherit bootloader
 
+  method private grub2_mkconfig_cmd +    let elems = [
+       "/sbin/grub2-mkconfig";
+       "/usr/sbin/grub2-mkconfig";
+       "/sbin/grub-mkconfig"
+       "/usr/sbin/grub-mkconfig"
+      ] in
+    try
+      List.find (
+        let e ->
+          try g#is_file ~followsymlinks:true e
+          with G.Error _ -> false
+      ) elems
+    with Not_found ->
+      error (f_"failed to find grub2-mkconfig binary (but Grub2 was
detected on guest)")
+
   method private grub2_update_console ~remove ()      let rex = Str.regexp
"\\(.*\\)\\bconsole=[xh]vc0\\b\\(.*\\)" in
 
@@ -218,7 +234,7 @@ object (self)
         g#aug_save ();
 
         try
-          ignore (g#command [| "grub2-mkconfig"; "-o";
grub_config |])
+          ignore (g#command [| grub2_mkconfig_cmd; "-o"; grub_config
|])
         with
           G.Error msg ->
             warning (f_"could not rebuild grub2 configuration file (%s). 
This may mean that grub output will not be sent to the serial port, but
otherwise should be harmless.  Original error message: %s")
@@ -290,7 +306,7 @@ object (self)
   method remove_console = self#grub2_update_console ~remove:true
 
   method update () -    ignore (g#command [| "grub2-mkconfig";
"-o"; grub_config |])
+    ignore (g#command [| grub2_mkconfig_cmd; "-o"; grub_config |])
 end
 
 let detect_bootloader (g : G.guestfs) inspect -- 
2.9.3

On Monday, 12 September 2016 13:20:47 CEST Tomáš Golembiovský
wrote:
> On Debian family of OSes Grub2 tools are prefixed with 'grub-', not
with
> 'grub2-'. We have to detect the correct name of the tool to use it.
> 
> Signed-off-by: Tomáš Golembiovský <tgolembi@redhat.com>
> ---
>  v2v/linux_bootloaders.ml | 20 ++++++++++++++++++--
>  1 file changed, 18 insertions(+), 2 deletions(-)
> 
> diff --git a/v2v/linux_bootloaders.ml b/v2v/linux_bootloaders.ml
> index a5e4c8d..0729f17 100644
> --- a/v2v/linux_bootloaders.ml
> +++ b/v2v/linux_bootloaders.ml
> @@ -189,6 +189,22 @@ class bootloader_grub2 (g : G.guestfs) grub_config
>  object (self)
>    inherit bootloader
>  
> +  method private grub2_mkconfig_cmd 
I'd make it a simple attribute of the object, just like grub_prefix in
class bootloader_grub1.
> +    let elems = [
> +       "/sbin/grub2-mkconfig";
> +       "/usr/sbin/grub2-mkconfig";
> +       "/sbin/grub-mkconfig"
> +       "/usr/sbin/grub-mkconfig"
> +      ] in
> +    try
> +      List.find (
> +        let e ->
> +          try g#is_file ~followsymlinks:true e
> +          with G.Error _ -> false
is_file returns false if a file does not exist, so there is no need to
catch the error (this currently swallows other errors than "does not
exist")
> +      ) elems
> +    with Not_found ->
> +      error (f_"failed to find grub2-mkconfig binary (but Grub2 was
detected on guest)")
> +
>    method private grub2_update_console ~remove () >      let rex =
Str.regexp "\\(.*\\)\\bconsole=[xh]vc0\\b\\(.*\\)" in
>  
> @@ -218,7 +234,7 @@ object (self)
>          g#aug_save ();
>  
>          try
> -          ignore (g#command [| "grub2-mkconfig"; "-o";
grub_config |])
> +          ignore (g#command [| grub2_mkconfig_cmd; "-o";
grub_config |])
>          with
>            G.Error msg ->
>              warning (f_"could not rebuild grub2 configuration file
(%s).  This may mean that grub output will not be sent to the serial port, but
otherwise should be harmless.  Original error message: %s")
> @@ -290,7 +306,7 @@ object (self)
>    method remove_console = self#grub2_update_console ~remove:true
>  
>    method update () > -    ignore (g#command [|
"grub2-mkconfig"; "-o"; grub_config |])
> +    ignore (g#command [| grub2_mkconfig_cmd; "-o"; grub_config
|])
>  end
>  
>  let detect_bootloader (g : G.guestfs) inspect 
LGTM otherwise.

-- 
Pino Toscano

On Mon, Sep 12, 2016 at 01:31:05PM +0200, Pino Toscano
wrote:
> > +    let elems = [
> > +       "/sbin/grub2-mkconfig";
> > +       "/usr/sbin/grub2-mkconfig";
> > +       "/sbin/grub-mkconfig"
> > +       "/usr/sbin/grub-mkconfig"
> > +      ] in
> > +    try
> > +      List.find (
> > +        let e ->
> > +          try g#is_file ~followsymlinks:true e
> > +          with G.Error _ -> false
> 
> is_file returns false if a file does not exist, so there is no need to
> catch the error (this currently swallows other errors than "does not
> exist")
Once you've made the change that Pino suggests, the code can be
refactored a bit more using currying:

    let elems = [
       "/sbin/grub2-mkconfig";
       "/usr/sbin/grub2-mkconfig";
       "/sbin/grub-mkconfig"
       "/usr/sbin/grub-mkconfig"
      ] in
    try List.find (g#is_file ~followsymlinks:true) elems
    with Not_found ->
      error (f_"failed to find grub2-mkconfig binary (but Grub2 was
detected on
guest)")

Rich.

-- 
Richard Jones, Virtualization Group, Red Hat http://people.redhat.com/~rjones
Read my programming and virtualization blog: http://rwmj.wordpress.com
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