[Xen-API] [PATCH] Fix terrible error message when bootloader fails

[David Scott <dave.scott@xxxxxxxxxxxxx>]

# HG changeset patch
# User David Scott <dave.scott@xxxxxxxxxxxxx>
# Date 1264517064 0
# Node ID ca18fc5c917111068f242fe8b21b9e9558f3d5a9
# Parent  22cd3f304b9e0818b80ac5a40e6d4c6438c5e58a
CA-37080: fix terrible error message when a 'rhlike' guest (e.g. CentOS) cannot 
be installed because an update file is missing in dom0.

Converts this:

[root@h07 ~]# xe vm-start vm=centos54
The bootloader returned an error
vm: 13b688dd-da80-1ee3-bbe8-875fffc5736f (centos54)
msg: Error from bootloader: Failed to parse the output of bootloader: ()

Into this:

[root@h07 ~]# xe vm-start vm=centos54
Error code: SUPPORT_PACKAGE_MISSING
Error parameters: Dom0 does not contain a required file: 
/opt/xensource/packages/files/guest-installer/el5.4-initrd-additions.cpio, ,

Thanks to Vern Burke for helping me debug this.

Signed-off-by: David Scott <dave.scott@xxxxxxxxxxxxx>

diff -r 22cd3f304b9e -r ca18fc5c9171 ocaml/xapi/bootloader.ml
--- a/ocaml/xapi/bootloader.ml  Thu Jan 21 15:45:09 2010 +0000
+++ b/ocaml/xapi/bootloader.ml  Tue Jan 26 14:44:24 2010 +0000
@@ -52,7 +52,7 @@
 
 let parse_output x = 
   let sexpr = "(" ^ x ^ ")" in
-  let parse_failed = Error(Printf.sprintf "Failed to parse the output of 
bootloader: %s" sexpr) in
+  let parse_failed = Error(Printf.sprintf "Expecting an s-expression; 
received: %s" sexpr) in
   let sexpr' = SExpr_TS.of_string sexpr in
   match sexpr' with
     (* linux (kernel /var/lib/xen/vmlinuz.y1Wmrp)(args 'root=/dev/sda1 ro') *)
@@ -68,6 +68,11 @@
        debug "Failed to parse: %s" sexpr;
        raise parse_failed
 
+let parse_exception x = 
+  match Stringext.String.split '\n' x with
+  | code :: params -> raise (Api_errors.Server_error(code, params))
+  | _ -> failwith (Printf.sprintf "Failed to parse stderr output of 
bootloader: %s" x)
+
 (** Extract the default kernel using the -q option *)
 let extract_default_kernel bootloader disks legacy_args extra_args 
pv_bootloader_args vm_uuid =
   let bootloader_path = List.assoc bootloader Xapi_globs.supported_bootloaders 
in
@@ -78,34 +83,11 @@
   let disk = List.hd disks in
   let cmdline = bootloader_args true extra_args legacy_args pv_bootloader_args 
disk vm_uuid in
   debug "Bootloader commandline: %s %s\n" bootloader_path (String.concat " " 
cmdline);
+  try
+       parse_output (Helpers.call_script ~log_successful_output:false 
bootloader_path cmdline)
+  with Forkhelpers.Spawn_internal_error(stderr, stdout, _) ->
+         parse_exception stderr
 
-  let result_out, result_in = Unix.pipe() in
-  let fds_to_close = ref [ result_out; result_in ] in
-  let close' fd = 
-    if List.mem fd !fds_to_close 
-    then (Unix.close fd; fds_to_close := List.filter (fun x -> x <> fd) 
!fds_to_close) in
-  finally  (* make sure I close all my open fds in the end *)
-    (fun () ->
-       (* Capture stderr output for logging *)
-       match with_logfile_fd "bootloader"
-       (fun log_fd ->
-         let pid = safe_close_and_exec None (Some result_in) (Some log_fd) [] 
bootloader_path cmdline in
-         (* parent *)
-         List.iter close' [ result_in ];
-         finally (* always waitpid eventually *)
-           (fun () ->
-              let output = Unixext.read_whole_file 500 500 result_out in
-              (* Do something with it *)
-              parse_output output)
-           (fun () -> waitpid pid)) with
-       | Success(_, x) -> debug "bootloader subprocess succeeded"; x
-       | Failure(log, Subprocess_failed n) ->
-          raise (Error (Printf.sprintf "Return code: %d; Log = %s" n log))
-       | Failure(log, exn) ->
-          debug "Error from bootloader: %s" log;
-          raise exn)
-    (fun () -> List.iter Unix.close !fds_to_close)
-         
 let delete_extracted_kernel x = 
   Unix.unlink x.kernel_path;
   match x.initrd_path with
1 file changed, 10 insertions(+), 28 deletions(-)
ocaml/xapi/bootloader.ml |   38 ++++++++++----------------------------

Attachment: xen-api.hg.patch
Description: Text Data

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