Xen devel - Oct 2012 - [PATCH] pygrub: Add option to list grub entries

# HG changeset patch
# Parent aa479945f718ff775c18afa2f37a391fca573114
# User carnold@suse.com
# Date 1350668686 21600
pygrub: Add option to list grub entries

The argument to "--entry" allows 2 syntaxes, either directly the entry
number
in menu.lst, or the whole string behind the "title" key word. This
poses the
following issue:
From Dom0 there is no way to guess the number and, or the complete title
string because this string contains the kernel version, which will change
with a kernel update.
This patch adds [-l|--list-entries] as an argument to pygrub.

Signed-off-by: Charles Arnold <carnold@suse.com>

diff -r c1c549c4fe9e tools/pygrub/src/pygrub
--- a/tools/pygrub/src/pygrub	Mon Oct 15 16:51:44 2012 +0100
+++ b/tools/pygrub/src/pygrub	Fri Oct 19 11:40:49 2012 -0600
@@ -595,7 +595,17 @@ def run_grub(file, entry, fs, cfg_args):
         sel = g.run()
 
     g = Grub(file, fs)
-    if interactive:
+
+    if list_entries:
+        for i in range(len(g.cf.images)):
+            img = g.cf.images[i]
+            print "title: %s" % img.title
+            print "  root: %s" % img.root
+            print "  kernel: %s" % img.kernel[1]
+            print "  args: %s" % img.args
+            print "  initrd: %s" % img.initrd[1]
+
+    if interactive and not list_entries:
         curses.wrapper(run_main)
     else:
         sel = g.cf.default
@@ -702,7 +712,7 @@ if __name__ == "__main__":
     sel = None
     
     def usage():
-        print >> sys.stderr, "Usage: %s [-q|--quiet]
[-i|--interactive] [-n|--not-really] [--output=] [--kernel=] [--ramdisk=]
[--args=] [--entry=] [--output-directory=] [--output-format=sxp|simple|simple0]
<image>" %(sys.argv[0],)
+        print >> sys.stderr, "Usage: %s [-q|--quiet]
[-i|--interactive] [-l|--list-entries] [-n|--not-really] [--output=] [--kernel=]
[--ramdisk=] [--args=] [--entry=] [--output-directory=]
[--output-format=sxp|simple|simple0] <image>" %(sys.argv[0],)
 
     def copy_from_image(fs, file_to_read, file_type, output_directory,
                         not_really):
@@ -736,8 +746,8 @@ if __name__ == "__main__":
             dataoff += len(data)
 
     try:
-        opts, args = getopt.gnu_getopt(sys.argv[1:],
''qinh::'',
-                                   ["quiet", "interactive",
"not-really", "help",
+        opts, args = getopt.gnu_getopt(sys.argv[1:],
''qilnh::'',
+                                   ["quiet", "interactive",
"list-entries", "not-really", "help",
                                     "output=",
"output-format=", "output-directory=",
                                     "entry=", "kernel=", 
                                     "ramdisk=", "args=",
"isconfig", "debug"])
@@ -753,6 +763,7 @@ if __name__ == "__main__":
     output = None
     entry = None
     interactive = True
+    list_entries = False
     isconfig = False
     debug = False
     not_really = False
@@ -771,6 +782,8 @@ if __name__ == "__main__":
             interactive = False
         elif o in ("-i", "--interactive"):
             interactive = True
+        elif o in ("-l", "--list-entries"):
+            list_entries = True
         elif o in ("-n", "--not-really"):
             not_really = True
         elif o in ("-h", "--help"):
@@ -855,6 +868,9 @@ if __name__ == "__main__":
             fs = None
             continue
 
+    if list_entries:
+        sys.exit(0)
+
     # Did looping through partitions find us a kernel?
     if not fs:
         raise RuntimeError, "Unable to find partition containing
kernel"

Charles Arnold writes ("[Xen-devel]  [PATCH] pygrub: Add option to list
grub entries"):
> pygrub: Add option to list grub entries
> 
> The argument to "--entry" allows 2 syntaxes, either directly the
entry number
> in menu.lst, or the whole string behind the "title" key word.
This poses the
> following issue:
> >From Dom0 there is no way to guess the number and, or the complete
title
> string because this string contains the kernel version, which will change
> with a kernel update.
> This patch adds [-l|--list-entries] as an argument to pygrub.
> +    if list_entries:
> +        for i in range(len(g.cf.images)):
> +            img = g.cf.images[i]
> +            print "title: %s" % img.title
> +            print "  root: %s" % img.root
> +            print "  kernel: %s" % img.kernel[1]
> +            print "  args: %s" % img.args
> +            print "  initrd: %s" % img.initrd[1]
Is it possible for any of these to contain newlines ?  I don''t think
so but I''m not entirely sure.  If it is then they need to be quoted
somehow or the caller may be unable to unambigously parse the output.

Ian.

>>> On 10/25/2012 at 09:02 AM, in message
<20617.21621.886298.796143@mariner.uk.xensource.com>, Ian Jackson
<Ian.Jackson@eu.citrix.com> wrote: 
> Charles Arnold writes ("[Xen-devel]  [PATCH] pygrub: Add option to
list grub
> entries"):
>> pygrub: Add option to list grub entries
>> 
>> The argument to "--entry" allows 2 syntaxes, either directly
the entry number
>> in menu.lst, or the whole string behind the "title" key word.
This poses the
>> following issue:
>> >From Dom0 there is no way to guess the number and, or the complete
title
>> string because this string contains the kernel version, which will
change
>> with a kernel update.
>> This patch adds [-l|--list-entries] as an argument to pygrub.
> 
>> +    if list_entries:
>> +        for i in range(len(g.cf.images)):
>> +            img = g.cf.images[i]
>> +            print "title: %s" % img.title
>> +            print "  root: %s" % img.root
>> +            print "  kernel: %s" % img.kernel[1]
>> +            print "  args: %s" % img.args
>> +            print "  initrd: %s" % img.initrd[1]
> 
> Is it possible for any of these to contain newlines ?  I don''t
think
> so but I''m not entirely sure.  If it is then they need to be
quoted
> somehow or the caller may be unable to unambigously parse the output.
> 
> Ian.
No, newlines in the menu.lst / grub.cfg files are treated as terminating
characters for each entry option.  Nothing I''ve read in the grub
specification
indicates that the entries can be wrapped with an escaped newline character.
My attempts to force a newline character in an entry always fails.  The
parsing code in GrubConf.py splits the config file at all newlines.

- Charles

Charles Arnold writes ("Re: [Xen-devel]  [PATCH] pygrub: Add option to list
grub entries"):
> No, newlines in the menu.lst / grub.cfg files are treated as terminating
> characters for each entry option.  Nothing I''ve read in the grub
specification
> indicates that the entries can be wrapped with an escaped newline
character.
> My attempts to force a newline character in an entry always fails.  The
> parsing code in GrubConf.py splits the config file at all newlines.
Excellent, thanks for checking.

Acked-by: Ian Jackson <ian.jackson@eu.citrix.com>
Committed-by: Ian Jackson <ian.jackson@eu.citrix.com>