1 files changed, 69 insertions, 0 deletions
diff --git a/pxeboot.check b/pxeboot.check
new file mode 100755
index 00000000..d7eb9b5c
--- /dev/null
+++ b/pxeboot.check
@@ -0,0 +1,69 @@
+#!/usr/bin/python
+
+import itertools
+import os
+import sys
+flatten = itertools.chain.from_iterable
+
+def powerset(iterable):
+    "powerset([1,2,3]) --> () (1,) (2,) (3,) (1,2) (1,3) (2,3) (1,2,3)"
+    s = list(iterable)
+    return flatten(itertools.combinations(s, r) for r in range(len(s)+1))
+
+valid_option_sets = frozenset((
+    ('spawn-novlan', frozenset(('PXEBOOT_DEPLOYER_INTERFACE',))),
+    ('spawn-vlan', frozenset(('PXEBOOT_DEPLOYER_INTERFACE',  'PXEBOOT_VLAN'))),
+    ('existing-dhcp', frozenset(('PXEBOOT_DEPLOYER_INTERFACE',
+                                 'PXEBOOT_CONFIG_TFTP_ADDRESS'))),
+    ('existing-server', frozenset(('PXEBOOT_CONFIG_TFTP_ADDRESS',
+                                   'PXEBOOT_ROOTFS_RSYNC_ADDRESS'))),
+))
+valid_modes = frozenset(mode for (mode, opt_set in valid_option_sets))
+
+
+def compute_matches(env):
+    complete_matches = set()
+    for mode, opt_set in valid_option_sets:
+        if all(k in env for k in opt_set):
+            complete_matches.add(opt_set)
+    return complete_matches
+complete_matches = compute_matches(os.environ)
+
+def word_separate_options(options):
+    assert options
+    s = options.pop(-1)
+    if options:
+        s = '%s and %s' % (', '.join(options), s)
+    return s
+
+
+valid_options = frozenset(flatten(opt_set for (mode, opt_set)
+                                  in valid_option_sets))
+matched_options = frozenset(o for o in valid_options)
+                            if o in os.environ)
+if not complete_matches:
+    addable_sets = frozenset(frozenset(os) - matched_options for os in
+                             valid_options
+                             if frozenset(os) - matched_options)
+    print('Please provide %s' % ' or '.join(
+            word_separate_options(list(opt_set))
+            for opt_set in addable_sets if opt_set))
+    sys.exit(1)
+elif len(complete_matches) > 1:
+    removable_sets = frozenset(matched_options - frozenset(os) for os in
+                               powerset(matched_options)
+                               if len(compute_matches(os)) == 1)
+    print('Please unset %s' % ' or '.join(
+            word_separate_options(list(opt_set))
+            for opt_set in removable_sets if opt_set))
+    sys.exit(1)
+
+if 'PXEBOOT_MODE' in os.environ:
+    mode = os.environ['PXEBOOT_MODE']
+else:
+    mode, = (mode for (mode, opt_set) in valid_option_sets
+             if all(o in os.environ for o in opt_set))
+
+if mode not in valid_modes:
+    print('%s is not a valid PXEBOOT_MODE' % mode)
+    sys.exit(1)