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lib: Fix nondeterministic command matches in rare cases
When a user erroneously defines two commands which can match the same input and at least one of the tokens defined last in the command is a selector or option, the matcher does not detect an ambiguous match and matches the command installed first (leftmost in the graph). Fix is to do a full walkthrough of the follow set when matching the final token in a command to check that there is exactly one possible match, and to throw an ambiguity error otherwise. Signed-off-by: Quentin Young <qlyoung@cumulusnetworks.com>
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@ -240,6 +240,11 @@ command_match_r (struct graph_node *start, vector vline, unsigned int n)
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struct cmd_token *tok = gn->data;
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if (tok->type == END_TKN)
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{
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if (currbest) // there is more than one END_TKN in the follow set
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{
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ambiguous = 1;
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break;
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}
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currbest = list_new();
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// node should have one child node with the element
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struct graph_node *leaf = vector_slot (gn->to, 0);
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@ -251,9 +256,10 @@ command_match_r (struct graph_node *start, vector vline, unsigned int n)
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struct cmd_element *el = leaf->data;
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listnode_add (currbest, el);
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currbest->del = (void (*)(void *)) &del_cmd_token;
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break;
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// do not break immediately; continue walking through the follow set
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// to ensure that there is exactly one END_TKN
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}
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else continue;
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continue;
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}
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// else recurse on candidate child node
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