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From: | Eric Blake |
Subject: | Re: [Qemu-devel] [PATCH 41/56] json: Nicer recovery from invalid leading zero |
Date: | Mon, 13 Aug 2018 11:33:14 -0500 |
User-agent: | Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.8.0 |
On 08/08/2018 07:03 AM, Markus Armbruster wrote:
For input 0123, the lexer produces the tokens JSON_ERROR 01 JSON_INTEGER 23 Reporting an error is correct; 0123 is invalid according to RFC 7159. But the error recovery isn't nice. Make the finite state machine eat digits before going into the error state. The lexer now produces JSON_ERROR 0123 Signed-off-by: Markus Armbruster <address@hidden> --- qobject/json-lexer.c | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-)
@@ -158,10 +159,14 @@ static const uint8_t json_lexer[][256] = { /* Zero */ [IN_ZERO] = { TERMINAL(JSON_INTEGER), - ['0' ... '9'] = IN_ERROR, + ['0' ... '9'] = IN_BAD_ZERO, ['.'] = IN_MANTISSA, },+ [IN_BAD_ZERO] = {+ ['0' ... '9'] = IN_BAD_ZERO, + }, +
Should IN_BAD_ZERO also consume '.' and/or 'e' (after all, '01e2 is a valid C constant, but not a valid JSON literal)? But I think your choice here is fine (again, add too much, and then the lexer has to track a lot of state; whereas this minimal addition catches the most obvious things with little effort).
Reviewed-by: Eric Blake <address@hidden> -- Eric Blake, Principal Software Engineer Red Hat, Inc. +1-919-301-3266 Virtualization: qemu.org | libvirt.org
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