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RFC 8259 on string contents:
All Unicode characters may be placed within the quotation marks,
except for the characters that MUST be escaped: quotation mark,
reverse solidus, and the control characters (U+0000 through
U+001F).
The QAPI schema parser accepts both less and more than JSON: it
accepts only ASCII with \u (less), and accepts control characters
other than LF (new line) unescaped. How it treats unescaped non-ASCII
input differs between Python 2 and Python 3.
Make it accept strictly less: require printable ASCII. Drop support
for \b, \f, \n, \r, \t.
Signed-off-by: Markus Armbruster <armbru@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Message-Id: <20190913201349.24332-7-armbru@redhat.com>
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The handling of \ inside QAPI strings was less than ideal, and
really only worked JSON's \/, \\, \", and our extension of \'
(an obvious extension, when you realize we use '' instead of ""
for strings). For other things, like '\n', it resulted in a
literal 'n' instead of a newline.
Of course, at the moment, we really have no use for escaped
characters, as QAPI has to map to C identifiers, and we currently
support ASCII only for that. But down the road, we may add
support for default values for string parameters to a command
or struct; if that happens, it would be nice to correctly support
all JSON escape sequences, such as \n or \uXXXX. This gets us
closer, by supporting Unicode escapes in the ASCII range.
Since JSON does not require \OCTAL or \xXX escapes, and our QMP
implementation does not understand them either, I intentionally
reject it here, but it would be an easy addition if we desired it.
Likewise, intentionally refusing the NUL byte means we don't have
to worry about C strings being shorter than the qapi input.
Signed-off-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Markus Armbruster <armbru@redhat.com>
Signed-off-by: Markus Armbruster <armbru@redhat.com>
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