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[Qemu-devel] [PATCH v2 25/60] json: Leave rejecting invalid escape seque
From: |
Markus Armbruster |
Subject: |
[Qemu-devel] [PATCH v2 25/60] json: Leave rejecting invalid escape sequences to parser |
Date: |
Fri, 17 Aug 2018 17:05:24 +0200 |
Both lexer and parser reject invalid escape sequences in strings. The
parser's check is useless.
The lexer ends the token right after the first non-well-formed byte.
This tends to lead to suboptimal error reporting. For instance, input
{"address@hidden": 1}
produces the tokens
JSON_LCURLY {
JSON_ERROR "abc\@
JSON_KEYWORD ijk
JSON_ERROR ": 1}\n
The parser then reports three errors
Invalid JSON syntax
JSON parse error, invalid keyword 'ijk'
Invalid JSON syntax
before it recovers at the newline.
Drop the lexer's escape sequence checking, and make it accept the same
characters after backslash it accepts elsewhere in strings. It now
produces
JSON_LCURLY {
JSON_STRING "address@hidden"
JSON_COLON :
JSON_INTEGER 1
JSON_RCURLY
and the parser reports just
JSON parse error, invalid escape sequence in string
While there, fix parse_string()'s inaccurate function comment.
Signed-off-by: Markus Armbruster <address@hidden>
---
qobject/json-lexer.c | 72 +++----------------------------------------
qobject/json-parser.c | 56 +++++++++++++++++++--------------
2 files changed, 37 insertions(+), 91 deletions(-)
diff --git a/qobject/json-lexer.c b/qobject/json-lexer.c
index 36fb665b12..af0a7fdb8a 100644
--- a/qobject/json-lexer.c
+++ b/qobject/json-lexer.c
@@ -80,6 +80,8 @@
* escape = %x5C ; \
* quotation-mark = %x22 ; "
* unescaped = %x20-21 / %x23-5B / %x5D-10FFFF
+ * [This lexer accepts any non-control character after escape, and
+ * leaves rejecting invalid ones to the parser.]
*
*
* Extensions over RFC 7159:
@@ -99,16 +101,8 @@
enum json_lexer_state {
IN_ERROR = 0, /* must really be 0, see json_lexer[] */
- IN_DQ_UCODE3,
- IN_DQ_UCODE2,
- IN_DQ_UCODE1,
- IN_DQ_UCODE0,
IN_DQ_STRING_ESCAPE,
IN_DQ_STRING,
- IN_SQ_UCODE3,
- IN_SQ_UCODE2,
- IN_SQ_UCODE1,
- IN_SQ_UCODE0,
IN_SQ_STRING_ESCAPE,
IN_SQ_STRING,
IN_ZERO,
@@ -144,37 +138,8 @@ static const uint8_t json_lexer[][256] = {
/* Relies on default initialization to IN_ERROR! */
/* double quote string */
- [IN_DQ_UCODE3] = {
- ['0' ... '9'] = IN_DQ_STRING,
- ['a' ... 'f'] = IN_DQ_STRING,
- ['A' ... 'F'] = IN_DQ_STRING,
- },
- [IN_DQ_UCODE2] = {
- ['0' ... '9'] = IN_DQ_UCODE3,
- ['a' ... 'f'] = IN_DQ_UCODE3,
- ['A' ... 'F'] = IN_DQ_UCODE3,
- },
- [IN_DQ_UCODE1] = {
- ['0' ... '9'] = IN_DQ_UCODE2,
- ['a' ... 'f'] = IN_DQ_UCODE2,
- ['A' ... 'F'] = IN_DQ_UCODE2,
- },
- [IN_DQ_UCODE0] = {
- ['0' ... '9'] = IN_DQ_UCODE1,
- ['a' ... 'f'] = IN_DQ_UCODE1,
- ['A' ... 'F'] = IN_DQ_UCODE1,
- },
[IN_DQ_STRING_ESCAPE] = {
- ['b'] = IN_DQ_STRING,
- ['f'] = IN_DQ_STRING,
- ['n'] = IN_DQ_STRING,
- ['r'] = IN_DQ_STRING,
- ['t'] = IN_DQ_STRING,
- ['/'] = IN_DQ_STRING,
- ['\\'] = IN_DQ_STRING,
- ['\''] = IN_DQ_STRING,
- ['\"'] = IN_DQ_STRING,
- ['u'] = IN_DQ_UCODE0,
+ [0x20 ... 0xFD] = IN_DQ_STRING,
},
[IN_DQ_STRING] = {
[0x20 ... 0xFD] = IN_DQ_STRING,
@@ -183,37 +148,8 @@ static const uint8_t json_lexer[][256] = {
},
/* single quote string */
- [IN_SQ_UCODE3] = {
- ['0' ... '9'] = IN_SQ_STRING,
- ['a' ... 'f'] = IN_SQ_STRING,
- ['A' ... 'F'] = IN_SQ_STRING,
- },
- [IN_SQ_UCODE2] = {
- ['0' ... '9'] = IN_SQ_UCODE3,
- ['a' ... 'f'] = IN_SQ_UCODE3,
- ['A' ... 'F'] = IN_SQ_UCODE3,
- },
- [IN_SQ_UCODE1] = {
- ['0' ... '9'] = IN_SQ_UCODE2,
- ['a' ... 'f'] = IN_SQ_UCODE2,
- ['A' ... 'F'] = IN_SQ_UCODE2,
- },
- [IN_SQ_UCODE0] = {
- ['0' ... '9'] = IN_SQ_UCODE1,
- ['a' ... 'f'] = IN_SQ_UCODE1,
- ['A' ... 'F'] = IN_SQ_UCODE1,
- },
[IN_SQ_STRING_ESCAPE] = {
- ['b'] = IN_SQ_STRING,
- ['f'] = IN_SQ_STRING,
- ['n'] = IN_SQ_STRING,
- ['r'] = IN_SQ_STRING,
- ['t'] = IN_SQ_STRING,
- ['/'] = IN_SQ_STRING,
- ['\\'] = IN_SQ_STRING,
- ['\''] = IN_SQ_STRING,
- ['\"'] = IN_SQ_STRING,
- ['u'] = IN_SQ_UCODE0,
+ [0x20 ... 0xFD] = IN_SQ_STRING,
},
[IN_SQ_STRING] = {
[0x20 ... 0xFD] = IN_SQ_STRING,
diff --git a/qobject/json-parser.c b/qobject/json-parser.c
index a9b227f56c..fa8d0fe416 100644
--- a/qobject/json-parser.c
+++ b/qobject/json-parser.c
@@ -106,30 +106,40 @@ static int hex2decimal(char ch)
}
/**
- * parse_string(): Parse a json string and return a QObject
+ * parse_string(): Parse a JSON string
*
- * string
- * ""
- * " chars "
- * chars
- * char
- * char chars
- * char
- * any-Unicode-character-
- * except-"-or-\-or-
- * control-character
- * \"
- * \\
- * \/
- * \b
- * \f
- * \n
- * \r
- * \t
- * \u four-hex-digits
+ * From RFC 7159 "The JavaScript Object Notation (JSON) Data
+ * Interchange Format":
+ *
+ * char = unescaped /
+ * escape (
+ * %x22 / ; " quotation mark U+0022
+ * %x5C / ; \ reverse solidus U+005C
+ * %x2F / ; / solidus U+002F
+ * %x62 / ; b backspace U+0008
+ * %x66 / ; f form feed U+000C
+ * %x6E / ; n line feed U+000A
+ * %x72 / ; r carriage return U+000D
+ * %x74 / ; t tab U+0009
+ * %x75 4HEXDIG ) ; uXXXX U+XXXX
+ * escape = %x5C ; \
+ * quotation-mark = %x22 ; "
+ * unescaped = %x20-21 / %x23-5B / %x5D-10FFFF
+ *
+ * Extensions over RFC 7159:
+ * - Extra escape sequence in strings:
+ * 0x27 (apostrophe) is recognized after escape, too
+ * - Single-quoted strings:
+ * Like double-quoted strings, except they're delimited by %x27
+ * (apostrophe) instead of %x22 (quotation mark), and can't contain
+ * unescaped apostrophe, but can contain unescaped quotation mark.
+ *
+ * Note:
+ * - Encoding is modified UTF-8.
+ * - Invalid Unicode characters are rejected.
+ * - Control characters \x00..\x1F are rejected by the lexer.
*/
-static QString *qstring_from_escaped_str(JSONParserContext *ctxt,
- JSONToken *token)
+static QString *parse_string(JSONParserContext *ctxt, JSONToken *token)
{
const char *ptr = token->str;
QString *str;
@@ -495,7 +505,7 @@ static QObject *parse_literal(JSONParserContext *ctxt)
switch (token->type) {
case JSON_STRING:
- return QOBJECT(qstring_from_escaped_str(ctxt, token));
+ return QOBJECT(parse_string(ctxt, token));
case JSON_INTEGER: {
/*
* Represent JSON_INTEGER as QNUM_I64 if possible, else as
--
2.17.1
- [Qemu-devel] [PATCH v2 04/60] qmp-cmd-test: Split off qmp-test, (continued)
- [Qemu-devel] [PATCH v2 04/60] qmp-cmd-test: Split off qmp-test, Markus Armbruster, 2018/08/17
- [Qemu-devel] [PATCH v2 05/60] qmp-test: Cover syntax and lexical errors, Markus Armbruster, 2018/08/17
- [Qemu-devel] [PATCH v2 14/60] check-qjson qmp-test: Cover control characters more thoroughly, Markus Armbruster, 2018/08/17
- [Qemu-devel] [PATCH v2 09/60] check-qjson: Cover escaped characters more thoroughly, part 2, Markus Armbruster, 2018/08/17
- [Qemu-devel] [PATCH v2 42/60] json: Improve names of lexer states related to numbers, Markus Armbruster, 2018/08/17
- [Qemu-devel] [PATCH v2 34/60] json: Don't pass null @tokens to json_parser_parse(), Markus Armbruster, 2018/08/17
- [Qemu-devel] [PATCH v2 23/60] json: Leave rejecting invalid UTF-8 to parser, Markus Armbruster, 2018/08/17
- [Qemu-devel] [PATCH v2 30/60] json: remove useless return value from lexer/parser, Markus Armbruster, 2018/08/17
- [Qemu-devel] [PATCH v2 25/60] json: Leave rejecting invalid escape sequences to parser,
Markus Armbruster <=
- [Qemu-devel] [PATCH v2 38/60] json: Pass lexical errors and limit violations to callback, Markus Armbruster, 2018/08/17
- [Qemu-devel] [PATCH v2 44/60] json: Fix latent parser aborts at end of input, Markus Armbruster, 2018/08/17
- [Qemu-devel] [PATCH v2 28/60] json: Fix \uXXXX for surrogate pairs, Markus Armbruster, 2018/08/17
- [Qemu-devel] [PATCH v2 21/60] json: Reject invalid UTF-8 sequences, Markus Armbruster, 2018/08/17
- [Qemu-devel] [PATCH v2 24/60] json: Accept overlong \xC0\x80 as U+0000 ("modified UTF-8"), Markus Armbruster, 2018/08/17