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Fix some minor spec-compliance issues in jsonpath lexer.
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Although the SQL/JSON tech report makes reference to ECMAScript which
allows both single- and double-quoted strings, all the rest of the
report speaks only of double-quoted string literals in jsonpaths.
That's more compatible with JSON itself; moreover single-quoted strings
are hard to use inside a jsonpath that is itself a single-quoted SQL
literal.  So guess that the intent is to allow only double-quoted
literals, and remove lexer support for single-quoted literals.
It'll be less painful to add this again later if we're wrong, than to
remove a shipped feature.

Also, adjust the lexer so that unrecognized backslash sequences are
treated as just meaning the escaped character, not as errors.  This
change has much better support in the standards, as JSON, JavaScript
and ECMAScript all make it plain that that's what's supposed to
happen.

Back-patch to v12.

Discussion: https://postgr.es/m/CAPpHfdvDci4iqNF9fhRkTqhe-5_8HmzeLt56drH%2B_Rv2rNRqfg@mail.gmail.com
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@tglsfdc
tglsfdc committed Sep 20, 2019
1 parent 96b6c82 commit e56cad8
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Showing 6 changed files with 38 additions and 235 deletions.
79 changes: 31 additions & 48 deletions src/backend/utils/adt/jsonpath_scan.l
View file
Original file line number Diff line number Diff line change
Expand Up @@ -59,25 +59,24 @@ fprintf_to_ereport(const char *fmt, const char *msg)
%option noyyfree

/*
* We use exclusive states for quoted, signle-quoted and non-quoted strings,
* quoted variable names and C-tyle comments.
* We use exclusive states for quoted and non-quoted strings,
* quoted variable names and C-style comments.
* Exclusive states:
* <xq> - quoted strings
* <xnq> - non-quoted strings
* <xvq> - quoted variable names
* <xsq> - single-quoted strings
* <xc> - C-style comment
*/

%x xq
%x xnq
%x xvq
%x xsq
%x xc

special [\?\%\$\.\[\]\{\}\(\)\|\&\!\=\<\>\@\#\,\*:\-\+\/]
any [^\?\%\$\.\[\]\{\}\(\)\|\&\!\=\<\>\@\#\,\*:\-\+\/\\\"\' \t\n\r\f]
special [\?\%\$\.\[\]\{\}\(\)\|\&\!\=\<\>\@\#\,\*:\-\+\/]
blank [ \t\n\r\f]
/* "other" means anything that's not special, blank, or '\' or '"' */
other [^\?\%\$\.\[\]\{\}\(\)\|\&\!\=\<\>\@\#\,\*:\-\+\/\\\" \t\n\r\f]

digit [0-9]
integer (0|[1-9]{digit}*)
Expand All @@ -95,7 +94,7 @@ hex_fail \\x{hex_dig}{0,1}

%%

<xnq>{any}+ {
<xnq>{other}+ {
addstring(false, yytext, yyleng);
}

Expand All @@ -105,13 +104,12 @@ hex_fail \\x{hex_dig}{0,1}
return checkKeyword();
}


<xnq>\/\* {
yylval->str = scanstring;
BEGIN xc;
}

<xnq>({special}|\"|\') {
<xnq>({special}|\") {
yylval->str = scanstring;
yyless(0);
BEGIN INITIAL;
Expand All @@ -124,39 +122,37 @@ hex_fail \\x{hex_dig}{0,1}
return checkKeyword();
}

<xnq,xq,xvq,xsq>\\[\"\'\\] { addchar(false, yytext[1]); }

<xnq,xq,xvq,xsq>\\b { addchar(false, '\b'); }
<xnq,xq,xvq>\\b { addchar(false, '\b'); }

<xnq,xq,xvq,xsq>\\f { addchar(false, '\f'); }
<xnq,xq,xvq>\\f { addchar(false, '\f'); }

<xnq,xq,xvq,xsq>\\n { addchar(false, '\n'); }
<xnq,xq,xvq>\\n { addchar(false, '\n'); }

<xnq,xq,xvq,xsq>\\r { addchar(false, '\r'); }
<xnq,xq,xvq>\\r { addchar(false, '\r'); }

<xnq,xq,xvq,xsq>\\t { addchar(false, '\t'); }
<xnq,xq,xvq>\\t { addchar(false, '\t'); }

<xnq,xq,xvq,xsq>\\v { addchar(false, '\v'); }
<xnq,xq,xvq>\\v { addchar(false, '\v'); }

<xnq,xq,xvq,xsq>{unicode}+ { parseUnicode(yytext, yyleng); }
<xnq,xq,xvq>{unicode}+ { parseUnicode(yytext, yyleng); }

<xnq,xq,xvq,xsq>{hex_char} { parseHexChar(yytext); }
<xnq,xq,xvq>{hex_char} { parseHexChar(yytext); }

<xnq,xq,xvq,xsq>{unicode}*{unicodefail} { yyerror(NULL, "invalid unicode sequence"); }
<xnq,xq,xvq>{unicode}*{unicodefail} { yyerror(NULL, "invalid unicode sequence"); }

<xnq,xq,xvq,xsq>{hex_fail} { yyerror(NULL, "invalid hex character sequence"); }
<xnq,xq,xvq>{hex_fail} { yyerror(NULL, "invalid hex character sequence"); }

<xnq,xq,xvq,xsq>{unicode}+\\ {
/* throw back the \\, and treat as unicode */
yyless(yyleng - 1);
parseUnicode(yytext, yyleng);
}
<xnq,xq,xvq>{unicode}+\\ {
/* throw back the \\, and treat as unicode */
yyless(yyleng - 1);
parseUnicode(yytext, yyleng);
}

<xnq,xq,xvq,xsq>\\. { yyerror(NULL, "escape sequence is invalid"); }
<xnq,xq,xvq>\\. { addchar(false, yytext[1]); }

<xnq,xq,xvq,xsq>\\ { yyerror(NULL, "unexpected end after backslash"); }
<xnq,xq,xvq>\\ { yyerror(NULL, "unexpected end after backslash"); }

<xq,xvq,xsq><<EOF>> { yyerror(NULL, "unexpected end of quoted string"); }
<xq,xvq><<EOF>> { yyerror(NULL, "unexpected end of quoted string"); }

<xq>\" {
yylval->str = scanstring;
Expand All @@ -170,16 +166,8 @@ hex_fail \\x{hex_dig}{0,1}
return VARIABLE_P;
}

<xsq>\' {
yylval->str = scanstring;
BEGIN INITIAL;
return STRING_P;
}

<xq,xvq>[^\\\"]+ { addstring(false, yytext, yyleng); }

<xsq>[^\\\']+ { addstring(false, yytext, yyleng); }

<xc>\*\/ { BEGIN INITIAL; }

<xc>[^\*]+ { }
Expand Down Expand Up @@ -210,7 +198,7 @@ hex_fail \\x{hex_dig}{0,1}

\> { return GREATER_P; }

\${any}+ {
\${other}+ {
addstring(true, yytext + 1, yyleng - 1);
addchar(false, '\0');
yylval->str = scanstring;
Expand Down Expand Up @@ -263,27 +251,22 @@ hex_fail \\x{hex_dig}{0,1}

({realfail1}|{realfail2}) { yyerror(NULL, "invalid floating point number"); }

{any}+ {
addstring(true, yytext, yyleng);
BEGIN xnq;
}

\" {
addchar(true, '\0');
BEGIN xq;
}

\' {
addchar(true, '\0');
BEGIN xsq;
}

\\ {
yyless(0);
addchar(true, '\0');
BEGIN xnq;
}

{other}+ {
addstring(true, yytext, yyleng);
BEGIN xnq;
}

<<EOF>> { yyterminate(); }

%%
Expand Down
18 changes: 6 additions & 12 deletions src/test/regress/expected/jsonpath.out
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Original file line number Diff line number Diff line change
Expand Up @@ -171,30 +171,24 @@ select '"\b\f\r\n\t\v\"\''\\"'::jsonpath;
"\b\f\r\n\t\u000b\"'\\"
(1 row)

select '''\b\f\r\n\t\v\"\''\\'''::jsonpath;
jsonpath
-------------------------
"\b\f\r\n\t\u000b\"'\\"
(1 row)

select '"\x50\u0067\u{53}\u{051}\u{00004C}"'::jsonpath;
jsonpath
----------
"PgSQL"
(1 row)

select '''\x50\u0067\u{53}\u{051}\u{00004C}'''::jsonpath;
jsonpath
----------
"PgSQL"
(1 row)

select '$.foo\x50\u0067\u{53}\u{051}\u{00004C}\t\"bar'::jsonpath;
jsonpath
---------------------
$."fooPgSQL\t\"bar"
(1 row)

select '"\z"'::jsonpath; -- unrecognized escape is just the literal char
jsonpath
----------
"z"
(1 row)

select '$.g ? ($.a == 1)'::jsonpath;
jsonpath
--------------------
Expand Down
78 changes: 0 additions & 78 deletions src/test/regress/expected/jsonpath_encoding.out
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Original file line number Diff line number Diff line change
Expand Up @@ -81,84 +81,6 @@ select '"null \\u0000 escape"'::jsonpath as not_an_escape;
"null \\u0000 escape"
(1 row)

-- checks for single-quoted values
-- basic unicode input
SELECT E'\'\u\''::jsonpath; -- ERROR, incomplete escape
ERROR: invalid Unicode escape
LINE 1: SELECT E'\'\u\''::jsonpath;
^
HINT: Unicode escapes must be \uXXXX or \UXXXXXXXX.
SELECT E'\'\u00\''::jsonpath; -- ERROR, incomplete escape
ERROR: invalid Unicode escape
LINE 1: SELECT E'\'\u00\''::jsonpath;
^
HINT: Unicode escapes must be \uXXXX or \UXXXXXXXX.
SELECT E'\'\u000g\''::jsonpath; -- ERROR, g is not a hex digit
ERROR: invalid Unicode escape
LINE 1: SELECT E'\'\u000g\''::jsonpath;
^
HINT: Unicode escapes must be \uXXXX or \UXXXXXXXX.
SELECT E'\'\u0000\''::jsonpath; -- OK, legal escape
ERROR: invalid Unicode escape value at or near "E'\'\u0000"
LINE 1: SELECT E'\'\u0000\''::jsonpath;
^
SELECT E'\'\uaBcD\''::jsonpath; -- OK, uppercase and lower case both OK
jsonpath
----------
"ꯍ"
(1 row)

-- handling of unicode surrogate pairs
select E'\'\ud83d\ude04\ud83d\udc36\''::jsonpath as correct_in_utf8;
correct_in_utf8
-----------------
"😄🐶"
(1 row)

select E'\'\ud83d\ud83d\''::jsonpath; -- 2 high surrogates in a row
ERROR: invalid Unicode surrogate pair at or near "E'\'\ud83d\ud83d"
LINE 1: select E'\'\ud83d\ud83d\''::jsonpath;
^
select E'\'\ude04\ud83d\''::jsonpath; -- surrogates in wrong order
ERROR: invalid Unicode surrogate pair at or near "E'\'\ude04"
LINE 1: select E'\'\ude04\ud83d\''::jsonpath;
^
select E'\'\ud83dX\''::jsonpath; -- orphan high surrogate
ERROR: invalid Unicode surrogate pair at or near "E'\'\ud83dX"
LINE 1: select E'\'\ud83dX\''::jsonpath;
^
select E'\'\ude04X\''::jsonpath; -- orphan low surrogate
ERROR: invalid Unicode surrogate pair at or near "E'\'\ude04"
LINE 1: select E'\'\ude04X\''::jsonpath;
^
--handling of simple unicode escapes
select E'\'the Copyright \u00a9 sign\''::jsonpath as correct_in_utf8;
correct_in_utf8
------------------------
"the Copyright © sign"
(1 row)

select E'\'dollar \u0024 character\''::jsonpath as correct_everywhere;
correct_everywhere
----------------------
"dollar $ character"
(1 row)

select E'\'dollar \\u0024 character\''::jsonpath as not_an_escape;
not_an_escape
----------------------
"dollar $ character"
(1 row)

select E'\'null \u0000 escape\''::jsonpath as not_unescaped;
ERROR: invalid Unicode escape value at or near "E'\'null \u0000"
LINE 1: select E'\'null \u0000 escape\''::jsonpath as not_unescaped;
^
select E'\'null \\u0000 escape\''::jsonpath as not_an_escape;
ERROR: unsupported Unicode escape sequence
LINE 1: select E'\'null \\u0000 escape\''::jsonpath as not_an_escape...
^
DETAIL: \u0000 cannot be converted to text.
-- checks for quoted key names
-- basic unicode input
SELECT '$."\u"'::jsonpath; -- ERROR, incomplete escape
Expand Down
72 changes: 0 additions & 72 deletions src/test/regress/expected/jsonpath_encoding_1.out
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Original file line number Diff line number Diff line change
Expand Up @@ -78,78 +78,6 @@ select '"null \\u0000 escape"'::jsonpath as not_an_escape;
"null \\u0000 escape"
(1 row)

-- checks for single-quoted values
-- basic unicode input
SELECT E'\'\u\''::jsonpath; -- ERROR, incomplete escape
ERROR: invalid Unicode escape
LINE 1: SELECT E'\'\u\''::jsonpath;
^
HINT: Unicode escapes must be \uXXXX or \UXXXXXXXX.
SELECT E'\'\u00\''::jsonpath; -- ERROR, incomplete escape
ERROR: invalid Unicode escape
LINE 1: SELECT E'\'\u00\''::jsonpath;
^
HINT: Unicode escapes must be \uXXXX or \UXXXXXXXX.
SELECT E'\'\u000g\''::jsonpath; -- ERROR, g is not a hex digit
ERROR: invalid Unicode escape
LINE 1: SELECT E'\'\u000g\''::jsonpath;
^
HINT: Unicode escapes must be \uXXXX or \UXXXXXXXX.
SELECT E'\'\u0000\''::jsonpath; -- OK, legal escape
ERROR: invalid Unicode escape value at or near "E'\'\u0000"
LINE 1: SELECT E'\'\u0000\''::jsonpath;
^
SELECT E'\'\uaBcD\''::jsonpath; -- OK, uppercase and lower case both OK
ERROR: Unicode escape values cannot be used for code point values above 007F when the server encoding is not UTF8 at or near "E'\'\uaBcD"
LINE 1: SELECT E'\'\uaBcD\''::jsonpath;
^
-- handling of unicode surrogate pairs
select E'\'\ud83d\ude04\ud83d\udc36\''::jsonpath as correct_in_utf8;
ERROR: Unicode escape values cannot be used for code point values above 007F when the server encoding is not UTF8 at or near "E'\'\ud83d\ude04"
LINE 1: select E'\'\ud83d\ude04\ud83d\udc36\''::jsonpath as correct_...
^
select E'\'\ud83d\ud83d\''::jsonpath; -- 2 high surrogates in a row
ERROR: invalid Unicode surrogate pair at or near "E'\'\ud83d\ud83d"
LINE 1: select E'\'\ud83d\ud83d\''::jsonpath;
^
select E'\'\ude04\ud83d\''::jsonpath; -- surrogates in wrong order
ERROR: invalid Unicode surrogate pair at or near "E'\'\ude04"
LINE 1: select E'\'\ude04\ud83d\''::jsonpath;
^
select E'\'\ud83dX\''::jsonpath; -- orphan high surrogate
ERROR: invalid Unicode surrogate pair at or near "E'\'\ud83dX"
LINE 1: select E'\'\ud83dX\''::jsonpath;
^
select E'\'\ude04X\''::jsonpath; -- orphan low surrogate
ERROR: invalid Unicode surrogate pair at or near "E'\'\ude04"
LINE 1: select E'\'\ude04X\''::jsonpath;
^
--handling of simple unicode escapes
select E'\'the Copyright \u00a9 sign\''::jsonpath as correct_in_utf8;
ERROR: Unicode escape values cannot be used for code point values above 007F when the server encoding is not UTF8 at or near "E'\'the Copyright \u00a9"
LINE 1: select E'\'the Copyright \u00a9 sign\''::jsonpath as correct...
^
select E'\'dollar \u0024 character\''::jsonpath as correct_everywhere;
correct_everywhere
----------------------
"dollar $ character"
(1 row)

select E'\'dollar \\u0024 character\''::jsonpath as not_an_escape;
not_an_escape
----------------------
"dollar $ character"
(1 row)

select E'\'null \u0000 escape\''::jsonpath as not_unescaped;
ERROR: invalid Unicode escape value at or near "E'\'null \u0000"
LINE 1: select E'\'null \u0000 escape\''::jsonpath as not_unescaped;
^
select E'\'null \\u0000 escape\''::jsonpath as not_an_escape;
ERROR: unsupported Unicode escape sequence
LINE 1: select E'\'null \\u0000 escape\''::jsonpath as not_an_escape...
^
DETAIL: \u0000 cannot be converted to text.
-- checks for quoted key names
-- basic unicode input
SELECT '$."\u"'::jsonpath; -- ERROR, incomplete escape
Expand Down
3 changes: 1 addition & 2 deletions src/test/regress/sql/jsonpath.sql
View file
Original file line number Diff line number Diff line change
Expand Up @@ -30,10 +30,9 @@ select '$.a/+-1'::jsonpath;
select '1 * 2 + 4 % -3 != false'::jsonpath;

select '"\b\f\r\n\t\v\"\''\\"'::jsonpath;
select '''\b\f\r\n\t\v\"\''\\'''::jsonpath;
select '"\x50\u0067\u{53}\u{051}\u{00004C}"'::jsonpath;
select '''\x50\u0067\u{53}\u{051}\u{00004C}'''::jsonpath;
select '$.foo\x50\u0067\u{53}\u{051}\u{00004C}\t\"bar'::jsonpath;
select '"\z"'::jsonpath; -- unrecognized escape is just the literal char
select '$.g ? ($.a == 1)'::jsonpath;
select '$.g ? (@ == 1)'::jsonpath;
Expand Down

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