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Fix for strings containing special JSON characters in get_json_object(). #8556

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merged 2 commits into from
Jun 30, 2021
Merged

Fix for strings containing special JSON characters in get_json_object(). #8556

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962265e
Use parse_string to explicitly and safely handle strings inside of ex…
nvdbaranec Jun 18, 2021
8b06c13
Doc change.
nvdbaranec Jun 18, 2021
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71 changes: 60 additions & 11 deletions cpp/src/strings/json/json_path.cu
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Original file line number Diff line number Diff line change
Expand Up @@ -98,6 +98,44 @@ class parser {
return false;
}

CUDA_HOST_DEVICE_CALLABLE bool is_hex_digit(char c)
{
return (c >= '0' && c <= '9') || (c >= 'a' && c <= 'f') || (c >= 'A' && c <= 'F');
}

CUDA_HOST_DEVICE_CALLABLE int64_t chars_left() { return input_len - ((pos - input) + 1); }

/**
* @brief Parse an escape sequence.
*
* Must be a valid sequence as specified by the JSON format
* https://www.json.org/json-en.html
*
* @returns True on success or false on fail.
*/
CUDA_HOST_DEVICE_CALLABLE bool parse_escape_seq()
{
if (*pos != '\\') { return false; }
char c = *++pos;

// simple case
if (c == '\"' || c == '\\' || c == '/' || c == 'b' || c == 'f' || c == 'n' || c == 'r' ||
c == 't') {
pos++;
return true;
}

// hex digits: must be of the form uXXXX where each X is a valid hex digit
if (c == 'u' && chars_left() >= 4 && is_hex_digit(pos[1]) && is_hex_digit(pos[2]) &&
is_hex_digit(pos[3]) && is_hex_digit(pos[4])) {
pos += 5;
return true;
}

// an illegal escape sequence.
return false;
}

/**
* @brief Parse a quote-enclosed JSON string.
*
Expand All @@ -122,12 +160,16 @@ class parser {

const char* start = ++pos;
while (!eof()) {
if (*pos == quote) {
// handle escaped characters
if (*pos == '\\') {
if (!parse_escape_seq()) { return parse_result::ERROR; }
} else if (*pos == quote) {
str = string_view(start, pos - start);
pos++;
return parse_result::SUCCESS;
} else {
pos++;
}
pos++;
}
}
}
Expand Down Expand Up @@ -229,15 +271,22 @@ class json_state : private parser {
int arr_count = 0;

while (!eof(end)) {
// could do some additional checks here. we know our current
// element type, so we could be more strict on what kinds of
// characters we expect to see.
switch (*end++) {
case '{': obj_count++; break;
case '}': obj_count--; break;
case '[': arr_count++; break;
case ']': arr_count--; break;
default: break;
// parse strings explicitly so we handle all interesting corner cases (such as strings
// containing {, }, [ or ]
if (is_quote(*end)) {
string_view str;
pos = end;
if (parse_string(str, false, *end) == parse_result::ERROR) { return parse_result::ERROR; }
end = pos;
} else {
char const c = *end++;
switch (c) {
case '{': obj_count++; break;
case '}': obj_count--; break;
case '[': arr_count++; break;
case ']': arr_count--; break;
default: break;
}
}
if (obj_count == 0 && arr_count == 0) { break; }
}
Expand Down
120 changes: 106 additions & 14 deletions cpp/tests/strings/json_tests.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -76,10 +76,10 @@ std::unique_ptr<cudf::column> drop_whitespace(cudf::column_view const& col)
return cudf::strings::replace(strings, targets, replacements);
}

struct JsonTests : public cudf::test::BaseFixture {
struct JsonPathTests : public cudf::test::BaseFixture {
};

TEST_F(JsonTests, GetJsonObjectRootOp)
TEST_F(JsonPathTests, GetJsonObjectRootOp)
{
// root
cudf::test::strings_column_wrapper input{json_string};
Expand All @@ -92,7 +92,7 @@ TEST_F(JsonTests, GetJsonObjectRootOp)
CUDF_TEST_EXPECT_COLUMNS_EQUIVALENT(*result, *expected);
}

TEST_F(JsonTests, GetJsonObjectChildOp)
TEST_F(JsonPathTests, GetJsonObjectChildOp)
{
{
cudf::test::strings_column_wrapper input{json_string};
Expand Down Expand Up @@ -187,7 +187,7 @@ TEST_F(JsonTests, GetJsonObjectChildOp)
}
}

TEST_F(JsonTests, GetJsonObjectWildcardOp)
TEST_F(JsonPathTests, GetJsonObjectWildcardOp)
{
{
cudf::test::strings_column_wrapper input{json_string};
Expand Down Expand Up @@ -291,7 +291,7 @@ TEST_F(JsonTests, GetJsonObjectWildcardOp)
}
}

TEST_F(JsonTests, GetJsonObjectSubscriptOp)
TEST_F(JsonPathTests, GetJsonObjectSubscriptOp)
{
{
cudf::test::strings_column_wrapper input{json_string};
Expand Down Expand Up @@ -378,7 +378,7 @@ TEST_F(JsonTests, GetJsonObjectSubscriptOp)
}
}

TEST_F(JsonTests, GetJsonObjectFilter)
TEST_F(JsonPathTests, GetJsonObjectFilter)
{
// queries that result in filtering/collating results (mostly meaning - generates new
// json instead of just returning parts of the existing string
Expand Down Expand Up @@ -449,7 +449,7 @@ TEST_F(JsonTests, GetJsonObjectFilter)
}
}

TEST_F(JsonTests, GetJsonObjectNullInputs)
TEST_F(JsonPathTests, GetJsonObjectNullInputs)
{
{
std::string str("{\"a\" : \"b\"}");
Expand All @@ -466,7 +466,7 @@ TEST_F(JsonTests, GetJsonObjectNullInputs)
}
}

TEST_F(JsonTests, GetJsonObjectEmptyQuery)
TEST_F(JsonPathTests, GetJsonObjectEmptyQuery)
{
// empty query -> null
{
Expand All @@ -480,7 +480,7 @@ TEST_F(JsonTests, GetJsonObjectEmptyQuery)
}
}

TEST_F(JsonTests, GetJsonObjectEmptyInputsAndOutputs)
TEST_F(JsonPathTests, GetJsonObjectEmptyInputsAndOutputs)
{
// empty input -> null
{
Expand Down Expand Up @@ -508,7 +508,7 @@ TEST_F(JsonTests, GetJsonObjectEmptyInputsAndOutputs)
}

// badly formed JSONpath strings
TEST_F(JsonTests, GetJsonObjectIllegalQuery)
TEST_F(JsonPathTests, GetJsonObjectIllegalQuery)
{
// can't have more than one root operator, or a root operator anywhere other
// than the beginning
Expand Down Expand Up @@ -581,7 +581,7 @@ TEST_F(JsonTests, GetJsonObjectIllegalQuery)
}

// queries that are legal, but reference invalid parts of the input
TEST_F(JsonTests, GetJsonObjectInvalidQuery)
TEST_F(JsonPathTests, GetJsonObjectInvalidQuery)
{
// non-existent field
{
Expand Down Expand Up @@ -628,7 +628,7 @@ TEST_F(JsonTests, GetJsonObjectInvalidQuery)
}
}

TEST_F(JsonTests, MixedOutput)
TEST_F(JsonPathTests, MixedOutput)
{
// various queries on:
// clang-format off
Expand Down Expand Up @@ -760,7 +760,7 @@ TEST_F(JsonTests, MixedOutput)
}
}

TEST_F(JsonTests, StripQuotes)
TEST_F(JsonPathTests, StripQuotes)
{
// we normally expect our outputs here to be
// b (no quotes)
Expand Down Expand Up @@ -801,7 +801,7 @@ TEST_F(JsonTests, StripQuotes)
}
}

TEST_F(JsonTests, AllowSingleQuotes)
TEST_F(JsonPathTests, AllowSingleQuotes)
{
// Tests allowing single quotes for strings.
// Note: this flag allows a mix of single and double quotes. it doesn't explicitly require
Expand Down Expand Up @@ -876,3 +876,95 @@ TEST_F(JsonTests, AllowSingleQuotes)
CUDF_TEST_EXPECT_COLUMNS_EQUIVALENT(*result, expected);
}
}

TEST_F(JsonPathTests, StringsWithSpecialChars)
{
// make sure we properly handle strings containing special characters
// like { } [ ], etc
// various queries on:

{
std::vector<std::string> input_strings{
// clang-format off
"{\"item\" : [{\"key\" : \"value[\"}]}",
// clang-format on
};

cudf::test::strings_column_wrapper input(input_strings.begin(), input_strings.end());
{
std::string json_path("$.item");

cudf::strings::get_json_object_options options;
options.set_allow_single_quotes(true);

auto result =
cudf::strings::get_json_object(cudf::strings_column_view(input), json_path, options);

// clang-format off
cudf::test::strings_column_wrapper expected({
"[{\"key\" : \"value[\"}]",
});
// clang-format on
CUDF_TEST_EXPECT_COLUMNS_EQUIVALENT(*result, expected);
}
}

{
std::vector<std::string> input_strings{
// clang-format off
"{\"a\" : \"[}{}][][{[\\\"}}[\\\"]\"}",
// clang-format on
};

cudf::test::strings_column_wrapper input(input_strings.begin(), input_strings.end());
{
std::string json_path("$.a");

cudf::strings::get_json_object_options options;
options.set_allow_single_quotes(true);

auto result =
cudf::strings::get_json_object(cudf::strings_column_view(input), json_path, options);

// clang-format off
cudf::test::strings_column_wrapper expected({
"[}{}][][{[\\\"}}[\\\"]",
});
// clang-format on
CUDF_TEST_EXPECT_COLUMNS_EQUIVALENT(*result, expected);
}
}
}

TEST_F(JsonPathTests, EscapeSequences)
{
// valid escape sequences in JSON include
// \" \\ \/ \b \f \n \r \t
// \uXXXX where X is a valid hex digit

std::vector<std::string> input_strings{
// clang-format off
"{\"a\" : \"\\\" \\\\ \\/ \\b \\f \\n \\r \\t\"}",
"{\"a\" : \"\\u1248 \\uacdf \\uACDF \\u10EF\"}"
// clang-format on
};

cudf::test::strings_column_wrapper input(input_strings.begin(), input_strings.end());
{
std::string json_path("$.a");

cudf::strings::get_json_object_options options;
options.set_allow_single_quotes(true);

auto result =
cudf::strings::get_json_object(cudf::strings_column_view(input), json_path, options);

// clang-format off
cudf::test::strings_column_wrapper expected({
"\\\" \\\\ \\/ \\b \\f \\n \\r \\t",
"\\u1248 \\uacdf \\uACDF \\u10EF"
});
// clang-format on
CUDF_TEST_EXPECT_COLUMNS_EQUIVALENT(*result, expected);
}
}
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nit: newline