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Fix data loss when mixing line and block comments #233

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Fix data loss when mixing line and block comments #233

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59 changes: 29 additions & 30 deletions parson.c
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Original file line number Diff line number Diff line change
Expand Up @@ -150,7 +150,7 @@ struct json_array_t {

/* Various */
static char * read_file(const char *filename);
static void remove_comments(char *string, const char *start_token, const char *end_token);
static void remove_comments(char *string);
static char * parson_strndup(const char *string, size_t n);
static char * parson_strdup(const char *string);
static int parson_sprintf(char * s, const char * format, ...);
Expand Down Expand Up @@ -236,38 +236,38 @@ static char * read_file(const char * filename) {
return file_contents;
}

static void remove_comments(char *string, const char *start_token, const char *end_token) {
static void remove_comments(char *string) {
/* Strips block and line comments in a single pass. Handling both styles
at once keeps a comment of one style from being misread as code by the
other (e.g. a block comment opener or a lone quote in a line comment). */
parson_bool_t in_string = PARSON_FALSE, escaped = PARSON_FALSE;
size_t i;
char *ptr = NULL, current_char;
size_t start_token_len = strlen(start_token);
size_t end_token_len = strlen(end_token);
if (start_token_len == 0 || end_token_len == 0) {
return;
}
while ((current_char = *string) != '\0') {
if (current_char == '\\' && !escaped) {
escaped = PARSON_TRUE;
string++;
continue;
} else if (current_char == '\"' && !escaped) {
in_string = !in_string;
} else if (!in_string && strncmp(string, start_token, start_token_len) == 0) {
for(i = 0; i < start_token_len; i++) {
string[i] = ' ';
char *end = NULL;
while (*string != '\0') {
if (in_string) {
if (escaped) {
escaped = PARSON_FALSE;
} else if (*string == '\\') {
escaped = PARSON_TRUE;
} else if (*string == '\"') {
in_string = PARSON_FALSE;
}
string = string + start_token_len;
ptr = strstr(string, end_token);
if (!ptr) {
return;
string++;
} else if (*string == '\"') {
in_string = PARSON_TRUE;
string++;
} else if (string[0] == '/' && string[1] == '*') {
end = strstr(string + 2, "*/");
end = end ? end + 2 : string + strlen(string);
while (string < end) {
*string++ = ' ';
}
for (i = 0; i < (ptr - string) + end_token_len; i++) {
string[i] = ' ';
} else if (string[0] == '/' && string[1] == '/') {
while (*string != '\0' && *string != '\n') {
*string++ = ' ';
}
string = ptr + end_token_len - 1;
} else {
string++;
}
escaped = PARSON_FALSE;
string++;
}
}

Expand Down Expand Up @@ -1405,8 +1405,7 @@ JSON_Value * json_parse_string_with_comments(const char *string) {
if (string_mutable_copy == NULL) {
return NULL;
}
remove_comments(string_mutable_copy, "/*", "*/");
remove_comments(string_mutable_copy, "//", "\n");
remove_comments(string_mutable_copy);
string_mutable_copy_ptr = string_mutable_copy;
result = parse_value((const char**)&string_mutable_copy_ptr, 0);
parson_free(string_mutable_copy);
Expand Down
41 changes: 41 additions & 0 deletions tests.c
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Original file line number Diff line number Diff line change
Expand Up @@ -55,6 +55,7 @@ void test_suite_1(void); /* Test 3 files from json.org + serialization*/
void test_suite_2(JSON_Value *value); /* Test correctness of parsed values */
void test_suite_2_no_comments(void);
void test_suite_2_with_comments(void);
void test_suite_2_mixed_comments(void); /* Test mixing block and line comments */
void test_suite_3(void); /* Test parsing valid and invalid strings */
void test_suite_4(void); /* Test deep copy function */
void test_suite_5(void); /* Test building json values from scratch */
Expand Down Expand Up @@ -127,6 +128,7 @@ int tests_main(int argc, char *argv[]) {
test_suite_1();
test_suite_2_no_comments();
test_suite_2_with_comments();
test_suite_2_mixed_comments();
test_suite_3();
test_suite_4();
test_suite_5();
Expand Down Expand Up @@ -308,6 +310,45 @@ void test_suite_2_with_comments(void) {
json_value_free(root_value);
}

void test_suite_2_mixed_comments(void) {
JSON_Value *root_value = NULL;
JSON_Object *root_object = NULL;

/* A block comment opener inside a line comment must not swallow data */
root_value = json_parse_string_with_comments(
"{\n"
" \"a\": 1, // matches src/*.c\n"
" \"b\": 2, /* required */\n"
" \"c\": 3\n"
"}");
root_object = json_object(root_value);
TEST(root_object != NULL);
TEST(json_object_get_count(root_object) == 3);
TEST(DBL_EQ(json_object_get_number(root_object, "b"), 2));
json_value_free(root_value);

/* A lone quote inside a line comment must not hide a block comment */
root_value = json_parse_string_with_comments(
"{\n"
" \"a\": 1, // 5\" screen\n"
" \"b\": /* px */ 2\n"
"}");
root_object = json_object(root_value);
TEST(root_object != NULL);
TEST(DBL_EQ(json_object_get_number(root_object, "b"), 2));
json_value_free(root_value);

/* A line comment opener inside a block comment is just comment text */
root_value = json_parse_string_with_comments("[1, /* see http://x */ 2]");
TEST(json_array_get_count(json_array(root_value)) == 2);
json_value_free(root_value);

/* Comment markers inside strings are preserved */
root_value = json_parse_string_with_comments("{\"u\": \"http://a/*b*/\"} // done");
TEST(STREQ(json_object_get_string(json_object(root_value), "u"), "http://a/*b*/"));
json_value_free(root_value);
}

void test_suite_3(void) {
/* Testing valid strings */
TEST(json_parse_string("{\"lorem\":\"ipsum\"}") != NULL);
Expand Down