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Fix incremental parsing of invalid numbers with exponents, such as "0e+-" and "12.3E12E12", while still allowing "0e+" in non-strict mode.

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Deprecate the json_parse_double() function from json_util.h
This commit is contained in:
Eric Haszlakiewicz
2020-06-27 15:32:19 +00:00
parent 84e6032883
commit 6eac6986c9
6 changed files with 120 additions and 17 deletions
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80
json_tokener.c
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@@ -97,6 +97,8 @@ static const char *json_tokener_errors[] = {
*/
static json_bool json_tokener_validate_utf8(const char c, unsigned int *nBytes);
static int json_tokener_parse_double(const char *buf, int len, double *retval);
const char *json_tokener_error_desc(enum json_tokener_error jerr)
{
int jerr_int = (int)jerr;
@@ -837,6 +839,25 @@ struct json_object *json_tokener_parse_ex(struct json_tokener *tok, const char *
int case_len = 0;
int is_exponent = 0;
int negativesign_next_possible_location = 1;
if (printbuf_length(tok->pb) > 0)
{
/* We don't save all state from the previous incremental parse
so we need to re-generate it based on the saved string so far.
*/
char *e_loc = strchr(tok->pb->buf, 'e');
if (!e_loc)
e_loc = strchr(tok->pb->buf, 'E');
if (e_loc)
{
char *last_saved_char =
&tok->pb->buf[printbuf_length(tok->pb) - 1];
is_exponent = 1;
/* If the "e" isn't at the end, we can't start with a '-' */
if (e_loc != last_saved_char)
negativesign_next_possible_location = -1;
// else leave it set to 1, i.e. start of the new input
}
}
while (c && strchr(json_number_chars, c))
{
++case_len;
@@ -847,8 +868,9 @@ struct json_object *json_tokener_parse_ex(struct json_tokener *tok, const char *
* protected from input starting with '.' or
* e/E.
*/
if (c == '.')
switch (c)
{
case '.':
if (tok->is_double != 0)
{
/* '.' can only be found once, and out of the exponent part.
@@ -859,9 +881,9 @@ struct json_object *json_tokener_parse_ex(struct json_tokener *tok, const char *
goto out;
}
tok->is_double = 1;
}
if (c == 'e' || c == 'E')
{
break;
case 'e': /* FALLTHRU */
case 'E':
if (is_exponent != 0)
{
/* only one exponent possible */
@@ -872,15 +894,19 @@ struct json_object *json_tokener_parse_ex(struct json_tokener *tok, const char *
tok->is_double = 1;
/* the exponent part can begin with a negative sign */
negativesign_next_possible_location = case_len + 1;
}
if (c == '-' && case_len != negativesign_next_possible_location)
{
/* If the negative sign is not where expected (ie
* start of input or start of exponent part), the
* input is invalid.
*/
tok->err = json_tokener_error_parse_number;
goto out;
break;
case '-':
if (case_len != negativesign_next_possible_location)
{
/* If the negative sign is not where expected (ie
* start of input or start of exponent part), the
* input is invalid.
*/
tok->err = json_tokener_error_parse_number;
goto out;
}
break;
default: break;
}
if (!ADVANCE_CHAR(str, tok) || !PEEK_CHAR(c, tok))
@@ -899,6 +925,22 @@ struct json_object *json_tokener_parse_ex(struct json_tokener *tok, const char *
tok->st_pos = 0;
goto redo_char;
}
if (tok->is_double && !(tok->flags & JSON_TOKENER_STRICT))
{
/* Trim some chars off the end, to allow things
like "123e+" to parse ok. */
while (printbuf_length(tok->pb) > 1)
{
char last_char = tok->pb->buf[printbuf_length(tok->pb) - 1];
if (last_char != 'e' && last_char != 'E' &&
last_char != '-' && last_char != '+')
{
break;
}
tok->pb->buf[printbuf_length(tok->pb) - 1] = '\0';
printbuf_length(tok->pb)--;
}
}
}
{
int64_t num64;
@@ -935,7 +977,8 @@ struct json_object *json_tokener_parse_ex(struct json_tokener *tok, const char *
}
}
else if (tok->is_double &&
json_parse_double(tok->pb->buf, &numd) == 0)
json_tokener_parse_double(
tok->pb->buf, printbuf_length(tok->pb), &numd) == 0)
{
current = json_object_new_double_s(numd, tok->pb->buf);
if (current == NULL)
@@ -1204,3 +1247,12 @@ size_t json_tokener_get_parse_end(struct json_tokener *tok)
assert(tok->char_offset >= 0); /* Drop this line when char_offset becomes a size_t */
return (size_t)tok->char_offset;
}
static int json_tokener_parse_double(const char *buf, int len, double *retval)
{
char *end;
*retval = strtod(buf, &end);
if (buf + len == end)
return 0; // It worked
return 1;
}