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Rewrite the json_tokener_state_inf handling in json_tokener to be simpler, and avoid needless copying of the input into a temporary buffer.

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This commit is contained in:
Eric Haszlakiewicz
2017-11-27 00:20:11 -05:00
parent 31a6c2fac8
commit f81da5e57a
1 changed files with 45 additions and 29 deletions
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74
json_tokener.c
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@@ -57,7 +57,8 @@
static const char json_null_str[] = "null"; static const char json_null_str[] = "null";
static const int json_null_str_len = sizeof(json_null_str) - 1; static const int json_null_str_len = sizeof(json_null_str) - 1;
static const char json_inf_str[] = "Infinity"; static const char json_inf_str[] = "Infinity";
static const int json_inf_str_len = sizeof(json_inf_str) - 1; static const char json_inf_str_lower[] = "infinity";
static const unsigned int json_inf_str_len = sizeof(json_inf_str) - 1;
static const char json_nan_str[] = "NaN"; static const char json_nan_str[] = "NaN";
static const int json_nan_str_len = sizeof(json_nan_str) - 1; static const int json_nan_str_len = sizeof(json_nan_str) - 1;
static const char json_true_str[] = "true"; static const char json_true_str[] = "true";
@@ -383,40 +384,55 @@ struct json_object* json_tokener_parse_ex(struct json_tokener *tok,
tok->depth--; tok->depth--;
goto redo_char; goto redo_char;
case json_tokener_state_inf: /* aka starts with 'i' */ case json_tokener_state_inf: /* aka starts with 'i' (or 'I', or "-i", or "-I") */
{ {
size_t size_inf; /* If we were guaranteed to have len set, then we could (usually) handle
* the entire "Infinity" check in a single strncmp (strncasecmp), but
* since len might be -1 (i.e. "read until \0"), we need to check it
* a character at a time.
* Trying to handle it both ways would make this code considerably more
* complicated with likely little performance benefit.
*/
int is_negative = 0; int is_negative = 0;
char *infbuf; const char *_json_inf_str = json_inf_str;
if (!(tok->flags & JSON_TOKENER_STRICT))
_json_inf_str = json_inf_str_lower;
printbuf_memappend_fast(tok->pb, &c, 1); /* Note: tok->st_pos must be 0 when state is set to json_tokener_state_inf */
size_inf = json_min(tok->st_pos+1, json_inf_str_len); while (tok->st_pos < (int)json_inf_str_len)
infbuf = tok->pb->buf; {
if (*infbuf == '-') char inf_char = *str;
if (!(tok->flags & JSON_TOKENER_STRICT))
inf_char = tolower(*str);
if (inf_char != _json_inf_str[tok->st_pos])
{
tok->err = json_tokener_error_parse_unexpected;
goto out;
}
tok->st_pos++;
(void)ADVANCE_CHAR(str, tok);
if (!PEEK_CHAR(c, tok))
{
/* out of input chars, for now at least */
goto out;
}
}
/* We checked the full length of "Infinity", so create the object.
* When handling -Infinity, the number parsing code will have dropped
* the "-" into tok->pb for us, so check it now.
*/
if (printbuf_length(tok->pb) > 0 && *(tok->pb->buf) == '-')
{ {
infbuf++;
is_negative = 1; is_negative = 1;
} }
if ((!(tok->flags & JSON_TOKENER_STRICT) && current = json_object_new_double(is_negative
strncasecmp(json_inf_str, infbuf, size_inf) == 0) || ? -INFINITY : INFINITY);
(strncmp(json_inf_str, infbuf, size_inf) == 0) if (current == NULL)
)
{
if (tok->st_pos == json_inf_str_len)
{
current = json_object_new_double(is_negative
? -INFINITY : INFINITY);
if(current == NULL)
goto out;
saved_state = json_tokener_state_finish;
state = json_tokener_state_eatws;
goto redo_char;
}
} else {
tok->err = json_tokener_error_parse_unexpected;
goto out; goto out;
} saved_state = json_tokener_state_finish;
tok->st_pos++; state = json_tokener_state_eatws;
goto redo_char;
} }
break; break;
case json_tokener_state_null: /* aka starts with 'n' */ case json_tokener_state_null: /* aka starts with 'n' */
@@ -934,7 +950,7 @@ struct json_object* json_tokener_parse_ex(struct json_tokener *tok,
} }
if (!ADVANCE_CHAR(str, tok)) if (!ADVANCE_CHAR(str, tok))
goto out; goto out;
} /* while(POP_CHAR) */ } /* while(PEEK_CHAR) */
out: out:
if (c && if (c &&