mirror/json-c
1
0
Fork 0
mirror of https://github.com/json-c/json-c.git synced 2026-03-21 14:09:06 +08:00
Code Issues Packages Projects Releases Wiki Activity

json_tokener: optimize parsing of integer values

Browse Source 
speedup for 32-bit: ~8%
speedup for 64-bit: ~9%
This commit is contained in:
Ramiro Polla
2018-12-08 19:28:46 +01:00
parent d98fc501fb
commit c9a0ac5886
3 changed files with 42 additions and 13 deletions
Download Patch File Download Diff File Expand all files Collapse all files

2
json_tokener.c
View File

@@ -824,7 +824,7 @@ struct json_object* json_tokener_parse_ex(struct json_tokener *tok,
{
int64_t num64;
double numd;
if (!tok->is_double && json_parse_int64(tok->pb->buf, &num64) == 0) {
if (!tok->is_double && json_parse_sanitized_int64(tok->pb->buf, tok->pb->bpos, &num64) == 0) {
if (num64 && tok->pb->buf[0]=='0' &&
(tok->flags & JSON_TOKENER_STRICT)) {
/* in strict mode, number must not start with 0 */

52
json_util.c
View File

@@ -39,10 +39,6 @@
#endif /* HAVE_UNISTD_H */
#ifdef WIN32
# if MSC_VER < 1800
/* strtoll is available only since Visual Studio 2013 */
# define strtoll _strtoi64
# endif
# define WIN32_LEAN_AND_MEAN
# include <windows.h>
# include <io.h>
@@ -195,16 +191,48 @@ int json_parse_double(const char *buf, double *retval)
return end == buf ? 1 : 0;
}
// The input buffer 'buf' must contain only digits (0 to 9), except
// for the first character, which may be a negative sign '-'.
int json_parse_sanitized_int64(const char *buf, size_t len, int64_t *retval)
{
uint64_t uval = 0;
int is_negative = (*buf == '-');
size_t ii = is_negative ? 1 : 0;
if (ii == len || buf[ii] == '\0')
return 1;
while (ii < len)
{
uint64_t tmp = (uval * 10) + buf[ii++] - '0';
// Check for overflow.
if ((int64_t) uval > (int64_t) tmp)
{
*retval = is_negative ? INT64_MIN : INT64_MAX;
return 0;
}
uval = tmp;
}
*retval = is_negative ? -uval : uval;
return 0;
}
int json_parse_int64(const char *buf, int64_t *retval)
{
char *end = NULL;
int64_t val;
errno = 0;
val = strtoll(buf, &end, 10);
if (end != buf)
*retval = val;
return ((val == 0 && errno != 0) || (end == buf)) ? 1 : 0;
size_t len = 0;
// Skip leading white spaces.
while (isspace(*buf))
buf++;
// Calculate length of valid input.
if (buf[len] == '-')
len++;
while (buf[len] >= '0' && buf[len] <= '9')
len++;
if (len == 0)
return 1;
return json_parse_sanitized_int64(buf, len, retval);
}
#ifndef HAVE_REALLOC

1
json_util.h
View File

@@ -90,6 +90,7 @@ extern int json_object_to_fd(int fd, struct json_object *obj, int flags);
const char *json_util_get_last_err(void);
extern int json_parse_sanitized_int64(const char *buf, size_t len, int64_t *retval);
extern int json_parse_int64(const char *buf, int64_t *retval);
extern int json_parse_double(const char *buf, double *retval);