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spa: json: check object key-value pair parity during parsing

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Check each object key is associated with value.  Disallow object or
array valued keys.

Add flag tracking whether the parser is at global top-level or not, as
there we may either be in object context or in a single-value context.

Save depth=0 array flag bit in state, so that spa_json_next preserves
its complete state across calls. The higher-depth flag bits can be in
temporary stack as they are not needed across calls.
This commit is contained in:
Pauli Virtanen 2024-03-24 22:21:43 +02:00
parent 921c8b99db
commit 3775e4e624
2 changed files with 138 additions and 44 deletions
Download patch file Download diff file Expand all files Collapse all files

83
spa/include/spa/utils/json.h
View file

@ -44,7 +44,7 @@ static inline void spa_json_init(struct spa_json * iter, const char *data, size_
{
*iter = SPA_JSON_INIT(data, size);
}
#define SPA_JSON_ENTER(iter) ((struct spa_json) { (iter)->cur, (iter)->end, (iter), (iter)->state & 0xf0, 0 })
#define SPA_JSON_ENTER(iter) ((struct spa_json) { (iter)->cur, (iter)->end, (iter), (iter)->state & 0xff0, 0 })
static inline void spa_json_enter(struct spa_json * iter, struct spa_json * sub)
{
@ -60,13 +60,14 @@ static inline int spa_json_next(struct spa_json * iter, const char **value)
int utf8_remain = 0;
enum {
__NONE, __STRUCT, __BARE, __STRING, __UTF8, __ESC, __COMMENT,
__ARRAY_FLAG = 0x10,
__OBJECT_FLAG = 0x20,
__ARRAY_FLAG = 0x10, /* in array context */
__PREV_ARRAY_FLAG = 0x20, /* depth=0 array context flag */
__ERROR_FLAG = 0x40,
__FLAGS = 0xf0,
__KEY_FLAG = 0x80, /* inside object key */
__SUB_FLAG = 0x100, /* not at top-level */
__FLAGS = 0xff0,
};
uint8_t object_stack[16] = {0};
uint8_t array_stack[SPA_N_ELEMENTS(object_stack)] = {0};
uint64_t array_stack[8] = {0}; /* array context flags of depths 1...512 */
*value = iter->cur;
@ -81,6 +82,7 @@ static inline int spa_json_next(struct spa_json * iter, const char **value)
flag = iter->state & __FLAGS;
switch (iter->state & ~__FLAGS) {
case __NONE:
flag &= ~(__KEY_FLAG | __PREV_ARRAY_FLAG);
iter->state = __STRUCT | flag;
iter->depth = 0;
goto again;
@ -91,21 +93,48 @@ static inline int spa_json_next(struct spa_json * iter, const char **value)
case ':': case '=':
if (flag & __ARRAY_FLAG)
goto error;
if (!(flag & __KEY_FLAG))
goto error;
iter->state |= __SUB_FLAG;
continue;
case '#':
iter->state = __COMMENT | flag;
continue;
case '"':
if (flag & __KEY_FLAG)
flag |= __SUB_FLAG;
if (!(flag & __ARRAY_FLAG))
SPA_FLAG_UPDATE(flag, __KEY_FLAG, !(flag & __KEY_FLAG));
*value = iter->cur;
iter->state = __STRING | flag;
continue;
case '[': case '{':
iter->state = __STRUCT | (cur == '[' ? __ARRAY_FLAG : __OBJECT_FLAG);
if ((iter->depth >> 3) < SPA_N_ELEMENTS(object_stack)) {
uint8_t mask = 1 << (iter->depth & 0x7);
SPA_FLAG_UPDATE(object_stack[iter->depth >> 3], mask, flag & __OBJECT_FLAG);
SPA_FLAG_UPDATE(array_stack[iter->depth >> 3], mask, flag & __ARRAY_FLAG);
if (!(flag & __ARRAY_FLAG)) {
/* At top-level we may be either in object context
* or in single-item context, and then we need ot
* accept array/object here.
*/
if ((iter->state & __SUB_FLAG) && !(flag & __KEY_FLAG))
goto error;
SPA_FLAG_CLEAR(flag, __KEY_FLAG);
}
iter->state = __STRUCT | __SUB_FLAG | flag;
SPA_FLAG_UPDATE(iter->state, __ARRAY_FLAG, cur == '[');
/* We need to remember previous array state across calls
* for depth=0, so store that in state. Others bits go to
* temporary stack.
*/
if (iter->depth == 0) {
SPA_FLAG_UPDATE(iter->state, __PREV_ARRAY_FLAG, flag & __ARRAY_FLAG);
} else if (((iter->depth-1) >> 6) < SPA_N_ELEMENTS(array_stack)) {
uint64_t mask = 1ULL << ((iter->depth-1) & 0x3f);
SPA_FLAG_UPDATE(array_stack[(iter->depth-1) >> 6], mask, flag & __ARRAY_FLAG);
} else {
/* too deep */
goto error;
}
*value = iter->cur;
if (++iter->depth > 1)
continue;
@ -114,9 +143,13 @@ static inline int spa_json_next(struct spa_json * iter, const char **value)
case '}': case ']':
if ((flag & __ARRAY_FLAG) && cur != ']')
goto error;
if ((flag & __OBJECT_FLAG) && cur != '}')
if (!(flag & __ARRAY_FLAG) && cur != '}')
goto error;
iter->state = __STRUCT;
if (flag & __KEY_FLAG) {
/* incomplete key-value pair */
goto error;
}
iter->state = __STRUCT | __SUB_FLAG | flag;
if (iter->depth == 0) {
if (iter->parent)
iter->parent->cur = iter->cur;
@ -125,12 +158,15 @@ static inline int spa_json_next(struct spa_json * iter, const char **value)
return 0;
}
--iter->depth;
if ((iter->depth >> 3) < SPA_N_ELEMENTS(object_stack)) {
uint8_t mask = 1 << (iter->depth & 0x7);
if (SPA_FLAG_IS_SET(object_stack[iter->depth >> 3], mask))
iter->state |= __OBJECT_FLAG;
if (SPA_FLAG_IS_SET(array_stack[iter->depth >> 3], mask))
iter->state |= __ARRAY_FLAG;
if (iter->depth == 0) {
SPA_FLAG_UPDATE(iter->state, __ARRAY_FLAG, flag & __PREV_ARRAY_FLAG);
} else if (((iter->depth-1) >> 6) < SPA_N_ELEMENTS(array_stack)) {
uint64_t mask = 1ULL << ((iter->depth-1) & 0x3f);
SPA_FLAG_UPDATE(iter->state, __ARRAY_FLAG,
SPA_FLAG_IS_SET(array_stack[(iter->depth-1) >> 6], mask));
} else {
/* too deep */
goto error;
}
continue;
case '\\':
@ -140,6 +176,10 @@ static inline int spa_json_next(struct spa_json * iter, const char **value)
/* allow bare ascii */
if (!(cur >= 32 && cur <= 126))
goto error;
if (flag & __KEY_FLAG)
flag |= __SUB_FLAG;
if (!(flag & __ARRAY_FLAG))
SPA_FLAG_UPDATE(flag, __KEY_FLAG, !(flag & __KEY_FLAG));
*value = iter->cur;
iter->state = __BARE | flag;
}
@ -227,6 +267,11 @@ static inline int spa_json_next(struct spa_json * iter, const char **value)
return 0;
}
if ((iter->state & __SUB_FLAG) && (iter->state & __KEY_FLAG)) {
/* incomplete key-value pair */
goto error;
}
if ((iter->state & ~__FLAGS) != __STRUCT) {
iter->state = __STRUCT | (iter->state & __FLAGS);
return iter->cur - *value;