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Tweak the default validation behaviour of the unpack API

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Now, by default, unpacking doesn't check that all array and object
items are accessed. The check can be enabled globally by using the
JSON_STRICT flag (formerly JSON_UNPACK_ONLY), or on a per-value basis
by using the new '!' format character. The '*' format character is
still available to disable the global check on a per-value basis.
This commit is contained in:
Petri Lehtinen 2011-01-29 21:38:07 +02:00
parent 7706abcbed
commit ef13fb9189
3 changed files with 58 additions and 52 deletions
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36
doc/apiref.rst
View File

@ -849,6 +849,7 @@ denotes the C type that is expected as the corresponding argument.
fourth, etc. format character represent a value. Any value may be
an object or array, i.e. recursive value building is supported.
The following functions compose the value building API:
.. function:: json_t *json_pack(const char *fmt, ...)
@ -896,10 +897,10 @@ and extract, or *unpack*, data from them. Like :ref:`building values
While a JSON value is unpacked, the type specified in the format
string is checked to match that of the JSON value. This is the
validation part of the process. By default, the unpacking functions
also check that all items of arrays and objects are unpacked. This
check be disabled with the format character ``*`` or by using the flag
``JSON_UNPACK_ONLY``.
validation part of the process. In addition to this, the unpacking
functions can also check that all items of arrays and objects are
unpacked. This check be enabled with the format character ``!`` or by
using the flag ``JSON_STRICT``. See below for details.
Here's the full list of format characters. The type in parentheses
denotes the JSON type, and the type in brackets (if any) denotes the C
@ -951,12 +952,21 @@ type whose address should be passed.
``fmt`` may contain objects and arrays as values, i.e. recursive
value extraction is supporetd.
``*``
This special format character is used to disable the check that
all object and array items are accessed on a per-value basis. It
``!``
This special format character is used to enable the check that
all object and array items are accessed, on a per-value basis. It
must appear inside an array or object as the last format character
before the closing bracket or brace.
before the closing bracket or brace. To enable the check globally,
use the ``JSON_STRICT`` unpacking flag.
``*``
This special format character is the opposite of ``!``. If the
``JSON_STRICT`` flag is used, ``*`` can be used to disable the
strict check on a per-value basis. It must appear inside an array
or object as the last format character before the closing bracket
or brace.
The following functions compose the parsing and validation API:
.. function:: int json_unpack(json_t *root, const char *fmt, ...)
@ -974,11 +984,11 @@ type whose address should be passed.
The following unpacking flags are available:
``JSON_UNPACK_ONLY``
Disable the validation step checking that all object and array
items are unpacked. This is equivalent to appending the format
character ``*`` to the end of every array and object in the format
string.
``JSON_STRICT``
Enable the extra validation step checking that all object and
array items are unpacked. This is equivalent to appending the
format character ``!`` to the end of every array and object in the
format string.
``JSON_VALIDATE_ONLY``
Don't extract any data, just validate the JSON value against the

2
src/jansson.h
View File

@ -195,7 +195,7 @@ json_t *json_pack_ex(json_error_t *error, size_t flags, const char *fmt, ...);
json_t *json_vpack_ex(json_error_t *error, size_t flags, const char *fmt, va_list ap);
#define JSON_VALIDATE_ONLY 0x1
#define JSON_UNPACK_ONLY 0x2
#define JSON_STRICT 0x2
int json_unpack(json_t *root, const char *fmt, ...);
int json_unpack_ex(json_t *root, json_error_t *error, size_t flags, const char *fmt, ...);

72
src/pack_unpack.c
View File

@ -192,26 +192,23 @@ static int unpack(scanner_t *s, json_t *root, va_list *ap);
static int unpack_object(scanner_t *s, json_t *root, va_list *ap)
{
int ret = -1;
int wildcard = 0;
int strict = 0;
/* Use a set (emulated by a hashtable) to check that all object
keys are accessed. Checking that the correct number of keys
were accessed is not enough, as the same key can be unpacked
multiple times.
*/
hashtable_t *key_set;
hashtable_t key_set;
if(!(s->flags & JSON_UNPACK_ONLY)) {
key_set = hashtable_create(jsonp_hash_key, jsonp_key_equal, NULL, NULL);
if(!key_set) {
set_error(s, "Out of memory");
return -1;
}
if(hashtable_init(&key_set, jsonp_hash_key, jsonp_key_equal, NULL, NULL)) {
set_error(s, "Out of memory");
return -1;
}
if(!json_is_object(root)) {
set_error(s, "Expected object, got %s", type_name(root));
goto error;
goto out;
}
next_token(s);
@ -219,67 +216,64 @@ static int unpack_object(scanner_t *s, json_t *root, va_list *ap)
const char *key;
json_t *value;
if(wildcard) {
set_error(s, "Expected '}' after '*', got '%c'", s->token);
goto error;
if(strict != 0) {
set_error(s, "Expected '}' after '%c', got '%c'",
(strict == 1 ? '!' : '*'), s->token);
goto out;
}
if(!s->token) {
set_error(s, "Unexpected end of format string");
goto error;
goto out;
}
if(s->token == '*') {
wildcard = 1;
if(s->token == '!' || s->token == '*') {
strict = (s->token == '!' ? 1 : -1);
next_token(s);
continue;
}
if(s->token != 's') {
set_error(s, "Expected format 's', got '%c'\n", *s->fmt);
goto error;
goto out;
}
key = va_arg(*ap, const char *);
if(!key) {
set_error(s, "NULL object key");
goto error;
goto out;
}
next_token(s);
value = json_object_get(root, key);
if(unpack(s, value, ap))
goto error;
if(!(s->flags & JSON_UNPACK_ONLY))
hashtable_set(key_set, (void *)key, NULL);
goto out;
hashtable_set(&key_set, (void *)key, NULL);
next_token(s);
}
if(s->flags & JSON_UNPACK_ONLY)
wildcard = 1;
if(strict == 0 && (s->flags & JSON_STRICT))
strict = 1;
if(!wildcard && key_set->size != json_object_size(root)) {
long diff = (long)json_object_size(root) - (long)key_set->size;
if(strict == 1 && key_set.size != json_object_size(root)) {
long diff = (long)json_object_size(root) - (long)key_set.size;
set_error(s, "%li object items left unpacked", diff);
goto error;
goto out;
}
ret = 0;
error:
if(!(s->flags & JSON_UNPACK_ONLY))
hashtable_destroy(key_set);
out:
hashtable_close(&key_set);
return ret;
}
static int unpack_array(scanner_t *s, json_t *root, va_list *ap)
{
size_t i = 0;
int wildcard = 0;
int strict = 0;
if(!json_is_array(root)) {
set_error(s, "Expected array, got %s", type_name(root));
@ -290,8 +284,10 @@ static int unpack_array(scanner_t *s, json_t *root, va_list *ap)
while(s->token != ']') {
json_t *value;
if(wildcard) {
set_error(s, "Expected ']' after '*', got '%c'", s->token);
if(strict != 0) {
set_error(s, "Expected ']' after '%c', got '%c'",
(strict == 1 ? '!' : '*'),
s->token);
return -1;
}
@ -300,8 +296,8 @@ static int unpack_array(scanner_t *s, json_t *root, va_list *ap)
return -1;
}
if(s->token == '*') {
wildcard = 1;
if(s->token == '!' || s->token == '*') {
strict = (s->token == '!' ? 1 : -1);
next_token(s);
continue;
}
@ -319,10 +315,10 @@ static int unpack_array(scanner_t *s, json_t *root, va_list *ap)
i++;
}
if(s->flags & JSON_UNPACK_ONLY)
wildcard = 1;
if(strict == 0 && (s->flags & JSON_STRICT))
strict = 1;
if(!wildcard && i != json_array_size(root)) {
if(strict == 1 && i != json_array_size(root)) {
long diff = (long)json_array_size(root) - (long)i;
set_error(s, "%li array items left upacked", diff);
return -1;