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Clarify ownership of the various objects involved in parsing JSON.

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FossilOrigin-Name: afe02a398a16d51bd7482b6fbe2fbd15d9ac4fd9cdbc9d2bf81f38b3391fc567
This commit is contained in:
drh
2023-07-25 20:26:47 +00:00
parent 440e696d5e
commit 59b8e666f6
4 changed files with 75 additions and 148 deletions
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205
src/json.c
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@@ -171,6 +171,17 @@ struct JsonParse {
** Utility routines for dealing with JsonString objects
**************************************************************************/
#if 0
/*
** This is a destructor for JSON strings. We make it a separate function
** so that the sqlite3ValueIsOfClass() function can be used to unambiguously
** identify sqlite3_value objects that are known JSON strings.
*/
static void jsonStringClass(void *p){
sqlite3RCStrUnref((char*)p);
}
#endif
/* Set the JsonString object to an empty string
*/
static void jsonZero(JsonString *p){
@@ -1700,16 +1711,27 @@ json_parse_restart:
** pParse.
**
** pParse is uninitialized when this routine is called.
**
** pParse->nJPRef set to 1. The caller becomes the owner of the
** the JsonParse object.
**
** pParse->bOwnsJson is to bTakeJson. If bTakeJson is 1, the newly initialized
** JsonParse object will become the own the zJson input string. If bTakeJson
** is 0, then the caller is responsible for preserving zJson for the lifetime
** of the JsonParse object.
*/
static int jsonParse(
JsonParse *pParse, /* Initialize and fill this JsonParse object */
sqlite3_context *pCtx, /* Report errors here */
char *zJson /* Input JSON text to be parsed */
char *zJson, /* Input JSON text to be parsed */
int bTakeJson /* Assume ownership of zJson if true */
){
int i;
memset(pParse, 0, sizeof(*pParse));
if( zJson==0 ) return 1;
pParse->zJson = zJson;
pParse->bOwnsJson = bTakeJson;
pParse->nJPRef = 1;
i = jsonParseValue(pParse, 0);
if( pParse->oom ) i = -1;
if( i>0 ){
@@ -1738,120 +1760,6 @@ static int jsonParse(
return 0;
}
#if 0
/*
** This is a destructor for JSON strings. We make it a separate function
** so that the sqlite3ValueIsOfClass() function can be used to unambiguously
** identify sqlite3_value objects that are known JSON strings.
*/
static void jsonClass(void *p){
sqlite3RCStrUnref((char*)p);
}
#endif
#if 0
/*
** Process SQL function argument pJson as a JSON string. Return a pointer
** to its parse.
**
** If any error is encountered, return a NULL pointer and leave an error
** message in pCtx.
*/
static JsonParse *jsonParseFromFunctionArg(
sqlite3_value *pJson, /* An SQL function argument containing JSON */
sqlite3_context *pCtx, /* For accessing the cache */
sqlite3_context *pErrCtx, /* For reporting errors */
int bUnchng /* Only accept cached parse that are unchanged */
){
JsonParse *pParse;
char *zJson;
int nJson;
JsonParse *pMatch = 0;
int iKey;
int iMinKey = 0;
u32 iMinHold = 0xffffffff;
u32 iMaxHold = 0;
char *zJson = (char*)sqlite3_value_text(pJson);
int nJson = sqlite3_value_bytes(pJson);
if( zJson==0 ) goto json_parse_value_nomem;
if( sqlite3ValueIsOfClass(pJson, jsonClass) ){
assert( zJson!=0 );
(void)sqlite3RCStrRef(zJson);
pParse = sqlite3RCStrGetAttachment(zJson, (void(*)(void*)jsonParseFree);
if( pParse ){
return pParse;
}
}else{
char *z = zJson;
zJson = sqlite3RCStrNew( nJson );
if( zJson==0 ) goto json_parse_value_nomem;
assert( strlen(z)==nJson );
memcpy(zJson, z, nJson+1);
}
/* At this point zJson is an RCStr object that does not yet have a
** parse. This procedure is holding its own reference to that zJson
** and needs to release it, or hand it off, prior to returning.
**
** The next step is to try to find a parse of the JSON that already
** exists in cache.
*/
for(iKey=0; iKey<JSON_CACHE_SZ; iKey++){
JsonParse *p;
p = (JsonParse*)sqlite3_get_auxdata(pCtx, JSON_CACHE_ID+iKey);
if( p==0 ){
iMinKey = iKey;
break;
}
if( pMatch==0
&& p->nJson==nJson
&& (p->isMod==0 || bUnchng==0)
&& memcmp(p->zJson,zJson,nJson)==0
){
p->nErr = 0;
pMatch = p;
}else if( p->iHold<iMinHold ){
iMinHold = p->iHold;
iMinKey = iKey;
}
if( p->iHold>iMaxHold ){
iMaxHold = p->iHold;
}
}
if( pMatch ){
pParse = pMatch;
pParse->iHold = iMaxHold+1;
}else{
/* No parse of zJson could be found in cache. So parse it afresh.
*/
pParse = sqlite3_malloc64( sizeof(JsonParse) );
if( pParse==0 ) goto json_parse_value_nomem;
if( jsonParse(pParse, pCtx, zJson) ){
sqlite3_free(pParse);
sqlite3RCStrUnref(zJson);
return 0;
}
pParse->bOwnsJson = 1;
pParse->nJson = nJson;
pParse->nJPRef = 1;
pParse->iHold = iMaxHold+1;
sqlite3_set_auxdata(pCtx, JSON_CACHE_ID+iMinKey, pParse,
(void(*)(void*))jsonParseFree);
pParse = (JsonParse*)sqlite3_get_auxdata(pCtx, JSON_CACHE_ID+iMinKey);
}
if( pParse ){
pParse->nJPRef++; /* The caller will own this object */
}
return pParse;
json_parse_value_nomem:
if( zJson ) sqlite3RCStrUnref(zJson);
if( pErrCtx ) sqlite3_result_error_nomem(pCtx);
return 0;
}
#endif
/* Mark node i of pParse as being a child of iParent. Call recursively
** to fill in all the descendants of node i.
@@ -1905,18 +1813,28 @@ static int jsonParseFindParents(JsonParse *pParse){
** Obtain a complete parse of the JSON found in the first argument
** of the argv array. Use the sqlite3_get_auxdata() cache for this
** parse if it is available. If the cache is not available or if it
** is no longer valid, parse the JSON again and return the new parse,
** and also register the new parse so that it will be available for
** is no longer valid, parse the JSON again and return the new parse.
** Also register the new parse so that it will be available for
** future sqlite3_get_auxdata() calls.
**
** If an error occurs and pErrCtx!=0 then report the error on pErrCtx
** and return NULL.
**
** If an error occurs and pErrCtx==0 then return the Parse object with
** JsonParse.nErr non-zero. If the caller invokes this routine with
** pErrCtx==0 and it gets back a JsonParse with nErr!=0, then the caller
** is responsible for invoking jsonParseFree() on the returned value.
** But the caller may invoke jsonParseFree() *only* if pParse->nErr!=0.
** The returned pointer (if it is not NULL) is owned by the cache in
** most cases, not the caller. The caller does NOT need to invoke
** jsonParseFree(), in most cases.
**
** Except, if an error occurs and pErrCtx==0 then return the JsonParse
** object with JsonParse.nErr non-zero and the caller will own the JsonParse
** object. In that case, it will be the responsibility of the caller to
** invoke jsonParseFree(). To summarize:
**
** pErrCtx!=0 || p->nErr==0 ==> Return value p is owned by the
** cache. Call does not need to
** free it.
**
** pErrCtx==0 && p->nErr!=0 ==> Return value is owned by the caller
** and so the caller must free it.
*/
static JsonParse *jsonParseCached(
sqlite3_context *pCtx,
@@ -1931,6 +1849,7 @@ static JsonParse *jsonParseCached(
int iMinKey = 0;
u32 iMinHold = 0xffffffff;
u32 iMaxHold = 0;
if( zJson==0 ) return 0;
for(iKey=0; iKey<JSON_CACHE_SZ; iKey++){
p = (JsonParse*)sqlite3_get_auxdata(pCtx, JSON_CACHE_ID+iKey);
@@ -1955,27 +1874,35 @@ static JsonParse *jsonParseCached(
if( pMatch ){
pMatch->nErr = 0;
pMatch->iHold = iMaxHold+1;
assert( pMatch->nJPRef>0 ); /* pMatch is owned by the cache */
return pMatch;
}
p = sqlite3_malloc64( sizeof(*p) + nJson + 1 );
p = sqlite3_malloc64( sizeof(*p) );
if( p==0 ){
sqlite3_result_error_nomem(pCtx);
return 0;
}
memset(p, 0, sizeof(*p));
p->zJson = (char*)&p[1];
memcpy((char*)p->zJson, zJson, nJson+1);
if( jsonParse(p, pErrCtx, p->zJson) ){
if( pErrCtx==0 ){
p->nErr = 1;
return p;
}
p->zJson = sqlite3RCStrNew( nJson );
if( p->zJson==0 ){
sqlite3_free(p);
sqlite3_result_error_nomem(pCtx);
return 0;
}
memcpy(p->zJson, zJson, nJson);
p->zJson[nJson] = 0;
if( jsonParse(p, pErrCtx, p->zJson, 1) ){
if( pErrCtx==0 ){
p->nErr = 1;
assert( p->nJPRef==1 ); /* Caller will own the new JsonParse object p */
return p;
}
jsonParseFree(p);
return 0;
}
p->nJPRef = 1;
p->nJson = nJson;
p->iHold = iMaxHold+1;
/* Transfer ownership of the new JsonParse to the cache */
sqlite3_set_auxdata(pCtx, JSON_CACHE_ID+iMinKey, p,
(void(*)(void*))jsonParseFree);
return (JsonParse*)sqlite3_get_auxdata(pCtx, JSON_CACHE_ID+iMinKey);
@@ -2357,7 +2284,7 @@ static void jsonParseFunc(
u32 i;
assert( argc==1 );
if( jsonParse(&x, ctx, (char*)sqlite3_value_text(argv[0])) ) return;
if( jsonParse(&x, ctx, (char*)sqlite3_value_text(argv[0]), 0) ) return;
jsonParseFindParents(&x);
jsonInit(&s, ctx);
for(i=0; i<x.nNode; i++){
@@ -2681,8 +2608,8 @@ static void jsonPatchFunc(
JsonNode *pResult; /* The result of the merge */
UNUSED_PARAMETER(argc);
if( jsonParse(&x, ctx, (char*)sqlite3_value_text(argv[0])) ) return;
if( jsonParse(&y, ctx, (char*)sqlite3_value_text(argv[1])) ){
if( jsonParse(&x, ctx, (char*)sqlite3_value_text(argv[0]), 0) ) return;
if( jsonParse(&y, ctx, (char*)sqlite3_value_text(argv[1]), 0) ){
jsonParseReset(&x);
return;
}
@@ -2758,7 +2685,7 @@ static void jsonRemoveFunc(
u32 i;
if( argc<1 ) return;
if( jsonParse(&x, ctx, (char*)sqlite3_value_text(argv[0])) ) return;
if( jsonParse(&x, ctx, (char*)sqlite3_value_text(argv[0]), 0) ) return;
assert( x.nNode );
for(i=1; i<(u32)argc; i++){
zPath = (const char*)sqlite3_value_text(argv[i]);
@@ -2880,7 +2807,7 @@ static void jsonReplaceFunc(
jsonWrongNumArgs(ctx, "replace");
return;
}
if( jsonParse(&x, ctx, (char*)sqlite3_value_text(argv[0])) ) return;
if( jsonParse(&x, ctx, (char*)sqlite3_value_text(argv[0]), 0) ) return;
assert( x.nNode );
for(i=1; i<(u32)argc; i+=2){
zPath = (const char*)sqlite3_value_text(argv[i]);
@@ -2926,7 +2853,7 @@ static void jsonSetFunc(
jsonWrongNumArgs(ctx, bIsSet ? "set" : "insert");
return;
}
if( jsonParse(&x, ctx, (char*)sqlite3_value_text(argv[0])) ) return;
if( jsonParse(&x, ctx, (char*)sqlite3_value_text(argv[0]), 0) ) return;
assert( x.nNode );
for(i=1; i<(u32)argc; i+=2){
zPath = (const char*)sqlite3_value_text(argv[i]);
@@ -3046,7 +2973,7 @@ static void jsonErrorFunc(
}else{
int n = 1;
u32 i;
const char *z = p->zJson;
const char *z = (const char*)sqlite3_value_text(argv[0]);
for(i=0; i<p->iErr && ALWAYS(z[i]); i++){
if( (z[i]&0xc0)!=0x80 ) n++;
}
@@ -3639,7 +3566,7 @@ static int jsonEachFilter(
p->zJson = sqlite3_malloc64( n+1 );
if( p->zJson==0 ) return SQLITE_NOMEM;
memcpy(p->zJson, z, (size_t)n+1);
if( jsonParse(&p->sParse, 0, p->zJson) ){
if( jsonParse(&p->sParse, 0, p->zJson, 0) ){
int rc = SQLITE_NOMEM;
if( p->sParse.oom==0 ){
sqlite3_free(cur->pVtab->zErrMsg);