public static RC Prepare_(Context ctx, string sql, int bytes, bool isPrepareV2, Vdbe reprepare, ref Vdbe stmtOut, ref string tailOut)
{
stmtOut = null;
tailOut = null;
string errMsg = null; // Error message
RC rc = RC.OK;
int i;
// Allocate the parsing context
Parse parse = new Parse(); // Parsing context
if (parse == null)
{
rc = RC.NOMEM;
goto end_prepare;
}
parse.Reprepare = reprepare;
parse.LastToken.data = null; //: C#?
Debug.Assert(tailOut == null);
Debug.Assert(!ctx.MallocFailed);
Debug.Assert(MutexEx.Held(ctx.Mutex));
// Check to verify that it is possible to get a read lock on all database schemas. The inability to get a read lock indicates that
// some other database connection is holding a write-lock, which in turn means that the other connection has made uncommitted changes
// to the schema.
//
// Were we to proceed and prepare the statement against the uncommitted schema changes and if those schema changes are subsequently rolled
// back and different changes are made in their place, then when this prepared statement goes to run the schema cookie would fail to detect
// the schema change. Disaster would follow.
//
// This thread is currently holding mutexes on all Btrees (because of the sqlite3BtreeEnterAll() in sqlite3LockAndPrepare()) so it
// is not possible for another thread to start a new schema change while this routine is running. Hence, we do not need to hold
// locks on the schema, we just need to make sure nobody else is holding them.
//
// Note that setting READ_UNCOMMITTED overrides most lock detection, but it does *not* override schema lock detection, so this all still
// works even if READ_UNCOMMITTED is set.
for (i = 0; i < ctx.DBs.length; i++)
{
Btree bt = ctx.DBs[i].Bt;
if (bt != null)
{
Debug.Assert(bt.HoldsMutex());
rc = bt.SchemaLocked();
if (rc != 0)
{
string dbName = ctx.DBs[i].Name;
sqlite3Error(ctx, rc, "database schema is locked: %s", dbName);
C.ASSERTCOVERAGE((ctx.Flags & Context.FLAG.ReadUncommitted) != 0);
goto end_prepare;
}
}
}
VTable.UnlockList(ctx);
parse.Ctx = ctx;
parse.QueryLoops = (double)1;
if (bytes >= 0 && (bytes == 0 || sql[bytes - 1] != 0))
{
int maxLen = ctx.aLimit[SQLITE_LIMIT_SQL_LENGTH];
C.ASSERTCOVERAGE(bytes == maxLen);
C.ASSERTCOVERAGE(bytes == maxLen + 1);
if (bytes > maxLen)
{
sqlite3Error(ctx, RC.TOOBIG, "statement too long");
rc = SysEx.ApiExit(ctx, RC.TOOBIG);
goto end_prepare;
}
string sqlCopy = sql.Substring(0, bytes);
if (sqlCopy != null)
{
parse.RunParser(sqlCopy, ref errMsg);
C._tagfree(ctx, ref sqlCopy);
parse.Tail = null; //: &sql[parse->Tail - sqlCopy];
}
else
{
parse.Tail = null; //: &sql[bytes];
}
}
else
{
parse.RunParser(sql, ref errMsg);
}
Debug.Assert((int)parse.QueryLoops == 1);
if (ctx.MallocFailed)
{
parse.RC = RC.NOMEM;
}
if (parse.RC == RC.DONE)
{
parse.RC = RC.OK;
}
if (parse.CheckSchema != 0)
{
SchemaIsValid(parse);
}
if (ctx.MallocFailed)
{
parse.RC = RC.NOMEM;
}
tailOut = (parse.Tail == null ? null : parse.Tail.ToString());
rc = parse.RC;
Vdbe v = parse.V;
#if !OMIT_EXPLAIN
if (rc == RC.OK && parse.V != null && parse.Explain != 0)
{
int first, max;
if (parse.Explain == 2)
{
v.SetNumCols(4);
first = 8;
max = 12;
}
else
{
v.SetNumCols(8);
first = 0;
max = 8;
}
for (i = first; i < max; i++)
{
v.SetColName(i - first, COLNAME_NAME, _colName[i], C.DESTRUCTOR_STATIC);
}
}
#endif
Debug.Assert(!ctx.Init.Busy || !isPrepareV2);
if (!ctx.Init.Busy)
{
Vdbe.SetSql(v, sql, (int)(sql.Length - (parse.Tail == null ? 0 : parse.Tail.Length)), isPrepareV2);
}
if (v != null && (rc != RC.OK || ctx.MallocFailed))
{
v.Finalize();
Debug.Assert(stmtOut == null);
}
else
{
stmtOut = v;
}
if (errMsg != null)
{
sqlite3Error(ctx, rc, "%s", errMsg);
C._tagfree(ctx, ref errMsg);
}
else
{
sqlite3Error(ctx, rc, null);
}
// Delete any TriggerPrg structures allocated while parsing this statement.
while (parse.TriggerPrg != null)
{
TriggerPrg t = parse.TriggerPrg;
parse.TriggerPrg = t.Next;
C._tagfree(ctx, ref t);
}
end_prepare:
//sqlite3StackFree( db, pParse );
rc = SysEx.ApiExit(ctx, rc);
Debug.Assert((RC)((int)rc & ctx.ErrMask) == rc);
return(rc);
}
