using System;
using System.Diagnostics;
using System.Text;

namespace Community.CsharpSqlite
{
  using sqlite3_value = Sqlite3.Mem;

  public partial class Sqlite3
  {
/*
** 2003 January 11
**
** The author disclaims copyright to this source code.  In place of
** a legal notice, here is a blessing:
**
**    May you do good and not evil.
**    May you find forgiveness for yourself and forgive others.
**    May you share freely, never taking more than you give.
**
*************************************************************************
** This file contains code used to implement the sqlite3_set_authorizer()
** API.  This facility is an optional feature of the library.  Embedded
** systems that do not need this facility may omit it by recompiling
** the library with -DSQLITE_OMIT_AUTHORIZATION=1
*************************************************************************
**  Included in SQLite3 port to C#-SQLite;  2008 Noah B Hart
**  C#-SQLite is an independent reimplementation of the SQLite software library
**
**  SQLITE_SOURCE_ID: 2010-08-23 18:52:01 42537b60566f288167f1b5864a5435986838e3a3
**
*************************************************************************
*/
//#include "sqliteInt.h"

/*
** All of the code in this file may be omitted by defining a single
** macro.
*/
#if NO_SQLITE_OMIT_AUTHORIZATION

/*
** Set or clear the access authorization function.
**
** The access authorization function is be called during the compilation
** phase to verify that the user has read and/or write access permission on
** various fields of the database.  The first argument to the auth function
** is a copy of the 3rd argument to this routine.  The second argument
** to the auth function is one of these constants:
**
**       SQLITE_CREATE_INDEX
**       SQLITE_CREATE_TABLE
**       SQLITE_CREATE_TEMP_INDEX
**       SQLITE_CREATE_TEMP_TABLE
**       SQLITE_CREATE_TEMP_TRIGGER
**       SQLITE_CREATE_TEMP_VIEW
**       SQLITE_CREATE_TRIGGER
**       SQLITE_CREATE_VIEW
**       SQLITE_DELETE
**       SQLITE_DROP_INDEX
**       SQLITE_DROP_TABLE
**       SQLITE_DROP_TEMP_INDEX
**       SQLITE_DROP_TEMP_TABLE
**       SQLITE_DROP_TEMP_TRIGGER
**       SQLITE_DROP_TEMP_VIEW
**       SQLITE_DROP_TRIGGER
**       SQLITE_DROP_VIEW
**       SQLITE_INSERT
**       SQLITE_PRAGMA
**       SQLITE_READ
**       SQLITE_SELECT
**       SQLITE_TRANSACTION
**       SQLITE_UPDATE
**
** The third and fourth arguments to the auth function are the name of
** the table and the column that are being accessed.  The auth function
** should return either SQLITE_OK, SQLITE_DENY, or SQLITE_IGNORE.  If
** SQLITE_OK is returned, it means that access is allowed.  SQLITE_DENY
** means that the SQL statement will never-run - the sqlite3_exec() call
** will return with an error.  SQLITE_IGNORE means that the SQL statement
** should run but attempts to read the specified column will return NULL
** and attempts to write the column will be ignored.
**
** Setting the auth function to NULL disables this hook.  The default
** setting of the auth function is NULL.
*/
int sqlite3_set_authorizer(
sqlite3 db,
int (*xAuth)(void*,int,const char*,const char*,const char*,const char),
void *pArg
){
sqlite3_mutex_enter(db->mutex);
db->xAuth = xAuth;
db->pAuthArg = pArg;
sqlite3ExpirePreparedStatements(db);
sqlite3_mutex_leave(db->mutex);
return SQLITE_OK;
}

/*
** Write an error message into pParse->zErrMsg that explains that the
** user-supplied authorization function returned an illegal value.
*/
static void sqliteAuthBadReturnCode(Parse *pParse){
sqlite3ErrorMsg(pParse, "authorizer malfunction");
pParse->rc = SQLITE_ERROR;
}

/*
** Invoke the authorization callback for permission to read column zCol from
** table zTab in database zDb. This function assumes that an authorization
** callback has been registered (i.e. that sqlite3.xAuth is not NULL).
**
** If SQLITE_IGNORE is returned and pExpr is not NULL, then pExpr is changed
** to an SQL NULL expression. Otherwise, if pExpr is NULL, then SQLITE_IGNORE
** is treated as SQLITE_DENY. In this case an error is left in pParse.
*/
int sqlite3AuthReadCol(
  Parse *pParse,                  /* The parser context */
  string zTab,               /* Table name */
  string zCol,               /* Column name */
  int iDb                         /* Index of containing database. */
){
  sqlite3 db = pParse->db;       /* Database handle */
  string zDb = db->aDb[iDb].zName; /* Name of attached database */
  int rc;                         /* Auth callback return code */

  rc = db->xAuth(db->pAuthArg, SQLITE_READ, zTab,zCol,zDb,pParse->zAuthContext);
  if( rc==SQLITE_DENY ){
if( db->nDb>2 || iDb!=0 ){
  sqlite3ErrorMsg(pParse, "access to %s.%s.%s is prohibited",zDb,zTab,zCol);
}else{
  sqlite3ErrorMsg(pParse, "access to %s.%s is prohibited", zTab, zCol);
}
pParse->rc = SQLITE_AUTH;
  }else if( rc!=SQLITE_IGNORE && rc!=SQLITE_OK ){
sqliteAuthBadReturnCode(pParse);
  }
  return rc;
}

/*
** The pExpr should be a TK_COLUMN expression.  The table referred to
** is in pTabList or else it is the NEW or OLD table of a trigger.
** Check to see if it is OK to read this particular column.
**
** If the auth function returns SQLITE_IGNORE, change the TK_COLUMN
** instruction into a TK_NULL.  If the auth function returns SQLITE_DENY,
** then generate an error.
*/
void sqlite3AuthRead(
Parse *pParse,        /* The parser context */
Expr *pExpr,          /* The expression to check authorization on */
Schema *pSchema,      /* The schema of the expression */
SrcList *pTabList     /* All table that pExpr might refer to */
){
sqlite3 db = pParse->db;
Table *pTab = 0;      /* The table being read */
string zCol;     /* Name of the column of the table */
int iSrc;             /* Index in pTabList->a[] of table being read */
int iDb;              /* The index of the database the expression refers to */
int iCol;             /* Index of column in table */

if( db->xAuth==0 ) return;
iDb = sqlite3SchemaToIndex(pParse->db, pSchema);
if( iDb<0 ){
/* An attempt to read a column out of a subquery or other
** temporary table. */
return;
}
  Debug.Assert( pExpr->op==TK_COLUMN || pExpr->op==TK_TRIGGER );
  if( pExpr->op==TK_TRIGGER ){
pTab = pParse->pTriggerTab;
  }else{
Debug.Assert( pTabList );
for(iSrc=0; ALWAYS(iSrc<pTabList->nSrc); iSrc++){
  if( pExpr->iTable==pTabList->a[iSrc].iCursor ){
    pTab = pTabList->a[iSrc].pTab;
	break;
  }
}
  }
  iCol = pExpr->iColumn;
  if( NEVER(pTab==0) ) return;

  if( iCol>=0 ){
Debug.Assert( iCol<pTab->nCol );
zCol = pTab->aCol[iCol].zName;
  }else if( pTab->iPKey>=0 ){
Debug.Assert( pTab->iPKey<pTab->nCol );
zCol = pTab->aCol[pTab->iPKey].zName;
}else{
zCol = "ROWID";
}
Debug.Assert( iDb>=0 && iDb<db->nDb );
  if( SQLITE_IGNORE==sqlite3AuthReadCol(pParse, pTab->zName, zCol, iDb) ){
pExpr->op = TK_NULL;
}
}

/*
** Do an authorization check using the code and arguments given.  Return
** either SQLITE_OK (zero) or SQLITE_IGNORE or SQLITE_DENY.  If SQLITE_DENY
** is returned, then the error count and error message in pParse are
** modified appropriately.
*/
int sqlite3AuthCheck(
Parse *pParse,
int code,
string zArg1,
string zArg2,
string zArg3
){
sqlite3 db = pParse->db;
int rc;

/* Don't do any authorization checks if the database is initialising
** or if the parser is being invoked from within sqlite3_declare_vtab.
*/
if( db->init.busy || IN_DECLARE_VTAB ){
return SQLITE_OK;
}

if( db->xAuth==0 ){
return SQLITE_OK;
}
rc = db->xAuth(db->pAuthArg, code, zArg1, zArg2, zArg3, pParse->zAuthContext);
if( rc==SQLITE_DENY ){
sqlite3ErrorMsg(pParse, "not authorized");
pParse->rc = SQLITE_AUTH;
}else if( rc!=SQLITE_OK && rc!=SQLITE_IGNORE ){
rc = SQLITE_DENY;
sqliteAuthBadReturnCode(pParse);
}
return rc;
}

/*
** Push an authorization context.  After this routine is called, the
** zArg3 argument to authorization callbacks will be zContext until
** popped.  Or if pParse==0, this routine is a no-op.
*/
void sqlite3AuthContextPush(
Parse *pParse,
AuthContext *pContext,
string zContext
){
Debug.Assert( pParse );
pContext->pParse = pParse;
pContext->zAuthContext = pParse->zAuthContext;
pParse->zAuthContext = zContext;
}

/*
** Pop an authorization context that was previously pushed
** by sqlite3AuthContextPush
*/
void sqlite3AuthContextPop(AuthContext *pContext){
if( pContext->pParse ){
pContext->pParse->zAuthContext = pContext->zAuthContext;
pContext->pParse = 0;
}
}

#endif //* SQLITE_OMIT_AUTHORIZATION */
  }
}
