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Change the SQLITE_READ authorization call for unreferenced tables to use

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an empty string for the column name, as this is less likely to impact legacy
authorization callbacks that assume column names are always non-NULL.

FossilOrigin-Name: 4139953ab528f20fa346409810edcb22adb6c1edc9d22f40b1b077ef842a2441
This commit is contained in:
drh
2017-05-11 12:05:23 +00:00
parent e694139788
commit 2336c935af
4 changed files with 21 additions and 13 deletions
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16
src/select.c
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@@ -5124,15 +5124,23 @@ int sqlite3Select(
SelectDest dest;
Select *pSub;
/* Issue SQLITE_READ authorizations with a NULL column name for any tables that
/* Issue SQLITE_READ authorizations with a fake column name for any tables that
** are referenced but from which no values are extracted. Examples of where these
** kinds of null SQLITE_READ authorizations would occur:
**
** SELECT count(*) FROM t1; -- SQLITE_READ t1 null
** SELECT t1.* FROM t1, t2; -- SQLITE_READ t2 null
** SELECT count(*) FROM t1; -- SQLITE_READ t1.""
** SELECT t1.* FROM t1, t2; -- SQLITE_READ t2.""
**
** The fake column name is an empty string. It is possible for a table to
** have a column named by the empty string, in which case there is no way to
** distinguish between an unreferenced table and an actual reference to the
** "" column. The original design was for the fake column name to be a NULL,
** which would be unambiguous. But legacy authorization callbacks might
** assume the column name is non-NULL and segfault. The use of an empty string
** for the fake column name seems safer.
*/
if( pItem->colUsed==0 ){
sqlite3AuthCheck(pParse, SQLITE_READ, pItem->zName, pItem->zDatabase, 0);
sqlite3AuthCheck(pParse, SQLITE_READ, pItem->zName, "", pItem->zDatabase);
}
#if !defined(SQLITE_OMIT_SUBQUERY) || !defined(SQLITE_OMIT_VIEW)