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Overview
Comment:Modify the sqlite3VdbeMemCompare() routine so that it does not modify any Mem.z values. Ticket #3376. (CVS 5706)
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SHA1: 2d4505510032bf903a9c5d582edda442a0592c77
User & Date: danielk1977 2008-09-16 12:06:08.000
References
2010-10-15
14:45
Cherry-pick the change at [2d4505510032bf9] into the 3.6.1 branch. (check-in: ecb1419e4b user: drh tags: branch-3.6.1)
Context
2008-09-16
14:38
If the xAccess() call used by "PRAGMA temp_store_directory = /new/path/" to determine if the supplied directory is writable returns an error, assume the directory is not writable. (CVS 5707) (check-in: e8418588f2 user: danielk1977 tags: trunk)
12:06
Modify the sqlite3VdbeMemCompare() routine so that it does not modify any Mem.z values. Ticket #3376. (CVS 5706) (check-in: 2d45055100 user: danielk1977 tags: trunk)
11:58
Add test case for ticket #3376. (CVS 5705) (check-in: c64260579d user: drh tags: trunk)
Changes
Side-by-Side Diff Ignore Whitespace Patch
Changes to src/vdbemem.c.
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*************************************************************************
**
** This file contains code use to manipulate "Mem" structure.  A "Mem"
** stores a single value in the VDBE.  Mem is an opaque structure visible
** only within the VDBE.  Interface routines refer to a Mem using the
** name sqlite_value
**
** $Id: vdbemem.c,v 1.122 2008/08/22 14:41:01 drh Exp $
** $Id: vdbemem.c,v 1.123 2008/09/16 12:06:08 danielk1977 Exp $
*/
#include "sqliteInt.h"
#include <ctype.h>
#include "vdbeInt.h"

/*
** Call sqlite3VdbeMemExpandBlob() on the supplied value (type Mem*)
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    if( pColl ){
      if( pMem1->enc==pColl->enc ){
        /* The strings are already in the correct encoding.  Call the
        ** comparison function directly */
        return pColl->xCmp(pColl->pUser,pMem1->n,pMem1->z,pMem2->n,pMem2->z);
      }else{
        u8 origEnc = pMem1->enc;
        const void *v1, *v2;
        int n1, n2;
        Mem c1;
        /* Convert the strings into the encoding that the comparison
        ** function expects */
        v1 = sqlite3ValueText((sqlite3_value*)pMem1, pColl->enc);
        n1 = v1==0 ? 0 : pMem1->n;
        Mem c2;
        memset(&c1, 0, sizeof(c1));
        memset(&c2, 0, sizeof(c2));
        sqlite3VdbeMemShallowCopy(&c1, pMem1, MEM_Ephem);
        sqlite3VdbeMemShallowCopy(&c2, pMem2, MEM_Ephem);
        v1 = sqlite3ValueText((sqlite3_value*)&c1, pColl->enc);
        n1 = v1==0 ? 0 : c1.n;
        assert( n1==sqlite3ValueBytes((sqlite3_value*)pMem1, pColl->enc) );
        v2 = sqlite3ValueText((sqlite3_value*)pMem2, pColl->enc);
        n2 = v2==0 ? 0 : pMem2->n;
        v2 = sqlite3ValueText((sqlite3_value*)&c2, pColl->enc);
        n2 = v2==0 ? 0 : c2.n;
        assert( n2==sqlite3ValueBytes((sqlite3_value*)pMem2, pColl->enc) );
        /* Do the comparison */
        rc = pColl->xCmp(pColl->pUser, n1, v1, n2, v2);
        /* Convert the strings back into the database encoding */
        sqlite3ValueText((sqlite3_value*)pMem1, origEnc);
        sqlite3ValueText((sqlite3_value*)pMem2, origEnc);
        sqlite3VdbeMemRelease(&c1);
        sqlite3VdbeMemRelease(&c2);
        return rc;
      }
    }
    /* If a NULL pointer was passed as the collate function, fall through
    ** to the blob case and use memcmp().  */
  }
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