Add comments and assert() statements to show that the return value from

sqlite3BtreeKeySize() and sqlite3BtreeData() usually do not matter.
Ticket #3968.  Also remove a NEVER() macro that can sometimes be true -
discovered while testing the previous change. (CVS 6893)

FossilOrigin-Name: 0c710c1be537127511d95b5b261c7bf26e1bc952

manifest

@@ -1,5 +1,5 @@
-C Simplifications\sto\sthe\sPRAGMA\sintegrity_check\slogic.\s\sRemove\sunreachable\scode.\s(CVS\s6892)
+C Add\scomments\sand\sassert()\sstatements\sto\sshow\sthat\sthe\sreturn\svalue\sfrom\nsqlite3BtreeKeySize()\sand\ssqlite3BtreeData()\susually\sdo\snot\smatter.\nTicket\s#3968.\s\sAlso\sremove\sa\sNEVER()\smacro\sthat\scan\ssometimes\sbe\strue\s-\ndiscovered\swhile\stesting\sthe\sprevious\schange.\s(CVS\s6893)
-D 2009-07-14T17:48:06
+D 2009-07-14T18:35:45
 F Makefile.arm-wince-mingw32ce-gcc fcd5e9cd67fe88836360bb4f9ef4cb7f8e2fb5a0
 F Makefile.in df9359da7a726ccb67a45db905c5447d5c00c6ef
 F Makefile.linux-gcc d53183f4aa6a9192d249731c90dbdffbd2c68654
@@ -204,11 +204,11 @@ F src/update.c a1bbe774bce495d62dce3df3f42a5f04c1de173a
 F src/utf.c 9541d28f40441812c0b40f00334372a0542c00ff
 F src/util.c 861d5b5c58be4921f0a254489ea94cb15f550ef8
 F src/vacuum.c 3fe0eebea6d2311c1c2ab2962887d11f7a4dcfb0
-F src/vdbe.c f76edc03ffef53ccbf9e38ecc73a65d29eb5b1bd
+F src/vdbe.c b6fadd91f509fbcb9108f1d1a5e0985735fb315d
 F src/vdbe.h 35a648bc3279a120da24f34d9a25213ec15daf8a
 F src/vdbeInt.h 831c254a6eef237ef4664c8381a0137586567007
 F src/vdbeapi.c 0ab8ada7260b32031ca97f338caecf0812460624
-F src/vdbeaux.c 5b3cacb685143ebe8ec8660a4dde08a8a45082ce
+F src/vdbeaux.c 1c3b0698073ddeab7bedc588b13e3fc441346b9e
 F src/vdbeblob.c a3f3e0e877fc64ea50165eec2855f5ada4477611
 F src/vdbemem.c 1618f685d19b4bcc96e40b3c478487bafd2ae246
 F src/vtab.c 00902f289521041712fb0293d0bf8688c7af8e48
@@ -740,7 +740,7 @@ F tool/speedtest2.tcl ee2149167303ba8e95af97873c575c3e0fab58ff
 F tool/speedtest8.c 2902c46588c40b55661e471d7a86e4dd71a18224
 F tool/speedtest8inst1.c 293327bc76823f473684d589a8160bde1f52c14e
 F tool/vdbe-compress.tcl 672f81d693a03f80f5ae60bfefacd8a349e76746
-P fa49666fb913f0d82e84bdfa2af3a294be04e47c
+P 17749fa5480069cc4909acd992ab26d10afb279d
-R c96e1acc2f48a31e75ce3ac536c3155e
+R 35cb54a841da615cb5c38b8f0cb072f6
 U drh
-Z 197c424f91353d8f0b9f8ad4f802f46f
+Z 3ca0e11ecfb15e2cf3df9913240d628c

manifest.uuid

@@ -1 +1 @@
-17749fa5480069cc4909acd992ab26d10afb279d
+0c710c1be537127511d95b5b261c7bf26e1bc952

src/vdbe.c

@@ -43,7 +43,7 @@
 ** in this file for details.  If in doubt, do not deviate from existing
 ** commenting and indentation practices when changing or adding code.
 **
-** $Id: vdbe.c,v 1.871 2009/07/14 02:33:02 drh Exp $
+** $Id: vdbe.c,v 1.872 2009/07/14 18:35:45 drh Exp $
 */
 #include "sqliteInt.h"
 #include "vdbeInt.h"
@@ -2055,14 +2055,16 @@ case OP_Column: {
       payloadSize = pC->payloadSize;
       zRec = (char*)pC->aRow;
     }else if( pC->isIndex ){
-      sqlite3BtreeKeySize(pCrsr, &payloadSize64);
+      rc = sqlite3BtreeKeySize(pCrsr, &payloadSize64);
+      assert( rc==SQLITE_OK );   /* True because of CursorMoveto() call above */
       /* sqlite3BtreeParseCellPtr() uses getVarint32() to extract the
       ** payload size, so it is impossible for payloadSize64 to be
       ** larger than 32 bits. */
       assert( (payloadSize64 & SQLITE_MAX_U32)==(u64)payloadSize64 );
       payloadSize = (u32)payloadSize64;
     }else{
-      sqlite3BtreeDataSize(pCrsr, &payloadSize);
+      rc = sqlite3BtreeDataSize(pCrsr, &payloadSize);
+      assert( rc==SQLITE_OK );   /* True because of CursorMoveto() call above */
     }
   }else if( pC->pseudoTable ){
     /* The record is the sole entry of a pseudo-table */
@@ -3591,7 +3593,8 @@ case OP_NewRowid: {           /* out2-prerelease */
         if( res ){
           v = 1;
         }else{
-          sqlite3BtreeKeySize(pC->pCursor, &v);
+          rc = sqlite3BtreeKeySize(pC->pCursor, &v);
+          assert( rc==SQLITE_OK );   /* Cannot fail following BtreeLast() */
           if( v==MAX_ROWID ){
             pC->useRandomRowid = 1;
           }else{
@@ -3888,13 +3891,15 @@ case OP_RowData: {
 
   if( pC->isIndex ){
     assert( !pC->isTable );
-    sqlite3BtreeKeySize(pCrsr, &n64);
+    rc = sqlite3BtreeKeySize(pCrsr, &n64);
+    assert( rc==SQLITE_OK );    /* True because of CursorMoveto() call above */
     if( n64>db->aLimit[SQLITE_LIMIT_LENGTH] ){
       goto too_big;
     }
     n = (u32)n64;
   }else{
-    sqlite3BtreeDataSize(pCrsr, &n);
+    rc = sqlite3BtreeDataSize(pCrsr, &n);
+    assert( rc==SQLITE_OK );    /* True because of CursorMoveto() call above */
     if( n>(u32)db->aLimit[SQLITE_LIMIT_LENGTH] ){
       goto too_big;
     }
@@ -3958,7 +3963,8 @@ case OP_Rowid: {                 /* out2-prerelease */
     if( pC->rowidIsValid ){
       v = pC->lastRowid;
     }else{
-      sqlite3BtreeKeySize(pC->pCursor, &v);
+      rc = sqlite3BtreeKeySize(pC->pCursor, &v);
+      assert( rc==SQLITE_OK );  /* Always so because of CursorMoveto() above */
     }
   }
   pOut->u.i = v;

src/vdbeaux.c

@@ -14,7 +14,7 @@
 ** to version 2.8.7, all this code was combined into the vdbe.c source file.
 ** But that file was getting too big so this subroutines were split out.
 **
-** $Id: vdbeaux.c,v 1.473 2009/07/14 14:15:27 drh Exp $
+** $Id: vdbeaux.c,v 1.474 2009/07/14 18:35:46 drh Exp $
 */
 #include "sqliteInt.h"
 #include "vdbeInt.h"
@@ -2593,8 +2593,10 @@ int sqlite3VdbeIdxRowid(sqlite3 *db, BtCursor *pCur, i64 *rowid){
   /* Get the size of the index entry.  Only indices entries of less
   ** than 2GiB are support - anything large must be database corruption.
   ** Any corruption is detected in sqlite3BtreeParseCellPtr(), though, so
-  ** this code can safely assume that nCellKey is 32-bits  */
+  ** this code can safely assume that nCellKey is 32-bits  
-  sqlite3BtreeKeySize(pCur, &nCellKey);
+  */
+  rc = sqlite3BtreeKeySize(pCur, &nCellKey);
+  assert( rc==SQLITE_OK );     /* pCur is always valid so KeySize cannot fail */
   assert( (nCellKey & SQLITE_MAX_U32)==(u64)nCellKey );
 
   /* Read in the complete content of the index entry */
@@ -2669,10 +2671,11 @@ int sqlite3VdbeIdxKeyCompare(
   BtCursor *pCur = pC->pCursor;
   Mem m;
 
-  sqlite3BtreeKeySize(pCur, &nCellKey);
+  rc = sqlite3BtreeKeySize(pCur, &nCellKey);
+  assert( rc==SQLITE_OK );    /* pCur is always valid so KeySize cannot fail */
   /* nCellKey will always be between 0 and 0xffffffff because of the say
   ** that btreeParseCellPtr() and sqlite3GetVarint32() are implemented */
-  if( NEVER(nCellKey<=0) || nCellKey>0x7fffffff ){
+  if( nCellKey<=0 || nCellKey>0x7fffffff ){
     *res = 0;
     return SQLITE_CORRUPT;
   }