From: drh <drh@noemail.net>
Date: Fri, 25 Jul 2014 18:01:06 +0000 (+0000)
Subject: Add constraints (enforced only when SQLITE_DEBUG is enabled) on the use of
X-Git-Tag: version-3.8.6~60
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=8af3f772c10e55d473e0cbe08e879101e66877ce;p=thirdparty%2Fsqlite.git

Add constraints (enforced only when SQLITE_DEBUG is enabled) on the use of
OP_Next and OP_Prev.

FossilOrigin-Name: 2230c74f1efa591770176c9b40e920724a3c39e1
---

diff --git a/manifest b/manifest
index a378b1468d..30ae97fa3c 100644
--- a/manifest
+++ b/manifest
@@ -1,5 +1,5 @@
-C Improve\sthe\sperformance\sof\sthe\sANALYZE\scommand\sby\staking\sadvantage\sof\nUNIQUE\sconstraints\son\sindices.
-D 2014-07-24T23:23:26.687
+C Add\sconstraints\s(enforced\sonly\swhen\sSQLITE_DEBUG\sis\senabled)\son\sthe\suse\sof\nOP_Next\sand\sOP_Prev.
+D 2014-07-25T18:01:06.435
 F Makefile.arm-wince-mingw32ce-gcc d6df77f1f48d690bd73162294bbba7f59507c72f
 F Makefile.in 5eb79e334a5de69c87740edd56af6527dd219308
 F Makefile.linux-gcc 91d710bdc4998cb015f39edf3cb314ec4f4d7e23
@@ -283,9 +283,9 @@ F src/update.c 01564b3c430f6c7b0a35afaf7aba7987206fa3a5
 F src/utf.c a0314e637768a030e6e84a957d0c4f6ba910cc05
 F src/util.c 3076bdd51cdbf60a6e2e57fada745be37133c73e
 F src/vacuum.c 3728d74919d4fb1356f9e9a13e27773db60b7179
-F src/vdbe.c fa74c6563486022920db4d73897bd9b837c7441d
+F src/vdbe.c c6a9094a56b3dd4769243051a512f89763af7de5
 F src/vdbe.h c63fad052c9e7388d551e556e119c0bcf6bebdf8
-F src/vdbeInt.h f41a7cf5a40e7abd994d5fe3a04589ae3e1154e7
+F src/vdbeInt.h f5513f2b5ac1e2c5128996c7ea23add256a301df
 F src/vdbeapi.c 24e40422382beb774daab11fe9fe9d37e8a04949
 F src/vdbeaux.c 1ffe0bbc3a2c8aedd95622de9be6b6d07b3d3c6b
 F src/vdbeblob.c 9205ce9d3b064d9600f8418a897fc88b5687d9ac
@@ -1184,8 +1184,7 @@ F tool/vdbe_profile.tcl 67746953071a9f8f2f668b73fe899074e2c6d8c1
 F tool/warnings-clang.sh f6aa929dc20ef1f856af04a730772f59283631d4
 F tool/warnings.sh 0abfd78ceb09b7f7c27c688c8e3fe93268a13b32
 F tool/win/sqlite.vsix deb315d026cc8400325c5863eef847784a219a2f
-P 6aea2258dd7d3967900cefe4cd0af48a7ee7e169 85e2badeeb7f7599eb6fd35512f9bd524f0b1b3f
-R ac28d1873bd62cdf71787453262a0966
-T +closed 85e2badeeb7f7599eb6fd35512f9bd524f0b1b3f
+P 114dcf33670fd98a1ebbac0e44f66b2d8bcccddf
+R f27032fe9d592a52e4ec63c28d270176
 U drh
-Z 72b5de0db489041a156923cd906bfefb
+Z 96714d48e7c72e5d439e8f51e5a0d88e
diff --git a/manifest.uuid b/manifest.uuid
index a9e63c9b42..9d6edd3229 100644
--- a/manifest.uuid
+++ b/manifest.uuid
@@ -1 +1 @@
-114dcf33670fd98a1ebbac0e44f66b2d8bcccddf
\ No newline at end of file
+2230c74f1efa591770176c9b40e920724a3c39e1
\ No newline at end of file
diff --git a/src/vdbe.c b/src/vdbe.c
index 093669a82d..60d8ebf3e5 100644
--- a/src/vdbe.c
+++ b/src/vdbe.c
@@ -3481,7 +3481,7 @@ case OP_Close: {
   break;
 }
 
-/* Opcode: SeekGe P1 P2 P3 P4 *
+/* Opcode: SeekGE P1 P2 P3 P4 *
 ** Synopsis: key=r[P3@P4]
 **
 ** If cursor P1 refers to an SQL table (B-Tree that uses integer keys), 
@@ -3493,9 +3493,13 @@ case OP_Close: {
 ** is greater than or equal to the key value. If there are no records 
 ** greater than or equal to the key and P2 is not zero, then jump to P2.
 **
+** This opcode leaves the cursor configured to move in forward order,
+** from the begining toward the end.  In other words, the cursor is
+** configured to use OP_Next, not OP_Prev.
+**
 ** See also: Found, NotFound, SeekLt, SeekGt, SeekLe
 */
-/* Opcode: SeekGt P1 P2 P3 P4 *
+/* Opcode: SeekGT P1 P2 P3 P4 *
 ** Synopsis: key=r[P3@P4]
 **
 ** If cursor P1 refers to an SQL table (B-Tree that uses integer keys), 
@@ -3507,9 +3511,13 @@ case OP_Close: {
 ** is greater than the key value. If there are no records greater than 
 ** the key and P2 is not zero, then jump to P2.
 **
+** This opcode leaves the cursor configured to move in forward order,
+** from the begining toward the end.  In other words, the cursor is
+** configured to use OP_Next, not OP_Prev.
+**
 ** See also: Found, NotFound, SeekLt, SeekGe, SeekLe
 */
-/* Opcode: SeekLt P1 P2 P3 P4 * 
+/* Opcode: SeekLT P1 P2 P3 P4 * 
 ** Synopsis: key=r[P3@P4]
 **
 ** If cursor P1 refers to an SQL table (B-Tree that uses integer keys), 
@@ -3521,9 +3529,13 @@ case OP_Close: {
 ** is less than the key value. If there are no records less than 
 ** the key and P2 is not zero, then jump to P2.
 **
+** This opcode leaves the cursor configured to move in reverse order,
+** from the end toward the beginning.  In other words, the cursor is
+** configured to use OP_Prev, not OP_Next.
+**
 ** See also: Found, NotFound, SeekGt, SeekGe, SeekLe
 */
-/* Opcode: SeekLe P1 P2 P3 P4 *
+/* Opcode: SeekLE P1 P2 P3 P4 *
 ** Synopsis: key=r[P3@P4]
 **
 ** If cursor P1 refers to an SQL table (B-Tree that uses integer keys), 
@@ -3535,6 +3547,10 @@ case OP_Close: {
 ** is less than or equal to the key value. If there are no records 
 ** less than or equal to the key and P2 is not zero, then jump to P2.
 **
+** This opcode leaves the cursor configured to move in reverse order,
+** from the end toward the beginning.  In other words, the cursor is
+** configured to use OP_Prev, not OP_Next.
+**
 ** See also: Found, NotFound, SeekGt, SeekGe, SeekLt
 */
 case OP_SeekLT:         /* jump, in3 */
@@ -3560,6 +3576,9 @@ case OP_SeekGT: {       /* jump, in3 */
   assert( pC->pCursor!=0 );
   oc = pOp->opcode;
   pC->nullRow = 0;
+#ifdef SQLITE_DEBUG
+  pC->seekOp = pOp->opcode;
+#endif
   if( pC->isTable ){
     /* The input value in P3 might be of any type: integer, real, string,
     ** blob, or NULL.  But it needs to be an integer before we can do
@@ -3715,6 +3734,10 @@ case OP_Seek: {    /* in2 */
 ** is a prefix of any entry in P1 then a jump is made to P2 and
 ** P1 is left pointing at the matching entry.
 **
+** This operation leaves the cursor in a state where it cannot be
+** advanced in either direction.  In other words, the Next and Prev
+** opcodes do not work after this operation.
+**
 ** See also: NotFound, NoConflict, NotExists. SeekGe
 */
 /* Opcode: NotFound P1 P2 P3 P4 *
@@ -3730,6 +3753,10 @@ case OP_Seek: {    /* in2 */
 ** falls through to the next instruction and P1 is left pointing at the
 ** matching entry.
 **
+** This operation leaves the cursor in a state where it cannot be
+** advanced in either direction.  In other words, the Next and Prev
+** opcodes do not work after this operation.
+**
 ** See also: Found, NotExists, NoConflict
 */
 /* Opcode: NoConflict P1 P2 P3 P4 *
@@ -3749,6 +3776,10 @@ case OP_Seek: {    /* in2 */
 ** This opcode is similar to OP_NotFound with the exceptions that the
 ** branch is always taken if any part of the search key input is NULL.
 **
+** This operation leaves the cursor in a state where it cannot be
+** advanced in either direction.  In other words, the Next and Prev
+** opcodes do not work after this operation.
+**
 ** See also: NotFound, Found, NotExists
 */
 case OP_NoConflict:     /* jump, in3 */
@@ -3771,6 +3802,9 @@ case OP_Found: {        /* jump, in3 */
   assert( pOp->p4type==P4_INT32 );
   pC = p->apCsr[pOp->p1];
   assert( pC!=0 );
+#ifdef SQLITE_DEBUG
+  pC->seekOp = 0;
+#endif
   pIn3 = &aMem[pOp->p3];
   assert( pC->pCursor!=0 );
   assert( pC->isTable==0 );
@@ -3842,6 +3876,10 @@ case OP_Found: {        /* jump, in3 */
 ** The OP_NotFound opcode performs the same operation on index btrees
 ** (with arbitrary multi-value keys).
 **
+** This opcode leaves the cursor in a state where it cannot be advanced
+** in either direction.  In other words, the Next and Prev opcodes will
+** not work following this opcode.
+**
 ** See also: Found, NotFound, NoConflict
 */
 case OP_NotExists: {        /* jump, in3 */
@@ -3855,6 +3893,9 @@ case OP_NotExists: {        /* jump, in3 */
   assert( pOp->p1>=0 && pOp->p1<p->nCursor );
   pC = p->apCsr[pOp->p1];
   assert( pC!=0 );
+#ifdef SQLITE_DEBUG
+  pC->seekOp = 0;
+#endif
   assert( pC->isTable );
   assert( pC->pseudoTableReg==0 );
   pCrsr = pC->pCursor;
@@ -4421,11 +4462,15 @@ case OP_NullRow: {
 
 /* Opcode: Last P1 P2 * * *
 **
-** The next use of the Rowid or Column or Next instruction for P1 
+** The next use of the Rowid or Column or Prev instruction for P1 
 ** will refer to the last entry in the database table or index.
 ** If the table or index is empty and P2>0, then jump immediately to P2.
 ** If P2 is 0 or if the table or index is not empty, fall through
 ** to the following instruction.
+**
+** This opcode leaves the cursor configured to move in reverse order,
+** from the end toward the beginning.  In other words, the cursor is
+** configured to use OP_Prev, not OP_Next.
 */
 case OP_Last: {        /* jump */
   VdbeCursor *pC;
@@ -4443,6 +4488,9 @@ case OP_Last: {        /* jump */
   pC->deferredMoveto = 0;
   pC->rowidIsValid = 0;
   pC->cacheStatus = CACHE_STALE;
+#ifdef SQLITE_DEBUG
+  pC->seekOp = OP_Last;
+#endif
   if( pOp->p2>0 ){
     VdbeBranchTaken(res!=0,2);
     if( res ) pc = pOp->p2 - 1;
@@ -4479,6 +4527,10 @@ case OP_Sort: {        /* jump */
 ** If the table or index is empty and P2>0, then jump immediately to P2.
 ** If P2 is 0 or if the table or index is not empty, fall through
 ** to the following instruction.
+**
+** This opcode leaves the cursor configured to move in forward order,
+** from the begining toward the end.  In other words, the cursor is
+** configured to use OP_Next, not OP_Prev.
 */
 case OP_Rewind: {        /* jump */
   VdbeCursor *pC;
@@ -4490,6 +4542,9 @@ case OP_Rewind: {        /* jump */
   assert( pC!=0 );
   assert( isSorter(pC)==(pOp->opcode==OP_SorterSort) );
   res = 1;
+#ifdef SQLITE_DEBUG
+  pC->seekOp = OP_Rewind;
+#endif
   if( isSorter(pC) ){
     rc = sqlite3VdbeSorterRewind(db, pC, &res);
   }else{
@@ -4516,6 +4571,10 @@ case OP_Rewind: {        /* jump */
 ** to the following instruction.  But if the cursor advance was successful,
 ** jump immediately to P2.
 **
+** The OP_Next opcode is only valid following an OP_SeekGT, OP_SeekGE, or
+** OP_Rewind opcode used to position the cursor.  OP_Next is not allowed
+** to follow OP_SeekLT, OP_SeekLE, or OP_Last.
+**
 ** The P1 cursor must be for a real table, not a pseudo-table.  P1 must have
 ** been opened prior to this opcode or the program will segfault.
 **
@@ -4544,6 +4603,11 @@ case OP_Rewind: {        /* jump */
 ** to the following instruction.  But if the cursor backup was successful,
 ** jump immediately to P2.
 **
+**
+** The OP_Prev opcode is only valid following an OP_SeekLT, OP_SeekLE, or
+** OP_Last opcode used to position the cursor.  OP_Prev is not allowed
+** to follow OP_SeekGT, OP_SeekGE, or OP_Rewind.
+**
 ** The P1 cursor must be for a real table, not a pseudo-table.  If P1 is
 ** not open then the behavior is undefined.
 **
@@ -4591,6 +4655,16 @@ case OP_Next:          /* jump */
   assert( pOp->opcode!=OP_Prev || pOp->p4.xAdvance==sqlite3BtreePrevious );
   assert( pOp->opcode!=OP_NextIfOpen || pOp->p4.xAdvance==sqlite3BtreeNext );
   assert( pOp->opcode!=OP_PrevIfOpen || pOp->p4.xAdvance==sqlite3BtreePrevious);
+
+  /* The Next opcode is only used after SeekGT, SeekGE, and Rewind.
+  ** The Prev opcode is only used after SeekLT, SeekLE, and Last. */
+  assert( pOp->opcode!=OP_Next || pOp->opcode!=OP_NextIfOpen
+       || pC->seekOp==OP_SeekGT || pC->seekOp==OP_SeekGE
+       || pC->seekOp==OP_Rewind );
+  assert( pOp->opcode!=OP_Prev || pOp->opcode!=OP_PrevIfOpen
+       || pC->seekOp==OP_SeekLT || pC->seekOp==OP_SeekLE
+       || pC->seekOp==OP_Last );
+
   rc = pOp->p4.xAdvance(pC->pCursor, &res);
 next_tail:
   pC->cacheStatus = CACHE_STALE;
diff --git a/src/vdbeInt.h b/src/vdbeInt.h
index f541aa7170..141573eef4 100644
--- a/src/vdbeInt.h
+++ b/src/vdbeInt.h
@@ -68,6 +68,9 @@ struct VdbeCursor {
   int pseudoTableReg;   /* Register holding pseudotable content. */
   i16 nField;           /* Number of fields in the header */
   u16 nHdrParsed;       /* Number of header fields parsed so far */
+#ifdef SQLITE_DEBUG
+  u8 seekOp;            /* Most recent seek operation on this cursor */
+#endif
   i8 iDb;               /* Index of cursor database in db->aDb[] (or -1) */
   u8 nullRow;           /* True if pointing to a row with no data */
   u8 rowidIsValid;      /* True if lastRowid is valid */