Minor simplifications to btree.c in support of full-coverage testing.

FossilOrigin-Name: 364df6c7735447cc2187923918a35bf62d82decc

manifest

@@ -1,8 +1,8 @@
 -----BEGIN PGP SIGNED MESSAGE-----
 Hash: SHA1
 
-C Tweaks\sto\scomments\sin\spager.c.\s\sFix\stwo\scompiler\swarnings.
-D 2010-08-14T12:42:45
+C Minor\ssimplifications\sto\sbtree.c\sin\ssupport\sof\sfull-coverage\stesting.
+D 2010-08-14T16:02:52
 F Makefile.arm-wince-mingw32ce-gcc d6df77f1f48d690bd73162294bbba7f59507c72f
 F Makefile.in ec08dc838fd8110fe24c92e5130bcd91cbb1ff2e
 F Makefile.linux-gcc 91d710bdc4998cb015f39edf3cb314ec4f4d7e23
@@ -116,7 +116,7 @@ F src/auth.c 523da7fb4979469955d822ff9298352d6b31de34
 F src/backup.c 51d83300fe0baee39405c416ceb19a58ed30a8ed
 F src/bitvec.c af50f1c8c0ff54d6bdb7a80e2fceca5a93670bef
 F src/btmutex.c 96a12f50f7a17475155971a241d85ec5171573ff
-F src/btree.c 042a5c0a6a8b6121019b258737872b1ab703d39e
+F src/btree.c 4d861dd1620afb925cd4192bbf37ae9adb0f9fa1
 F src/btree.h b4ba2fdf6b64c7c376bdfffa826af6b786b151d9
 F src/btreeInt.h 5b034ff54800046cc5870605d683ac1f9134bd99
 F src/build.c 0018d49629fc4807100c988dd191dd95e185bb38
@@ -846,14 +846,14 @@ F tool/speedtest2.tcl ee2149167303ba8e95af97873c575c3e0fab58ff
 F tool/speedtest8.c 2902c46588c40b55661e471d7a86e4dd71a18224
 F tool/speedtest8inst1.c 293327bc76823f473684d589a8160bde1f52c14e
 F tool/vdbe-compress.tcl d70ea6d8a19e3571d7ab8c9b75cba86d1173ff0f
-P d8bbab78fa56b076dfafb36daa7d6ef0b07f9a44
-R 00ed3364cfce8a4105ed9a3a25cad7ed
+P 68a49f7fe382e4d36e1259cdeec956c942906ddb
+R b1c481dfca4b477e31b2e4af146892a8
 U drh
-Z 25d17dd4620d7e65e11d0b88322d1479
+Z e57dcfeb0f939d5ce958fed0088bea4e
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manifest.uuid

@@ -1 +1 @@
-68a49f7fe382e4d36e1259cdeec956c942906ddb
+364df6c7735447cc2187923918a35bf62d82decc

src/btree.c

@@ -32,7 +32,16 @@ int sqlite3BtreeTrace=1;  /* True to enable tracing */
 # define TRACE(X)
 #endif
 
-
+/*
+** Extract a 2-byte big-endian integer from an array of unsigned bytes.
+** But if the value is zero, make it 65536.
+**
+** This routine is used to extract the "offset to cell content area" value
+** from the header of a btree page.  If the page size is 65536 and the page
+** is empty, the offset should be 65536, but the 2-byte value stores zero.
+** This routine makes the necessary adjustment to 65536.
+*/
+#define get2byteNotZero(X)  (((((int)get2byte(X))-1)&0xffff)+1)
 
 #ifndef SQLITE_OMIT_SHARED_CACHE
 /*
@@ -1154,8 +1163,7 @@ static int allocateSpace(MemPage *pPage, int nByte, int *pIdx){
   nFrag = data[hdr+7];
   assert( pPage->cellOffset == hdr + 12 - 4*pPage->leaf );
   gap = pPage->cellOffset + 2*pPage->nCell;
-  top = get2byte(&data[hdr+5]);
-  if( top==0 ) top = 65536;
+  top = get2byteNotZero(&data[hdr+5]);
   if( gap>top ) return SQLITE_CORRUPT_BKPT;
   testcase( gap+2==top );
   testcase( gap+1==top );
@@ -1165,8 +1173,7 @@ static int allocateSpace(MemPage *pPage, int nByte, int *pIdx){
     /* Always defragment highly fragmented pages */
     rc = defragmentPage(pPage);
     if( rc ) return rc;
-    top = get2byte(&data[hdr+5]);
-    if( top==0 ) top = 65536;
+    top = get2byteNotZero(&data[hdr+5]);
   }else if( gap+2<=top ){
     /* Search the freelist looking for a free slot big enough to satisfy 
     ** the request. The allocation is made from the first free slot in 
@@ -1208,8 +1215,7 @@ static int allocateSpace(MemPage *pPage, int nByte, int *pIdx){
   if( gap+2+nByte>top ){
     rc = defragmentPage(pPage);
     if( rc ) return rc;
-    top = get2byte(&data[hdr+5]);
-    if( top==0 ) top = 65536;
+    top = get2byteNotZero(&data[hdr+5]);
     assert( gap+nByte<=top );
   }
 
@@ -1392,8 +1398,7 @@ static int btreeInitPage(MemPage *pPage){
     pPage->nOverflow = 0;
     usableSize = pBt->usableSize;
     pPage->cellOffset = cellOffset = hdr + 12 - 4*pPage->leaf;
-    top = get2byte(&data[hdr+5]);
-    if( top==0 ) top = 65536;
+    top = get2byteNotZero(&data[hdr+5]);
     pPage->nCell = get2byte(&data[hdr+3]);
     if( pPage->nCell>MX_CELL(pBt) ){
       /* To many cells for a single page.  The page must be corrupt */
@@ -5490,7 +5495,7 @@ static void assemblePage(
 
   /* Check that the page has just been zeroed by zeroPage() */
   assert( pPage->nCell==0 );
-  assert( get2byte(&data[hdr+5])==(nUsable&0xffff) );
+  assert( get2byteNotZero(&data[hdr+5])==nUsable );
 
   pCellptr = &data[pPage->cellOffset + nCell*2];
   cellbody = nUsable;
@@ -5556,7 +5561,8 @@ static int balance_quick(MemPage *pParent, MemPage *pPage, u8 *pSpace){
   assert( sqlite3PagerIswriteable(pParent->pDbPage) );
   assert( pPage->nOverflow==1 );
 
-  if( pPage->nCell<=0 ) return SQLITE_CORRUPT_BKPT;
+  /* This error condition is now caught prior to reaching this function */
+  if( NEVER(pPage->nCell<=0) ) return SQLITE_CORRUPT_BKPT;
 
   /* Allocate a new page. This page will become the right-sibling of 
   ** pPage. Make the parent page writable, so that the new divider cell
@@ -7665,8 +7671,7 @@ static int checkTreePage(
   if( hit==0 ){
     pCheck->mallocFailed = 1;
   }else{
-    int contentOffset = get2byte(&data[hdr+5]);
-    if( contentOffset==0 ) contentOffset = 65536;
+    int contentOffset = get2byteNotZero(&data[hdr+5]);
     assert( contentOffset<=usableSize );  /* Enforced by btreeInitPage() */
     memset(hit+contentOffset, 0, usableSize-contentOffset);
     memset(hit, 1, contentOffset);