Another approach at attempting to contain the damage caused by corruption

that leaves MemPage.isInit clear.  Works better than the previous but is
still not perfect.

FossilOrigin-Name: ba964eb0f3dac957367bc03cb3800800e8f2758403467bdbfb44e7e1a7d9cebf

manifest

@@ -1,5 +1,5 @@
-C Disallow\sthe\sone-pass\soptimization\sfor\sDELETE\sif\sthe\sWHERE\sclause\scontains\na\ssubquery.\s\sFix\sfor\sthe\sproblem\sreported\sby\n[forum:/forumpost/e61252062c9d286d|forum\spost\se61252062c9d286d].\s\sThis\sfix\nis\smore\srestrictive\sthan\snecessary.\s\sIt\scould\sbe\srelaxed\sif\sthe\ssubquery\sdoes\nnot\sinvolve\sthe\stable\sthat\sis\sthe\ssubject\sof\sthe\sDELETE.
-D 2023-03-15T17:58:51.689
+C Another\sapproach\sat\sattempting\sto\scontain\sthe\sdamage\scaused\sby\scorruption\nthat\sleaves\sMemPage.isInit\sclear.\s\sWorks\sbetter\sthan\sthe\sprevious\sbut\sis\nstill\snot\sperfect.
+D 2023-03-16T02:30:43.826
 F .fossil-settings/empty-dirs dbb81e8fc0401ac46a1491ab34a7f2c7c0452f2f06b54ebb845d024ca8283ef1
 F .fossil-settings/ignore-glob 35175cdfcf539b2318cb04a9901442804be81cd677d8b889fcc9149c21f239ea
 F LICENSE.md df5091916dbb40e6e9686186587125e1b2ff51f022cc334e886c19a0e9982724
@@ -564,7 +564,7 @@ F src/auth.c f4fa91b6a90bbc8e0d0f738aa284551739c9543a367071f55574681e0f24f8cf
 F src/backup.c a2891172438e385fdbe97c11c9745676bec54f518d4447090af97189fd8e52d7
 F src/bitvec.c 7c849aac407230278445cb069bebc5f89bf2ddd87c5ed9459b070a9175707b3d
 F src/btmutex.c 6ffb0a22c19e2f9110be0964d0731d2ef1c67b5f7fabfbaeb7b9dabc4b7740ca
-F src/btree.c c547e099f853de61835ff45da8d956a932d02ecf1ffd472a1f2a103b83e6dd40
+F src/btree.c b7318b5a3cb40a1a42d0a42e175783a02c88a1ef4972b20fba93fd0e237e0781
 F src/btree.h aa354b9bad4120af71e214666b35132712b8f2ec11869cb2315c52c81fad45cc
 F src/btreeInt.h 06bb2c1a07172d5a1cd27a2a5d617b93b1e976c5873709c31964786f86365a6e
 F src/build.c 4fed662d383527c808d85f53b9c544ead425ac8b9c7cb38501a64e3797921d41
@@ -2050,8 +2050,8 @@ F vsixtest/vsixtest.tcl 6a9a6ab600c25a91a7acc6293828957a386a8a93
 F vsixtest/vsixtest.vcxproj.data 2ed517e100c66dc455b492e1a33350c1b20fbcdc
 F vsixtest/vsixtest.vcxproj.filters 37e51ffedcdb064aad6ff33b6148725226cd608e
 F vsixtest/vsixtest_TemporaryKey.pfx e5b1b036facdb453873e7084e1cae9102ccc67a0
-P 4c4e66f293d7768cceb875a936ca0f4cd910473e20b9910698cc1e1ce221a7d4
-R 934d92c186df99d22e77975c034c41b7
+P 44e83f8b8fab5b46fd50461b5bad9b31437607f259e8b284852ca3be0d376c8a
+R 333e88ec9c338e26ffc59fb44537a76f
 U drh
-Z 54012e32e8462771957ea3ef7763a915
+Z 5abd6e9065f4915bbe0135e8f0ac1b31
 # Remove this line to create a well-formed Fossil manifest.

manifest.uuid

@@ -1 +1 @@
-73f0036f045bf37193b6e87ae45b578c5831614c530488257c69666178da3aa5
+ba964eb0f3dac957367bc03cb3800800e8f2758403467bdbfb44e7e1a7d9cebf

src/btree.c

@@ -2142,6 +2142,7 @@ static SQLITE_NOINLINE int btreeCellSizeCheck(MemPage *pPage){
 static int btreeInitPage(MemPage *pPage){
   u8 *data;          /* Equal to pPage->aData */
   BtShared *pBt;        /* The main btree structure */
+  int rc = SQLITE_OK;
 
   assert( pPage->pBt!=0 );
   assert( pPage->pBt->db!=0 );
@@ -2155,7 +2156,14 @@ static int btreeInitPage(MemPage *pPage){
   data = pPage->aData + pPage->hdrOffset;
   /* EVIDENCE-OF: R-28594-02890 The one-byte flag at offset 0 indicating
   ** the b-tree page type. */
-  if( decodeFlags(pPage, data[0]) ){
+  pPage->nCell = get2byte(&data[3]);
+  if( decodeFlags(pPage, data[0]) || pPage->nCell>MX_CELL(pBt) ){
+    BtCursor *pCur;
+    for(pCur=pBt->pCursor; pCur; pCur=pCur->pNext){
+      sqlite3BtreeClearCursor(pCur);
+      pCur->eState = CURSOR_FAULT;
+      pCur->skipNext = SQLITE_CORRUPT;
+    }
     return SQLITE_CORRUPT_PAGE(pPage);
   }
   assert( pBt->pageSize>=512 && pBt->pageSize<=65536 );
@@ -2167,11 +2175,6 @@ static int btreeInitPage(MemPage *pPage){
   pPage->aDataOfst = pPage->aData + pPage->childPtrSize;
   /* EVIDENCE-OF: R-37002-32774 The two-byte integer at offset 3 gives the
   ** number of cells on the page. */
-  pPage->nCell = get2byte(&data[3]);
-  if( pPage->nCell>MX_CELL(pBt) ){
-    /* To many cells for a single page.  The page must be corrupt */
-    return SQLITE_CORRUPT_PAGE(pPage);
-  }
   testcase( pPage->nCell==MX_CELL(pBt) );
   /* EVIDENCE-OF: R-24089-57979 If a page contains no cells (which is only
   ** possible for a root page of a table that contains no rows) then the
@@ -2183,9 +2186,9 @@ static int btreeInitPage(MemPage *pPage){
   pPage->nFree = -1;  /* Indicate that this value is yet uncomputed */
   pPage->isInit = 1;
   if( pBt->db->flags & SQLITE_CellSizeCk ){
-    return btreeCellSizeCheck(pPage);
+    rc = btreeCellSizeCheck(pPage);
   }
-  return SQLITE_OK;
+  return rc;
 }
 
 /*