In the pager, avoid checking for the illegal page number 0 except when creating

a new page.

FossilOrigin-Name: dee20ba982125ea98c280ad1571789af0f393903

manifest

@@ -1,5 +1,5 @@
-C Further\srefinements\sto\sthe\svirtual\smethod\simplementation\sof\s\nsqlite3PagerGet().
-D 2016-12-13T15:53:22.192
+C In\sthe\spager,\savoid\schecking\sfor\sthe\sillegal\spage\snumber\s0\sexcept\swhen\screating\na\snew\spage.
+D 2016-12-13T18:34:01.957
 F Makefile.in 7639c6a09da11a9c7c6f2630fc981ee588d1072d
 F Makefile.linux-gcc 7bc79876b875010e8c8f9502eb935ca92aa3c434
 F Makefile.msc b8ca53350ae545e3562403d5da2a69cec79308da
@@ -375,10 +375,10 @@ F src/os_setup.h 0dbaea40a7d36bf311613d31342e0b99e2536586
 F src/os_unix.c 30e2c43e4955db990e5b5a81e901f8aa74cc8820
 F src/os_win.c cf90abd4e50d9f56d2c20ce8e005aff55d7bd8e9
 F src/os_win.h 7b073010f1451abe501be30d12f6bc599824944a
-F src/pager.c 642b1968fdaa6219aa562ae17b9a3745dfca10f5
+F src/pager.c 38b3a02f5f5e49224a006d17c842c106a93cb5b9
 F src/pager.h d1e944291030351f362a0a7da9b5c3e34e603e39
 F src/parse.y 29153738a7322054359320eb00b5a4cd44389f20
-F src/pcache.c 219fc5238d5c80e2990ab01e1459db3a96866447
+F src/pcache.c 51070ec9b8251bbf9c6ea3d35fd96a458752929e
 F src/pcache.h 2cedcd8407eb23017d92790b112186886e179490
 F src/pcache1.c e3967219b2a92b9edcb9324a4ba75009090d3953
 F src/pragma.c d932ba278654617cdd281f88a790a3185fca7c44
@@ -1536,7 +1536,7 @@ F vsixtest/vsixtest.tcl 6a9a6ab600c25a91a7acc6293828957a386a8a93
 F vsixtest/vsixtest.vcxproj.data 2ed517e100c66dc455b492e1a33350c1b20fbcdc
 F vsixtest/vsixtest.vcxproj.filters 37e51ffedcdb064aad6ff33b6148725226cd608e
 F vsixtest/vsixtest_TemporaryKey.pfx e5b1b036facdb453873e7084e1cae9102ccc67a0
-P df5bb90d208e0633056389e97696d260e3830e8d
-R f50bcbf9b53ee7a4a76924f315bdb191
+P 67df44464847b43f8c0b186157e31cc66c1e5796
+R 96cb62ad3fe18d08872a93c1ec7681b1
 U drh
-Z 01ed48a40bff392ec009867b80e6ecce
+Z 5d3a5e7b85c439c40dd9c8767b987c29

manifest.uuid

@@ -1 +1 @@
-67df44464847b43f8c0b186157e31cc66c1e5796
+dee20ba982125ea98c280ad1571789af0f393903

src/pager.c

@@ -5366,15 +5366,11 @@ static int getPageNormal(
   u8 noContent;                   /* True if PAGER_GET_NOCONTENT is set */
   sqlite3_pcache_page *pBase;
 
-  if( pgno==0 ){
-    return SQLITE_CORRUPT_BKPT;
-  }
   assert( pPager->errCode==SQLITE_OK );
   assert( pPager->eState>=PAGER_READER );
   assert( assert_pager_state(pPager) );
   assert( pPager->hasHeldSharedLock==1 );
 
-
   pBase = sqlite3PcacheFetch(pPager->pPCache, pgno, 3);
   if( pBase==0 ){
     pPg = 0;
@@ -5399,17 +5395,19 @@ static int getPageNormal(
 
   }else{
     /* The pager cache has created a new page. Its content needs to 
-    ** be initialized.  */
-
-    pPg->pPager = pPager;
-
-    /* The maximum page number is 2^31. Return SQLITE_CORRUPT if a page
-    ** number greater than this, or the unused locking-page, is requested. */
-    if( pgno>PAGER_MAX_PGNO || pgno==PAGER_MJ_PGNO(pPager) ){
+    ** be initialized. But first some error checks:
+    **
+    ** (1) Minimum page number is 1
+    ** (2) The maximum page number is 2^31
+    ** (3) Never try to fetch the locking page
+    */
+    if( pgno==0 || pgno>PAGER_MAX_PGNO || pgno==PAGER_MJ_PGNO(pPager) ){
       rc = SQLITE_CORRUPT_BKPT;
       goto pager_acquire_err;
     }
 
+    pPg->pPager = pPager;
+
     assert( !isOpen(pPager->fd) || !MEMDB );
     noContent = (flags & PAGER_GET_NOCONTENT)!=0;
     if( !isOpen(pPager->fd) || pPager->dbSize<pgno || noContent ){

src/pcache.c

@@ -108,7 +108,7 @@ struct PCache {
 int sqlite3PcachePageSanity(PgHdr *pPg){
   PCache *pCache;
   assert( pPg!=0 );
-  assert( pPg->pgno>0 );    /* Page number is 1 or more */
+  assert( pPg->pgno>0 || pPg->pPager==0 );    /* Page number is 1 or more */
   pCache = pPg->pCache;
   assert( pCache!=0 );      /* Every page has an associated PCache */
   if( pPg->flags & PGHDR_CLEAN ){
@@ -372,7 +372,6 @@ sqlite3_pcache_page *sqlite3PcacheFetch(
   assert( pCache!=0 );
   assert( pCache->pCache!=0 );
   assert( createFlag==3 || createFlag==0 );
-  assert( pgno>0 );
   assert( pCache->eCreate==((pCache->bPurgeable && pCache->pDirty) ? 1 : 2) );
 
   /* eCreate defines what to do if the page does not exist.