Make sure a WAL frame of all zeros is detected as an invalid frame.

FossilOrigin-Name: 02d99ad4b51065c67cc7689916130774be1c4c87

manifest

@@ -1,8 +1,8 @@
 -----BEGIN PGP SIGNED MESSAGE-----
 Hash: SHA1
 
-C Fix\sup\stest_osinst.c\sto\swork\swith\sSQLITE_OMIT_VIRTUALTABLE.
-D 2010-05-24T12:34:15
+C Make\ssure\sa\sWAL\sframe\sof\sall\szeros\sis\sdetected\sas\san\sinvalid\sframe.
+D 2010-05-24T13:28:36
 F Makefile.arm-wince-mingw32ce-gcc fcd5e9cd67fe88836360bb4f9ef4cb7f8e2fb5a0
 F Makefile.in a5cad1f8f3e021356bfcc6c77dc16f6f1952bbc3
 F Makefile.linux-gcc d53183f4aa6a9192d249731c90dbdffbd2c68654
@@ -227,7 +227,7 @@ F src/vdbeblob.c 5327132a42a91e8b7acfb60b9d2c3b1c5c863e0e
 F src/vdbemem.c 2a82f455f6ca6f78b59fb312f96054c04ae0ead1
 F src/vdbetrace.c 864cef96919323482ebd9986f2132435115e9cc2
 F src/vtab.c a0f8a40274e4261696ef57aa806de2776ab72cda
-F src/wal.c 93e13dfc60e036091eec8c90da4ff9595e97e932
+F src/wal.c e8c58e529bcc50c0fb3797bc39750e802cbace78
 F src/wal.h 434f76f51225bb614e43ccb6bd2341541ba6a06e
 F src/walker.c 3112bb3afe1d85dc52317cb1d752055e9a781f8f
 F src/where.c 75fee9e255b62f773fcadd1d1f25b6f63ac7a356
@@ -817,14 +817,14 @@ F tool/speedtest2.tcl ee2149167303ba8e95af97873c575c3e0fab58ff
 F tool/speedtest8.c 2902c46588c40b55661e471d7a86e4dd71a18224
 F tool/speedtest8inst1.c 293327bc76823f473684d589a8160bde1f52c14e
 F tool/vdbe-compress.tcl d70ea6d8a19e3571d7ab8c9b75cba86d1173ff0f
-P 65ba804dd1d31d1eef6ae3f40a3ade344a410b84
-R 0975a148083609eb5447373024159739
+P 51fd38152b92db637d1d346fca35ec2d3e4d4f57
+R 3ae8439c7818113b3e55b5c33ec15fc6
 U drh
-Z 8f7b7419862e6cd292f6daada9d7ada1
+Z 157804aa9c723c5bf0d5892d1297d942
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manifest.uuid

@@ -1 +1 @@
-51fd38152b92db637d1d346fca35ec2d3e4d4f57
+02d99ad4b51065c67cc7689916130774be1c4c87

src/wal.c

@@ -451,6 +451,7 @@ static int walDecodeFrame(
   u8 *aFrame                      /* Frame data */
 ){
   int nativeCksum;                /* True for native byte-order checksums */
+  u32 pgno;                       /* Page number of the frame */
   u32 aCksum[2];
   assert( WAL_FRAME_HDRSIZE==24 );
 
@@ -461,6 +462,13 @@ static int walDecodeFrame(
     return 0;
   }
 
+  /* A frame is only valid if the page number is creater than zero.
+  */
+  pgno = sqlite3Get4byte(&aFrame[0]);
+  if( pgno==0 ){
+    return 0;
+  }
+
   /* A frame is only valid if a checksum of the first 16 bytes
   ** of the frame-header, and the frame-data matches
   ** the checksum in the last 8 bytes of the frame-header.
@@ -478,7 +486,7 @@ static int walDecodeFrame(
   /* If we reach this point, the frame is valid.  Return the page number
   ** and the new database size.
   */
-  *piPage = sqlite3Get4byte(&aFrame[0]);
+  *piPage = pgno;
   *pnTruncate = sqlite3Get4byte(&aFrame[4]);
   return 1;
 }