Merge in changes that cause the first sector of the WAL file to be synced

when the WAL restarts.  This is a fix for the power-loss corruption
problem described in ticket [ff5be73dee086]

FossilOrigin-Name: 44ca4d123385d759c11919865525c998c2e35bdb

diff --cc manifest
index 6676da8ac42f5a9bc103fff96ee4370ac6bb5046,bc2dd4cdeae7a0594b50b394b7ca105cb581b926..f48b9a0540dc39015af239f6f4d3a4700eb6768a
--- 1/manifest
--- 2/manifest
+++ b/manifest
@@@ -1,5 -1,5 +1,5 @@@
- C Add\stests\sto\swalcrash3.test.
- D 2011-12-17T08:10:34.481
 -C Enhance\sthe\sWAL\sheader\ssync\sso\sthat\sit\shonors\sthe\svarious\ssynchronous\npragmas,\ssettings,\sand\sdevice\scharacteristics.
 -D 2011-12-16T21:26:26.087
++C Merge\sin\schanges\sthat\scause\sthe\sfirst\ssector\sof\sthe\sWAL\sfile\sto\sbe\ssynced\nwhen\sthe\sWAL\srestarts.\s\sThis\sis\sa\sfix\sfor\sthe\spower-loss\scorruption\nproblem\sdescribed\sin\sticket\s[ff5be73dee086]
++D 2011-12-17T13:45:28.989
  F Makefile.arm-wince-mingw32ce-gcc d6df77f1f48d690bd73162294bbba7f59507c72f
  F Makefile.in 5b4a3e12a850b021547e43daf886b25133b44c07
  F Makefile.linux-gcc 91d710bdc4998cb015f39edf3cb314ec4f4d7e23
@@@ -250,8 -250,8 +250,8 @@@ F src/vdbemem.c 2fc78b3e0fabcc1eaa23cd7
  F src/vdbesort.c 468d43c057063e54da4f1988b38b4f46d60e7790
  F src/vdbetrace.c d6e50e04e1ec498150e519058f617d91b8f5c843
  F src/vtab.c e9318d88feac85be8e27ee783ac8f5397933fc8a
- F src/wal.c 8f6fd4900934124f6c2701448c13038cbc02a4f4
- F src/wal.h 66b40bd91bc29a5be1c88ddd1f5ade8f3f48728a
 -F src/wal.c 20022b733ce06f77cc1d7f154da32987b57532ae
++F src/wal.c 89a60a8bf8daa805b819f97b2049a62ae5618707
+ F src/wal.h 42f8313f7aaf8913e2d1fdf7b47025c23491ea1d
  F src/walker.c 3112bb3afe1d85dc52317cb1d752055e9a781f8f
  F src/where.c af623942514571895818b9b7ae11db95ae3b3d88
  F test/8_3_names.test 631ea964a3edb091cf73c3b540f6bcfdb36ce823
@@@ -984,7 -984,7 +984,7 @@@ F tool/tostr.awk e75472c2f98dd76e06b8c9
  F tool/vdbe-compress.tcl d70ea6d8a19e3571d7ab8c9b75cba86d1173ff0f
  F tool/warnings-clang.sh 9f406d66e750e8ac031c63a9ef3248aaa347ef2a
  F tool/warnings.sh fbc018d67fd7395f440c28f33ef0f94420226381
- P 7b63b11b93396079131686abb36c4221354fa50e
- R 177c457106f4a322f13cf8ef2b836d21
- U dan
- Z c66e15671707eedc5457d2cd5fb751c5
 -P 91d0437c0702904d27f0ef7b1b52d0797efe1826
 -R 5f78dbf89e78a567743daf43caa5df96
++P d76880428013ae2c5be00d87bb3e1695af6f706f 9799241f7de952c4d1ea8bf6508b577d2b57a370
++R a66c21780a9737a3739ef721dbd80b71
+ U drh
 -Z da5e946383fd5dfe4d9a2957cf126f26
++Z 8683a36598a7c916281a4627e543388f

diff --cc manifest.uuid
index 47932d748d7d958d9f4bad2d1b3e0647a8ce0df1,433b9f5a98bc34f27cb2c4dfbbc5636cf1ff3888..9c694594adbc4a1f09cfa4fba8cfeb29aca03d25
--- 1/manifest.uuid
--- 2/manifest.uuid
+++ b/manifest.uuid
@@@ -1,1 -1,1 +1,1 @@@
- d76880428013ae2c5be00d87bb3e1695af6f706f
 -9799241f7de952c4d1ea8bf6508b577d2b57a370
++44ca4d123385d759c11919865525c998c2e35bdb

diff --cc src/wal.c
index 047368406ff157b02cb264dbc9e0716ffe7324f3,34ddb1b1e2eec63eb348a2758f08a1ce1e240e17..03c482554ee1342abb9528a71258a669d0f53390
--- 1/src/wal.c
--- 2/src/wal.c
+++ b/src/wal.c
@@@ -1094,6 -1097,6 +1097,7 @@@ static int walIndexRecover(Wal *pWal)
      int szPage;                   /* Page size according to the log */
      u32 magic;                    /* Magic value read from WAL header */
      u32 version;                  /* Magic value read from WAL header */
++    int isValid;                  /* True if this frame is valid */
  
      /* Read in the WAL header. */
      rc = sqlite3OsRead(pWal->pWalFd, aBuf, WAL_HDRSIZE, 0);
@@@ -1149,17 -1152,17 +1153,25 @@@
  
      /* Read all frames from the log file. */
      iFrame = 0;
++    isValid = 1;
      for(iOffset=WAL_HDRSIZE; (iOffset+szFrame)<=nSize; iOffset+=szFrame){
        u32 pgno;                   /* Database page number for frame */
        u32 nTruncate;              /* dbsize field from frame header */
--      int isValid;                /* True if this frame is valid */
  
        /* Read and decode the next log frame. */
++      iFrame++;
        rc = sqlite3OsRead(pWal->pWalFd, aFrame, szFrame, iOffset);
        if( rc!=SQLITE_OK ) break;
++      if( sqlite3Get4byte(&aFrame[8]) ==
++            1+sqlite3Get4byte((u8*)&pWal->hdr.aSalt[0]) ){
++        pWal->hdr.mxFrame = 0;
++        pWal->hdr.nPage = 0;
++        break;
++      }
++      if( !isValid ) continue;
        isValid = walDecodeFrame(pWal, &pgno, &nTruncate, aData, aFrame);
--      if( !isValid ) break;
--      rc = walIndexAppend(pWal, ++iFrame, pgno);
++      if( !isValid ) continue;
++      rc = walIndexAppend(pWal, iFrame, pgno);
        if( rc!=SQLITE_OK ) break;
  
        /* If nTruncate is non-zero, this is a commit record. */