From: drh Date: Thu, 20 Nov 2014 15:30:50 +0000 (+0000) Subject: Ensure that when the number of cells on a page drops to zero that the freelist X-Git-Tag: version-3.8.8~147 X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=fdab02635c2304acc99b04272235463e1ed1ac51;p=thirdparty%2Fsqlite.git Ensure that when the number of cells on a page drops to zero that the freelist and fragment counter are both cleared. Also add evidence marks corresponding to file-format documentation. FossilOrigin-Name: ef9fbc08b0a047042deeb2d6007d67028fefb9e2 --- diff --git a/manifest b/manifest index fe5a6d1bb4..7541704f57 100644 --- a/manifest +++ b/manifest @@ -1,5 +1,5 @@ -C Fix\sthe\sencoding\sof\ssome\sintegers\sto\suse\sthe\sminimum\samount\sof\sspace:\n-128,\s-32768,\s-8388608,\s-217483648,\sand\s-140737488355328. -D 2014-11-20T02:58:10.344 +C Ensure\sthat\swhen\sthe\snumber\sof\scells\son\sa\spage\sdrops\sto\szero\sthat\sthe\sfreelist\nand\sfragment\scounter\sare\sboth\scleared.\s\sAlso\sadd\sevidence\smarks\scorresponding\nto\sfile-format\sdocumentation. +D 2014-11-20T15:30:50.141 F Makefile.arm-wince-mingw32ce-gcc d6df77f1f48d690bd73162294bbba7f59507c72f F Makefile.in a226317fdf3f4c895fb3cfedc355b4d0868ce1fb F Makefile.linux-gcc 91d710bdc4998cb015f39edf3cb314ec4f4d7e23 @@ -173,7 +173,7 @@ F src/auth.c b56c78ebe40a2110fd361379f7e8162d23f92240 F src/backup.c 7ddee9c7d505e07e959a575b18498f17c71e53ea F src/bitvec.c 19a4ba637bd85f8f63fc8c9bae5ade9fb05ec1cb F src/btmutex.c 49ca66250c7dfa844a4d4cb8272b87420d27d3a5 -F src/btree.c d0a7cfc8788ad028c86020637df70c789615196e +F src/btree.c 4db5e06ca2d1a5437be7075251fa702c76179b0e F src/btree.h e31a3a3ebdedb1caf9bda3ad5dbab3db9b780f6e F src/btreeInt.h 3363e18fd76f69a27a870b25221b2345b3fd4d21 F src/build.c 67bb05b1077e0cdaccb2e36bfcbe7a5df9ed31e8 @@ -1221,7 +1221,7 @@ F tool/vdbe_profile.tcl 67746953071a9f8f2f668b73fe899074e2c6d8c1 F tool/warnings-clang.sh f6aa929dc20ef1f856af04a730772f59283631d4 F tool/warnings.sh 0abfd78ceb09b7f7c27c688c8e3fe93268a13b32 F tool/win/sqlite.vsix deb315d026cc8400325c5863eef847784a219a2f -P 9a9627e178a67bbfc85366aaea900e674d22fb53 -R acb3727f628d804856a9646910d389b3 +P 2d7c8da5f16e64eaa7b0c2d66898682ea3d102a0 +R aa709859c03f6b1c53283cb1512cbe99 U drh -Z ae13a50368fe7d7b53b7e4276c8588bd +Z 12bf55f57cbfdde86aed8c230487a6ad diff --git a/manifest.uuid b/manifest.uuid index 1ae875991f..e8ed272102 100644 --- a/manifest.uuid +++ b/manifest.uuid @@ -1 +1 @@ -2d7c8da5f16e64eaa7b0c2d66898682ea3d102a0 \ No newline at end of file +ef9fbc08b0a047042deeb2d6007d67028fefb9e2 \ No newline at end of file diff --git a/src/btree.c b/src/btree.c index f61078cac6..5ae5986cfa 100644 --- a/src/btree.c +++ b/src/btree.c @@ -1139,6 +1139,11 @@ static void ptrmapPutOvflPtr(MemPage *pPage, u8 *pCell, int *pRC){ ** end of the page and all free space is collected into one ** big FreeBlk that occurs in between the header and cell ** pointer array and the cell content area. +** +** EVIDENCE-OF: R-44582-60138 SQLite may from time to time reorganize a +** b-tree page so that there are no freeblocks or fragment bytes, all +** unused bytes are contained in the unallocated space region, and all +** cells are packed tightly at the end of the page. */ static int defragmentPage(MemPage *pPage){ int i; /* Loop counter */ @@ -1262,6 +1267,8 @@ static u8 *pageFindSlot(MemPage *pPg, int nByte, int *pRc, int *pbDefrag){ testcase( x==4 ); testcase( x==3 ); if( x<4 ){ + /* EVIDENCE-OF: R-11498-58022 In a well-formed b-tree page, the total + ** number of bytes in fragments may not exceed 60. */ if( aData[hdr+7]>=60 ){ if( pbDefrag ) *pbDefrag = 1; return 0; @@ -1316,19 +1323,13 @@ static int allocateSpace(MemPage *pPage, int nByte, int *pIdx){ assert( pPage->cellOffset == hdr + 12 - 4*pPage->leaf ); gap = pPage->cellOffset + 2*pPage->nCell; assert( gap<=65536 ); - top = get2byte(&data[hdr+5]); - if( gap>top ){ - if( top==0 ){ - /* EVIDENCE-OF: R-29356-02391 If the database uses a 65536-byte page size - ** and the reserved space is zero (the usual value for reserved space) - ** then the cell content offset of an empty page wants to be 65536. - ** However, that integer is too large to be stored in a 2-byte unsigned - ** integer, so a value of 0 is used in its place. */ - top = 65536; - }else{ - return SQLITE_CORRUPT_BKPT; - } - } + /* EVIDENCE-OF: R-29356-02391 If the database uses a 65536-byte page size + ** and the reserved space is zero (the usual value for reserved space) + ** then the cell content offset of an empty page wants to be 65536. + ** However, that integer is too large to be stored in a 2-byte unsigned + ** integer, so a value of 0 is used in its place. */ + top = get2byteNotZero(&data[hdr+5]); + if( gap>top ) return SQLITE_CORRUPT_BKPT; /* If there is enough space between gap and top for one more cell pointer ** array entry offset, and if the freelist is not empty, then search the @@ -1497,18 +1498,32 @@ static int decodeFlags(MemPage *pPage, int flagByte){ pPage->childPtrSize = 4-4*pPage->leaf; pBt = pPage->pBt; if( flagByte==(PTF_LEAFDATA | PTF_INTKEY) ){ + /* EVIDENCE-OF: R-03640-13415 A value of 5 means the page is an interior + ** table b-tree page. */ + assert( (PTF_LEAFDATA|PTF_INTKEY)==5 ); + /* EVIDENCE-OF: R-20501-61796 A value of 13 means the page is a leaf + ** table b-tree page. */ + assert( (PTF_LEAFDATA|PTF_INTKEY|PTF_LEAF)==13 ); pPage->intKey = 1; pPage->intKeyLeaf = pPage->leaf; pPage->noPayload = !pPage->leaf; pPage->maxLocal = pBt->maxLeaf; pPage->minLocal = pBt->minLeaf; }else if( flagByte==PTF_ZERODATA ){ + /* EVIDENCE-OF: R-27225-53936 A value of 2 means the page is an interior + ** index b-tree page. */ + assert( (PTF_ZERODATA)==2 ); + /* EVIDENCE-OF: R-16571-11615 A value of 10 means the page is a leaf + ** index b-tree page. */ + assert( (PTF_ZERODATA|PTF_LEAF)==10 ); pPage->intKey = 0; pPage->intKeyLeaf = 0; pPage->noPayload = 0; pPage->maxLocal = pBt->maxLocal; pPage->minLocal = pBt->minLocal; }else{ + /* EVIDENCE-OF: R-47608-56469 Any other value for the b-tree page type is + ** an error. */ return SQLITE_CORRUPT_BKPT; } pPage->max1bytePayload = pBt->max1bytePayload; @@ -1548,21 +1563,33 @@ static int btreeInitPage(MemPage *pPage){ hdr = pPage->hdrOffset; data = pPage->aData; + /* EVIDENCE-OF: R-28594-02890 The one-byte flag at offset 0 indicating + ** the b-tree page type. */ if( decodeFlags(pPage, data[hdr]) ) return SQLITE_CORRUPT_BKPT; assert( pBt->pageSize>=512 && pBt->pageSize<=65536 ); pPage->maskPage = (u16)(pBt->pageSize - 1); pPage->nOverflow = 0; usableSize = pBt->usableSize; - pPage->cellOffset = cellOffset = hdr + 12 - 4*pPage->leaf; + pPage->cellOffset = cellOffset = hdr + 8 + pPage->childPtrSize; pPage->aDataEnd = &data[usableSize]; pPage->aCellIdx = &data[cellOffset]; + /* EVIDENCE-OF: R-58015-48175 The two-byte integer at offset 5 designates + ** the start of the cell content area. A zero value for this integer is + ** interpreted as 65536. */ top = get2byteNotZero(&data[hdr+5]); + /* EVIDENCE-OF: R-37002-32774 The two-byte integer at offset 3 gives the + ** number of cells on the page. */ pPage->nCell = get2byte(&data[hdr+3]); if( pPage->nCell>MX_CELL(pBt) ){ /* To many cells for a single page. The page must be corrupt */ return SQLITE_CORRUPT_BKPT; } 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 + ** offset to the cell content area will equal the page size minus the + ** bytes of reserved space. */ + assert( pPage->nCell>0 || top==usableSize || CORRUPT_DB ); /* A malformed database page might cause us to read past the end ** of page when parsing a cell. @@ -1596,13 +1623,20 @@ static int btreeInitPage(MemPage *pPage){ } #endif - /* Compute the total free space on the page */ + /* Compute the total free space on the page + ** EVIDENCE-OF: R-23588-34450 The two-byte integer at offset 1 gives the + ** start of the first freeblock on the page, or is zero if there are no + ** freeblocks. */ pc = get2byte(&data[hdr+1]); - nFree = data[hdr+7] + top; + nFree = data[hdr+7] + top; /* Init nFree to non-freeblock free space */ while( pc>0 ){ u16 next, size; if( pciCellLast ){ - /* Start of free block is off the page */ + /* EVIDENCE-OF: R-55530-52930 In a well-formed b-tree page, there will + ** always be at least one cell before the first freeblock. + ** + ** Or, the freeblock is off the end of the page + */ return SQLITE_CORRUPT_BKPT; } next = get2byte(&data[pc]); @@ -5959,9 +5993,17 @@ static void dropCell(MemPage *pPage, int idx, int sz, int *pRC){ return; } pPage->nCell--; - memmove(ptr, ptr+2, 2*(pPage->nCell - idx)); - put2byte(&data[hdr+3], pPage->nCell); - pPage->nFree += 2; + if( pPage->nCell==0 ){ + memset(&data[hdr+1], 0, 4); + data[hdr+7] = 0; + put2byte(&data[hdr+5], pPage->pBt->usableSize); + pPage->nFree = pPage->pBt->usableSize - pPage->hdrOffset + - pPage->childPtrSize - 8; + }else{ + memmove(ptr, ptr+2, 2*(pPage->nCell - idx)); + put2byte(&data[hdr+3], pPage->nCell); + pPage->nFree += 2; + } } /* @@ -8609,8 +8651,14 @@ static int checkTreePage( assert( contentOffset<=usableSize ); /* Enforced by btreeInitPage() */ memset(hit+contentOffset, 0, usableSize-contentOffset); memset(hit, 1, contentOffset); + /* EVIDENCE-OF: R-37002-32774 The two-byte integer at offset 3 gives the + ** number of cells on the page. */ nCell = get2byte(&data[hdr+3]); + /* EVIDENCE-OF: R-23882-45353 The cell pointer array of a b-tree page + ** immediately follows the b-tree page header. */ cellStart = hdr + 12 - 4*pPage->leaf; + /* EVIDENCE-OF: R-02776-14802 The cell pointer array consists of K 2-byte + ** integer offsets to the cell contents. */ for(i=0; i=pc; j--) hit[j]++; } } + /* EVIDENCE-OF: R-20690-50594 The second field of the b-tree page header + ** is the offset of the first freeblock, or zero if there are no + ** freeblocks on the page. */ i = get2byte(&data[hdr+1]); while( i>0 ){ int size, j; @@ -8633,7 +8684,13 @@ static int checkTreePage( size = get2byte(&data[i+2]); assert( i+size<=usableSize ); /* Enforced by btreeInitPage() */ for(j=i+size-1; j>=i; j--) hit[j]++; + /* EVIDENCE-OF: R-58208-19414 The first 2 bytes of a freeblock are a + ** big-endian integer which is the offset in the b-tree page of the next + ** freeblock in the chain, or zero if the freeblock is the last on the + ** chain. */ j = get2byte(&data[i]); + /* EVIDENCE-OF: R-06866-39125 Freeblocks are always connected in order of + ** increasing offset. */ assert( j==0 || j>i+size ); /* Enforced by btreeInitPage() */ assert( j<=usableSize-4 ); /* Enforced by btreeInitPage() */ i = j; @@ -8647,6 +8704,11 @@ static int checkTreePage( break; } } + /* EVIDENCE-OF: R-43263-13491 The total number of bytes in all fragments + ** is stored in the fifth field of the b-tree page header. + ** EVIDENCE-OF: R-07161-27322 The one-byte integer at offset 7 gives the + ** number of fragmented free bytes within the cell content area. + */ if( cnt!=data[hdr+7] ){ checkAppendMsg(pCheck, "Fragmentation of %d bytes reported as %d on page %d",