181 lines
5.4 KiB
Diff
181 lines
5.4 KiB
Diff
Add an experimental fix to avoid attempting to mmap memory from an
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offset that is not a multiple of the system page size on systems with
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page sizes larger than 32KB.
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Patch by Dan Kennedy <danielk1977@gmail.com>.
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--- sqlite-autoconf/sqlite3.c.orig 2014-03-22 23:44:47.055908203 -0400
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+++ sqlite-autoconf/sqlite3.c 2014-03-22 23:44:06.716552734 -0400
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@@ -24010,6 +24010,7 @@
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/* Forward reference */
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static int openDirectory(const char*, int*);
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+static int unixGetpagesize(void);
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/*
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** Many system calls are accessed through pointer-to-functions so that
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@@ -24133,6 +24134,9 @@
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#define osMremap ((void*(*)(void*,size_t,size_t,int,...))aSyscall[23].pCurrent)
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#endif
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+ { "getpagesize", (sqlite3_syscall_ptr)unixGetpagesize, 0 },
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+#define osGetpagesize ((int(*)(void))aSyscall[24].pCurrent)
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+
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}; /* End of the overrideable system calls */
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/*
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@@ -27792,6 +27796,36 @@
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return rc;
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}
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+/*
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+** Return the system page size.
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+**
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+** This function should not be called directly by other code in this file.
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+** Instead, it should be called via macro osGetpagesize().
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+*/
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+static int unixGetpagesize(void){
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+#if defined(_BSD_SOURCE)
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+ return getpagesize();
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+#else
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+ return (int)sysconf(_SC_PAGESIZE);
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+#endif
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+}
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+
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+/*
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+** Return the minimum number of 32KB shm regions that should be mapped at
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+** a time, assuming that each mapping must be an integer multiple of the
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+** current system page-size.
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+**
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+** Usually, this is 1. The exception seems to be systems that are configured
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+** to use 64KB pages - in this case each mapping must cover at least two
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+** shm regions.
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+*/
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+static int unixShmRegionPerMap(void){
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+ int shmsz = 32*1024; /* SHM region size */
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+ int pgsz = osGetpagesize(); /* System page size */
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+ assert( ((pgsz-1)&pgsz)==0 ); /* Page size must be a power of 2 */
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+ if( pgsz<shmsz ) return 1;
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+ return pgsz/shmsz;
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+}
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/*
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** Purge the unixShmNodeList list of all entries with unixShmNode.nRef==0.
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@@ -27803,10 +27837,11 @@
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unixShmNode *p = pFd->pInode->pShmNode;
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assert( unixMutexHeld() );
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if( p && p->nRef==0 ){
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+ int nShmPerMap = unixShmRegionPerMap();
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int i;
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assert( p->pInode==pFd->pInode );
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sqlite3_mutex_free(p->mutex);
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- for(i=0; i<p->nRegion; i++){
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+ for(i=0; i<p->nRegion; i+=nShmPerMap){
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if( p->h>=0 ){
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osMunmap(p->apRegion[i], p->szRegion);
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}else{
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@@ -28013,6 +28048,8 @@
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unixShm *p;
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unixShmNode *pShmNode;
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int rc = SQLITE_OK;
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+ int nShmPerMap = unixShmRegionPerMap();
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+ int nReqRegion;
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/* If the shared-memory file has not yet been opened, open it now. */
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if( pDbFd->pShm==0 ){
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@@ -28028,9 +28065,12 @@
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assert( pShmNode->h>=0 || pDbFd->pInode->bProcessLock==1 );
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assert( pShmNode->h<0 || pDbFd->pInode->bProcessLock==0 );
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- if( pShmNode->nRegion<=iRegion ){
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+ /* Minimum number of regions required to be mapped. */
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+ nReqRegion = ((iRegion+nShmPerMap) / nShmPerMap) * nShmPerMap;
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+
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+ if( pShmNode->nRegion<nReqRegion ){
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char **apNew; /* New apRegion[] array */
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- int nByte = (iRegion+1)*szRegion; /* Minimum required file size */
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+ int nByte = nReqRegion*szRegion; /* Minimum required file size */
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struct stat sStat; /* Used by fstat() */
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pShmNode->szRegion = szRegion;
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@@ -28079,17 +28119,19 @@
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/* Map the requested memory region into this processes address space. */
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apNew = (char **)sqlite3_realloc(
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- pShmNode->apRegion, (iRegion+1)*sizeof(char *)
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+ pShmNode->apRegion, nReqRegion*sizeof(char *)
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);
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if( !apNew ){
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rc = SQLITE_IOERR_NOMEM;
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goto shmpage_out;
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}
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pShmNode->apRegion = apNew;
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- while(pShmNode->nRegion<=iRegion){
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+ while( pShmNode->nRegion<nReqRegion ){
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+ int nMap = szRegion*nShmPerMap;
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+ int i;
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void *pMem;
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if( pShmNode->h>=0 ){
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- pMem = osMmap(0, szRegion,
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+ pMem = osMmap(0, nMap,
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pShmNode->isReadonly ? PROT_READ : PROT_READ|PROT_WRITE,
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MAP_SHARED, pShmNode->h, szRegion*(i64)pShmNode->nRegion
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);
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@@ -28105,8 +28147,11 @@
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}
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memset(pMem, 0, szRegion);
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}
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- pShmNode->apRegion[pShmNode->nRegion] = pMem;
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- pShmNode->nRegion++;
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+
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+ for(i=0; i<nShmPerMap; i++){
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+ pShmNode->apRegion[pShmNode->nRegion+i] = &((char*)pMem)[szRegion*i];
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+ }
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+ pShmNode->nRegion += nShmPerMap;
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}
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}
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@@ -28321,19 +28366,6 @@
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}
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/*
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-** Return the system page size.
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-*/
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-static int unixGetPagesize(void){
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-#if HAVE_MREMAP
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- return 512;
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-#elif defined(_BSD_SOURCE)
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- return getpagesize();
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-#else
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- return (int)sysconf(_SC_PAGESIZE);
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-#endif
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-}
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-
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-/*
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** Attempt to set the size of the memory mapping maintained by file
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** descriptor pFd to nNew bytes. Any existing mapping is discarded.
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**
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@@ -28369,8 +28401,12 @@
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if( (pFd->ctrlFlags & UNIXFILE_RDONLY)==0 ) flags |= PROT_WRITE;
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if( pOrig ){
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- const int szSyspage = unixGetPagesize();
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+#if HAVE_MREMAP
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+ i64 nReuse = pFd->mmapSize;
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+#else
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+ const int szSyspage = osGetpagesize();
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i64 nReuse = (pFd->mmapSize & ~(szSyspage-1));
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+#endif
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u8 *pReq = &pOrig[nReuse];
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/* Unmap any pages of the existing mapping that cannot be reused. */
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@@ -31116,7 +31152,7 @@
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/* Double-check that the aSyscall[] array has been constructed
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** correctly. See ticket [bb3a86e890c8e96ab] */
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- assert( ArraySize(aSyscall)==24 );
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+ assert( ArraySize(aSyscall)==25 );
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/* Register all VFSes defined in the aVfs[] array */
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for(i=0; i<(sizeof(aVfs)/sizeof(sqlite3_vfs)); i++){
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