SQLite

** the effect on the database file of an OS crash or power failure.  This
** is used to test the ability of SQLite to recover from those situations.
*/
#if SQLITE_TEST          /* This file is used for the testing only */
#include "sqliteInt.h"
#include "os.h"
#include "tcl.h"


/*
** A copy of the original sqlite3Io structure
*/
static struct sqlite3IoVtbl origIo;

/*
** The OsFile structure for the crash-test backend.  The pBase field
** points to an OsFile structure for the native backend.
*/
struct OsFile {
  u8 **apBlk;         /* Array of blocks that have been written to. */
  int nBlk;           /* Size of apBlock. */
  i64 offset;         /* Next character to be read from the file */
  int nMaxWrite;      /* Largest offset written to. */
  char *zName;        /* File name */
  OsFile *pBase;      /* Base class */
  OsFile *pNext;      /* Next in a list of them all */
};

/*

  sqlite3OsLeaveMutex();
  return r;
}

/*
** A list of all open files.
*/
static OsFile *pAllFiles = 0;

/*
** Initialise the os_test.c specific fields of pFile.
*/
static void initFile(OsFile **pId, char const *zName, OsFile *pBase){
  OsFile *pFile = *pId = sqliteMalloc(sizeof(OsFile) + strlen(zName)+1);
  pFile->nMaxWrite = 0; 
  pFile->offset = 0;
  pFile->nBlk = 0; 
  pFile->apBlk = 0; 
  pFile->zName = (char *)(&pFile[1]);
  strcpy(pFile->zName, zName);
  pFile->pBase = pBase;
  pFile->pNext = pAllFiles;
  pAllFiles = pFile;
}

/*
** Undo the work done by initFile. Delete the OsFile structure
** and unlink the structure from the pAllFiles list.
*/
static void closeFile(OsFile **pId){
  OsFile *pFile = *pId;
  if( pFile==pAllFiles ){
    pAllFiles = pFile->pNext;
  }else{
    OsFile *p;
    for(p=pAllFiles; p->pNext!=pFile; p=p->pNext ){
      assert( p );
    }
    p->pNext = pFile->pNext;
  }
  sqliteFree(*pId);
  *pId = 0;
}

/*






** Read block 'blk' off of the real disk file and into the cache of pFile.


*/
static int readBlockIntoCache(OsFile *pFile, int blk){
  if( blk>=pFile->nBlk ){
    int n = ((pFile->nBlk * 2) + 100 + blk);
    /* if( pFile->nBlk==0 ){ printf("DIRTY %s\n", pFile->zName); } */
    pFile->apBlk = (u8 **)sqliteRealloc(pFile->apBlk, n * sizeof(u8*));
    if( !pFile->apBlk ) return SQLITE_NOMEM;
    memset(&pFile->apBlk[pFile->nBlk], 0, (n - pFile->nBlk)*sizeof(u8*));
    pFile->nBlk = n;

/*
** Write the cache of pFile to disk. If crash is non-zero, randomly
** skip blocks when writing. The cache is deleted before returning.
*/
static int writeCache2(OsFile *pFile, int crash){
  int i;
  int nMax = pFile->nMaxWrite;

  int rc = SQLITE_OK;


  for(i=0; i<pFile->nBlk; i++){
    u8 *p = pFile->apBlk[i];
    if( p ){
      int skip = 0;
      int trash = 0;
      if( crash ){
        char random;

      sqliteFree(p);
    }
  }
  sqliteFree(pFile->apBlk);
  pFile->nBlk = 0;
  pFile->apBlk = 0;
  pFile->nMaxWrite = 0;




  return rc;
}

/*
** Write the cache to disk.
*/
static int writeCache(OsFile *pFile){
  if( pFile->apBlk ){
    int c = crashRequired(pFile->zName);
    if( c ){
      OsFile *p;
#ifdef TRACE_WRITECACHE
      printf("\nCrash during sync of %s\n", pFile->zName);
#endif
      for(p=pAllFiles; p; p=p->pNext){
        writeCache2(p, 1);
      }
      exit(-1);
    }else{
      return writeCache2(pFile, 0);
    }
  }
  return SQLITE_OK;
}

/*
** Close the file.
*/
static int crashClose(OsFile **pId){
  OsFile *pFile = *pId;
  if( pFile ){
    /* printf("CLOSE %s (%d blocks)\n", pFile->zName, pFile->nBlk); */
    writeCache(pFile);
    origIo.xClose(&pFile->pBase);
  }
  closeFile(pId);
  return SQLITE_OK;
}

static int crashSeek(OsFile *id, i64 offset){
  id->offset = offset;
  return SQLITE_OK;
}

static int crashRead(OsFile *id, void *pBuf, int amt){
  i64 offset;       /* The current offset from the start of the file */
  i64 end;          /* The byte just past the last byte read */
  int blk;            /* Block number the read starts on */
  int i;
  u8 *zCsr;
  int rc = SQLITE_OK;
  OsFile *pFile = id;

  offset = pFile->offset;
  end = offset+amt;
  blk = (offset/BLOCKSIZE);

  zCsr = (u8 *)pBuf;
  for(i=blk; i*BLOCKSIZE<end; i++){
    int off = 0;
    int len = 0;

      len = len - (BLOCK_OFFSET(i+1)-end);
    }

    if( i<pFile->nBlk && pFile->apBlk[i]){
      u8 *pBlk = pFile->apBlk[i];
      memcpy(zCsr, &pBlk[off], len);
    }else{
      rc = origIo.xSeek(id->pBase, BLOCK_OFFSET(i) + off);
      if( rc!=SQLITE_OK ) return rc;
      rc = origIo.xRead(id->pBase, zCsr, len);
      if( rc!=SQLITE_OK ) return rc;
    }

    zCsr += len;
  }
  assert( zCsr==&((u8 *)pBuf)[amt] );

  id->offset = end;
  return rc;
}

static int crashWrite(OsFile *id, const void *pBuf, int amt){
  i64 offset;       /* The current offset from the start of the file */
  i64 end;          /* The byte just past the last byte written */
  int blk;            /* Block number the write starts on */
  int i;
  const u8 *zCsr;
  int rc = SQLITE_OK;


  offset = id->offset;
  end = offset+amt;
  blk = (offset/BLOCKSIZE);

  zCsr = (u8 *)pBuf;
  for(i=blk; i*BLOCKSIZE<end; i++){
    u8 *pBlk;
    int off = 0;
    int len = 0;

    /* Make sure the block is in the cache */
    rc = readBlockIntoCache(id, i);
    if( rc!=SQLITE_OK ) return rc;

    /* Write into the cache */
    pBlk = id->apBlk[i];
    assert( pBlk );

    if( BLOCK_OFFSET(i) < offset ){
      off = offset-BLOCK_OFFSET(i);
    }
    len = BLOCKSIZE - off;
    if( BLOCK_OFFSET(i+1) > end ){
      len = len - (BLOCK_OFFSET(i+1)-end);
    }
    memcpy(&pBlk[off], zCsr, len);
    zCsr += len;
  }
  if( id->nMaxWrite<end ){
    id->nMaxWrite = end;
  }
  assert( zCsr==&((u8 *)pBuf)[amt] );
  id->offset = end;

  return rc;
}

/*
** Sync the file. First flush the write-cache to disk, then call the
** real sync() function.
*/
static int crashSync(OsFile *id, int dataOnly){
  int rc;
  /* printf("SYNC %s (%d blocks)\n", (*id)->zName, (*id)->nBlk); */
  rc = writeCache(id);
  /* if( rc!=SQLITE_OK ) return rc; rc = origIo.xSync(id->pBase, dataOnly); */

  return rc;
}

/*
** Truncate the file. Set the internal OsFile.nMaxWrite variable to the new
** file size to ensure that nothing in the write-cache past this point
** is written to disk.
*/
static int crashTruncate(OsFile *id, i64 nByte){

  id->nMaxWrite = nByte;
  return origIo.xTruncate(id->pBase, nByte);
}

/*
** Return the size of the file. If the cache contains a write that extended
** the file, then return this size instead of the on-disk size.
*/
static int crashFileSize(OsFile *id, i64 *pSize){
  int rc = origIo.xFileSize(id->pBase, pSize);

  if( rc==SQLITE_OK && pSize && *pSize<id->nMaxWrite ){
    *pSize = id->nMaxWrite;
  }
  return rc;
}

/*
** The three functions used to open files. All that is required is to
** initialise the os_test.c specific fields and then call the corresponding
** os_unix.c function to really open the file.
*/
static int crashOpenReadWrite(const char *zFilename, OsFile **pId,int *pRdonly){
  OsFile *pBase = 0;
  int rc = origIo.xOpenReadWrite(zFilename, &pBase, pRdonly);
  if( !rc ){
    initFile(pId, zFilename, pBase);
  }
  return rc;
}
static int crashOpenExclusive(const char *zFilename, OsFile **pId, int delFlag){
  OsFile *pBase = 0;
  int rc = origIo.xOpenExclusive(zFilename, &pBase, delFlag);
  if( !rc ){
    initFile(pId, zFilename, pBase);
  }
  return rc;
}
static int crashOpenReadOnly(const char *zFilename, OsFile **pId){
  OsFile *pBase = 0;
  int rc = origIo.xOpenReadOnly(zFilename, &pBase);
  if( !rc ){
    initFile(pId, zFilename, pBase);
  }
  return rc;
}

/*
** OpenDirectory and SyncDirectory are no-ops
*/
static int crashOpenDir(const char *zName, OsFile *id){
  return SQLITE_OK;
}
static int crashSyncDir(const char *zName){
  return SQLITE_OK;
}

/*
** Locking primitives are passed through into the underlying
** file descriptor.
*/
int crashLock(OsFile *id, int lockType){
  return origIo.xLock(id->pBase, lockType);
}
int crashUnlock(OsFile *id, int lockType){
  return origIo.xUnlock(id->pBase, lockType);
}
int crashCheckReservedLock(OsFile *id){
  return origIo.xCheckReservedLock(id->pBase);
}
void crashSetFullSync(OsFile *id, int setting){
  return;  /* This is a no-op */
}
int crashLockState(OsFile *id){
  return origIo.xLockState(id->pBase);
}

/*
** Return the underlying file handle.
*/
int crashFileHandle(OsFile *id){
  return origIo.xFileHandle(id->pBase);
}

/*
** tclcmd:   sqlite_crashparams DELAY CRASHFILE
**
** This procedure implements a TCL command that enables crash testing
** in testfixture.  Once enabled, crash testing cannot be disabled.

  zFile = Tcl_GetStringFromObj(objv[2], &nFile);
  if( nFile>=sizeof(zCrashFile)-1 ){
    Tcl_AppendResult(interp, "crash file name too big", 0);
    return TCL_ERROR;
  }
  setCrashParams(delay, zFile);
  origIo = sqlite3Io;
  /* xDelete unchanged */
  /* xFileExists unchanged */
  sqlite3Io.xOpenReadWrite = crashOpenReadWrite;
  sqlite3Io.xOpenExclusive = crashOpenExclusive;
  sqlite3Io.xOpenReadOnly = crashOpenReadOnly;
  sqlite3Io.xOpenDirectory = crashOpenDir;
  sqlite3Io.xSyncDirectory = crashSyncDir;
  /* xTempFileName unchanged */
  /* xIsDirWritable unchanged */
  sqlite3Io.xClose = crashClose;
  sqlite3Io.xRead = crashRead;
  sqlite3Io.xWrite = crashWrite;
  sqlite3Io.xSeek = crashSeek;
  sqlite3Io.xSync = crashSync;
  sqlite3Io.xTruncate = crashTruncate;
  sqlite3Io.xFileSize = crashFileSize;
  /* xFullPathname unchanged */
  sqlite3Io.xLock = crashLock;
  sqlite3Io.xUnlock = crashUnlock;
  sqlite3Io.xCheckReservedLock = crashCheckReservedLock;
  sqlite3Io.xSetFullSync = crashSetFullSync;
  sqlite3Io.xFileHandle = crashFileHandle;
  sqlite3Io.xLockState = crashLockState;
  return TCL_OK;
}


/*
** This procedure registers the TCL procedures defined in this file.
*/
int Sqlitetest6_Init(Tcl_Interp *interp){

  Tcl_CreateObjCommand(interp, "sqlite3_crashparams", crashParamsObjCmd, 0, 0);

  return TCL_OK;
}

#endif /* SQLITE_TEST */