SQLite

  unsigned char eFileLock;            /* The type of lock held on this fd */
  int lastErrno;                      /* The unix errno from last I/O error */
  void *lockingContext;               /* Locking style specific state */
  UnixUnusedFd *pUnused;              /* Pre-allocated UnixUnusedFd */
  int fileFlags;                      /* Miscellanous flags */
  const char *zPath;                  /* Name of the file */
  unixShm *pShm;                      /* Shared memory segment information */
  int szChunk;                        /* Configured by FCNTL_CHUNK_SIZE */
#if SQLITE_ENABLE_LOCKING_STYLE
  int openFlags;                      /* The flags specified at open() */
#endif
#if SQLITE_ENABLE_LOCKING_STYLE || defined(__APPLE__)
  unsigned fsFlags;                   /* cached details from statfs() */
#endif
#if OS_VXWORKS

  while( amt>0 && (wrote = seekAndWrite(pFile, offset, pBuf, amt))>0 ){
    amt -= wrote;
    offset += wrote;
    pBuf = &((char*)pBuf)[wrote];
  }
  SimulateIOError(( wrote=(-1), amt=1 ));
  SimulateDiskfullError(( wrote=0, amt=1 ));

  /* If the user has configured a chunk-size for this file, it could be
  ** that the file needs to be extended at this point. 
  */
  if( pFile->szChunk && amt==0 ){
    i64 nSize;                    /* Required file size */
    struct stat buf;              /* Used to hold return values of fstat() */
    int rc = fstat(pFile->h, &buf);
    if( rc!=0 ) return SQLITE_IOERR_FSTAT;
    nSize = ((offset+amt+pFile->szChunk-1) / pFile->szChunk) * pFile->szChunk;
    if( nSize>(i64)buf.st_size ){
#ifdef HAVE_POSIX_FALLOCATE
      if( posix_fallocate(pFile->h, buf.st_size, nSize-buf.st_size) ){
        return SQLITE_IOERR_WRITE;
      }
#else
      /* If the OS does not have posix_fallocate(), fake it. First use
      ** ftruncate() to set the file size, then write a single byte to
      ** the last byte in each block within the extended region.
      */
      int nBlk = buf.st_blksize;  /* File-system block size */
      i64 iWrite;                 /* Next offset to write to */

      if( ftruncate(pFile->h, nSize) ){
	pFile->lastErrno = errno;
	return SQLITE_IOERR_TRUNCATE;
      }
      iWrite = ((buf.st_size + 2*nBlk - 1)/nBlk)*nBlk-1;
      do {
	wrote = seekAndWrite(pFile, iWrite, "", 1);
	iWrite += nBlk;
      } while( wrote==1 && iWrite<nSize );
      if( wrote!=1 ) amt = 1;
#endif
    }
  }

  if( amt>0 ){
    if( wrote<0 ){
      /* lastErrno set by seekAndWrite */
      return SQLITE_IOERR_WRITE;
    }else{
      pFile->lastErrno = 0; /* not a system error */
      return SQLITE_FULL;
    }
  }

  return SQLITE_OK;
}

#ifdef SQLITE_TEST
/*
** Count the number of fullsyncs and normal syncs.  This is used to test
** that syncs and fullsyncs are occurring at the right times.

  return rc;
}

/*
** Truncate an open file to a specified size
*/
static int unixTruncate(sqlite3_file *id, i64 nByte){
  unixFile *pFile = (unixFile *)id;
  int rc;
  assert( pFile );
  SimulateIOError( return SQLITE_IOERR_TRUNCATE );

  /* If the user has configured a chunk-size for this file, truncate the
  ** file so that it consists of an integer number of chunks (i.e. the
  ** actual file size after the operation may be larger than the requested
  ** size).
  */
  if( pFile->szChunk ){
    nByte = ((nByte + pFile->szChunk - 1)/pFile->szChunk) * pFile->szChunk;
  }

  rc = ftruncate(pFile->h, (off_t)nByte);
  if( rc ){
    pFile->lastErrno = errno;
    return SQLITE_IOERR_TRUNCATE;
  }else{
#ifndef NDEBUG
    /* If we are doing a normal write to a database file (as opposed to
    ** doing a hot-journal rollback or a write to some file other than a
    ** normal database file) and we truncate the file to zero length,
    ** that effectively updates the change counter.  This might happen
    ** when restoring a database using the backup API from a zero-length
    ** source.
    */
    if( pFile->inNormalWrite && nByte==0 ){
      pFile->transCntrChng = 1;
    }
#endif

    return SQLITE_OK;
  }
}

    case SQLITE_FCNTL_LOCKSTATE: {
      *(int*)pArg = ((unixFile*)id)->eFileLock;
      return SQLITE_OK;
    }
    case SQLITE_LAST_ERRNO: {
      *(int*)pArg = ((unixFile*)id)->lastErrno;
      return SQLITE_OK;
    }
    case SQLITE_FCNTL_CHUNK_SIZE: {
      ((unixFile*)id)->szChunk = *(int *)pArg;
      return SQLITE_OK;				    
    }
    case SQLITE_FCNTL_SIZE_HINT: {
#if 0 /* No performance advantage seen on Linux */
      sqlite3_int64 szFile = *(sqlite3_int64*)pArg;
      unixFile *pFile = (unixFile*)id;
      ftruncate(pFile->h, szFile);
#endif

** file run faster.
*/
#define SQLITE_FCNTL_LOCKSTATE        1
#define SQLITE_GET_LOCKPROXYFILE      2
#define SQLITE_SET_LOCKPROXYFILE      3
#define SQLITE_LAST_ERRNO             4
#define SQLITE_FCNTL_SIZE_HINT        5
#define SQLITE_FCNTL_CHUNK_SIZE       6

/*
** CAPI3REF: Mutex Handle
**
** The mutex module within SQLite defines [sqlite3_mutex] to be an
** abstract type for a mutex object.  The SQLite core never looks
** at the internal representation of an [sqlite3_mutex].  It only

  if( iArg!=0 ) {
    Tcl_AppendResult(interp, "Unexpected non-zero errno: ",
                     Tcl_GetStringFromObj(Tcl_NewIntObj(iArg), 0), " ", 0);
    return TCL_ERROR;
  }
  return TCL_OK;  
}

/*
** tclcmd:   file_control_chunksize_test DB DBNAME SIZE
**
** This TCL command runs the sqlite3_file_control interface and
** verifies correct operation of the SQLITE_GET_LOCKPROXYFILE and
** SQLITE_SET_LOCKPROXYFILE verbs.
*/
static int file_control_chunksize_test(
  ClientData clientData, /* Pointer to sqlite3_enable_XXX function */
  Tcl_Interp *interp,    /* The TCL interpreter that invoked this command */
  int objc,              /* Number of arguments */
  Tcl_Obj *CONST objv[]  /* Command arguments */
){
  int nSize;                      /* New chunk size */
  char *zDb;                      /* Db name ("main", "temp" etc.) */
  sqlite3 *db;                    /* Database handle */
  int rc;                         /* file_control() return code */

  if( objc!=4 ){
    Tcl_WrongNumArgs(interp, 1, objv, "DB DBNAME SIZE");
    return TCL_ERROR;
  }
  if( getDbPointer(interp, Tcl_GetString(objv[1]), &db) 
   || Tcl_GetIntFromObj(interp, objv[3], &nSize)
  ){
   return TCL_ERROR;
  }
  zDb = Tcl_GetString(objv[2]);
  if( zDb[0]=='\0' ) zDb = NULL;

  rc = sqlite3_file_control(db, zDb, SQLITE_FCNTL_CHUNK_SIZE, (void *)&nSize);
  if( rc ){
    Tcl_SetResult(interp, (char *)sqlite3TestErrorName(rc), TCL_STATIC);
    return TCL_ERROR;
  }
  return TCL_OK;
}

/*
** tclcmd:   file_control_lockproxy_test DB PWD
**
** This TCL command runs the sqlite3_file_control interface and
** verifies correct operation of the SQLITE_GET_LOCKPROXYFILE and
** SQLITE_SET_LOCKPROXYFILE verbs.

     { "vfs_unlink_test",            vfs_unlink_test,     0   },
     { "vfs_initfail_test",          vfs_initfail_test,   0   },
     { "vfs_unregister_all",         vfs_unregister_all,  0   },
     { "vfs_reregister_all",         vfs_reregister_all,  0   },
     { "file_control_test",          file_control_test,   0   },
     { "file_control_lasterrno_test", file_control_lasterrno_test,  0   },
     { "file_control_lockproxy_test", file_control_lockproxy_test,  0   },
     { "file_control_chunksize_test", file_control_chunksize_test,  0   },
     { "sqlite3_vfs_list",           vfs_list,     0   },

     /* Functions from os.h */
#ifndef SQLITE_OMIT_UTF16
     { "add_test_collate",        test_collate, 0            },
     { "add_test_collate_needed", test_collate_needed, 0     },
     { "add_test_function",       test_function, 0           },

# 2010 July 28
#
# The author disclaims copyright to this source code.  In place of
# a legal notice, here is a blessing:
#
#    May you do good and not evil.
#    May you find forgiveness for yourself and forgive others.
#    May you share freely, never taking more than you give.
#
#***********************************************************************
#

set testdir [file dirname $argv0]
source $testdir/tester.tcl

if {$::tcl_platform(platform)!="unix"} {
  finish_test
  return
}

file_control_chunksize_test db main [expr 1024*1024]

do_test fallocate-1.1 {
  execsql {
    PRAGMA page_size = 1024;
    PRAGMA auto_vacuum = 1;
    CREATE TABLE t1(a, b);
  }
  file size test.db
} [expr 1*1024*1024]

do_test fallocate-1.2 {
  execsql { INSERT INTO t1 VALUES(1, zeroblob(1024*900)) }
  file size test.db
} [expr 1*1024*1024]

do_test fallocate-1.3 {
  execsql { INSERT INTO t1 VALUES(2, zeroblob(1024*900)) }
  file size test.db
} [expr 2*1024*1024]

do_test fallocate-1.4 {
  execsql { DELETE FROM t1 WHERE a = 1 }
  file size test.db
} [expr 1*1024*1024]

do_test fallocate-1.5 {
  execsql { DELETE FROM t1 WHERE a = 2 }
  file size test.db
} [expr 1*1024*1024]

do_test fallocate-1.6 {
  execsql { PRAGMA freelist_count }
} {0}

finish_test