SQLite

**    May you find forgiveness for yourself and forgive others.
**    May you share freely, never taking more than you give.
**
******************************************************************************
**
** This file contains code that is specific to Unix systems.
**
** $Id: os_unix.c,v 1.195 2008/07/30 17:28:04 drh Exp $
*/
#include "sqliteInt.h"
#if SQLITE_OS_UNIX              /* This file is used on unix only */

/*
** If SQLITE_ENABLE_LOCKING_STYLE is defined, then several different 
** locking implementations are provided:

  rc = fstat(fd, &statbuf);
  if( rc!=0 ){
#ifdef EOVERFLOW
    if( errno==EOVERFLOW ) return SQLITE_NOLFS;
#endif
    return SQLITE_IOERR;
  }

  /* On OS X on an msdos filesystem, the inode number is reported
  ** incorrectly for zero-size files.  See ticket #3260.  To work
  ** around this problem (we consider it a bug in OS X, not SQLite)
  ** we always increase the file size to 1 by writing a single byte
  ** prior to accessing the inode number.  The one byte written is
  ** an ASCII 'S' character which also happens to be the first byte
  ** in the header of every SQLite database.  In this way, if there
  ** is a race condition such that another thread has already populated
  ** the first page of the database, no damage is done.
  */
  if( statbuf.st_size==0 ){
    write(fd, "S", 1);
    rc = fstat(fd, &statbuf);
    if( rc!=0 ){
      return SQLITE_IOERR;
    }
  }

  memset(&key1, 0, sizeof(key1));
  key1.dev = statbuf.st_dev;
  key1.ino = statbuf.st_ino;
#if SQLITE_THREADSAFE
  if( threadsOverrideEachOthersLocks<0 ){
    testThreadLockingBehavior(fd);

  assert( id );
  rc = fstat(((unixFile*)id)->h, &buf);
  SimulateIOError( rc=1 );
  if( rc!=0 ){
    return SQLITE_IOERR_FSTAT;
  }
  *pSize = buf.st_size;

  /* When opening a zero-size database, the findLockInfo() procedure
  ** writes a single byte into that file in order to work around a bug
  ** in the OS-X msdos filesystem.  In order to avoid problems with upper
  ** layers, we need to report this file size as zero even though it is
  ** really 1.   Ticket #3260.
  */
  if( *pSize==1 ) *pSize = 0;


  return SQLITE_OK;
}

/*
** This routine checks if there is a RESERVED lock held on the specified
** file by this or any other process. If such a lock is held, return
** non-zero.  If the file is unlocked or holds only SHARED locks, then

#***********************************************************************
# This file implements regression tests for SQLite library.  The
# focus of this file is testing the incremental vacuum feature.
#
# Note: There are also some tests for incremental vacuum and IO 
# errors in incrvacuum_ioerr.test.
#
# $Id: incrvacuum.test,v 1.19 2008/07/30 17:28:04 drh Exp $

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

# If this build of the library does not support auto-vacuum, omit this
# whole file.
ifcapable {!autovacuum || !pragma} {
  finish_test
  return
}

#---------------------------------------------------------------------
# Test the pragma on an empty database.
#
do_test incrvacuum-1.1 {
  execsql {
    pragma auto_vacuum;
  }
} $sqlite_options(default_autovacuum)
do_test incrvacuum-1.2.0 {
  # File size is sometimes 1 instead of 0 due to the hack we put in
  # to work around ticket #3260.  Search for comments on #3260 in
  # os_unix.c.
  expr {[file size test.db] > 1}
} {0}
do_test incrvacuum-1.2 {
  # This command will create the database.
  execsql {
    pragma auto_vacuum = 'full';
    pragma auto_vacuum;
  }

db2 close
db close
file delete -force test.db test.db-journal
sqlite3 db test.db  ;  set ::DB [sqlite3_connection_pointer db]
sqlite3 db2 test.db

do_test incrvacuum-13.1 {
  # File size is sometimes 1 instead of 0 due to the hack we put in
  # to work around ticket #3260.  Search for comments on #3260 in
  # os_unix.c.
  expr {[file size test.db]>1}
} {0}
do_test incrvacuum-13.2 {
  set ::STMT [sqlite3_prepare $::DB {PRAGMA auto_vacuum = 2} -1 DUMMY]
  execsql {
    PRAGMA auto_vacuum = none;
    PRAGMA default_cache_size = 1024;
    PRAGMA auto_vacuum;

#
#***********************************************************************
#
# The focus of this file is testing some specific characteristics of the 
# IO traffic generated by SQLite (making sure SQLite is not writing out
# more database pages than it has to, stuff like that).
#
# $Id: io.test,v 1.17 2008/07/30 17:28:04 drh Exp $

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

db close
sqlite3_simulate_device
sqlite3 db test.db -vfs devsym

  do_test io-3.1 {
    db close
    file delete -force test.db test.db-journal
    sqlite3 db test.db -vfs devsym
    db eval {
      PRAGMA auto_vacuum=OFF;
    }
    # File size might be 1 due to the hack to work around ticket #3260.
    # Search for #3260 in os_unix.c for additional information.
    expr {[file size test.db]>1}
  } {0}
  do_test io-3.2 {
    execsql { CREATE TABLE abc(a, b) }
    nSync
    execsql {
      PRAGMA cache_size = 10;
      BEGIN;