**      + for named semaphore locks (VxWorks only)
**      + for AFP filesystem locks (MacOSX only)
**      + for proxy locks (MacOSX only)
**   *  The routine used to detect an appropriate locking style
**   *  sqlite3_file methods not associated with locking
**   *  Implementations of sqlite3_os_init() and sqlite3_os_end()
**
** $Id: os_unix.c,v 1.222 2008/11/28 15:37:20 drh Exp $
*/
#include "sqliteInt.h"
#if SQLITE_OS_UNIX              /* This file is used on unix only */

/*
** This module implements the following locking styles:
**
................................................................................
#endif

/*
** Maximum supported path-length.
*/
#define MAX_PATHNAME 512

/*
** The locking styles are associated with the different file locking
** capabilities supported by different file systems.  
**
** POSIX     support for shared and exclusive byte-range locks 
**
** NONE      no locking will be attempted, this is only used for
**           read-only file systems currently
**
** DOTLOCK   isn't a true locking style, it refers to the use of a special
**           file named the same as the database file with a '.lock'
**           extension, this can be used on file systems that do not
**           offer any reliable file locking
**
** FLOCK     only a single file-global exclusive lock  (Not on VxWorks)
**
** NAMEDSEM  similar to DOTLOCK but uses a named semaphore instead of an
**           indicator file.  (VxWorks only)
**
** AFP       support exclusive byte-range locks  (MacOSX only)
**
** PROXY     uses a second file to represent the lock state of the database
**           file which is never actually locked, a third file controls
**           access to the proxy  (MacOSX only)
**
** Note that because FLOCK and NAMEDSEM are never used together, they
** share the same code number (3).  The locking mode numbering is 
** chosen so that a set of locking modes that are contiguous integers
** from 1 to N.  On generic unix systems without flock() support,
** the modes are 1..3.  On generic unix with flock() support, the modes
** are 1..4.  On VxWorks, the modes are 1..4.  On MacOSX the modes
** are 1..6.
*/
#define LOCKING_STYLE_POSIX        1
#define LOCKING_STYLE_NONE         2
#define LOCKING_STYLE_DOTFILE      3
#define LOCKING_STYLE_FLOCK        4
#define LOCKING_STYLE_NAMEDSEM     4
#define LOCKING_STYLE_AFP          5
#define LOCKING_STYLE_PROXY        6

#define LOCKING_STYLE_AUTOMATIC    0  /* Choose lock style automatically */

/*
** Only set the lastErrno if the error code is a real error and not 
** a normal expected return code of SQLITE_BUSY or SQLITE_OK
*/
#define IS_LOCK_ERROR(x)  ((x != SQLITE_OK) && (x != SQLITE_BUSY))


................................................................................
** On anything other than linux, assume threads override each others locks.
*/
static void testThreadLockingBehavior(int fd_orig){
  UNUSED_PARAMETER(fd_orig);
  threadsOverrideEachOthersLocks = 1;
}
#endif /* SQLITE_THERADSAFE && defined(__linux__) */

/*
** If we are currently in a different thread than the thread that the
** unixFile argument belongs to, then transfer ownership of the unixFile
** over to the current thread.
**
** A unixFile is only owned by a thread on systems where one thread is
** unable to override locks created by a different thread.  RedHat9 is
** an example of such a system.
**
** Ownership transfer is only allowed if the unixFile is currently unlocked.
** If the unixFile is locked and an ownership is wrong, then return
** SQLITE_MISUSE.  SQLITE_OK is returned if everything works.
*/
#if SQLITE_THREADSAFE && defined(__linux__)
static int transferOwnership(unixFile *pFile){
  int rc;
  pthread_t hSelf;
  if( threadsOverrideEachOthersLocks ){
    /* Ownership transfers not needed on this system */
    return SQLITE_OK;
  }
  hSelf = pthread_self();
  if( pthread_equal(pFile->tid, hSelf) ){
    /* We are still in the same thread */
    OSTRACE1("No-transfer, same thread\n");
    return SQLITE_OK;
  }
  if( pFile->locktype!=NO_LOCK ){
    /* We cannot change ownership while we are holding a lock! */
    return SQLITE_MISUSE;
  }
  OSTRACE4("Transfer ownership of %d from %d to %d\n",
            pFile->h, pFile->tid, hSelf);
  pFile->tid = hSelf;
  if (pFile->pLock != NULL) {
    releaseLockInfo(pFile->pLock);
    rc = findLockInfo(pFile, &pFile->pLock, 0);
    OSTRACE5("LOCK    %d is now %s(%s,%d)\n", pFile->h,
           locktypeName(pFile->locktype),
           locktypeName(pFile->pLock->locktype), pFile->pLock->cnt);
    return rc;
  } else {
    return SQLITE_OK;
  }
}
#else  /* if not SQLITE_THREADSAFE */
  /* On single-threaded builds, ownership transfer is a no-op */
# define transferOwnership(X) SQLITE_OK
#endif /* SQLITE_THREADSAFE */


/*
** Release a unixLockInfo structure previously allocated by findLockInfo().
*/
static void releaseLockInfo(struct unixLockInfo *pLock){
  if( pLock ){
    pLock->nRef--;
................................................................................
    *ppOpen = pOpen;
  }

exit_findlockinfo:
  return rc;
}


















































/*
** 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, set *pResOut
** to a non-zero value otherwise *pResOut is set to zero.  The return value
** is set to SQLITE_OK unless an I/O error occurs during lock checking.
*/
................................................................................
**         connections from reading or writing the database.
**
**    (2)  An application crash or power loss can leave stale lock files
**         sitting around that need to be cleared manually.
**
** Nevertheless, a dotlock is an appropriate locking mode for use if no
** other locking strategy is available.





*/

/*
** The file suffix added to the data base filename in order to create the
** lock file.
*/
#define DOTLOCK_SUFFIX ".lock"

/* Dotlock-style reserved lock checking following the behavior of 
** unixCheckReservedLock, see the unixCheckReservedLock function comments */








static int dotlockCheckReservedLock(sqlite3_file *id, int *pResOut) {
  int rc = SQLITE_OK;
  int reserved = 0;
  unixFile *pFile = (unixFile*)id;

  SimulateIOError( return SQLITE_IOERR_CHECKRESERVEDLOCK; );
  
  assert( pFile );

  /* Check if a thread in this process holds such a lock */
  if( pFile->locktype>SHARED_LOCK ){
    reserved = 1;
  }
  
  /* Otherwise see if some other process holds it. */
  if( !reserved ){
    char *zLockFile = (char *)pFile->lockingContext;
    struct stat statBuf;
    
    if( lstat(zLockFile, &statBuf)==0 ){
      /* file exists, someone else has the lock */

      reserved = 1;
    }else{
      /* file does not exist, we could have it if we want it */
      int tErrno = errno;
      if( ENOENT != tErrno ){
        rc = sqliteErrorFromPosixError(tErrno, SQLITE_IOERR_CHECKRESERVEDLOCK);
        pFile->lastErrno = tErrno;



      }
    }
  }
  OSTRACE4("TEST WR-LOCK %d %d %d\n", pFile->h, rc, reserved);

  *pResOut = reserved;
  return rc;
}




























static int dotlockLock(sqlite3_file *id, int locktype) {
  unixFile *pFile = (unixFile*)id;
  int fd;
  char *zLockFile = (char *)pFile->lockingContext;
  int rc=SQLITE_OK;

  /* if we already have a lock, it is exclusive.  

  ** Just adjust level and punt on outta here. */


  if (pFile->locktype > NO_LOCK) {
    pFile->locktype = locktype;
#if !OS_VXWORKS
    /* Always update the timestamp on the old file */
    utimes(zLockFile, NULL);
#endif
    rc = SQLITE_OK;
    goto dotlock_end_lock;
  }
  
  /* check to see if lock file already exists */
  struct stat statBuf;
  if (lstat(zLockFile,&statBuf) == 0){
    rc = SQLITE_BUSY; /* it does, busy */
    goto dotlock_end_lock;
  }
  
  /* grab an exclusive lock */
  fd = open(zLockFile,O_RDONLY|O_CREAT|O_EXCL,0600);
  if( fd<0 ){
    /* failed to open/create the file, someone else may have stolen the lock */
    int tErrno = errno;
................................................................................
      rc = SQLITE_BUSY;
    } else {
      rc = sqliteErrorFromPosixError(tErrno, SQLITE_IOERR_LOCK);
      if( IS_LOCK_ERROR(rc) ){
        pFile->lastErrno = tErrno;
      }
    }
    goto dotlock_end_lock;
  } 
  if( close(fd) ){
    pFile->lastErrno = errno;
    rc = SQLITE_IOERR_CLOSE;
  }
  
  /* got it, set the type and return ok */
  pFile->locktype = locktype;

 dotlock_end_lock:
  return rc;
}










static int dotlockUnlock(sqlite3_file *id, int locktype) {
  unixFile *pFile = (unixFile*)id;
  char *zLockFile = (char *)pFile->lockingContext;

  assert( pFile );
  OSTRACE5("UNLOCK  %d %d was %d pid=%d\n", pFile->h, locktype,
	   pFile->locktype, getpid());
  assert( locktype<=SHARED_LOCK );
  
  /* no-op if possible */
  if( pFile->locktype==locktype ){
    return SQLITE_OK;
  }
  
  /* shared can just be set because we always have an exclusive */


  if (locktype==SHARED_LOCK) {
    pFile->locktype = locktype;
    return SQLITE_OK;
  }
  
  /* no, really, unlock. */

  if (unlink(zLockFile) ) {
    int rc, tErrno = errno;
    if( ENOENT != tErrno ){
      rc = sqliteErrorFromPosixError(tErrno, SQLITE_IOERR_UNLOCK);
    }
    if( IS_LOCK_ERROR(rc) ){
      pFile->lastErrno = tErrno;
    }
................................................................................
**
** Use the flock() system call to do file locking.
**
** Omit this section if SQLITE_ENABLE_LOCKING_STYLE is turned off or if
** compiling for VXWORKS.
*/
#if SQLITE_ENABLE_LOCKING_STYLE && !OS_VXWORKS


/*
** The flockLockingContext is not used
*/
typedef void flockLockingContext;

/* flock-style reserved lock checking following the behavior of 
................................................................................
#endif /* SQLITE_IGNORE_FLOCK_LOCK_ERRORS */
  *pResOut = reserved;
  return rc;
}

static int flockLock(sqlite3_file *id, int locktype) {
  int rc = SQLITE_OK;
  int lrc;
  unixFile *pFile = (unixFile*)id;

  assert( pFile );

  /* if we already have a lock, it is exclusive.  
  ** Just adjust level and punt on outta here. */
  if (pFile->locktype > NO_LOCK) {
................................................................................
** Proxy locking is only available on MacOSX 
*/
#if defined(__DARWIN__) && SQLITE_ENABLE_LOCKING_STYLE


static int getDbPathForUnixFile(unixFile *pFile, char *dbPath);
static int getLockPath(const char *dbPath, char *lPath, size_t maxLen);
static sqlite3_io_methods *ioMethodForLockingStyle(int style);
static int createProxyUnixFile(const char *path, unixFile **ppFile);
static int fillInUnixFile(sqlite3_vfs *pVfs, int h, int dirfd, sqlite3_file *pId, const char *zFilename, int noLock, int isDelete);
static int takeConch(unixFile *pFile);
static int releaseConch(unixFile *pFile);
static int unixRandomness(sqlite3_vfs *pVfs, int nBuf, char *zBuf);

/*
** Tests a byte-range locking query to see if byte range locks are 
** supported, if not we fall back to dotlockLockingStyle.
** On vxWorks we fall back to semLockingStyle.
*/
static int testLockingStyle(int fd){
  struct flock lockInfo;

  /* Test byte-range lock using fcntl(). If the call succeeds, 
  ** assume that the file-system supports POSIX style locks. 
  */
  lockInfo.l_len = 1;
  lockInfo.l_start = 0;
  lockInfo.l_whence = SEEK_SET;
  lockInfo.l_type = F_RDLCK;
  if( fcntl(fd, F_GETLK, &lockInfo)!=-1 ) {
    return LOCKING_STYLE_POSIX;
  }
  
  /* Testing for flock() can give false positives.  So if if the above 
  ** test fails, then we fall back to using dot-file style locking (or
  ** named-semaphore locking on vxworks).
  */
  return (OS_VXWORKS ? LOCKING_STYLE_NAMEDSEM : LOCKING_STYLE_DOTFILE);
}


#ifdef SQLITE_TEST
/* simulate multiple hosts by creating unique hostid file paths */
int sqlite3_hostid_num = 0;
#endif

/*
................................................................................
      rc = createProxyUnixFile(path, &pCtx->lockProxy);
    }
    if( rc==SQLITE_OK ){
      pCtx->conchHeld = 1;

      if( tLockPath ){
        pCtx->lockProxyPath = sqlite3DbStrDup(0, tLockPath);
        if( pCtx->lockProxy->pMethod ==
                    ioMethodForLockingStyle(LOCKING_STYLE_AFP) ){
          ((afpLockingContext *)pCtx->lockProxy->lockingContext)->dbPath =
                     pCtx->lockProxyPath;
        }
      }
    } else {
      conchFile->pMethod->xUnlock((sqlite3_file*)conchFile, NO_LOCK);
    }
................................................................................
    /* all memory is allocated, proxys are created and assigned, 
    ** switch the locking context and pMethod then return.
    */
    pCtx->dbPath = sqlite3DbStrDup(0, dbPath);
    pCtx->oldLockingContext = pFile->lockingContext;
    pFile->lockingContext = pCtx;
    pCtx->pOldMethod = pFile->pMethod;
    pFile->pMethod = ioMethodForLockingStyle(LOCKING_STYLE_PROXY);
  }else{
    if( pCtx->conchFile ){ 
      rc = pCtx->conchFile->pMethod->xClose((sqlite3_file *)pCtx->conchFile);
      if( rc ) return rc;
      sqlite3_free(pCtx->conchFile);
    }
    sqlite3_free(pCtx->conchFilePath); 
................................................................................
*/
static int unixFileControl(sqlite3_file *id, int op, void *pArg){
  switch( op ){
    case SQLITE_FCNTL_LOCKSTATE: {
      *(int*)pArg = ((unixFile*)id)->locktype;
      return SQLITE_OK;
    }
    case SQLITE_GET_LOCKPROXYFILE: {



#if SQLITE_ENABLE_LOCKING_STYLE

      unixFile *pFile = (unixFile*)id;
      if( pFile->pMethod == ioMethodForLockingStyle(LOCKING_STYLE_PROXY) ){
        proxyLockingContext *pCtx = (proxyLockingContext*)pFile->lockingContext;
        takeConch(pFile);
        if( pCtx->lockProxyPath ){
          *(const char **)pArg = pCtx->lockProxyPath;
        }else{
          *(const char **)pArg = ":auto: (not held)";
        }
      } else {
        *(const char **)pArg = NULL;
      }
#else
      *(void**)pArg = NULL;
#endif
      return SQLITE_OK;
    }
    case SQLITE_SET_LOCKPROXYFILE: {
#if SQLITE_ENABLE_LOCKING_STYLE
      unixFile *pFile = (unixFile*)id;
      int rc = SQLITE_OK;
      int isProxyStyle = (pFile->pMethod == ioMethodForLockingStyle(LOCKING_STYLE_PROXY));
      if( pArg==NULL || (const char *)pArg==0 ){
        if( isProxyStyle ){
          // turn off proxy locking - not supported
          rc = SQLITE_ERROR /*SQLITE_PROTOCOL? SQLITE_MISUSE?*/;
        }else{
          // turn off proxy locking - already off - NOOP
          rc = SQLITE_OK;
        }
      }else{
        const char *proxyPath = (const char *)pArg;
        if( isProxyStyle ){
          proxyLockingContext *pCtx = 
            (proxyLockingContext*)pFile->lockingContext;


          if( !strcmp(pArg, ":auto:") || (pCtx->lockProxyPath && !strncmp(pCtx->lockProxyPath, proxyPath, MAXPATHLEN)) ){

            rc = SQLITE_OK;
          }else{
            rc = switchLockProxyPath(pFile, proxyPath);
          }
        }else{
          // turn on proxy file locking 
          rc = transformUnixFileForLockProxy(pFile, proxyPath);
        }
      }
      return rc;
#else
      return SQLITE_ERROR /*SQLITE_PROTOCOL? SQLITE_MISUSE?*/;
#endif
    }
    case SQLITE_LAST_ERRNO: {
      *(int*)pArg = ((unixFile*)id)->lastErrno;
      return SQLITE_OK;
    }
      

  }
  return SQLITE_ERROR;
}

/*
** Return the sector size in bytes of the underlying block device for
** the specified file. This is almost always 512 bytes, but may be
................................................................................
/*
** Here ends the implementation of all sqlite3_file methods.
**
********************** End sqlite3_file Methods *******************************
******************************************************************************/

/*
** The following constant array describes all of the methods for the
** sqlite3_file object for each of the various locking modes.
**

** The order in which the methods are defined is important and must
** agree with the numeric values of the method identifier constants.
** For example, LOCKING_STYLE_UNIX has a numeric value of zero, so
** it must be the 0-th entry in the array.
*/
#define IOMETHODS(xClose, xLock, xUnlock, xCheckReservedLock) {  \

   1,                          /* iVersion */                    \
   xClose,                     /* xClose */                      \
   unixRead,                   /* xRead */                       \
   unixWrite,                  /* xWrite */                      \
   unixTruncate,               /* xTruncate */                   \
   unixSync,                   /* xSync */                       \
   unixFileSize,               /* xFileSize */                   \
   xLock,                      /* xLock */                       \
   xUnlock,                    /* xUnlock */                     \
   xCheckReservedLock,         /* xCheckReservedLock */          \
   unixFileControl,            /* xFileControl */                \
   unixSectorSize,             /* xSectorSize */                 \
   unixDeviceCharacteristics   /* xDeviceCapabilities */         \




}








static sqlite3_io_methods aIoMethod[] = {
  IOMETHODS(unixClose, unixLock, unixUnlock, unixCheckReservedLock),
  IOMETHODS(nolockClose, nolockLock, nolockUnlock, nolockCheckReservedLock),
  IOMETHODS(dotlockClose, dotlockLock, dotlockUnlock,dotlockCheckReservedLock),

































#if OS_VXWORKS
  IOMETHODS(semClose, semLock, semUnlock, semCheckReservedLock),
#elif SQLITE_ENABLE_LOCKING_STYLE
  IOMETHODS(flockClose, flockLock, flockUnlock, flockCheckReservedLock),








#endif

#if defined(__DARWIN__) && SQLITE_ENABLE_LOCKING_STYLE
  IOMETHODS(afpClose, afpLock, afpUnlock, afpCheckReservedLock),
  IOMETHODS(proxyClose, proxyLock, proxyUnlock, proxyCheckReservedLock),
















#endif
  /* The order of the IOMETHODS macros above is important.  It must be the
  ** same order as the LOCKING_STYLE numbers
  */
};

/****************************************************************************
**************************** sqlite3_vfs methods ****************************
**
** This division contains the implementation of methods on the
** sqlite3_vfs object.
*/


/* 
** If SQLITE_ENABLE_LOCKING_STYLE is defined, this function Examines the 
** f_fstypename entry in the statfs structure as returned by stat() for 
** the file system hosting the database file and selects  the appropriate
** locking style based on its value.  These values and assignments are 
** based on Darwin/OSX behavior and have not been thoroughly tested on 
** other systems.



**
** If SQLITE_ENABLE_LOCKING_STYLE is not defined, this function always
** returns LOCKING_STYLE_POSIX.

*/
#if SQLITE_ENABLE_LOCKING_STYLE
static int detectLockingStyle(
  sqlite3_vfs *pVfs,

  const char *filePath, 
  int fd

){
#if OS_VXWORKS
  if( !filePath ){
    return LOCKING_STYLE_NONE;
  }
  if( pVfs->pAppData ){
    return SQLITE_PTR_TO_INT(pVfs->pAppData);
  }
  if (access(filePath, 0) != -1){
    return testLockingStyle(fd);
  }
#else
  struct Mapping {
    const char *zFilesystem;
    int eLockingStyle;

  } aMap[] = {
    { "hfs",    LOCKING_STYLE_POSIX },
    { "ufs",    LOCKING_STYLE_POSIX },
    { "afpfs",  LOCKING_STYLE_AFP },
#ifdef SQLITE_ENABLE_AFP_LOCKING_SMB
    { "smbfs",  LOCKING_STYLE_AFP },
#else
    { "smbfs",  LOCKING_STYLE_FLOCK },
#endif
    { "webdav", LOCKING_STYLE_NONE },
    { 0, 0 }
  };
  int i;
  struct statfs fsInfo;


  if( !filePath ){
    return LOCKING_STYLE_NONE;

  }
  if( pVfs && pVfs->pAppData ){
    return SQLITE_PTR_TO_INT(pVfs->pAppData);
  }

  if( statfs(filePath, &fsInfo) != -1 ){
    if( fsInfo.f_flags & MNT_RDONLY ){
      return LOCKING_STYLE_NONE;

    }
    for(i=0; aMap[i].zFilesystem; i++){
      if( strcmp(fsInfo.f_fstypename, aMap[i].zFilesystem)==0 ){
        return aMap[i].eLockingStyle;
      }
    }
  }

  /* Default case. Handles, amongst others, "nfs". */
  return testLockingStyle(fd);  
#endif /* if OS_VXWORKS */
  return LOCKING_STYLE_POSIX;











}
#else
  #define detectLockingStyle(x,y,z) LOCKING_STYLE_POSIX

#endif /* if SQLITE_ENABLE_LOCKING_STYLE */














/*
** Initialize the contents of the unixFile structure pointed to by pId.
**
** When locking extensions are enabled, the filepath and locking style 
** are needed to determine the unixFile pMethod to use for locking operations.
** The locking-style specific lockingContext data structure is created 
** and assigned here also.
*/
static int fillInUnixFile(
  sqlite3_vfs *pVfs,      /* Pointer to vfs object */
  int h,                  /* Open file descriptor of file being opened */
  int dirfd,              /* Directory file descriptor */
  sqlite3_file *pId,      /* Write to the unixFile structure here */
  const char *zFilename,  /* Name of the file being opened */
  int noLock,             /* Omit locking if true */
  int isDelete            /* Delete on close if true */
){
  int eLockingStyle;
  unixFile *pNew = (unixFile *)pId;
  int rc = SQLITE_OK;

  assert( pNew->pLock==NULL );
  assert( pNew->pOpen==NULL );

  /* Parameter isDelete is only used on vxworks. Parameter pVfs is only
  ** used if ENABLE_LOCKING_STYLE is defined. Express this explicitly 
  ** here to prevent compiler warnings about unused parameters.
  */

  if( !OS_VXWORKS ) UNUSED_PARAMETER(isDelete);

  if( !SQLITE_ENABLE_LOCKING_STYLE ) UNUSED_PARAMETER(pVfs);


  if( !OS_VXWORKS && !SQLITE_ENABLE_LOCKING_STYLE ) UNUSED_PARAMETER(zFilename);



  OSTRACE3("OPEN    %-3d %s\n", h, zFilename);    
  pNew->h = h;
  pNew->dirfd = dirfd;
  SET_THREADID(pNew);

#if OS_VXWORKS
................................................................................
  if( pNew->pId==0 ){
    noLock = 1;
    rc = SQLITE_NOMEM;
  }
#endif

  if( noLock ){
    eLockingStyle = LOCKING_STYLE_NONE;
  }else{
    eLockingStyle = detectLockingStyle(pVfs, zFilename, h);
#if SQLITE_ENABLE_LOCKING_STYLE
    /* Cache zFilename in the locking context (AFP and dotlock override) for
    ** proxyLock activation is possible (remote proxy is based on db name)
    ** zFilename remains valid until file is closed, to support */
    pNew->lockingContext = (void*)zFilename;
#endif
  }

   
  switch( eLockingStyle ){

    case LOCKING_STYLE_POSIX: {
      unixEnterMutex();
      rc = findLockInfo(pNew, &pNew->pLock, &pNew->pOpen);
      unixLeaveMutex();
      break;
    }

#if SQLITE_ENABLE_LOCKING_STYLE

#if !OS_VXWORKS
    case LOCKING_STYLE_AFP: {

      /* AFP locking uses the file path so it needs to be included in
      ** the afpLockingContext.
      */
      afpLockingContext *pCtx;
      pNew->lockingContext = pCtx = sqlite3_malloc( sizeof(*pCtx) );
      if( pCtx==0 ){
        rc = SQLITE_NOMEM;
      }else{
        /* NB: zFilename exists and remains valid until the file is closed
        ** according to requirement F11141.  So we do not need to make a
        ** copy of the filename. */
        pCtx->dbPath = zFilename;
        srandomdev();
        unixEnterMutex();
        rc = findLockInfo(pNew, NULL, &pNew->pOpen);
        unixLeaveMutex();        
      }
      break;
    }
#endif

    case LOCKING_STYLE_DOTFILE: {

      /* Dotfile locking uses the file path so it needs to be included in
      ** the dotlockLockingContext 
      */
      char *zLockFile;
      int nFilename;
      nFilename = strlen(zFilename) + 6;
      zLockFile = (char *)sqlite3_malloc(nFilename);
      if( zLockFile==0 ){
        rc = SQLITE_NOMEM;
      }else{
        sqlite3_snprintf(nFilename, zLockFile, "%s" DOTLOCK_SUFFIX, zFilename);
      }
      pNew->lockingContext = zLockFile;
      break;
    }


#if OS_VXWORKS
    case LOCKING_STYLE_NAMEDSEM: {

      /* Named semaphore locking uses the file path so it needs to be
      ** included in the semLockingContext
      */
      unixEnterMutex();
      rc = findLockInfo(pNew, &pNew->pLock, &pNew->pOpen);
      if( (rc==SQLITE_OK) && (pNew->pOpen->pSem==NULL) ){
        char *zSemName = pNew->pOpen->aSemName;
        int n;
        sqlite3_snprintf(MAX_PATHNAME, zSemName, "%s.sem",
                         pNew->pId->zCanonicalName);
        for( n=0; zSemName[n]; n++ )
          if( zSemName[n]=='/' ) zSemName[n] = '_';
        pNew->pOpen->pSem = sem_open(zSemName, O_CREAT, 0666, 1);
        if( pNew->pOpen->pSem == SEM_FAILED ){
          rc = SQLITE_NOMEM;
          pNew->pOpen->aSemName[0] = '\0';
        }
      }
      unixLeaveMutex();
      break;
    }
#endif

    case LOCKING_STYLE_FLOCK: 
    case LOCKING_STYLE_NONE: 
      break;
#endif
  }
  
  pNew->lastErrno = 0;
#if OS_VXWORKS
  if( rc!=SQLITE_OK ){
    unlink(zFilename);
    isDelete = 0;
  }
  pNew->isDelete = isDelete;
#endif
  if( rc!=SQLITE_OK ){
    if( dirfd>=0 ) close(dirfd); /* silent leak if fail, already in error */
    close(h);
  }else{
    pNew->pMethod = &aIoMethod[eLockingStyle-1];
    OpenCounter(+1);
  }
  return rc;
}

#if SQLITE_ENABLE_LOCKING_STYLE
static sqlite3_io_methods *ioMethodForLockingStyle(int style){
  return &aIoMethod[style];
}

static int getDbPathForUnixFile(unixFile *pFile, char *dbPath){
  if( pFile->pMethod==ioMethodForLockingStyle(LOCKING_STYLE_AFP) ){


    /* afp style keeps a reference to the db path in the filePath field 
    ** of the struct */

    strlcpy(dbPath, ((afpLockingContext *)pFile->lockingContext)->dbPath, 


            MAXPATHLEN);
    return SQLITE_OK;
  }
  if( pFile->pMethod==ioMethodForLockingStyle(LOCKING_STYLE_DOTFILE) ){
    /* dot lock style uses the locking context to store the dot lock
    ** file path */
    int len = strlen((char *)pFile->lockingContext) - strlen(DOTLOCK_SUFFIX);
    strlcpy(dbPath, (char *)pFile->lockingContext, len + 1);
    return SQLITE_OK;
  }
  /* all other styles use the locking context to store the db file path */

  strlcpy(dbPath, (char *)pFile->lockingContext, MAXPATHLEN);

  return SQLITE_OK;
}
#endif

/*
** Open a file descriptor to the directory containing file zFilename.
** If successful, *pFd is set to the opened file descriptor and
................................................................................

#if SQLITE_PREFER_PROXY_LOCKING
  if( zPath!=NULL && !noLock ){
    char *envforce = getenv("SQLITE_FORCE_PROXY_LOCKING");
    int useProxy = 0;

    /* SQLITE_FORCE_PROXY_LOCKING==1 means force always use proxy, 
     ** 0 means never use proxy, NULL means use proxy for non-local files only
     */
    if( envforce!=NULL ){
      useProxy = atoi(envforce)>0;
    }else{
      struct statfs fsInfo;

      if( statfs(zPath, &fsInfo) == -1 ){
				((unixFile*)pFile)->lastErrno = errno;
................................................................................
*/
int sqlite3_os_init(void){ 
  /* Macro to define the static contents of an sqlite3_vfs structure for
  ** the unix backend. The two parameters are the values to use for
  ** the sqlite3_vfs.zName and sqlite3_vfs.pAppData fields, respectively.
  ** 
  */
  #define UNIXVFS(zVfsName, pVfsAppData) {                  \
    1,                    /* iVersion */                    \
    sizeof(unixFile),     /* szOsFile */                    \
    MAX_PATHNAME,         /* mxPathname */                  \
    0,                    /* pNext */                       \
    zVfsName,             /* zName */                       \
    (void *)pVfsAppData,  /* pAppData */                    \
    unixOpen,             /* xOpen */                       \
    unixDelete,           /* xDelete */                     \
    unixAccess,           /* xAccess */                     \
    unixFullPathname,     /* xFullPathname */               \
    unixDlOpen,           /* xDlOpen */                     \
    unixDlError,          /* xDlError */                    \
    unixDlSym,            /* xDlSym */                      \
................................................................................
    unixDlClose,          /* xDlClose */                    \
    unixRandomness,       /* xRandomness */                 \
    unixSleep,            /* xSleep */                      \
    unixCurrentTime,      /* xCurrentTime */                \
    unixGetLastError      /* xGetLastError */               \
  }

  int i;
  static sqlite3_vfs aVfs[] = {
    UNIXVFS("unix",         LOCKING_STYLE_AUTOMATIC), 
    UNIXVFS("unix-posix",   LOCKING_STYLE_POSIX), 



    UNIXVFS("unix-none",    LOCKING_STYLE_NONE),
    UNIXVFS("unix-dotfile", LOCKING_STYLE_DOTFILE),
#if OS_VXWORKS
    UNIXVFS("unix-namedsem",LOCKING_STYLE_NAMEDSEM),
#endif
#if SQLITE_ENABLE_LOCKING_STYLE

    UNIXVFS("unix-flock",   LOCKING_STYLE_FLOCK), 
#endif
#if SQLITE_ENABLE_LOCKING_STYLE && defined(__DARWIN__)
    UNIXVFS("unix-afp",     LOCKING_STYLE_AFP), 
    UNIXVFS("unix-proxy",   LOCKING_STYLE_PROXY)
#endif
  };
  for(i=0; i<(sizeof(aVfs)/sizeof(sqlite3_vfs)); i++){
    sqlite3_vfs_register(&aVfs[i], i==0);
  }
  return SQLITE_OK; 
}

**      + for named semaphore locks (VxWorks only)
**      + for AFP filesystem locks (MacOSX only)
**      + for proxy locks (MacOSX only)
**   *  The routine used to detect an appropriate locking style
**   *  sqlite3_file methods not associated with locking
**   *  Implementations of sqlite3_os_init() and sqlite3_os_end()
**
** $Id: os_unix.c,v 1.223 2008/11/29 00:56:53 drh Exp $
*/
#include "sqliteInt.h"
#if SQLITE_OS_UNIX              /* This file is used on unix only */

/*
** This module implements the following locking styles:
**
................................................................................
#endif

/*
** Maximum supported path-length.
*/
#define MAX_PATHNAME 512












































/*
** Only set the lastErrno if the error code is a real error and not 
** a normal expected return code of SQLITE_BUSY or SQLITE_OK
*/
#define IS_LOCK_ERROR(x)  ((x != SQLITE_OK) && (x != SQLITE_BUSY))


................................................................................
** On anything other than linux, assume threads override each others locks.
*/
static void testThreadLockingBehavior(int fd_orig){
  UNUSED_PARAMETER(fd_orig);
  threadsOverrideEachOthersLocks = 1;
}
#endif /* SQLITE_THERADSAFE && defined(__linux__) */




















































/*
** Release a unixLockInfo structure previously allocated by findLockInfo().
*/
static void releaseLockInfo(struct unixLockInfo *pLock){
  if( pLock ){
    pLock->nRef--;
................................................................................
    *ppOpen = pOpen;
  }

exit_findlockinfo:
  return rc;
}

/*
** If we are currently in a different thread than the thread that the
** unixFile argument belongs to, then transfer ownership of the unixFile
** over to the current thread.
**
** A unixFile is only owned by a thread on systems that use LinuxThreads.
**
** Ownership transfer is only allowed if the unixFile is currently unlocked.
** If the unixFile is locked and an ownership is wrong, then return
** SQLITE_MISUSE.  SQLITE_OK is returned if everything works.
*/
#if SQLITE_THREADSAFE && defined(__linux__)
static int transferOwnership(unixFile *pFile){
  int rc;
  pthread_t hSelf;
  if( threadsOverrideEachOthersLocks ){
    /* Ownership transfers not needed on this system */
    return SQLITE_OK;
  }
  hSelf = pthread_self();
  if( pthread_equal(pFile->tid, hSelf) ){
    /* We are still in the same thread */
    OSTRACE1("No-transfer, same thread\n");
    return SQLITE_OK;
  }
  if( pFile->locktype!=NO_LOCK ){
    /* We cannot change ownership while we are holding a lock! */
    return SQLITE_MISUSE;
  }
  OSTRACE4("Transfer ownership of %d from %d to %d\n",
            pFile->h, pFile->tid, hSelf);
  pFile->tid = hSelf;
  if (pFile->pLock != NULL) {
    releaseLockInfo(pFile->pLock);
    rc = findLockInfo(pFile, &pFile->pLock, 0);
    OSTRACE5("LOCK    %d is now %s(%s,%d)\n", pFile->h,
           locktypeName(pFile->locktype),
           locktypeName(pFile->pLock->locktype), pFile->pLock->cnt);
    return rc;
  } else {
    return SQLITE_OK;
  }
}
#else  /* if not SQLITE_THREADSAFE */
  /* On single-threaded builds, ownership transfer is a no-op */
# define transferOwnership(X) SQLITE_OK
#endif /* SQLITE_THREADSAFE */


/*
** 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, set *pResOut
** to a non-zero value otherwise *pResOut is set to zero.  The return value
** is set to SQLITE_OK unless an I/O error occurs during lock checking.
*/
................................................................................
**         connections from reading or writing the database.
**
**    (2)  An application crash or power loss can leave stale lock files
**         sitting around that need to be cleared manually.
**
** Nevertheless, a dotlock is an appropriate locking mode for use if no
** other locking strategy is available.
**
** Dotfile locking works by creating a file in the same directory as the
** database and with the same name but with a ".lock" extension added.
** The existance of a lock file implies an EXCLUSIVE lock.  All other lock
** types (SHARED, RESERVED, PENDING) are mapped into EXCLUSIVE.
*/

/*
** The file suffix added to the data base filename in order to create the
** lock file.
*/
#define DOTLOCK_SUFFIX ".lock"

/*
** 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, set *pResOut
** to a non-zero value otherwise *pResOut is set to zero.  The return value
** is set to SQLITE_OK unless an I/O error occurs during lock checking.
**
** In dotfile locking, either a lock exists or it does not.  So in this
** variation of CheckReservedLock(), *pResOut is set to true if any lock
** is held on the file and false if the file is unlocked.
*/
static int dotlockCheckReservedLock(sqlite3_file *id, int *pResOut) {
  int rc = SQLITE_OK;
  int reserved = 0;
  unixFile *pFile = (unixFile*)id;

  SimulateIOError( return SQLITE_IOERR_CHECKRESERVEDLOCK; );
  
  assert( pFile );

  /* Check if a thread in this process holds such a lock */
  if( pFile->locktype>SHARED_LOCK ){
    /* Either this connection or some other connection in the same process









    ** holds a lock on the file.  No need to check further. */
    reserved = 1;
  }else{





    /* The lock is held if and only if the lockfile exists */
    const char *zLockFile = (const char*)pFile->lockingContext;
    reserved = access(zLockFile, 0)==0;
  }


  OSTRACE4("TEST WR-LOCK %d %d %d\n", pFile->h, rc, reserved);

  *pResOut = reserved;
  return rc;
}

/*
** Lock the file with the lock specified by parameter locktype - one
** of the following:
**
**     (1) SHARED_LOCK
**     (2) RESERVED_LOCK
**     (3) PENDING_LOCK
**     (4) EXCLUSIVE_LOCK
**
** Sometimes when requesting one lock state, additional lock states
** are inserted in between.  The locking might fail on one of the later
** transitions leaving the lock state different from what it started but
** still short of its goal.  The following chart shows the allowed
** transitions and the inserted intermediate states:
**
**    UNLOCKED -> SHARED
**    SHARED -> RESERVED
**    SHARED -> (PENDING) -> EXCLUSIVE
**    RESERVED -> (PENDING) -> EXCLUSIVE
**    PENDING -> EXCLUSIVE
**
** This routine will only increase a lock.  Use the sqlite3OsUnlock()
** routine to lower a locking level.
**
** With dotfile locking, we really only support state (4): EXCLUSIVE.
** But we track the other locking levels internally.
*/
static int dotlockLock(sqlite3_file *id, int locktype) {
  unixFile *pFile = (unixFile*)id;
  int fd;
  char *zLockFile = (char *)pFile->lockingContext;
  int rc = SQLITE_OK;



  /* If we have any lock, then the lock file already exists.  All we have
  ** to do is adjust our internal record of the lock level.
  */
  if( pFile->locktype > NO_LOCK ){
    pFile->locktype = locktype;
#if !OS_VXWORKS
    /* Always update the timestamp on the old file */
    utimes(zLockFile, NULL);
#endif
    return SQLITE_OK;








  }
  
  /* grab an exclusive lock */
  fd = open(zLockFile,O_RDONLY|O_CREAT|O_EXCL,0600);
  if( fd<0 ){
    /* failed to open/create the file, someone else may have stolen the lock */
    int tErrno = errno;
................................................................................
      rc = SQLITE_BUSY;
    } else {
      rc = sqliteErrorFromPosixError(tErrno, SQLITE_IOERR_LOCK);
      if( IS_LOCK_ERROR(rc) ){
        pFile->lastErrno = tErrno;
      }
    }
    return rc;
  } 
  if( close(fd) ){
    pFile->lastErrno = errno;
    rc = SQLITE_IOERR_CLOSE;
  }
  
  /* got it, set the type and return ok */
  pFile->locktype = locktype;


  return rc;
}

/*
** Lower the locking level on file descriptor pFile to locktype.  locktype
** must be either NO_LOCK or SHARED_LOCK.
**
** If the locking level of the file descriptor is already at or below
** the requested locking level, this routine is a no-op.
**
** When the locking level reaches NO_LOCK, delete the lock file.
*/
static int dotlockUnlock(sqlite3_file *id, int locktype) {
  unixFile *pFile = (unixFile*)id;
  char *zLockFile = (char *)pFile->lockingContext;

  assert( pFile );
  OSTRACE5("UNLOCK  %d %d was %d pid=%d\n", pFile->h, locktype,
	   pFile->locktype, getpid());
  assert( locktype<=SHARED_LOCK );
  
  /* no-op if possible */
  if( pFile->locktype==locktype ){
    return SQLITE_OK;
  }

  /* To downgrade to shared, simply update our internal notion of the
  ** lock state.  No need to mess with the file on disk.
  */
  if( locktype==SHARED_LOCK ){
    pFile->locktype = SHARED_LOCK;
    return SQLITE_OK;
  }
  
  /* To fully unlock the database, delete the lock file */
  assert( locktype==NO_LOCK );
  if( unlink(zLockFile) ){
    int rc, tErrno = errno;
    if( ENOENT != tErrno ){
      rc = sqliteErrorFromPosixError(tErrno, SQLITE_IOERR_UNLOCK);
    }
    if( IS_LOCK_ERROR(rc) ){
      pFile->lastErrno = tErrno;
    }
................................................................................
**
** Use the flock() system call to do file locking.
**
** Omit this section if SQLITE_ENABLE_LOCKING_STYLE is turned off or if
** compiling for VXWORKS.
*/
#if SQLITE_ENABLE_LOCKING_STYLE && !OS_VXWORKS
#include <sys/file.h>

/*
** The flockLockingContext is not used
*/
typedef void flockLockingContext;

/* flock-style reserved lock checking following the behavior of 
................................................................................
#endif /* SQLITE_IGNORE_FLOCK_LOCK_ERRORS */
  *pResOut = reserved;
  return rc;
}

static int flockLock(sqlite3_file *id, int locktype) {
  int rc = SQLITE_OK;

  unixFile *pFile = (unixFile*)id;

  assert( pFile );

  /* if we already have a lock, it is exclusive.  
  ** Just adjust level and punt on outta here. */
  if (pFile->locktype > NO_LOCK) {
................................................................................
** Proxy locking is only available on MacOSX 
*/
#if defined(__DARWIN__) && SQLITE_ENABLE_LOCKING_STYLE


static int getDbPathForUnixFile(unixFile *pFile, char *dbPath);
static int getLockPath(const char *dbPath, char *lPath, size_t maxLen);

static int createProxyUnixFile(const char *path, unixFile **ppFile);
static int fillInUnixFile(sqlite3_vfs *pVfs, int h, int dirfd, sqlite3_file *pId, const char *zFilename, int noLock, int isDelete);
static int takeConch(unixFile *pFile);
static int releaseConch(unixFile *pFile);
static int unixRandomness(sqlite3_vfs *pVfs, int nBuf, char *zBuf);




























#ifdef SQLITE_TEST
/* simulate multiple hosts by creating unique hostid file paths */
int sqlite3_hostid_num = 0;
#endif

/*
................................................................................
      rc = createProxyUnixFile(path, &pCtx->lockProxy);
    }
    if( rc==SQLITE_OK ){
      pCtx->conchHeld = 1;

      if( tLockPath ){
        pCtx->lockProxyPath = sqlite3DbStrDup(0, tLockPath);
        if( pCtx->lockProxy->pMethod == &afpIoMethods ){

          ((afpLockingContext *)pCtx->lockProxy->lockingContext)->dbPath =
                     pCtx->lockProxyPath;
        }
      }
    } else {
      conchFile->pMethod->xUnlock((sqlite3_file*)conchFile, NO_LOCK);
    }
................................................................................
    /* all memory is allocated, proxys are created and assigned, 
    ** switch the locking context and pMethod then return.
    */
    pCtx->dbPath = sqlite3DbStrDup(0, dbPath);
    pCtx->oldLockingContext = pFile->lockingContext;
    pFile->lockingContext = pCtx;
    pCtx->pOldMethod = pFile->pMethod;
    pFile->pMethod = &proxyIoMethods;
  }else{
    if( pCtx->conchFile ){ 
      rc = pCtx->conchFile->pMethod->xClose((sqlite3_file *)pCtx->conchFile);
      if( rc ) return rc;
      sqlite3_free(pCtx->conchFile);
    }
    sqlite3_free(pCtx->conchFilePath); 
................................................................................
*/
static int unixFileControl(sqlite3_file *id, int op, void *pArg){
  switch( op ){
    case SQLITE_FCNTL_LOCKSTATE: {
      *(int*)pArg = ((unixFile*)id)->locktype;
      return SQLITE_OK;
    }
    case SQLITE_LAST_ERRNO: {
      *(int*)pArg = ((unixFile*)id)->lastErrno;
      return SQLITE_OK;
    }
#if SQLITE_ENABLE_LOCKING_STYLE && defined(__DARWIN__)
    case SQLITE_GET_LOCKPROXYFILE: {
      unixFile *pFile = (unixFile*)id;
      if( pFile->pMethod == &proxyIoMethods ){
        proxyLockingContext *pCtx = (proxyLockingContext*)pFile->lockingContext;
        takeConch(pFile);
        if( pCtx->lockProxyPath ){
          *(const char **)pArg = pCtx->lockProxyPath;
        }else{
          *(const char **)pArg = ":auto: (not held)";
        }
      } else {
        *(const char **)pArg = NULL;
      }



      return SQLITE_OK;
    }
    case SQLITE_SET_LOCKPROXYFILE: {

      unixFile *pFile = (unixFile*)id;
      int rc = SQLITE_OK;
      int isProxyStyle = (pFile->pMethod == &proxyIoMethods);
      if( pArg==NULL || (const char *)pArg==0 ){
        if( isProxyStyle ){
          /* turn off proxy locking - not supported */
          rc = SQLITE_ERROR /*SQLITE_PROTOCOL? SQLITE_MISUSE?*/;
        }else{
          /* turn off proxy locking - already off - NOOP */
          rc = SQLITE_OK;
        }
      }else{
        const char *proxyPath = (const char *)pArg;
        if( isProxyStyle ){
          proxyLockingContext *pCtx = 
            (proxyLockingContext*)pFile->lockingContext;
          if( !strcmp(pArg, ":auto:") 
           || (pCtx->lockProxyPath &&
               !strncmp(pCtx->lockProxyPath, proxyPath, MAXPATHLEN))
          ){
            rc = SQLITE_OK;
          }else{
            rc = switchLockProxyPath(pFile, proxyPath);
          }
        }else{
          /* turn on proxy file locking */
          rc = transformUnixFileForLockProxy(pFile, proxyPath);
        }
      }
      return rc;



    }





#endif
  }
  return SQLITE_ERROR;
}

/*
** Return the sector size in bytes of the underlying block device for
** the specified file. This is almost always 512 bytes, but may be
................................................................................
/*
** Here ends the implementation of all sqlite3_file methods.
**
********************** End sqlite3_file Methods *******************************
******************************************************************************/

/*
** Each instance of this macro generates two objects:

**
**   *  A constant sqlite3_io_methods object call METHOD that has locking
**      methods CLOSE, LOCK, UNLOCK, CKRESLOCK.
**
**   *  An I/O method finder function called FINDER that returns a pointer
**      to the METHOD object in the previous bullet.
*/
#define IOMETHODS(FINDER, METHOD, CLOSE, LOCK, UNLOCK, CKLOCK)               \
static const sqlite3_io_methods METHOD = {                                   \
   1,                          /* iVersion */                                \
   CLOSE,                      /* xClose */                                  \
   unixRead,                   /* xRead */                                   \
   unixWrite,                  /* xWrite */                                  \
   unixTruncate,               /* xTruncate */                               \
   unixSync,                   /* xSync */                                   \
   unixFileSize,               /* xFileSize */                               \
   LOCK,                       /* xLock */                                   \
   UNLOCK,                     /* xUnlock */                                 \
   CKLOCK,                     /* xCheckReservedLock */                      \
   unixFileControl,            /* xFileControl */                            \
   unixSectorSize,             /* xSectorSize */                             \
   unixDeviceCharacteristics   /* xDeviceCapabilities */                     \
};                                                                           \
static const sqlite3_io_methods *FINDER(const char *z, int h){               \
  UNUSED_PARAMETER(z); UNUSED_PARAMETER(h);                                  \
  return &METHOD;                                                            \
}

/*
** Here are all of the sqlite3_io_methods objects for each of the
** locking strategies.  Functions that return pointers to these methods
** are also created.
*/
IOMETHODS(
  posixIoFinder,            /* Finder function name */
  posixIoMethods,           /* sqlite3_io_methods object name */



  unixClose,                /* xClose method */
  unixLock,                 /* xLock method */
  unixUnlock,               /* xUnlock method */
  unixCheckReservedLock     /* xCheckReservedLock method */
);
IOMETHODS(
  nolockIoFinder,           /* Finder function name */
  nolockIoMethods,          /* sqlite3_io_methods object name */
  nolockClose,              /* xClose method */
  nolockLock,               /* xLock method */
  nolockUnlock,             /* xUnlock method */
  nolockCheckReservedLock   /* xCheckReservedLock method */
);
IOMETHODS(
  dotlockIoFinder,          /* Finder function name */
  dotlockIoMethods,         /* sqlite3_io_methods object name */
  dotlockClose,             /* xClose method */
  dotlockLock,              /* xLock method */
  dotlockUnlock,            /* xUnlock method */
  dotlockCheckReservedLock  /* xCheckReservedLock method */
);

#if SQLITE_ENABLE_LOCKING_STYLE
IOMETHODS(
  flockIoFinder,            /* Finder function name */
  flockIoMethods,           /* sqlite3_io_methods object name */
  flockClose,               /* xClose method */
  flockLock,                /* xLock method */
  flockUnlock,              /* xUnlock method */
  flockCheckReservedLock    /* xCheckReservedLock method */
);
#endif

#if OS_VXWORKS



IOMETHODS(
  semIoFinder,              /* Finder function name */
  semIoMethods,             /* sqlite3_io_methods object name */
  semClose,                 /* xClose method */
  semLock,                  /* xLock method */
  semUnlock,                /* xUnlock method */
  semCheckReservedLock      /* xCheckReservedLock method */
);
#endif

#if defined(__DARWIN__) && SQLITE_ENABLE_LOCKING_STYLE


IOMETHODS(
  afpIoFinder,              /* Finder function name */
  afpIoMethods,             /* sqlite3_io_methods object name */
  afpClose,                 /* xClose method */
  afpLock,                  /* xLock method */
  afpUnlock,                /* xUnlock method */
  afpCheckReservedLock      /* xCheckReservedLock method */
);
IOMETHODS(
  proxyIoFinder,            /* Finder function name */
  proxyIoMethods,           /* sqlite3_io_methods object name */
  proxyClose,               /* xClose method */
  proxyLock,                /* xLock method */
  proxyUnlock,              /* xUnlock method */
  proxyCheckReservedLock    /* xCheckReservedLock method */
);
#endif












#if defined(__DARWIN__) && SQLITE_ENABLE_LOCKING_STYLE
/* 






** This procedure attempts to determine the best locking strategy for
** the given database file.  It then returns the sqlite3_io_methods
** object that implements that strategy.
**


** This is for MacOSX only.
*/



static const sqlite3_io_methods *autolockIoFinder(
  const char *filePath,    /* name of the database file */

  int fd                   /* file descriptor open on the database file */
){











  static const struct Mapping {
    const char *zFilesystem;

    const sqlite3_io_methods *pMethods;
  } aMap[] = {
    { "hfs",    &posixIoMethods },
    { "ufs",    &posixIoMethods },
    { "afpfs",  &afpIoMethods },
#ifdef SQLITE_ENABLE_AFP_LOCKING_SMB
    { "smbfs",  &afpIoMethods },
#else
    { "smbfs",  &flockIoMethods },
#endif
    { "webdav", &nolockIoMethods },
    { 0, 0 }
  };
  int i;
  struct statfs fsInfo;
  struct flock lockInfo;

  if( !filePath ){

    return &nolockIoMethods;
  }




  if( statfs(filePath, &fsInfo) != -1 ){
    if( fsInfo.f_flags & MNT_RDONLY ){

      return &nolockIoMethods;
    }
    for(i=0; aMap[i].zFilesystem; i++){
      if( strcmp(fsInfo.f_fstypename, aMap[i].zFilesystem)==0 ){
        return aMap[i].pMethods;
      }
    }
  }

  /* Default case. Handles, amongst others, "nfs".



  ** Test byte-range lock using fcntl(). If the call succeeds, 
  ** assume that the file-system supports POSIX style locks. 
  */
  lockInfo.l_len = 1;
  lockInfo.l_start = 0;
  lockInfo.l_whence = SEEK_SET;
  lockInfo.l_type = F_RDLCK;
  if( fcntl(fd, F_GETLK, &lockInfo)!=-1 ) {
    return &posixIoMethods;
  }else{
    return &dotlockIoMethods;
  }


}
#endif /* defined(__DARWIN__) && SQLITE_ENABLE_LOCKING_STYLE */

/*
** An abstract type for a pointer to a IO method finder function:
*/
typedef const sqlite3_io_methods *(*finder_type)(const char*,int);


/****************************************************************************
**************************** sqlite3_vfs methods ****************************
**
** This division contains the implementation of methods on the
** sqlite3_vfs object.
*/

/*
** Initialize the contents of the unixFile structure pointed to by pId.





*/
static int fillInUnixFile(
  sqlite3_vfs *pVfs,      /* Pointer to vfs object */
  int h,                  /* Open file descriptor of file being opened */
  int dirfd,              /* Directory file descriptor */
  sqlite3_file *pId,      /* Write to the unixFile structure here */
  const char *zFilename,  /* Name of the file being opened */
  int noLock,             /* Omit locking if true */
  int isDelete            /* Delete on close if true */
){
  const sqlite3_io_methods *pLockingStyle;
  unixFile *pNew = (unixFile *)pId;
  int rc = SQLITE_OK;

  assert( pNew->pLock==NULL );
  assert( pNew->pOpen==NULL );

  /* Parameter isDelete is only used on vxworks. Parameter pVfs is only
  ** used if ENABLE_LOCKING_STYLE is defined. Express this explicitly 
  ** here to prevent compiler warnings about unused parameters.
  */
#if !OS_VXWORKS
  UNUSED_PARAMETER(isDelete);
#endif
#if !SQLITE_ENABLE_LOCKING_STYLE
  UNUSED_PARAMETER(pVfs);
#endif
#if !OS_VXWORKS && !SQLITE_ENABLE_LOCKING_STYLE
  UNUSED_PARAMETER(zFilename);
#endif

  OSTRACE3("OPEN    %-3d %s\n", h, zFilename);    
  pNew->h = h;
  pNew->dirfd = dirfd;
  SET_THREADID(pNew);

#if OS_VXWORKS
................................................................................
  if( pNew->pId==0 ){
    noLock = 1;
    rc = SQLITE_NOMEM;
  }
#endif

  if( noLock ){
    pLockingStyle = &nolockIoMethods;
  }else{
    pLockingStyle = (*(finder_type)pVfs->pAppData)(zFilename, h);
#if SQLITE_ENABLE_LOCKING_STYLE
    /* Cache zFilename in the locking context (AFP and dotlock override) for
    ** proxyLock activation is possible (remote proxy is based on db name)
    ** zFilename remains valid until file is closed, to support */
    pNew->lockingContext = (void*)zFilename;
#endif
  }


  if( pLockingStyle == &posixIoMethods ){


    unixEnterMutex();
    rc = findLockInfo(pNew, &pNew->pLock, &pNew->pOpen);
    unixLeaveMutex();

  }

#if SQLITE_ENABLE_LOCKING_STYLE && defined(__DARWIN__)



  else if( pLockingStyle == &apfIoMethods ){
    /* AFP locking uses the file path so it needs to be included in
    ** the afpLockingContext.
    */
    afpLockingContext *pCtx;
    pNew->lockingContext = pCtx = sqlite3_malloc( sizeof(*pCtx) );
    if( pCtx==0 ){
      rc = SQLITE_NOMEM;
    }else{
      /* NB: zFilename exists and remains valid until the file is closed
      ** according to requirement F11141.  So we do not need to make a
      ** copy of the filename. */
      pCtx->dbPath = zFilename;
      srandomdev();
      unixEnterMutex();
      rc = findLockInfo(pNew, NULL, &pNew->pOpen);
      unixLeaveMutex();        
    }

  }
#endif

#if SQLITE_ENABLE_LOCKING_STYLE
  else if( pLockingStyle == &dotlockIoMethods ){
    /* Dotfile locking uses the file path so it needs to be included in
    ** the dotlockLockingContext 
    */
    char *zLockFile;
    int nFilename;
    nFilename = strlen(zFilename) + 6;
    zLockFile = (char *)sqlite3_malloc(nFilename);
    if( zLockFile==0 ){
      rc = SQLITE_NOMEM;
    }else{
      sqlite3_snprintf(nFilename, zLockFile, "%s" DOTLOCK_SUFFIX, zFilename);
    }
    pNew->lockingContext = zLockFile;

  }
#endif

#if OS_VXWORKS

  else if( pLockingStyle == &semIoMethods ){
    /* Named semaphore locking uses the file path so it needs to be
    ** included in the semLockingContext
    */
    unixEnterMutex();
    rc = findLockInfo(pNew, &pNew->pLock, &pNew->pOpen);
    if( (rc==SQLITE_OK) && (pNew->pOpen->pSem==NULL) ){
      char *zSemName = pNew->pOpen->aSemName;
      int n;
      sqlite3_snprintf(MAX_PATHNAME, zSemName, "%s.sem",
                       pNew->pId->zCanonicalName);
      for( n=0; zSemName[n]; n++ )
        if( zSemName[n]=='/' ) zSemName[n] = '_';
      pNew->pOpen->pSem = sem_open(zSemName, O_CREAT, 0666, 1);
      if( pNew->pOpen->pSem == SEM_FAILED ){
        rc = SQLITE_NOMEM;
        pNew->pOpen->aSemName[0] = '\0';
      }
    }
    unixLeaveMutex();

  }
#endif






  
  pNew->lastErrno = 0;
#if OS_VXWORKS
  if( rc!=SQLITE_OK ){
    unlink(zFilename);
    isDelete = 0;
  }
  pNew->isDelete = isDelete;
#endif
  if( rc!=SQLITE_OK ){
    if( dirfd>=0 ) close(dirfd); /* silent leak if fail, already in error */
    close(h);
  }else{
    pNew->pMethod = pLockingStyle;
    OpenCounter(+1);
  }
  return rc;
}

#if SQLITE_ENABLE_LOCKING_STYLE




static int getDbPathForUnixFile(unixFile *pFile, char *dbPath){

#if defined(__DARWIN__)
  if( pFile->pMethod == &afpIoMethods ){
    /* afp style keeps a reference to the db path in the filePath field 
    ** of the struct */
    assert( strlen((char*)pFile->lockingContext)<=MAXPATHLEN );
    strcpy(dbPath, ((afpLockingContext *)pFile->lockingContext)->dbPath)
  }else
#endif
  if( pFile->pMethod == &dotlockIoMethods ){



    /* dot lock style uses the locking context to store the dot lock
    ** file path */
    int len = strlen((char *)pFile->lockingContext) - strlen(DOTLOCK_SUFFIX);
    memcpy(dbPath, (char *)pFile->lockingContext, len + 1);
  }else{

    /* all other styles use the locking context to store the db file path */
    assert( strlen((char*)pFile->lockingContext)<=MAXPATHLEN );
    strcpy(dbPath, (char *)pFile->lockingContext);
  }
  return SQLITE_OK;
}
#endif

/*
** Open a file descriptor to the directory containing file zFilename.
** If successful, *pFd is set to the opened file descriptor and
................................................................................

#if SQLITE_PREFER_PROXY_LOCKING
  if( zPath!=NULL && !noLock ){
    char *envforce = getenv("SQLITE_FORCE_PROXY_LOCKING");
    int useProxy = 0;

    /* SQLITE_FORCE_PROXY_LOCKING==1 means force always use proxy, 
    ** 0 means never use proxy, NULL means use proxy for non-local files only
    */
    if( envforce!=NULL ){
      useProxy = atoi(envforce)>0;
    }else{
      struct statfs fsInfo;

      if( statfs(zPath, &fsInfo) == -1 ){
				((unixFile*)pFile)->lastErrno = errno;
................................................................................
*/
int sqlite3_os_init(void){ 
  /* Macro to define the static contents of an sqlite3_vfs structure for
  ** the unix backend. The two parameters are the values to use for
  ** the sqlite3_vfs.zName and sqlite3_vfs.pAppData fields, respectively.
  ** 
  */
  #define UNIXVFS(VFSNAME, FINDER) {                        \
    1,                    /* iVersion */                    \
    sizeof(unixFile),     /* szOsFile */                    \
    MAX_PATHNAME,         /* mxPathname */                  \
    0,                    /* pNext */                       \
    VFSNAME,              /* zName */                       \
    (void*)FINDER,        /* pAppData */                    \
    unixOpen,             /* xOpen */                       \
    unixDelete,           /* xDelete */                     \
    unixAccess,           /* xAccess */                     \
    unixFullPathname,     /* xFullPathname */               \
    unixDlOpen,           /* xDlOpen */                     \
    unixDlError,          /* xDlError */                    \
    unixDlSym,            /* xDlSym */                      \
................................................................................
    unixDlClose,          /* xDlClose */                    \
    unixRandomness,       /* xRandomness */                 \
    unixSleep,            /* xSleep */                      \
    unixCurrentTime,      /* xCurrentTime */                \
    unixGetLastError      /* xGetLastError */               \
  }

  unsigned int i;
  static sqlite3_vfs aVfs[] = {
#if SQLITE_ENABLE_LOCKING_STYLE && defined(__DARWIN__)
    UNIXVFS("unix",          autolockIoFinder ),
#else
    UNIXVFS("unix",          posixIoFinder ),
#endif
    UNIXVFS("unix-none",     nolockIoFinder ),
    UNIXVFS("unix-dotfile",  dotlockIoFinder ),
#if OS_VXWORKS
    UNIXVFS("unix-namedsem", semIoFinder ),
#endif
#if SQLITE_ENABLE_LOCKING_STYLE
    UNIXVFS("unix-posix",    posixIoFinder ),
    UNIXVFS("unix-flock",    flockIoFinder ),
#endif
#if SQLITE_ENABLE_LOCKING_STYLE && defined(__DARWIN__)
    UNIXVFS("unix-afp",      afpIoFinder ),
    UNIXVFS("unix-proxy",    proxyIoFinder ),
#endif
  };
  for(i=0; i<(sizeof(aVfs)/sizeof(sqlite3_vfs)); i++){
    sqlite3_vfs_register(&aVfs[i], i==0);
  }
  return SQLITE_OK; 
}

**    May you share freely, never taking more than you give.
**
*************************************************************************
** Code for testing all sorts of SQLite interfaces.  This code
** is not included in the SQLite library.  It is used for automated
** testing of the SQLite library.
**
** $Id: test1.c,v 1.332 2008/11/28 15:37:20 drh Exp $
*/
#include "sqliteInt.h"
#include "tcl.h"
#include <stdlib.h>
#include <string.h>

/*
................................................................................
  if( objc!=2 ){
    Tcl_AppendResult(interp, "wrong # args: should be \"",
                     Tcl_GetStringFromObj(objv[0], 0), " DB", 0);
    return TCL_ERROR;
  }
  if( getDbPointer(interp, Tcl_GetString(objv[1]), &db) ) return TCL_ERROR;
  
#ifdef SQLITE_ENABLE_LOCKING_STYLE
	{
    char *proxyPath = "test.proxy";
    char *testPath;
		rc = sqlite3_file_control(db, NULL, SQLITE_SET_LOCKPROXYFILE, proxyPath);

    if( rc ) { Tcl_SetObjResult(interp, Tcl_NewIntObj(rc)); return TCL_ERROR; }

    rc = sqlite3_file_control(db, NULL, SQLITE_GET_LOCKPROXYFILE, &testPath);
    if( strncmp(proxyPath,testPath,11) ) {
      Tcl_AppendResult(interp, "Lock proxy file did not match the previously assigned value", 0);

      return TCL_ERROR;
    }

    if( rc ) { Tcl_SetObjResult(interp, Tcl_NewIntObj(rc)); return TCL_ERROR; }


		rc = sqlite3_file_control(db, NULL, SQLITE_SET_LOCKPROXYFILE, proxyPath);

    if( rc ) { Tcl_SetObjResult(interp, Tcl_NewIntObj(rc)); return TCL_ERROR; }


  }
#endif
  return TCL_OK;  
}


/*

**    May you share freely, never taking more than you give.
**
*************************************************************************
** Code for testing all sorts of SQLite interfaces.  This code
** is not included in the SQLite library.  It is used for automated
** testing of the SQLite library.
**
** $Id: test1.c,v 1.333 2008/11/29 00:56:53 drh Exp $
*/
#include "sqliteInt.h"
#include "tcl.h"
#include <stdlib.h>
#include <string.h>

/*
................................................................................
  if( objc!=2 ){
    Tcl_AppendResult(interp, "wrong # args: should be \"",
                     Tcl_GetStringFromObj(objv[0], 0), " DB", 0);
    return TCL_ERROR;
  }
  if( getDbPointer(interp, Tcl_GetString(objv[1]), &db) ) return TCL_ERROR;
  
#if defined(SQLITE_ENABLE_LOCKING_STYLE) && defined(__DARWIN__)
  {
    char *proxyPath = "test.proxy";
    char *testPath;
    rc = sqlite3_file_control(db, NULL, SQLITE_SET_LOCKPROXYFILE, proxyPath);
    if( rc ){
      Tcl_SetObjResult(interp, Tcl_NewIntObj(rc)); return TCL_ERROR;
    }
    rc = sqlite3_file_control(db, NULL, SQLITE_GET_LOCKPROXYFILE, &testPath);
    if( strncmp(proxyPath,testPath,11) ) {
      Tcl_AppendResult(interp, "Lock proxy file did not match the "
                               "previously assigned value", 0);
      return TCL_ERROR;
    }
    if( rc ){
      Tcl_SetObjResult(interp, Tcl_NewIntObj(rc));
      return TCL_ERROR;
    }
    rc = sqlite3_file_control(db, NULL, SQLITE_SET_LOCKPROXYFILE, proxyPath);
    if( rc ){
      Tcl_SetObjResult(interp, Tcl_NewIntObj(rc));
      return TCL_ERROR;
    }
  }
#endif
  return TCL_OK;  
}


/*

** 
** This file contains code used for testing the SQLite system.
** None of the code in this file goes into a deliverable build.
** 
** The focus of this file is providing the TCL testing layer
** access to compile-time constants.
**
** $Id: test_config.c,v 1.43 2008/11/21 00:10:35 aswift Exp $
*/

#include "sqliteLimit.h"

#include "sqliteInt.h"
#include "tcl.h"
#include <stdlib.h>
................................................................................

#ifdef SQLITE_OMIT_SCHEMA_VERSION_PRAGMAS
  Tcl_SetVar2(interp, "sqlite_options", "schema_version", "0", TCL_GLOBAL_ONLY);
#else
  Tcl_SetVar2(interp, "sqlite_options", "schema_version", "1", TCL_GLOBAL_ONLY);
#endif

#ifdef SQLITE_ENABLE_LOCKING_STYLE
    Tcl_SetVar2(interp, "sqlite_options", "lock_proxy_pragmas", "1", TCL_GLOBAL_ONLY);
#else
    Tcl_SetVar2(interp, "sqlite_options", "lock_proxy_pragmas", "0", TCL_GLOBAL_ONLY);
#endif
    
    
#ifdef SQLITE_OMIT_SHARED_CACHE
  Tcl_SetVar2(interp, "sqlite_options", "shared_cache", "0", TCL_GLOBAL_ONLY);
#else
  Tcl_SetVar2(interp, "sqlite_options", "shared_cache", "1", TCL_GLOBAL_ONLY);

** 
** This file contains code used for testing the SQLite system.
** None of the code in this file goes into a deliverable build.
** 
** The focus of this file is providing the TCL testing layer
** access to compile-time constants.
**
** $Id: test_config.c,v 1.44 2008/11/29 00:56:54 drh Exp $
*/

#include "sqliteLimit.h"

#include "sqliteInt.h"
#include "tcl.h"
#include <stdlib.h>
................................................................................

#ifdef SQLITE_OMIT_SCHEMA_VERSION_PRAGMAS
  Tcl_SetVar2(interp, "sqlite_options", "schema_version", "0", TCL_GLOBAL_ONLY);
#else
  Tcl_SetVar2(interp, "sqlite_options", "schema_version", "1", TCL_GLOBAL_ONLY);
#endif

#if defined(SQLITE_ENABLE_LOCKING_STYLE) && defined(__DARWIN__)
  Tcl_SetVar2(interp,"sqlite_options","lock_proxy_pragmas","1",TCL_GLOBAL_ONLY);
#else
  Tcl_SetVar2(interp,"sqlite_options","lock_proxy_pragmas","0",TCL_GLOBAL_ONLY);
#endif
    
    
#ifdef SQLITE_OMIT_SHARED_CACHE
  Tcl_SetVar2(interp, "sqlite_options", "shared_cache", "0", TCL_GLOBAL_ONLY);
#else
  Tcl_SetVar2(interp, "sqlite_options", "shared_cache", "1", TCL_GLOBAL_ONLY);