SQLite

**   *  sqlite3_file methods not associated with locking.
**   *  Definitions of sqlite3_io_methods objects for all locking
**      methods plus "finder" functions for each locking method.
**   *  sqlite3_vfs method implementations.
**   *  Definitions of sqlite3_vfs objects for all locking methods
**      plus implementations of sqlite3_os_init() and sqlite3_os_end().
**
** $Id: os_unix.c,v 1.226 2008/12/03 21:26:20 aswift Exp $
*/
#include "sqliteInt.h"
#if SQLITE_OS_UNIX              /* This file is used on unix only */

/*
** There are various methods for file locking used for concurrency
** control:

    return SQLITE_OK;
  }
end_create_proxy:    
  close(fd); /* silently leak fd if error, we're already in error */
  sqlite3_free(pNew);
  return rc;
}
static const sqlite3_io_methods afpIoMethods;
static int unixWrite(
                     sqlite3_file *id, 
                     const void *pBuf, 
                     int amt,
                     sqlite3_int64 offset 
                     );
static int unixRead(
                    sqlite3_file *id, 
                    void *pBuf, 
                    int amt,
                    sqlite3_int64 offset
                    );
/* takes the conch by taking a shared lock and read the contents conch, if 
** lockPath is non-NULL, the host ID and lock file path must match.  A NULL 
** lockPath means that the lockPath in the conch file will be used if the 
** host IDs match, or a new lock path will be generated automatically 
** and written to the conch file.
*/
static int proxyTakeConch(unixFile *pFile){

    sqlite3_free(oldPath);
    pCtx->lockProxyPath = sqlite3DbStrDup(0, path);
  }
  
  return rc;
}

static const sqlite3_io_methods dotlockIoMethods;
/*
** pFile is a file that has been opened by a prior xOpen call.  dbPath
** is a string buffer at least MAXPATHLEN+1 characters in size.
**
** This routine find the filename associated with pFile and writes it
** int dbPath.
*/
static int proxyGetDbPathForUnixFile(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;
}
static const sqlite3_io_methods proxyIoMethods;
/*
** Takes an already filled in unix file and alters it so all file locking 
** will be performed on the local proxy lock file.  The following fields
** are preserved in the locking context so that they can be restored and 
** the unix structure properly cleaned up at close time:
**  ->lockingContext
**  ->pMethod

  if( pLockingStyle == &posixIoMethods ){
    unixEnterMutex();
    rc = findLockInfo(pNew, &pNew->pLock, &pNew->pOpen);
    unixLeaveMutex();
  }

#if SQLITE_ENABLE_LOCKING_STYLE && defined(__DARWIN__)
  else if( pLockingStyle == &afpIoMethods ){
    /* 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;