XrdOucSxeq.cc

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/******************************************************************************/
/*                                                                            */
/*                         X r d O u c S x e q . c c                          */
/*                                                                            */
/* (c) 2009 by the Board of Trustees of the Leland Stanford, Jr., University  */
/*                            All Rights Reserved                             */
/*   Produced by Andrew Hanushevsky for Stanford University under contract    */
/*              DE-AC02-76-SFO0515 with the Department of Energy              */
/******************************************************************************/
  
//         $Id: XrdOucSxeq.cc 34000 2010-06-21 06:49:56Z ganis $

const char *XrdOucSxeqCVSID = "$Id: XrdOucSxeq.cc 34000 2010-06-21 06:49:56Z ganis $";

#include <errno.h>
#include <fcntl.h>
#include <stdlib.h>
#include <string.h>
#include <strings.h>
#include <unistd.h>
#include <sys/param.h>
#include <sys/stat.h>
#include <sys/types.h>

#include "XrdOuc/XrdOucSxeq.hh"
#include "XrdSys/XrdSysPlatform.hh"

/******************************************************************************/
/*                           C o n s t r u c t o r                            */
/******************************************************************************/
  
XrdOucSxeq::XrdOucSxeq(int sOpts, const char *path)
{
   static const int AMode = S_IRUSR | S_IWUSR | S_IRGRP | S_IROTH;
   lokFN = strdup(path);
   lokUL = 0;

// Open the file, creating it
//
   if ((lokFD = open(lokFN, O_CREAT|O_RDWR, AMode)) < 0) lokRC = errno;
      else {lokRC = 0;
            if (sOpts) Serialize(sOpts);
           }
}

/******************************************************************************/
  
XrdOucSxeq::XrdOucSxeq(const char *sfx1, const char *sfx2, const char *Dir)
{
   static const int AMode = S_IRUSR | S_IWUSR | S_IRGRP | S_IROTH;
   char pbuff[MAXPATHLEN+1], *pP;

// Construct the lock file name
//
   strcpy(pbuff, Dir);
   pP = pbuff + strlen(Dir);
   if (*sfx1 != '/' && *(pP-1) != '/') *pP++ = '/';
   strcpy(pP, sfx1);
   if (sfx2) strcpy(pP+strlen(sfx1), sfx2);
   lokFN = strdup(pbuff);
   lokUL = 0;

// Open the file, creating it
//
   if ((lokFD = open(lokFN, O_CREAT|O_RDWR, AMode)) < 0) lokRC = errno;
      else lokRC = 0;
}

/******************************************************************************/
/*                            D e s t r u c t o r                             */
/******************************************************************************/
  
XrdOucSxeq::~XrdOucSxeq()
{

// Check if we should unlink this file we need to do so while it's locked)
//
   if (lokFD >= 0 && lokUL) unlink(lokFN);

// Close the file and free th file name
//
   if (lokFD >= 0) close(lokFD);
   free(lokFN);
}

/******************************************************************************/
/*                               R e l e a s e                                */
/******************************************************************************/
  
int XrdOucSxeq::Release()
{
   FLOCK_t lock_args;
   int rc;

// If the file is not open, return failure
//
   if (lokFD < 0) return 0;

// Establish locking options
//
   bzero(&lock_args, sizeof(lock_args));
   lock_args.l_type = F_UNLCK;

// Now perform the action
//
   do {rc = fcntl(lokFD, F_SETLKW, &lock_args);}
      while(rc < 0 && errno == EINTR);

// Determine result
//
   if (rc < 0) {lokRC = errno; return 0;}

// We succeeded, unlink is not possible now
//
   lokUL = 0;
   lokRC = 0;
   return 1;
}
  
/******************************************************************************/
/*                             S e r i a l i z e                              */
/******************************************************************************/
  
int XrdOucSxeq::Serialize(int Opts)
{
   FLOCK_t lock_args;
   int Act, rc;

// If the file is not open, return failure
//
   if (lokFD < 0) return 0;

// Establish lock flags
//

// Establish locking options
//
   bzero(&lock_args, sizeof(lock_args));
   lock_args.l_type = (Opts & Share ? F_RDLCK : F_WRLCK);
   Act = (Opts & noWait ? F_SETLK : F_SETLKW);

// Now perform the action
//
   do {rc = fcntl(lokFD, Act, &lock_args);} while(rc < 0 && errno == EINTR);

// Determine result
//
   if (rc < 0) {lokRC = errno; return 0;}

// We succeeded check if an unlink is possible
//
   if (Opts & Unlink && !(Opts & Share)) lokUL = 1;
   lokRC = 0;
   return 1;
}

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