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/*
** Copyright 1998 - 2006 Double Precision, Inc.
** See COPYING for distribution information.
*/
#include "dotlock.h"
#include "funcs.h"
#include "xconfig.h"
#include "mio.h"
#include "buffer.h"
#include "alarmsleep.h"
#include "alarmtimer.h"
#include "varlist.h"
#include "config.h"
#include <sys/types.h>
#if HAVE_SYS_STAT_H
#include <sys/stat.h>
#endif
#include <stdlib.h>
DotLock::DotLock() : refresh(this)
{
}
DotLock::~DotLock()
{
Unlock();
}
void DotLock::Unlock()
{
refresh.Cancel();
Close();
}
int DotLock::attemptlock(const char *templock, const char *finallock)
{
Mio mio;
Buffer b;
static Buffer errbuf;
if (mio.Open(templock, O_CREAT | O_WRONLY, 0644) < 0)
{
errbuf="Unable to create a dot-lock at ";
errbuf += (const char *)templock;
errbuf += ".\n";
errbuf += '\0';
throw (const char *)errbuf;
}
b.append( (unsigned long)getpid() );
b += '\n';
if (mio.write((const char *)b, b.Length()) < 0 || mio.flush() < 0)
{
mio.Close();
unlink(templock);
throw "Unable to write to a dot-lock.";
}
mio.Close();
if (mio.errflag())
{
unlink(templock);
throw "Unable to close a dot-lock.";
}
try
{
struct stat buf;
if (link(templock, finallock) < 0)
; /* ignored */
int rc=stat(templock, &buf);
if (rc == 0 && buf.st_nlink == 2)
{
name(finallock);
unlink(templock);
return (0);
}
unlink(templock);
}
catch (...)
{
unlink(templock);
throw;
}
return (-1);
}
void DotLock::Lock(const char *lockfile)
{
Unlock();
unsigned nseconds=GetLockSleep();
unsigned timeout=GetLockTimeout();
const char *q, *r;
refresh_interval=GetLockRefresh();
for (q=r=lockfile; *q; q++)
if (*q == '/') r=q+1;
q= TempName( r-lockfile ? lockfile:"", r-lockfile);
struct stat last_stat;
int has_last_stat=0;
AlarmTimer stat_timer;
memset(&last_stat, 0, sizeof(last_stat));
while (attemptlock(q, lockfile))
{
struct stat current_stat;
if (stat(lockfile, ¤t_stat) == 0)
{
if (!has_last_stat ||
current_stat.st_ino != last_stat.st_ino ||
current_stat.st_ctime != last_stat.st_ctime ||
current_stat.st_atime != last_stat.st_atime)
{
has_last_stat=1;
last_stat=current_stat;
stat_timer.Set(timeout);
}
else if (stat_timer.Expired())
{
unlink(lockfile);
}
}
AlarmSleep sleep(nseconds);
}
if (refresh_interval >= 10)
refresh.Set(refresh_interval);
}
void DotLock::LockMailbox(const char *mailbox)
{
struct stat stat_buf;
Buffer dotlock_name;
if (stat(mailbox, &stat_buf) < 0 ||
( !S_ISCHR(stat_buf.st_mode) && !S_ISBLK(stat_buf.st_mode)))
{
dotlock_name=mailbox;
const char *p=GetLockExt();
if (!p || !*p) dotlock_name += LOCKEXT_DEF;
else dotlock_name += p;
dotlock_name += '\0';
Lock( dotlock_name );
}
}
void DotLock::dorefresh()
{
chmod(filename, 0644);
refresh.Set(refresh_interval);
}
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