cosync.c revision 3f54fd611f536639ec30dd53c48e5ec1897cc7d9
/***********************************************************************
* *
* This software is part of the ast package *
* Copyright (c) 1990-2012 AT&T Intellectual Property *
* and is licensed under the *
* Eclipse Public License, Version 1.0 *
* by AT&T Intellectual Property *
* *
* A copy of the License is available at *
* http://www.eclipse.org/org/documents/epl-v10.html *
* (with md5 checksum b35adb5213ca9657e911e9befb180842) *
* *
* Information and Software Systems Research *
* AT&T Research *
* Florham Park NJ *
* *
* Glenn Fowler <gsf@research.att.com> *
* *
***********************************************************************/
#pragma prototyped
/*
* Glenn Fowler
* AT&T Research
*
* sync all outstanding file operations for file opened on fd
* if file==0 then fd used
* if fd<0 then file used
* if mode<0 then fd not created
*
* NOTE: this is an unfortunate NFS workaround that should be done by fsync()
*/
#include "colib.h"
#include <ls.h>
#include "FEATURE/nfsd"
int
cosync(Coshell_t* co, const char* file, int fd, int mode)
{
#if defined(_cmd_nfsd)
if (!co || (co->flags & CO_SERVER))
{
char tmp[PATH_MAX];
if (file && *file)
{
register const char* s;
register char* t;
register char* b;
int td;
/*
* writing to a dir apparently flushes the
* attribute cache for all entries in the dir
*/
s = file;
b = t = tmp;
while (t < &tmp[sizeof(tmp) - 1])
{
if (!(*t = *s++)) break;
if (*t++ == '/') b = t;
}
s = "..nfs..botch..";
t = b;
while (t < &tmp[sizeof(tmp) - 1] && (*t++ = *s++));
*t = 0;
if ((td = open(tmp, O_WRONLY|O_CREAT|O_TRUNC|O_cloexec, 0)) >= 0)
close(td);
unlink(tmp);
if (fd >= 0 && mode >= 0)
{
if ((td = open(file, mode|O_cloexec)) < 0)
return(-1);
close(fd);
dup2(td, fd);
close(td);
}
}
#if defined(F_SETLK)
else
{
int clean = 0;
struct flock lock;
if (fd < 0)
{
if (!file || mode < 0 || (fd = open(file, O_RDONLY|O_cloexec)) < 0) return(-1);
clean = 1;
}
/*
* this sets the VNOCACHE flag across NFS
*/
lock.l_type = F_RDLCK;
lock.l_whence = 0;
lock.l_start = 0;
lock.l_len = 1;
if (!fcntl(fd, F_SETLK, &lock))
{
lock.l_type = F_UNLCK;
fcntl(fd, F_SETLK, &lock);
}
if (clean) close(fd);
/*
* 4.1 has a bug that lets VNOCACHE linger after unlock
* VNOCACHE inhibits mapping which kills exec
* the double rename flushes the incore vnode (and VNOCACHE)
*
* this kind of stuff doesn't happen with *real* file systems
*/
if (file && *file)
{
strcpy(tmp, file);
fd = strlen(tmp) - 1;
tmp[fd] = (tmp[fd] == '*') ? '?' : '*';
if (!rename(file, tmp)) rename(tmp, file);
}
}
#endif
}
#endif
return(0);
}