Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!tut.cis.ohio-state.edu!ucbvax!hplabs!hpda!hpcuhb!hp-ses!wunder
From: wunder@hp-ses.SDE.HP.COM (Walter Underwood)
Newsgroups: comp.sys.hp
Subject: Re: linking BSD type software on HP-UX
Message-ID: <920022@hp-ses.SDE.HP.COM>
Date: 27 Mar 89 19:31:59 GMT
References: <940@eastman.UUCP>
Organization: HP SW Engineering Systems - Palo Alto, CA
Lines: 94


   In the aufs part, a function called "flock" was required, if we want
   to use shared volumes using the file server.  HP-UX has "lockf", but
   it is different from "flock".

Here is an flock() emulation.  flock() handles shared locks plus
exclusive locks.  This only does exclusive locks.  The locking
available from fcntl() is equivalent to flock(), so this really should
be rewritten to use fcntl().

Someone else suggested replacing bcopy() with memcpy().  This is not
always safe.  bcopy() handles overlapping strings correctly, memcpy()
does not (it may be optimized for speed, using word moves).

wunder

-----------------
# This is a shell archive.  Remove anything before this line,
# then unpack it by saving it in a file and typing "sh file".
#
# Wrapped by Walter Underwood <wunder@hp-ses> on Mon Mar 27 11:26:10 1989
#
# This archive contains:
#	bsd1.h	flock.c	
#

unset LANG

echo x - bsd1.h
cat >bsd1.h <<'@EOF'
/* 
 * Berkeley to HP-UX library functionality mappings
 * These routines are not supported by HP.  	    
 *
 * To use these, also include <sys/param.h>
 */

/* signal(2) mapping */
#define  SIGCHLD       SIGCLD

/* Helpful macros with select(2) */
#define NFDBITS		(sizeof(int) * NBBY)
#define	FD_SET(n, p)	((p)->fds_bits[(n)/NFDBITS] |= (1 << ((n) % NFDBITS)))
#define	FD_CLR(n, p)	((p)->fds_bits[(n)/NFDBITS] &= ~(1 << ((n) % NFDBITS)))
#define	FD_ISSET(n, p)	((p)->fds_bits[(n)/NFDBITS] & (1 << ((n) % NFDBITS)))
#define FD_ZERO(p)	(memset((char *)(p), 0, sizeof(*(p))))

/* These definitions are in <sys/file.h> on BSD 4.3 */
/*
 * Flock call.
 */
#define	LOCK_SH		1	/* shared lock */
#define	LOCK_EX		2	/* exclusive lock */
#define	LOCK_NB		4	/* don't block when locking */
#define	LOCK_UN		8	/* unlock */
@EOF

chmod 644 bsd1.h

echo x - flock.c
cat >flock.c <<'@EOF'
#include <unistd.h>
#include <sys/file.h>
#include "bsd1.h"		/* defines normally in <sys/file.h> */

flock(fd, operation)
int fd, operation;
{
int UN,NB,SH,EX;
int newop = 0;

    UN = LOCK_UN & operation;
    NB = LOCK_NB & operation;
    SH = LOCK_SH & operation;
    EX = LOCK_EX & operation;

    if (UN) 
        newop = F_ULOCK;
    else
        if (NB)
            newop = F_TLOCK;
        else
            if (SH || EX)
                newop = F_LOCK;
            else
                return(-1);  /* no operations set */      

     return(lockf(fd, newop, 0));
}
@EOF

chmod 644 flock.c

exit 0