/* Copyright (C) 1995, 1989, 1998 Transarc Corporation - All rights reserved */
/*
 * (C) COPYRIGHT IBM CORPORATION 1987, 1988
 * LICENSED MATERIALS - PROPERTY OF IBM
 */
/*
 * afs_vnop_open.c
 *
 * Implements:
 * afs_open
 *
 */


#include "../afs/param.h"	/* Should be always first */
#include "../afs/sysincludes.h"	/* Standard vendor system headers */
#include "../afs/afsincludes.h"	/* Afs-based standard headers */
#include "../afs/afs_stats.h" /* statistics */
#include "../afs/afs_cbqueue.h"
#include "../afs/nfsclient.h"
#include "../afs/afs_osidnlc.h"



/* given a vnode ptr, open flags and credentials, open the file.  No access
 * checks are done here, instead they're done by afs_create or afs_access,
 * both called by the vn_open call.
 */
#ifdef AFS_SGI64_ENV
afs_open(bhv, avcp, aflags, acred)
    bhv_desc_t *bhv;
#else
afs_open(avcp, aflags, acred)
#endif
    register struct vcache **avcp;
    afs_int32 aflags;
    struct AFS_UCRED *acred; 
{
    register afs_int32 code;
    struct vrequest treq;
    register struct vcache *tvc;
    int writing;
    
    AFS_STATCNT(afs_open);
    if (code = afs_InitReq(&treq, acred)) return code;
#ifdef AFS_SGI64_ENV
    /* avcpp can be, but is not necesarily, bhp's vnode. */
    tvc = (struct vcache *)BHV_TO_VNODE(bhv);
#else
    tvc = *avcp;
#endif
    afs_Trace2(afs_iclSetp, CM_TRACE_OPEN, ICL_TYPE_POINTER, tvc,
	       ICL_TYPE_INT32, aflags);
    code = afs_VerifyVCache(tvc, &treq);
    if (code) goto done;
    if (aflags & (FWRITE | FTRUNC)) writing = 1;
    else writing = 0;
    if (vType(tvc) == VDIR) {
	/* directory */
	if (writing) {
	    code = EISDIR;
	    goto done;
	}
	else {
	    if (!afs_AccessOK(tvc, 
			((tvc->states & CForeign) ? PRSFS_READ: PRSFS_LOOKUP),
			&treq, CHECK_MODE_BITS)) {
		code = EACCES;
		goto done;
	    }
	}
    }
    else {
#ifdef	AFS_SUN5_ENV
	if (AFS_NFSXLATORREQ(acred) &&  (aflags & FREAD)) {
	    if (!afs_AccessOK(tvc, PRSFS_READ, &treq,
			      CHECK_MODE_BITS|CMB_ALLOW_EXEC_AS_READ)) {
		code = EACCES;
		goto done;
	    }
	}
#endif
#ifdef	AFS_AIX41_ENV
	if (aflags & FRSHARE) {
	    /*
	     * Hack for AIX 4.1:
	     *	Apparently it is possible for a file to get mapped without
	     *	either VNOP_MAP or VNOP_RDWR being called, if (1) it is a
	     *	sharable library, and (2) it has already been loaded.  We must
	     *	ensure that the credp is up to date.  We detect the situation
	     *	by checking for O_RSHARE at open time.
	     */
	    /*
	     * We keep the caller's credentials since an async daemon will
	     * handle the request at some point. We assume that the same
	     * credentials will be used.
	     */
	    ObtainWriteLock(&tvc->lock,140);
	    if (!tvc->credp || (tvc->credp != acred)) {
	        crhold(acred);
	        if (tvc->credp) {
	            struct ucred *crp = tvc->credp;
	            tvc->credp = (struct ucred *)0;
	            crfree(crp);
	        }
	        tvc->credp = acred;
	    }
	    ReleaseWriteLock(&tvc->lock);
	}
#endif
	/* normal file or symlink */
	osi_FlushText(tvc); /* only needed to flush text if text locked last time */
#if defined(AFS_SUN_ENV) || defined(AFS_ALPHA_ENV) || defined(AFS_SUN5_ENV)
	afs_BozonLock(&tvc->pvnLock, tvc);
#endif
	osi_FlushPages(tvc, acred);
#if defined(AFS_SUN_ENV) || defined(AFS_ALPHA_ENV) || defined(AFS_SUN5_ENV)
	afs_BozonUnlock(&tvc->pvnLock, tvc);
#endif
    }
    /* set date on file if open in O_TRUNC mode */
    if (aflags & FTRUNC) {
	/* this fixes touch */
	ObtainWriteLock(&tvc->lock,123);
	tvc->m.Date = osi_Time();
	tvc->states |= CDirty;
	ReleaseWriteLock(&tvc->lock);
    }
    ObtainReadLock(&tvc->lock);
    if (writing) tvc->execsOrWriters++;
    tvc->opens++;
#if defined(AFS_SGI_ENV)
    if (writing && tvc->cred == NULL) {
	crhold(acred);
	tvc->cred = acred;
    }
#endif
    ReleaseReadLock(&tvc->lock);
done:
    code = afs_CheckCode(code, &treq, 4); /* avoid AIX -O bug */

    afs_Trace2(afs_iclSetp, CM_TRACE_OPEN, ICL_TYPE_POINTER, tvc,
	       ICL_TYPE_INT32, 999999);

    return code;
}