/*-------------------------------------------------------------------------
 *
 * fe-pqufs.c--
 *    Unix filesystem abstractions for large objects
 *
 * Copyright (c) 1994, Regents of the University of California
 *
 *
 * IDENTIFICATION
 *    /usr/local/devel/pglite/cvs/src/libpq/fe-pqufs.c,v 1.3 1995/01/16 22:42:44 jolly Exp
 *
 *-------------------------------------------------------------------------
 */
/*
 * Unix abstractions for large objects.
 *
 * p_open, p_read, p_write, p_close
 *
 * p_creat, p_lseek, p_tell
 * p_ftruncate *
 *
 * p_stat (certain fields in the stat structure, e.g device, are
 *         meaningless.  Other fields, such as the times, are not valid yet.)
 *
 * p_rename, p_mkdir, p_rmdir, p_unlink
 *
 * p_opendir, p_readdir, p_rewinddir, p_closedir
 *
 *
 * These p_* calls are translated to fastpath function calls in backend's 
 * address space.  The large object file handles reside in, and the 
 * operations occur in backend's address space.
 *
 * These two calls are local functions that do not call the fastpath.  Each 
 * pathname in the p_* calls are translated to an absolute pathname using the
 * current working directory, initially "/".
 * p_chdir *
 * p_getwd *
 *
 * The semantics of the p_* calls are, for the most part, the same as the 
 * unix calls.
 *
 * Extent of the similarity with the Unix filesystem
 * -------------------------------------------------
 * There is no idea or support of a '.' or '..' file.  The functions opendir, 
 * readdir, telldir, seekdir, rewinddir and closedir are instead implemented 
 * as queries.
 */

#include "lib/dllist.h"
#include "libpq/libpq.h"
#include "storage/fd.h"
#include "libpq-fe.h"
#include "libpq/libpq-fs.h"
#include "postgres.h"
#include "fmgr.h"
#include "tcop/fastpath.h"

#ifndef MAXPATHLEN
#define MAXPATHLEN 1024
#endif

int p_errno = 0;			/* error code */

int
lo_open(Oid lobjId, int mode)
{
    int fd;
    PQArgBlock argv[2];
    char *ret;

    argv[0].isint = 1;
    argv[0].len = 4;
    argv[0].u.integer = lobjId;

    argv[1].isint = 1;
    argv[1].len = 4;
    argv[1].u.integer = mode;
    
    ret = PQfn(F_LO_OPEN,&fd,sizeof(int32),NULL,1,argv,2); 
    if (ret == NULL)
      return -1;
    else if (*ret == 'V')
      return -1;
    else {
	p_errno = fd>=0 ? 0 : -fd;

	/* have to do this to reset offset in shared fd cache */
	/* but only if fd is valid */
	if (fd >= 0 && lo_lseek(fd, 0L, SEEK_SET) < 0)
		return -1;

	return fd;
    }
}

int
lo_close(int fd)
{
    PQArgBlock argv[1];
    char *pqret;
    int retval;

    argv[0].isint = 1;
    argv[0].len = 4;
    argv[0].u.integer = fd;
    pqret = PQfn(F_LO_CLOSE,&retval,sizeof(int32),NULL,1,argv,1);
    if (pqret == NULL)
      return -1;
    else if (*pqret == 'V')
      return -1;
    else {
	p_errno = retval>=0 ? 0 : -retval;
	return retval;
    }
}

int
lo_read(int fd, char *buf, int len)
{
    return (PQfsread(fd, buf, len));
}

int
lo_write(int fd, char *buf, int len)
{
    return (PQfswrite(fd, buf, len));
}

int
lo_lseek(int fd, int offset, int whence)
{
    PQArgBlock argv[3];
    char *pqret;
    int retval;
    
    argv[0].isint = 1;
    argv[0].len = 4;
    argv[0].u.integer = fd;
    
    argv[1].isint = 1;
    argv[1].len = 4;
    argv[1].u.integer = offset;

    argv[2].isint = 1;
    argv[2].len = 4;
    argv[2].u.integer = whence;

    pqret = PQfn(F_LO_LSEEK,&retval,sizeof(int32),NULL,1,argv,3);

    if (pqret == NULL)
      return -1;
    else if (*pqret == 'V')
      return -1;
    else {
	p_errno = retval>=0 ? 0 : -retval;
	return retval;
    }
}


Oid
lo_creat(int mode)
{
    PQArgBlock argv[1];
    char *pqret;
    int retval;

    argv[0].isint = 1;
    argv[0].len = 4;
    argv[0].u.integer = mode;
    pqret = PQfn(F_LO_CREAT,&retval,sizeof(int32),NULL,1,argv,1);
    if (pqret == NULL)
      return -1;
    else if (*pqret == 'V')
      return -1;
    else {
	p_errno = retval>=0 ? 0 : -retval;
	return (Oid)retval;
    }
}


int
lo_tell(int fd)
{
    int retval;
    PQArgBlock argv[1];
    char *pqret;

    argv[0].isint = 1;
    argv[0].len = 4;
    argv[0].u.integer = fd;

    pqret = PQfn(F_LO_TELL,&retval,sizeof(int32),NULL,1,argv,1);

    if (pqret == NULL)
      return -1;
    else if (*pqret == 'V')
      return -1;
    else {
	p_errno = retval>=0 ? 0 : -retval;
	return retval;
    }
}

int
lo_unlink(Oid lobjId)
{
    PQArgBlock argv[1];
    char *pqret;
    int retval;

    argv[0].isint = 1;
    argv[0].len = 4;
    argv[0].u.integer = lobjId;

    pqret = PQfn(F_LO_UNLINK,&retval,sizeof(int32),NULL,1,argv,1);

    if (pqret == NULL)
      return -1;
    else if (*pqret == 'V')
      return -1;
    else {
	p_errno = retval>=0 ? 0 : -retval;
	return retval;
    }
}

int
p_ferror(int fd)
{
    return 0; /* no errors reported yet... */
}