/* Copyright (c) 1992 Regents of the University of California */

#ifndef lint
static char SCCSid[] = "@(#)fropen.c 2.5 9/8/92 LBL";
#endif

/*
 * Find and open a Radiance library file.
 */

#include <stdio.h>

#include "paths.h"

char  *libpath = NULL;          /* library search path */


FILE *
fropen(fname)                   /* find file and open for reading */
register char  *fname;
{
	extern char  *strcpy(), *getenv();
	FILE  *fp;
	char  pname[MAXPATH];
	register char  *sp, *cp;

	if (fname == NULL)
		return(NULL);

	if (ISDIRSEP(fname[0]) || fname[0] == '.')      /* absolute path */
		return(fopen(fname, "r"));
		
	if (libpath == NULL) {                  /* get search path */
		libpath = getenv(ULIBVAR);
		if (libpath == NULL)
			libpath = DEFPATH;
	}
						/* check search path */
	sp = libpath;
	do {
		cp = pname;
		while (*sp && (*cp = *sp++) != PATHSEP)
			cp++;
		if (cp > pname && !ISDIRSEP(cp[-1]))
			*cp++ = DIRSEP;
		strcpy(cp, fname);
		if ((fp = fopen(pname, "r")) != NULL)
			return(fp);                     /* got it! */
	} while (*sp);
					/* not found */
	return(NULL);
}