/*
 * addfile(), nextfile(): maintain a circular buffer of file names
 */

#include "m.h"

#define LIBRARY "/opt/m/lib/"

#define MAXFILES 512

static char *files[MAXFILES];
static char **start = files;	/* location to return for nextfile */
static char **stop = files;	/* next free location for addfile() */
static int nfiles = 0;		/* number of file names in buffer */

#define inc(p) if( ++p >= files + MAXFILES) p = files

void addfile( char *name)
{
    if( nfiles == MAXFILES) {
	yyerror("file list overflow in addfile()");
	return;
    }

    if( (*stop = strdup(name)) == NULL)
	yyerror("strdup() failed in addfile()");
    else {
	inc( stop);
	++nfiles;
    }
}

FILE *nextfile( void)
{
    FILE *f = NULL;
    char name[BUFSIZ];

    while( nfiles > 0) {
#ifdef DEBUG
	if( prog_debug)
	    dprint("nextfile: %s\n", *start);
#endif
	--nfiles;
	if( (f = fopen( *start, "r")) == NULL) {
	    (void) strcat( strcpy( name, LIBRARY), *start);
	    if( (f = fopen( name, "r")) == NULL)
		dprint("could not open %s or %s\n", *start, name);
	}
	free( *start);
	inc(start);
	if( f)
	    break;
    }

    return (f == NULL) ? stdin : f;
}