/*
   =============================================================================
	newver.c -- read and update a GEMDOS version message object file
	Version 1 -- 1988-10-28  -- D.N. Lynx Crowe
	(c) Copyright 1988 -- D.N. Lynx Crowe -- All rights reserved

	Compiled and linked with the GEMDOS Alcyon C developer's package.

	NOTE:  Because we use the Alcyon GEMDOS object file format,
	which is specific to the Atari,  this code is NON-PORTABLE.

	The idea, however, is adaptable to a wide variety of systems
	and object file formats.

	Note also that the fopen() function in the Alcyon C library does not
	support the "r+" option,  making it necessary to close the file and
	then open it again before writing.  This is a serious shortcoming of
	the Alcyon C library,  as it makes updating files only possible by a
	series of questionable maneuvers, (e.g. opening, closing, and reopening
	the file, or using open(), then fdopen(), etc.).
   =============================================================================
*/

#include "stdio.h"		/* Atari GEMDOS standard I/O definitions */
#include "stddefs.h"		/* some usefull standard C definitions */
#include "objdefs.h"		/* GEMDOS object file definitions */

#define	VERFILE		"verdate.o"	/* version message file */

extern	int	errno;	/* system error code */

extern	char	*now();	/* get formatted system date and time */

FILE	*fp;		/* VERFILE file pointer */

			/* 000000000011111111112 */
			/* 012345678901234567890 */
char	dtg[22];	/* yyyy-mm-dd  hh:mm:ss  zero terminated string */

			/* 000000000011 */
			/* 012345678901 */
char	verstr[12];	/* yyyymmdd.vv   zero terminated string */

struct vb {		/* VERFILE buffer (66 bytes) */

	struct EXFILE	hdr;
	char		ver[12];
	struct SYMBOL	sym;
	char		rem[12];

} verbuf;

/* 
*/
	
/*
   =============================================================================
	read and update an Alcyon/GEMDOS format version message object file
   =============================================================================
*/

main()
{
	short	len, rc, vn, vp1, vp2;

	len = sizeof verbuf;

	/* first, read the old version message object file */

	if ((FILE *)NULL EQ (fp = fopenb(VERFILE, "r"))) {

		printf("ERROR -- Unable to open \"%s\" for reading  (errno = %d)\n",
			VERFILE, errno);

		exit(1);
	}

	rewind(fp);

	if (1 NE (rc = fread(&verbuf, len, 1, fp))) {

		printf("ERROR -- Unable to read \"%s\"  (rc = %d, errno = %d)\n",
			VERFILE, rc, errno);

		if (ferror(fp))
			printf("  File system ERROR.\n");
		else if (feof(fp))
			printf("  Premature EOF.\n");
		else
			printf("  Neither ERROR or EOF set -- very odd\n");

		fclose(fp);
		exit(1);
	}

	fclose(fp);
/* 
*/

	/* next, set the date and version */

	now(dtg);	/* set date and time */

	memcpy(&verstr[0], &dtg[0], 4);
	memcpy(&verstr[4], &dtg[5], 2);
	memcpy(&verstr[6], &dtg[8], 2);
	strcpy(&verstr[8], ".01");

	if (memcmp(verbuf.ver, verstr, 8)) {	/* if date is different ... */

		strcpy(verbuf.ver, verstr);	/* ... it's today's 1st version */

	} else {	/* ... otherwise,  it's today's next version */

		vn = ((verbuf.ver[ 9] - '0') * 10) +
		      (verbuf.ver[10] - '0') + 1;

		if (vn GE 100) {	/* too many versions today ? */

			printf("WARNING -- version number rolled over to 00.\n");
			vn = 0;
		}

		vp1 = vn / 10;
		vp2 = vn - (vp1 * 10);

		verbuf.ver[ 9] = vp1 + '0';
		verbuf.ver[10] = vp2 + '0';
	}

/* 
*/
	/* finally, re-write the version message object file */

	if ((FILE *)NULL EQ (fp = fopenb(VERFILE, "w"))) {

		printf("ERROR -- Unable to open \"%s\" for writing  (errno = %d)\n",
			VERFILE, errno);

		exit(1);
	}

	rewind(fp);

	if (1 NE (rc = fwrite(&verbuf, len, 1, fp))) {

		printf("ERROR -- Unable to write to \"%s\"  (rc = %d, errno = %d)\n",
			VERFILE, rc, errno);

		if (ferror(fp))
			printf("  File system ERROR.\n");
		else if (feof(fp))
			printf("  Premature EOF.\n");
		else
			printf("  Neither ERROR or EOF set -- very odd\n");

		fclose(fp);
		exit(1);
	}

	fclose(fp);
	printf("Current version:  %s\n", verbuf.ver);
	exit(0);
}