Proposed magic number patch

[John Cowan]

The following patch adds a "magic number" to compiled zoneinfo
files.  The affected files are zic.c and tzfile.h.  In essence,
the first four bytes of zoneinfo files are set to
"\0x14\0x1a\0x54\0x5a", which in ASCII is "^T^ZTZ".
This patch is trivial, but will assist in the automatic
recognition of zoneinfo files by the Unix "file" command.

*** tzfile.h Sat Jul 19 13:14:50 1997
--- tzfile.new.h Tue Oct  7 16:36:24 1997
***************
*** 46,52 ****
  */
  
  struct tzhead {
! 	char	tzh_reserved[20];	/* reserved for future use */
  	char	tzh_ttisgmtcnt[4];	/* coded number of trans. time flags */
  	char	tzh_ttisstdcnt[4];	/* coded number of trans. time flags */
  	char	tzh_leapcnt[4];		/* coded number of leap seconds */
--- 46,53 ----
  */
  
  struct tzhead {
! 	char	tzh_magic[4];		/* magic string: "^T^ZTZ" */
! 	char	tzh_reserved[16];	/* reserved for future use */
  	char	tzh_ttisgmtcnt[4];	/* coded number of trans. time flags */
  	char	tzh_ttisstdcnt[4];	/* coded number of trans. time flags */
  	char	tzh_leapcnt[4];		/* coded number of leap seconds */
*** zic.c Tue Sep 23 16:37:14 1997
--- zic.new.c Tue Oct  7 16:34:30 1997
***************
*** 1468,1473 ****
--- 1468,1475 ----
  	convert(eitol(typecnt), tzh.tzh_typecnt);
  	convert(eitol(charcnt), tzh.tzh_charcnt);
  #define DO(field)	(void) fwrite((void *) tzh.field, (size_t) sizeof tzh.field, (size_t) 1, fp)
+ 	strncpy(tzh.tzh_magic, "\0x14\0x1a\0x54\0x5a", 4);
+ 	DO(tzh_magic);
  	DO(tzh_reserved);
  	DO(tzh_ttisgmtcnt);
  	DO(tzh_ttisstdcnt);

-- 
John Cowan	http://www.ccil.org/~cowan		cowan at ccil.org
			e'osai ko sarji la lojban