/*
* Produce time-stamp in the format suitable for HTTP's Date headers:
*
* Date: Sun, 05 Nov 2006 16:18:01 GMT
* and the Set-Cookie headers:
* Set-Cookie: .......; expires=Sun, 17-Jan-2038 19:14:07 GMT
*
* Although this can, of course, be done from TCL directly ([clock format]),
* Tcl's method breaks, when the server is running in non-C locale.
* Regardless of the locale, the Date-header must be in English and
* this function takes care of that. Plus it is over 4 times faster...
* Neither asctime() nor gmtime() would not work, because they
* don't put a coma after the name of the weekday...
*
* Each command takes an optional argument specifying the date (in seconds
* since epoch). If not specified, httpdate assumes the current date, and
* the cookiedate -- a week from now.
*
* Written by Mikhail T. <mi+httpdate@aldan.algebra.com> in search of glory
* but without ANY AND ALL WARRANTIES OR APPLICABILITIES FOR ANY PURPOSES.
* Released into the wild under BSD license.
*
* Tested on FreeBSD-6.2 against Tcl-8.4. November 2006...
*/
#include <tcl.h>
#include <sys/time.h>
#include <errno.h>
#include <sys/limits.h>
/*
* Using this method of copying short strings as integers instead of
* relying on memcpy cuts the execution time from 3.53 microseconds to
* 3.26 microseconds (or 8%) on my Opteron 275. Plus it is fun...
* It is only safe, because the positions of both the month's name and
* the weekday happen to be at 4-byte allignment, so the code is safe
* from SIGBUS on all (?) known platforms...
*/
typedef union {
char string[4];
#if !defined(CHAR_BIT) || CHAR_BIT == 8
int32_t intrep;
#elif CHAR_BIT == 16
int64_t intrep;
#else
# error "Unexpected or unknown value of CHAR_BIT on this system"
#endif
} fourcharstring;
static const fourcharstring months[] = {
{ "Jan " }, { "Feb " }, { "Mar " }, { "Apr " }, { "May " }, { "Jun " },
{ "Jul " }, { "Aug " }, { "Sep " }, { "Oct " }, { "Nov " }, { "Dec " }
};
static const fourcharstring weekdays[] = {
{ "Sun," }, { "Mon," }, { "Tue," }, { "Wed," }, { "Thu," },
{ "Fri," }, { "Sat," }
};
enum {
HTTPDATE,
COOKIEDATE
};
static int
httpdate(ClientData flavour, Tcl_Interp *I, int argc, Tcl_Obj *CONST objv[])
{
union {
fourcharstring fields[7];
char date[30];
} date;
struct tm tm;
time_t tSec;
Tcl_WideInt wSec;
switch (argc) {
case 1:
time(&tSec);
if ((intptr_t)flavour == COOKIEDATE)
/* Default for cookies is a week from now */
tSec += 7*24*60*60;
break;
case 2:
if (Tcl_GetWideIntFromObj(I, objv[1], &wSec) != TCL_OK)
return TCL_ERROR;
tSec = wSec;
break;
default:
Tcl_WrongNumArgs(I, 1, objv, "?GMT-seconds?");
return TCL_ERROR;
}
gmtime_r(&tSec, &tm);
sprintf(date.date + 4, " %02d XXX %d %02d:%02d:%02d GMT",
tm.tm_mday, tm.tm_year + 1900, tm.tm_hour,
tm.tm_min, tm.tm_sec);
/*
* Now deal with our 4-character strings
*/
date.fields[0].intrep = weekdays[tm.tm_wday].intrep;
date.fields[2].intrep = months[tm.tm_mon].intrep;
if ((intptr_t)flavour == COOKIEDATE)
date.date[7] = date.date[11] = '-';
Tcl_SetObjResult(I, Tcl_NewStringObj(date.date, 29));
return TCL_OK;
}
int
Httpdate_Init(Tcl_Interp *I)
{
Tcl_CreateObjCommand(I, "HttpdDate", httpdate, (void *)HTTPDATE, NULL);
Tcl_CreateObjCommand(I, "cookiedate", httpdate, (void *)COOKIEDATE, NULL);
return TCL_OK;
}
