[tz] [PATCH] Support building zic.exe and zdump.exe natively on Windows with Visual Studio nmake.

[Paul Eggert]

Thanks for sending us that. However, I'd like the source code to be kept 
as POSIX-like as possible, to simplify maintenance, so I'd rather not 
add a lot of #ifdefs in the code proper.

Can you use MinGW for the port instead? That should make maintenance 
considerably simpler, since MinGW supports things like 'getopt' so we 
wouldn't have to supply our own implementation. My impression is that 
MinGW would avoid the need for many of the #ifdefs. See:

http://www.mingw.org/

On 01/25/2018 01:31 AM, Manuela Friedrich wrote:
> In localtime.c use native localtime(), gmtime(), ctime() and mktime().
Why? localtime.c should be implementing localtime, not using the 
MS-Windows-supplied localtime.

> Also use int or __int64 respectively for ssize_t type and check for Windows drive letters in tzloadbody().

For something like that how about just compiling with -Dssize_t=long. 
That should be good enough for MS-Windows and will mean we don't need to 
change the .c files.

> In private.h and zdump.c define strotimax depending on Visual Studio version.
> It needs to be strtol for up to VS 2010 and stroll for higher versions.

tzcode configures this sort of thing with CFLAGS in the makefile. I 
applied the attached patch to the tz development version on GitHub 
<https://github.com/eggert/tz>. So you should be able to build with 
-DHAVE_STRTOLL=0 on older MS-Windows platforms.

> In zdump.c need prototype for gmtime_r() to suffice return type requirements.
> Also use __time64_t variables on Windows instead of time_t.
> In main() variable declarations had to be moved to the top to avoid compile errors.

I hope this is handled better in MinGW so that we don't have to worry 
about redeclaring gmtime_r or using __time64_t instead of time_t. If 
not, then this is better handled in private.h, which already does this 
sort of thing.

> In zic.c dolink() need to have an extra mkdirs() call for Windows as we don't have link support here and the previous mkdirs() calls wouldn't have been called therefore.

Thanks, I put that into the attached patch too.

> Also itsdir() needs separate Windows part to check for directory flag as the namesslashdot Linux alternative alway returns directory on Windows.

Could you explain what goes wrong with namesslashdot on MS-Windows? I 
don't see the bug here. nameslashdot tests whether a file F is a 
directory by statting "F/.". Why doesn't this approach work on MS-Windows?

> Add nmake specific Makefile.nmake based on existing Makefile.

I hope MinGW makes this unnecessary.
> @@ -401,6 +409,13 @@ tzloadbody(char const *name, struct state *sp, bool doextend,
>   	if (name[0] == ':')
>   		++name;
>   	doaccess = name[0] == '/';
> +#ifdef _WIN32
> +	/*
> +	** DOS drive specifier?
> +	*/
> +	if (isalpha(name[0]) && name[1]==':' && name[2] == '\\')
> +		doaccess = true;
> +#endif
>   	if (!doaccess) {
>   		size_t namelen = strlen(name);
>   		if (sizeof lsp->fullname - sizeof tzdirslash <= namelen)

This change should not be needed, as there's no need to support absolute 
file names as TZ specifiers under MS-Windows. (Even if we did, the above 
code would not work on some MS-Windows variants; it's better to avoid 
this messy situation.)
> diff --git a/zdump.c b/zdump.c
> index 60a027e..fc90662 100644
> --- a/zdump.c
> +++ b/zdump.c
> @@ -4,6 +4,9 @@
>   */
>   
>   #include "version.h"
> +#ifdef _WIN32
> +#include <stdlib.h>
> +#endif

I don't see why this is needed, as private.h includes stdlib.h.

> +	struct tm *	newtmp;
>   	bool iflag = false;
> +	bool newtm_ok;
>   
>   	cutlotime = absolute_min_time;
>   	cuthitime = absolute_max_time;
> @@ -531,7 +563,6 @@ main(int argc, char *argv[])
>   	for (i = optind; i < argc; ++i) {
>   		timezone_t tz = tzalloc(argv[i]);
>   		char const *ab;
> -		time_t t;
>   		struct tm tm, newtm;
>   		bool tm_ok;
>   		if (!tz) {
> @@ -562,12 +593,12 @@ main(int argc, char *argv[])
>   		  }
>   		}
>   		while (t < cuthitime) {
> -		  time_t newt = ((t < absolute_max_time - SECSPERDAY / 2
> +		  newt = ((t < absolute_max_time - SECSPERDAY / 2
>   				  && t + SECSPERDAY / 2 < cuthitime)
>   				 ? t + SECSPERDAY / 2
>   				 : cuthitime);
> -		  struct tm *newtmp = localtime_rz(tz, &newt, &newtm);
> -		  bool newtm_ok = newtmp != NULL;
> +		  newtmp = localtime_rz(tz, &newt, &newtm);
> +		  newtm_ok = newtmp != NULL;
>   		  if (tm_ok != newtm_ok
>   		      || (tm_ok && (delta(&newtm, &tm) != newt - t
>   				    || newtm.tm_isdst != tm.tm_isdst

I don't see why these changes are needed, as the code is valid C89 code 
without them.

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