[PATCH v6 2/2] strbuf: change an always NULL/"" strbuf_addftime() param to bool

["Ævar Arnfjörð Bjarmason" <avarab@gmail.com>]

strbuf_addstr() allows callers to pass a time zone name for expanding
%Z. The only current caller either passes the empty string or NULL, in
which case %Z is handed over verbatim to strftime(3).  Replace that
string parameter with a flag controlling whether to remove %Z from the
format specification. This simplifies the code.

Commit-message-by: René Scharfe <l.s.r@web.de>
Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
---

On Sat, Jun 24 2017, Junio C. Hamano jotted:
> René Scharfe <l.s.r@web.de> writes:
>> Here's an attempt at a commit message that would have be easier to
>> understand for me:
>>
>>   strbuf_addstr() allows callers to pass a time zone name for expanding
>>   %Z.  The only current caller either passes the empty string or NULL,
>>   in which case %Z is handed over verbatim to strftime(3).  Replace that
>>   string parameter with a flag controlling whether to remove %Z from the
>>   format specification.  This simplifies the code.
>
> I think the first one is strbuf_addftime(); other than that, I think
> this version explains what is going on in this patch than the
> original.
>
> I'll wait for Ævar to respond, but my inclination is to take the
> patch with the above tweaks to the log message, as the change is
> easy to revert if we find it necessary.

Thanks both. Here's a v6 with those changes, sorry about the delay.

 date.c   | 2 +-
 strbuf.c | 5 ++---
 strbuf.h | 5 +++--
 3 files changed, 6 insertions(+), 6 deletions(-)

diff --git a/date.c b/date.c
index 1fd6d66375..c3e673fd04 100644
--- a/date.c
+++ b/date.c
@@ -256,7 +256,7 @@ const char *show_date(timestamp_t time, int tz, const struct date_mode *mode)
 			tm->tm_hour, tm->tm_min, tm->tm_sec, tz);
 	else if (mode->type == DATE_STRFTIME)
 		strbuf_addftime(&timebuf, mode->strftime_fmt, tm, tz,
-				mode->local ? NULL : "");
+				!mode->local);
 	else
 		strbuf_addf(&timebuf, "%.3s %.3s %d %02d:%02d:%02d %d%c%+05d",
 				weekday_names[tm->tm_wday],
diff --git a/strbuf.c b/strbuf.c
index c4e91a6656..89d22e3b09 100644
--- a/strbuf.c
+++ b/strbuf.c
@@ -779,7 +779,7 @@ char *xstrfmt(const char *fmt, ...)
 }
 
 void strbuf_addftime(struct strbuf *sb, const char *fmt, const struct tm *tm,
-		     int tz_offset, const char *tz_name)
+		     int tz_offset, int suppress_tz_name)
 {
 	struct strbuf munged_fmt = STRBUF_INIT;
 	size_t hint = 128;
@@ -808,8 +808,7 @@ void strbuf_addftime(struct strbuf *sb, const char *fmt, const struct tm *tm,
 			fmt++;
 			break;
 		case 'Z':
-			if (tz_name) {
-				strbuf_addstr(&munged_fmt, tz_name);
+			if (suppress_tz_name) {
 				fmt++;
 				break;
 			}
diff --git a/strbuf.h b/strbuf.h
index 6809d7daa8..2075384e0b 100644
--- a/strbuf.h
+++ b/strbuf.h
@@ -337,11 +337,12 @@ extern void strbuf_vaddf(struct strbuf *sb, const char *fmt, va_list ap);
  * `tz_offset` is in decimal hhmm format, e.g. -600 means six hours west
  * of Greenwich, and it's used to expand %z internally.  However, tokens
  * with modifiers (e.g. %Ez) are passed to `strftime`.
- * `tz_name` is used to expand %Z internally unless it's NULL.
+ * `suppress_tz_name`, when set, expands %Z internally to the empty
+ * string rather than passing it to `strftime`.
  */
 extern void strbuf_addftime(struct strbuf *sb, const char *fmt,
 			    const struct tm *tm, int tz_offset,
-			    const char *tz_name);
+			    int suppress_tz_name);
 
 /**
  * Read a given size of data from a FILE* pointer to the buffer.
-- 
2.13.1.611.g7e3b11ae1