There is no portable way to pass timezone information to strftime. Add
parameters for timezone offset and name to strbuf_addftime and let it
handle the timezone-related format specifiers %z and %Z internally.
Callers can opt out for %Z by passing NULL as timezone name. %z is
always handled internally -- this helps on Windows, where strftime would
expand it to a timezone name (same as %Z), in violation of POSIX.
Modifiers are not handled, e.g. %Ez is still passed to strftime.
Use an empty string as timezone name in show_date (the only current
caller) for now because we only have the timezone offset in non-local
mode. POSIX allows %Z to resolve to an empty string in case of missing
information.
Helped-by: Ulrich Mueller <ulm@xxxxxxxxxx>
Helped-by: Jeff King <peff@xxxxxxxx>
Signed-off-by: Rene Scharfe <l.s.r@xxxxxx>
---
Changes from v3:
- Updated developer documentation in strbuf.h.
- Added short note to user documentation.
Documentation/rev-list-options.txt | 3 ++-
date.c | 2 +-
strbuf.c | 41 ++++++++++++++++++++++++++++++++++----
strbuf.h | 10 ++++++++--
t/t0006-date.sh | 6 ++++++
5 files changed, 54 insertions(+), 8 deletions(-)
diff --git a/Documentation/rev-list-options.txt b/Documentation/rev-list-options.txt
index a46f70c2b1..34ae2553f1 100644
--- a/Documentation/rev-list-options.txt
+++ b/Documentation/rev-list-options.txt
@@ -768,7 +768,8 @@ timezone value.
1970). As with `--raw`, this is always in UTC and therefore `-local`
has no effect.
+
-`--date=format:...` feeds the format `...` to your system `strftime`.
+`--date=format:...` feeds the format `...` to your system `strftime`,
+except for %z and %Z, which are handled internally.
Use `--date=format:%c` to show the date in your system locale's
preferred format. See the `strftime` manual for a complete list of
format placeholders. When using `-local`, the correct syntax is
diff --git a/date.c b/date.c
index 63fa99685e..5580577334 100644
--- a/date.c
+++ b/date.c
@@ -246,7 +246,7 @@ const char *show_date(timestamp_t time, int tz, const struct date_mode *mode)
month_names[tm->tm_mon], tm->tm_year + 1900,
tm->tm_hour, tm->tm_min, tm->tm_sec, tz);
else if (mode->type == DATE_STRFTIME)
- strbuf_addftime(&timebuf, mode->strftime_fmt, tm);
+ strbuf_addftime(&timebuf, mode->strftime_fmt, tm, tz, "");
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 00457940cf..be3b9e37b1 100644
--- a/strbuf.c
+++ b/strbuf.c
@@ -785,14 +785,48 @@ char *xstrfmt(const char *fmt, ...)
return ret;
}
-void strbuf_addftime(struct strbuf *sb, const char *fmt, const struct tm *tm)
+void strbuf_addftime(struct strbuf *sb, const char *fmt, const struct tm *tm,
+ int tz_offset, const char *tz_name)
{
+ struct strbuf munged_fmt = STRBUF_INIT;
size_t hint = 128;
size_t len;
if (!*fmt)
return;
+ /*
+ * There is no portable way to pass timezone information to
+ * strftime, so we handle %z and %Z here.
+ */
+ for (;;) {
+ const char *percent = strchrnul(fmt, '%');
+ strbuf_add(&munged_fmt, fmt, percent - fmt);
+ if (!*percent)
+ break;
+ fmt = percent + 1;
+ switch (*fmt) {
+ case '%':
+ strbuf_addstr(&munged_fmt, "%%");
+ fmt++;
+ break;
+ case 'z':
+ strbuf_addf(&munged_fmt, "%+05d", tz_offset);
+ fmt++;
+ break;
+ case 'Z':
+ if (tz_name) {
+ strbuf_addstr(&munged_fmt, tz_name);
+ fmt++;
+ break;
+ }
+ /* FALLTHROUGH */
+ default:
+ strbuf_addch(&munged_fmt, '%');
+ }
+ }
+ fmt = munged_fmt.buf;
+
strbuf_grow(sb, hint);
len = strftime(sb->buf + sb->len, sb->alloc - sb->len, fmt, tm);
@@ -804,17 +838,16 @@ void strbuf_addftime(struct strbuf *sb, const char *fmt, const struct tm *tm)
* output contains at least one character, and then drop the extra
* character before returning.
*/
- struct strbuf munged_fmt = STRBUF_INIT;
- strbuf_addf(&munged_fmt, "%s ", fmt);
+ strbuf_addch(&munged_fmt, ' ');
while (!len) {
hint *= 2;
strbuf_grow(sb, hint);
len = strftime(sb->buf + sb->len, sb->alloc - sb->len,
munged_fmt.buf, tm);
}
- strbuf_release(&munged_fmt);
len--; /* drop munged space */
}
+ strbuf_release(&munged_fmt);
strbuf_setlen(sb, sb->len + len);
}
diff --git a/strbuf.h b/strbuf.h
index 80047b1bb7..4559035c47 100644
--- a/strbuf.h
+++ b/strbuf.h
@@ -340,8 +340,14 @@ extern void strbuf_vaddf(struct strbuf *sb, const char *fmt, va_list ap);
/**
* Add the time specified by `tm`, as formatted by `strftime`.
- */
-extern void strbuf_addftime(struct strbuf *sb, const char *fmt, const struct tm *tm);
+ * `tz_name` is used to expand %Z internally unless it's NULL.
+ * `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`.
+ */
+extern void strbuf_addftime(struct strbuf *sb, const char *fmt,
+ const struct tm *tm, int tz_offset,
+ const char *tz_name);
/**
* Read a given size of data from a FILE* pointer to the buffer.
diff --git a/t/t0006-date.sh b/t/t0006-date.sh
index 42d4ea61ef..71082008f0 100755
--- a/t/t0006-date.sh
+++ b/t/t0006-date.sh
@@ -51,6 +51,12 @@ check_show iso-local "$TIME" '2016-06-15 14:13:20 +0000'
check_show raw-local "$TIME" '1466000000 +0000'
check_show unix-local "$TIME" '1466000000'
+check_show 'format:%z' "$TIME" '+0200'
+check_show 'format-local:%z' "$TIME" '+0000'
+check_show 'format:%Z' "$TIME" ''
+check_show 'format:%%z' "$TIME" '%z'
+check_show 'format-local:%%z' "$TIME" '%z'
+
# arbitrary time absurdly far in the future
FUTURE="5758122296 -0400"
check_show iso "$FUTURE" "2152-06-19 18:24:56 -0400" TIME_IS_64BIT,TIME_T_IS_64BIT
--
2.13.0