strbuf: let strbuf_addftime handle %z and %Z itself

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@gentoo.org>
Helped-by: Jeff King <peff@peff.net>
Signed-off-by: Rene Scharfe <l.s.r@web.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

diff --git a/Documentation/rev-list-options.txt b/Documentation/rev-list-options.txt
index a02f7324c01ee5811441d2a6dcb93aafd892298c..3921066b7f4d3d654aa451ab767aad6795470598 100644 (file)
--- a/Documentation/rev-list-options.txt
+++ b/Documentation/rev-list-options.txt
@@ -764,7 +764,8 @@ 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 a996331f5b33703c9f70844c6b49453ec39d16a7..6eccbd85465761b51fc10b60bf411e2e0c9f530e 100644 (file)
--- a/date.c
+++ b/date.c
@@ -233,7 +233,7 @@ const char *show_date(unsigned long 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 00457940cfc163fed58b0206f5167c25c2c71b8a..be3b9e37b1d969e86e913cc69ccab935f516a063 100644 (file)
--- 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 80047b1bb7b826699deff3e8c2590a2a00a5c121..4559035c47268c0603119b90c7278c08c6b99a09 100644 (file)
--- 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 c0c910867d75368832ce8b297e9dd82ee984a85a..fded9dbd686150fdfb31c023d6ccad476205e8b8 100755 (executable)
--- 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" LONG_IS_64BIT