There were so far only 42 different conversion specifications in

strftime(3), add another one. :)  %z yields the local timezone's offset
in hours and minutes, as used in RFC822 headers.  There's a precedence
for this in Lunux' libc, and Internet software (like Perl scripts)
start using it.

OKed by (wrt. the code freeze): jkh

2 files changed, 22 insertions, 0 deletions

diff --git a/lib/libc/stdtime/strftime.3 b/lib/libc/stdtime/strftime.3
index c4d2d8c..9b21843 100644
--- a/lib/libc/stdtime/strftime.3
+++ b/lib/libc/stdtime/strftime.3
@@ -202,6 +202,11 @@ is replaced by the year with century as a decimal number.
 is replaced by the year without century as a decimal number (00-99).
 .It Cm \&%Z
 is replaced by the time zone name.
+.It Cm \&%z
+is replaced by the time zone offset from UTC; a leading plus sign stands for
+east of UTC, a minus sign for west of UTC, hours and minutes follow
+with two digits each and no delimiter between them (common form for
+RFC 822 date headers).
 .It Cm %+
 is replaced by national representation of the date and time
 (the format is similar to that produced by
@@ -241,6 +246,7 @@ with a lot of extensions including
 .Ql %t ,
 .Ql %u ,
 .Ql \&%V ,
+.Ql %z ,
 .Ql %+ .
 
 The peculiar week number and year in the replacements of
diff --git a/lib/libc/stdtime/strftime.c b/lib/libc/stdtime/strftime.c
index 9aa891f..6404d9c 100644
--- a/lib/libc/stdtime/strftime.c
+++ b/lib/libc/stdtime/strftime.c
@@ -397,6 +397,22 @@ label:
 						pt, ptlim);
 				} else  pt = _add("?", pt, ptlim);
 				continue;
+			case 'z':
+				{
+					long absoff;
+					if (t->tm_gmtoff >= 0) {
+						absoff = t->tm_gmtoff;
+						pt = _add("+", pt, ptlim);
+					} else {
+						absoff = -t->tm_gmtoff;
+						pt = _add("-", pt, ptlim);
+					}
+					pt = _conv(absoff / 3600, "%02d",
+						pt, ptlim);
+					pt = _conv((absoff % 3600) / 60, "%02d",
+						pt, ptlim);
+				};
+				continue;
 			case '+':
 				pt = _fmt(Locale->date_fmt, t, pt, ptlim);
 				continue;