printf: allow 0 as a flag and allow multiple flags
The '%' character in a format specification may be followed by
one or more flags from the list "+- #0". BusyBox printf didn't
support the '0' flag or allow multiple flags to be provided.
As a result the formats '%0*d' and '%0 d' were considered to be
invalid.
The lack of support for '0' was pointed out by Andrew Snyder on the
musl mailing list:
https://www.openwall.com/lists/musl/2021/12/14/2
function old new delta
printf_main 860 891 +31
.rodata 99281 99282 +1
------------------------------------------------------------------------------
(add/remove: 0/0 grow/shrink: 2/0 up/down: 32/0) Total: 32 bytes
Signed-off-by: Ron Yorston <rmy@pobox.com>
Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
diff --git a/testsuite/printf.tests b/testsuite/printf.tests
index 050edef..728bbf4 100755
--- a/testsuite/printf.tests
+++ b/testsuite/printf.tests
@@ -143,4 +143,14 @@
"printf: %r: invalid format\n""1\n" \
"" ""
+testing "printf treats leading 0 as flag" \
+ "${bb}printf '%0*d\n' 2 1 2>&1; echo \$?" \
+ "01\n""0\n" \
+ "" ""
+
+testing "printf handles multiple flags" \
+ "${bb}printf '%0 d\n' 2 2>&1; echo \$?" \
+ " 2\n""0\n" \
+ "" ""
+
exit $FAILCOUNT