use %m printf specifier where appropriate

function                                             old     new   delta
out                                                   85      75     -10
udhcpd_main                                         1472    1461     -11
open_stdio_to_tty                                     98      85     -13
init_exec                                            245     232     -13
udhcpc_main                                         2763    2749     -14
do_cmd                                              4771    4755     -16
status_line_bold_errno                                32      14     -18
------------------------------------------------------------------------------
(add/remove: 0/0 grow/shrink: 0/7 up/down: 0/-95)             Total: -95 bytes

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>

1 files changed, 11 insertions, 0 deletions

diff --git a/include/libbb.h b/include/libbb.h
index aff2825ac..daccf154a 100644
--- a/include/libbb.h
+++ b/include/libbb.h
@@ -162,6 +162,17 @@
 #ifndef HAVE_XTABS
 # define XTABS TAB3
 #endif
+/*
+ * Use '%m' to append error string on platforms that support it,
+ * '%s' and strerror() on those that don't.
+ */
+#ifdef HAVE_PRINTF_PERCENTM
+# define STRERROR_FMT    "%m"
+# define STRERROR_ERRNO  /*nothing*/
+#else
+# define STRERROR_FMT    "%s"
+# define STRERROR_ERRNO  ,strerror(errno)
+#endif
 
 
 /* Some libc's forget to declare these, do it ourself */