libbb: add strncpy_IFNAMSIZ

function                                             old     new   delta
...
udhcp_read_interface                                 225     220      -5
brctl_main                                          1151    1146      -5
add_interface                                        109     104      -5
ipaddr_list_or_flush                                2174    2167      -7
do_add_ioctl                                          88      80      -8
vconfig_main                                         249     240      -9
do_del_ioctl                                          78      68     -10
do_iplink                                           1186    1173     -13
do_if_fetch                                          766     753     -13
buffer_fill_and_print                                196     179     -17
parse_args                                          1709    1684     -25
------------------------------------------------------------------------------
(add/remove: 0/0 grow/shrink: 2/20 up/down: 11/-140)         Total: -129 bytes

1 files changed, 8 insertions, 0 deletions

diff --git a/libbb/xfuncs.c b/libbb/xfuncs.c
index e2aee136c..f3c3c538c 100644
--- a/libbb/xfuncs.c
+++ b/libbb/xfuncs.c
@@ -40,6 +40,14 @@ int FAST_FUNC close_on_exec_on(int fd)
         return fcntl(fd, F_SETFD, FD_CLOEXEC);
 }
 
+char* FAST_FUNC strncpy_IFNAMSIZ(char *dst, const char *src)
+{
+#ifndef IFNAMSIZ
+        enum { IFNAMSIZ = 16 };
+#endif
+        return strncpy(dst, src, IFNAMSIZ);
+}
+
 /* Convert unsigned long long value into compact 4-char
  * representation. Examples: "1234", "1.2k", " 27M", "123T"
  * String is not terminated (buf[4] is untouched) */