[PATCH iproute2-next 3/9] utils: Reimplement ll_idx_n2a() and introduce ll_idx_a2n()

[Serhey Popovych <serhe.popovych@gmail.com>]

Now all users of ll_idx_n2a() replaced with ll_index_to_name() we can
move it's functionality to ll_index_to_name() and implement index to
name conversion using snprintf() and "if%u".

Use %u specifier in "if%..." template consistently: network device
indexes are always greather than zero.

Also introduce ll_idx_n2a() conterpart: ll_idx_a2n() that is used
to translate name of the "if%u" form to index using sscanf().

Signed-off-by: Serhey Popovych <serhe.popovych@gmail.com>
---
 include/ll_map.h |    4 +++-
 lib/ll_map.c     |   31 +++++++++++++++++++++----------
 2 files changed, 24 insertions(+), 11 deletions(-)

diff --git a/include/ll_map.h b/include/ll_map.h
index c8474e6..8546ff9 100644
--- a/include/ll_map.h
+++ b/include/ll_map.h
@@ -8,9 +8,11 @@ int ll_remember_index(const struct sockaddr_nl *who,
 void ll_init_map(struct rtnl_handle *rth);
 unsigned ll_name_to_index(const char *name);
 const char *ll_index_to_name(unsigned idx);
-const char *ll_idx_n2a(unsigned idx, char *buf);
 int ll_index_to_type(unsigned idx);
 int ll_index_to_flags(unsigned idx);
 unsigned namehash(const char *str);
 
+const char *ll_idx_n2a(unsigned int idx);
+unsigned int ll_idx_a2n(const char *name);
+
 #endif /* __LL_MAP_H__ */
diff --git a/lib/ll_map.c b/lib/ll_map.c
index f65614f..0afe689 100644
--- a/lib/ll_map.c
+++ b/lib/ll_map.c
@@ -136,8 +136,26 @@ int ll_remember_index(const struct sockaddr_nl *who,
 	return 0;
 }
 
-const char *ll_idx_n2a(unsigned idx, char *buf)
+const char *ll_idx_n2a(unsigned int idx)
 {
+	static char buf[IFNAMSIZ];
+
+	snprintf(buf, sizeof(buf), "if%u", idx);
+	return buf;
+}
+
+unsigned int ll_idx_a2n(const char *name)
+{
+	unsigned int idx;
+
+	if (sscanf(name, "if%u", &idx) != 1)
+		return 0;
+	return idx;
+}
+
+const char *ll_index_to_name(unsigned int idx)
+{
+	static char buf[IFNAMSIZ];
 	const struct ll_cache *im;
 
 	if (idx == 0)
@@ -148,18 +166,11 @@ const char *ll_idx_n2a(unsigned idx, char *buf)
 		return im->name;
 
 	if (if_indextoname(idx, buf) == NULL)
-		snprintf(buf, IFNAMSIZ, "if%d", idx);
+		snprintf(buf, IFNAMSIZ, "if%u", idx);
 
 	return buf;
 }
 
-const char *ll_index_to_name(unsigned idx)
-{
-	static char nbuf[IFNAMSIZ];
-
-	return ll_idx_n2a(idx, nbuf);
-}
-
 int ll_index_to_type(unsigned idx)
 {
 	const struct ll_cache *im;
@@ -196,7 +207,7 @@ unsigned ll_name_to_index(const char *name)
 
 	idx = if_nametoindex(name);
 	if (idx == 0)
-		sscanf(name, "if%u", &idx);
+		idx = ll_idx_a2n(name);
 	return idx;
 }
 
-- 
1.7.10.4