Add _buf() functions to bypass static string buffers

We have a number of static buffers in use in libosmo*.  This means
the related functions are not usable in a thread-safe way.  While
we so far don't have many multi-threaded programs in the osmocom
universe, the static buffers also prevent us from calling the same
e.g. string-ify function twice within a single printf() call.

Let's make sure there's an alternative function in all those cases,
where the user can pass in a caller-allocated buffer + size, and make
the 'classic' function with the static buffer a wrapper around that
_buf() variant.

Change-Id: Ibf85f79e93244f53b2684ff6f1095c5b41203e05

1 files changed, 10 insertions, 6 deletions

diff --git a/src/gb/gprs_ns.c b/src/gb/gprs_ns.c
index c7ff78ed..fc120cec 100644
--- a/src/gb/gprs_ns.c
+++ b/src/gb/gprs_ns.c
@@ -1525,17 +1525,15 @@ int gprs_ns_rcvmsg(struct gprs_ns_inst *nsi, struct msgb *msg,
 	return rc;
 }
 
-const char *gprs_ns_ll_str(const struct gprs_nsvc *nsvc)
+char *gprs_ns_ll_str_buf(char *buf, size_t buf_len, const struct gprs_nsvc *nsvc)
 {
-	static char buf[80];
-
 	switch(nsvc->ll) {
 	case GPRS_NS_LL_UDP:
-		snprintf(buf, sizeof(buf), "%s:%u",
+		snprintf(buf, buf_len, "%s:%u",
 			 inet_ntoa(nsvc->ip.bts_addr.sin_addr), osmo_ntohs(nsvc->ip.bts_addr.sin_port));
 		break;
 	case GPRS_NS_LL_FR_GRE:
-		snprintf(buf, sizeof(buf), "%s:%u",
+		snprintf(buf, buf_len, "%s:%u",
 			 inet_ntoa(nsvc->frgre.bts_addr.sin_addr), osmo_ntohs(nsvc->frgre.bts_addr.sin_port));
 		break;
 	default:
@@ -1543,11 +1541,17 @@ const char *gprs_ns_ll_str(const struct gprs_nsvc *nsvc)
 		break;
 	}
 
-	buf[sizeof(buf) - 1] = '\0';
+	buf[buf_len - 1] = '\0';
 
 	return buf;
 }
 
+const char *gprs_ns_ll_str(const struct gprs_nsvc *nsvc)
+{
+	static char buf[80];
+	return gprs_ns_ll_str_buf(buf, sizeof(buf), nsvc);
+}
+
 void gprs_ns_ll_copy(struct gprs_nsvc *nsvc, struct gprs_nsvc *other)
 {
 	nsvc->ll = other->ll;