Convert osmo_bts_sock.cpp to C

There's no real point in using C++ there, and using C++ makes the
compiler fail to use llist_head in multi-bts patches added later due to:
"""
'offsetof' within non-standard-layout type is conditionally-supported
"""

Change-Id: I8965b5cc5a713e64788b5b6aa183d3035341ddbb

src/Makefile.am

@@ -65,7 +65,7 @@ libgprs_la_SOURCES = \
 	decoding.cpp \
 	llc.cpp \
 	rlc.cpp \
-	osmobts_sock.cpp \
+	osmobts_sock.c \
 	gprs_codel.c \
 	coding_scheme.c \
 	egprs_rlc_compression.cpp \

src/osmobts_sock.c

@@ -25,13 +25,13 @@
 #include <assert.h>
 #include <sys/socket.h>
 #include <sys/un.h>
-extern "C" {
+
 #include <osmocom/core/select.h>
 #include <osmocom/core/msgb.h>
 #include <osmocom/core/linuxlist.h>
 #include <osmocom/core/logging.h>
 #include <osmocom/core/timer.h>
-}
+
 
 #include <pcu_l1_if.h>
 #include <gprs_debug.h>
@@ -41,9 +41,7 @@ extern "C" {
 #include <tbf.h>
 #include <pdch.h>
 
-extern "C" {
 int l1if_close_pdch(void *obj);
-}
 
 /*
  * osmo-bts PCU socket functions
@@ -115,7 +113,7 @@ static void pcu_sock_close(int lost)
 		}
 #endif
 		for (ts = 0; ts < 8; ts++)
-			bts->trx[trx].pdch[ts].disable();
+			pdch_disable(&bts->trx[trx].pdch[ts]);
 /* FIXME: NOT ALL RESOURCES are freed in this case... inconsistent with the other code. Share the code with pcu_l1if.c
 for the reset. */
 		bts_trx_free_all_tbf(&bts->trx[trx]);

src/pcu_l1_if.h

@@ -150,19 +150,18 @@ void pcu_l1if_tx_ptcch(struct gprs_rlcmac_bts *bts,
 void pcu_l1if_tx_agch(bitvec * block, int len);
 
 void pcu_l1if_tx_pch(bitvec * block, int plen, uint16_t pgroup);
-
-int pcu_tx_txt_ind(enum gsm_pcu_if_text_type t, const char *fmt, ...);
-
-int pcu_l1if_open(void);
-void pcu_l1if_close(void);
-
-int pcu_rx(uint8_t msg_type, struct gsm_pcu_if *pcu_prim);
-int pcu_sock_send(struct msgb *msg);
 #endif
 
 #ifdef __cplusplus
 extern "C" {
 #endif
+int pcu_rx(uint8_t msg_type, struct gsm_pcu_if *pcu_prim);
+int pcu_l1if_open(void);
+void pcu_l1if_close(void);
+int pcu_sock_send(struct msgb *msg);
+
+int pcu_tx_txt_ind(enum gsm_pcu_if_text_type t, const char *fmt, ...);
+
 int pcu_rx_rts_req_pdtch(uint8_t trx, uint8_t ts,
 	uint32_t fn, uint8_t block_nr);
 int pcu_rx_rts_req_ptcch(uint8_t trx, uint8_t ts,

src/pdch.cpp

@@ -1031,3 +1031,7 @@ void pdch_free_all_tbf(struct gprs_rlcmac_pdch *pdch)
 			tbf_free(tbf);
 	}
 }
+
+void pdch_disable(struct gprs_rlcmac_pdch *pdch) {
+	pdch->disable();
+}

src/pdch.h

@@ -188,6 +188,7 @@ inline bool gprs_rlcmac_pdch::is_enabled() const
 extern "C" {
 #endif
 void pdch_free_all_tbf(struct gprs_rlcmac_pdch *pdch);
+void pdch_disable(struct gprs_rlcmac_pdch *pdch);
 #ifdef __cplusplus
 }
 #endif

tests/tbf/TbfTest.cpp

@@ -166,7 +166,7 @@ static uint8_t llc_data[200];
 
 /* override, requires '-Wl,--wrap=pcu_sock_send' */
 int __real_pcu_sock_send(struct msgb *msg);
-int __wrap_pcu_sock_send(struct msgb *msg)
+extern "C" int __wrap_pcu_sock_send(struct msgb *msg)
 {
 	return 0;
 }