Add a common MAC address printing routine

* print_mac.c: New file.
* Makefile.am (strace_SOURCES): Add it.
* defs.h (sprint_mac_addr): New declaration.
(print_mac_addr): New function, a thin wrapper around sprint_mac_addr.
* print_fields.h (PRINT_FIELD_MAC, PRINT_FIELD_MAC_SZ): New macros.
* rtnl_link.c (decode_ifla_bridge_id): Use PRINT_FIELD_MAC for bridge
address printing.
* sock.c (print_ifreq) <case SIOCGIFHWADDR>: Use print_mac_addr for
ifr_hwaddr printing.
* sockaddr.c (print_sockaddr_data_bt): Use print_mac_addr for
{sco,rc,l2}_bdaddr field printing.

Co-Authored-by: Dmitry V. Levin <[email protected]>

Author: esyr

Makefile.am

@@ -242,6 +242,7 @@ strace_SOURCES =	\
 	print_group_req.c \
 	print_fields.h	\
 	print_ifindex.c	\
+	print_mac.c	\
 	print_mq_attr.c	\
 	print_msgbuf.c	\
 	print_sg_req_info.c \

defs.h

@@ -687,6 +687,9 @@ extern const char *sprintflags_ex(const char *prefix, const struct xlat *xlat,
 extern const char *sprinttime(long long sec);
 extern const char *sprinttime_nsec(long long sec, unsigned long long nsec);
 extern const char *sprinttime_usec(long long sec, unsigned long long usec);
+
+extern const char *sprint_mac_addr(const uint8_t addr[], size_t size);
+
 extern void print_symbolic_mode_t(unsigned int);
 extern void print_numeric_umode_t(unsigned short);
 extern void print_numeric_long_umask(unsigned long);
@@ -969,6 +972,13 @@ extern void tprints(const char *str);
 extern void tprintf_comment(const char *fmt, ...) ATTRIBUTE_FORMAT((printf, 1, 2));
 extern void tprints_comment(const char *str);
 
+static inline void
+print_mac_addr(const char *prefix, const uint8_t addr[], size_t size)
+{
+	tprints(prefix);
+	tprints(sprint_mac_addr(addr, size));
+}
+
 #if SUPPORTED_PERSONALITIES > 1
 extern void set_personality(unsigned int personality);
 extern unsigned current_personality;

print_fields.h

@@ -220,4 +220,17 @@
 		printpath((tcp_), (where_).field_);			\
 	} while (0)
 
+#define PRINT_FIELD_MAC(prefix_, where_, field_)			\
+	PRINT_FIELD_MAC_SZ((prefix_), (where_), field_,			\
+			   ARRAY_SIZE((where_).field_))
+
+#define PRINT_FIELD_MAC_SZ(prefix_, where_, field_, size_)		\
+	do {								\
+		static_assert(sizeof(((where_).field_)[0]) == 1,	\
+			      "MAC address is not a byte array");	\
+		STRACE_PRINTF("%s%s=", (prefix_), #field_);		\
+		print_mac_addr("", (const uint8_t *) ((where_).field_),	\
+			       (size_));				\
+	} while (0)
+
 #endif /* !STRACE_PRINT_FIELDS_H */

print_mac.c

@@ -0,0 +1,55 @@
+/*
+ * Copyright (c) 2018 The strace developers.
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ * 3. The name of the author may not be used to endorse or promote products
+ *    derived from this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
+ * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
+ * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
+ * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
+ * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
+ * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#include "defs.h"
+
+#include "error_prints.h"
+#include "xstring.h"
+
+#ifndef MAX_ADDR_LEN
+# define MAX_ADDR_LEN 32
+#endif
+
+const char *
+sprint_mac_addr(const uint8_t addr[], size_t size)
+{
+	static char res[MAX_ADDR_LEN * 3];
+
+	if (size > MAX_ADDR_LEN) {
+		error_func_msg("Address size (%zu) is more than maximum "
+			       "supported (%u)", size, MAX_ADDR_LEN);
+
+		return NULL;
+	}
+
+	char *ptr = res;
+
+	for (size_t i = 0; i < size; i++)
+		ptr = xappendstr(res, ptr, "%s%02x", i ? ":" : "", addr[i]);
+
+	return res;
+}

rtnl_link.c

@@ -113,10 +113,9 @@ decode_ifla_bridge_id(struct tcb *const tcp,
 	if (len < sizeof(id))
 		return false;
 	else if (!umove_or_printaddr(tcp, addr, &id)) {
-		tprintf("{prio=[%u, %u], addr=%02x:%02x:%02x:%02x:%02x:%02x}",
-			id.prio[0], id.prio[1],
-			id.addr[0], id.addr[1], id.addr[2],
-			id.addr[3], id.addr[4], id.addr[5]);
+		tprintf("{prio=[%u, %u]", id.prio[0], id.prio[1]);
+		PRINT_FIELD_MAC(", ", id, addr);
+		tprints("}");
 	}
 
 	return true;

sock.c

@@ -78,11 +78,8 @@ print_ifreq(struct tcb *const tcp, const unsigned int code,
 	case SIOCGIFHWADDR: {
 		/* XXX Are there other hardware addresses
 		   than 6-byte MACs?  */
-		const unsigned char *bytes =
-			(unsigned char *) &ifr->ifr_hwaddr.sa_data;
-		tprintf("ifr_hwaddr=%02x:%02x:%02x:%02x:%02x:%02x",
-			bytes[0], bytes[1], bytes[2],
-			bytes[3], bytes[4], bytes[5]);
+		print_mac_addr("ifr_hwaddr=",
+			       (const uint8_t *) &ifr->ifr_hwaddr.sa_data, 6);
 		break;
 	}
 	case SIOCSIFFLAGS:

sockaddr.c

@@ -384,29 +384,22 @@ print_sockaddr_data_bt(const void *const buf, const int addrlen)
 		}
 		case sizeof(struct sockaddr_sco): {
 			const struct sockaddr_sco *const sco = buf;
-			tprintf("sco_bdaddr=%02x:%02x:%02x:%02x:%02x:%02x",
-				sco->sco_bdaddr.b[0], sco->sco_bdaddr.b[1],
-				sco->sco_bdaddr.b[2], sco->sco_bdaddr.b[3],
-				sco->sco_bdaddr.b[4], sco->sco_bdaddr.b[5]);
+			print_mac_addr("sco_bdaddr=", sco->sco_bdaddr.b,
+				       sizeof(sco->sco_bdaddr.b));
 			break;
 		}
 		case sizeof(struct sockaddr_rc): {
 			const struct sockaddr_rc *const rc = buf;
-			tprintf("rc_bdaddr=%02x:%02x:%02x:%02x:%02x:%02x"
-				", rc_channel=%u",
-				rc->rc_bdaddr.b[0], rc->rc_bdaddr.b[1],
-				rc->rc_bdaddr.b[2], rc->rc_bdaddr.b[3],
-				rc->rc_bdaddr.b[4], rc->rc_bdaddr.b[5],
-				rc->rc_channel);
+			print_mac_addr("rc_bdaddr=", rc->rc_bdaddr.b,
+				       sizeof(rc->rc_bdaddr.b));
+			tprintf(", rc_channel=%u", rc->rc_channel);
 			break;
 		}
 		case sizeof(struct sockaddr_l2): {
 			const struct sockaddr_l2 *const l2 = buf;
 			print_bluetooth_l2_psm("l2_psm=", l2->l2_psm);
-			tprintf(", l2_bdaddr=%02x:%02x:%02x:%02x:%02x:%02x",
-				l2->l2_bdaddr.b[0], l2->l2_bdaddr.b[1],
-				l2->l2_bdaddr.b[2], l2->l2_bdaddr.b[3],
-				l2->l2_bdaddr.b[4], l2->l2_bdaddr.b[5]);
+			print_mac_addr(", l2_bdaddr=", l2->l2_bdaddr.b,
+				       sizeof(l2->l2_bdaddr.b));
 			print_bluetooth_l2_cid(", l2_cid=", l2->l2_cid);
 			tprints(", l2_bdaddr_type=");
 			printxval_index(bdaddr_types, l2->l2_bdaddr_type,