Make getfdproto return enum instead of string

Introduce a new enum type sock_proto and use it instead of strings for socket
protocols identification.

* defs.h (sock_proto): New enum.
(get_proto_by_name): New function.
* socketutils.c (protocols): New static table.
(print_sockaddr_by_inode): Use it.  Change type of "proto" argument
to sock_proto.
(get_proto_by_name): New function.
* util.c (getfdproto): Use it.  Change return type to sock_proto.
(printfd): Update.

defs.h

@@ -437,6 +437,17 @@ extern const struct xlat whence_codes[];
 # define NEED_UID16_PARSERS 0
 #endif
 
+enum sock_proto {
+	SOCK_PROTO_UNKNOWN,
+	SOCK_PROTO_UNIX,
+	SOCK_PROTO_TCP,
+	SOCK_PROTO_UDP,
+	SOCK_PROTO_TCPv6,
+	SOCK_PROTO_UDPv6,
+	SOCK_PROTO_NETLINK
+};
+extern enum sock_proto get_proto_by_name(const char *);
+
 typedef enum {
 	CFLAG_NONE = 0,
 	CFLAG_ONLY_STATS,
@@ -636,7 +647,7 @@ extern void printpathn(struct tcb *, long, unsigned int);
 #define TIMESPEC_TEXT_BUFSIZE \
 		(sizeof(intmax_t)*3 * 2 + sizeof("{tv_sec=%jd, tv_nsec=%jd}"))
 extern void printfd(struct tcb *, int);
-extern bool print_sockaddr_by_inode(const unsigned long, const char *);
+extern bool print_sockaddr_by_inode(const unsigned long, const enum sock_proto);
 extern bool print_sockaddr_by_inode_cached(const unsigned long);
 extern void print_dirfd(struct tcb *, int);
 extern void printsock(struct tcb *, long, int);

socketutils.c

@@ -438,44 +438,59 @@ netlink_print(const int fd, const unsigned long inode)
 				     netlink_parse_response);
 }
 
+static const struct {
+	const char *const name;
+	bool (*const print)(int, unsigned long);
+} protocols[] = {
+	[SOCK_PROTO_UNIX] = { "UNIX", unix_print },
+	[SOCK_PROTO_TCP] = { "TCP", tcp_v4_print },
+	[SOCK_PROTO_UDP] = { "UDP", udp_v4_print },
+	[SOCK_PROTO_TCPv6] = { "TCPv6", tcp_v6_print },
+	[SOCK_PROTO_UDPv6] = { "UDPv6", udp_v6_print },
+	[SOCK_PROTO_NETLINK] = { "NETLINK", netlink_print }
+};
+
+enum sock_proto
+get_proto_by_name(const char *const name)
+{
+	unsigned int i;
+	for (i = (unsigned int) SOCK_PROTO_UNKNOWN + 1;
+	     i < ARRAY_SIZE(protocols); ++i) {
+		if (protocols[i].name && !strcmp(name, protocols[i].name))
+			return (enum sock_proto) i;
+	}
+	return SOCK_PROTO_UNKNOWN;
+}
+
 /* Given an inode number of a socket, print out the details
  * of the ip address and port. */
+
 bool
-print_sockaddr_by_inode(const unsigned long inode, const char *const proto_name)
+print_sockaddr_by_inode(const unsigned long inode, const enum sock_proto proto)
 {
-	static const struct {
-		const char *const name;
-		bool (*const print)(int, unsigned long);
-	} protocols[] = {
-		{ "TCP", tcp_v4_print },
-		{ "UDP", udp_v4_print },
-		{ "TCPv6", tcp_v6_print },
-		{ "UDPv6", udp_v6_print },
-		{ "UNIX", unix_print },
-		{ "NETLINK", netlink_print }
-	};
+	if ((unsigned int) proto >= ARRAY_SIZE(protocols) ||
+	    (proto != SOCK_PROTO_UNKNOWN && !protocols[proto].print))
+		return false;
 
 	const int fd = socket(AF_NETLINK, SOCK_RAW, NETLINK_SOCK_DIAG);
 	if (fd < 0)
 		return false;
 	bool r = false;
-	unsigned int i;
-
-	if (proto_name) {
-		for (i = 0; i < ARRAY_SIZE(protocols); ++i) {
-			if (strcmp(proto_name, protocols[i].name) == 0) {
-				r = protocols[i].print(fd, inode);
-				break;
-			}
-		}
 
+	if (proto != SOCK_PROTO_UNKNOWN) {
+		r = protocols[proto].print(fd, inode);
 		if (!r) {
-			tprintf("%s:[%lu]", proto_name, inode);
+			tprintf("%s:[%lu]", protocols[proto].name, inode);
 			r = true;
 		}
 	} else {
-		for (i = 0; i < ARRAY_SIZE(protocols); ++i) {
-			if ((r = protocols[i].print(fd, inode)))
+		unsigned int i;
+		for (i = (unsigned int) SOCK_PROTO_UNKNOWN + 1;
+		     i < ARRAY_SIZE(protocols); ++i) {
+			if (!protocols[i].print)
+				continue;
+			r = protocols[i].print(fd, inode);
+			if (r)
 				break;
 		}
 	}

util.c

@@ -472,30 +472,33 @@ sprinttime(time_t t)
 	return buf;
 }
 
-static char *
-getfdproto(struct tcb *tcp, int fd, char *buf, unsigned bufsize)
+static enum sock_proto
+getfdproto(struct tcb *tcp, int fd)
 {
 #ifdef HAVE_SYS_XATTR_H
+	size_t bufsize = 256;
+	char buf[bufsize];
 	ssize_t r;
 	char path[sizeof("/proc/%u/fd/%u") + 2 * sizeof(int)*3];
 
 	if (fd < 0)
-		return NULL;
+		return SOCK_PROTO_UNKNOWN;
 
 	sprintf(path, "/proc/%u/fd/%u", tcp->pid, fd);
 	r = getxattr(path, "system.sockprotoname", buf, bufsize - 1);
 	if (r <= 0)
-		return NULL;
+		return SOCK_PROTO_UNKNOWN;
 	else {
 		/*
 		 * This is a protection for the case when the kernel
 		 * side does not append a null byte to the buffer.
 		 */
 		buf[r] = '\0';
-		return buf;
+
+		return get_proto_by_name(buf);
 	}
 #else
-	return NULL;
+	return SOCK_PROTO_UNKNOWN;
 #endif
 }
 
@@ -516,9 +519,8 @@ printfd(struct tcb *tcp, int fd)
 				strtoul(path + socket_prefix_len, NULL, 10);
 
 			if (!print_sockaddr_by_inode_cached(inode)) {
-				char buf[256];
-				const char *proto =
-					getfdproto(tcp, fd, buf, sizeof(buf));
+				const enum sock_proto proto =
+					getfdproto(tcp, fd);
 				if (!print_sockaddr_by_inode(inode, proto))
 					tprints(path);
 			}