libbb: introduce kernel-style BUILD_BUG_ON()

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>

include/libbb.h

@@ -1901,6 +1901,7 @@ extern const char bb_default_login_shell[] ALIGN1;
 
 
 #define ARRAY_SIZE(x) ((unsigned)(sizeof(x) / sizeof((x)[0])))
+#define BUILD_BUG_ON(condition) ((void)sizeof(char[1 - 2*!!(condition)]))
 
 
 /* We redefine ctype macros. Unicode-correct handling of char types

libbb/procps.c

@@ -283,7 +283,6 @@ int FAST_FUNC procps_read_smaps(pid_t pid, struct smaprec *total,
 }
 #endif
 
-void BUG_comm_size(void);
 procps_status_t* FAST_FUNC procps_scan(procps_status_t* sp, int flags)
 {
 	if (!sp)
@@ -385,8 +384,7 @@ procps_status_t* FAST_FUNC procps_scan(procps_status_t* sp, int flags)
 			/*if (!cp || cp[1] != ' ')
 				continue;*/
 			cp[0] = '\0';
-			if (sizeof(sp->comm) < 16)
-				BUG_comm_size();
+			BUILD_BUG_ON(sizeof(sp->comm) < 16);
 			comm1 = strchr(buf, '(');
 			/*if (comm1)*/
 				safe_strncpy(sp->comm, comm1 + 1, sizeof(sp->comm));

networking/ftpgetput.c

@@ -62,9 +62,6 @@ struct globals {
 } FIX_ALIASING;
 #define G (*(struct globals*)&bb_common_bufsiz1)
 enum { BUFSZ = COMMON_BUFSIZE - offsetof(struct globals, buf) };
-struct BUG_G_too_big {
-	char BUG_G_too_big[sizeof(G) <= COMMON_BUFSIZE ? 1 : -1];
-};
 #define user           (G.user          )
 #define password       (G.password      )
 #define lsa            (G.lsa           )
@@ -72,7 +69,9 @@ struct BUG_G_too_big {
 #define verbose_flag   (G.verbose_flag  )
 #define do_continue    (G.do_continue   )
 #define buf            (G.buf           )
-#define INIT_G() do { } while (0)
+#define INIT_G() do { \
+	BUILD_BUG_ON(sizeof(G) > COMMON_BUFSIZE); \
+} while (0)
 
 
 static void ftp_die(const char *msg) NORETURN;

networking/isrv.c

@@ -194,7 +194,6 @@ static void handle_accept(isrv_state_t *state, int fd)
 		remove_peer(state, n); /* unsuccesful peer start */
 }
 
-void BUG_sizeof_fd_set_is_strange(void);
 static void handle_fd_set(isrv_state_t *state, fd_set *fds, int (*h)(int, void **))
 {
 	enum { LONG_CNT = sizeof(fd_set) / sizeof(long) };
@@ -203,8 +202,7 @@ static void handle_fd_set(isrv_state_t *state, fd_set *fds, int (*h)(int, void *
 	/* need to know value at _the beginning_ of this routine */
 	int fd_cnt = FD_COUNT;
 
-	if (LONG_CNT * sizeof(long) != sizeof(fd_set))
-		BUG_sizeof_fd_set_is_strange();
+	BUILD_BUG_ON(LONG_CNT * sizeof(long) != sizeof(fd_set));
 
 	fds_pos = 0;
 	while (1) {

networking/ping.c

@@ -396,10 +396,8 @@ struct globals {
 #define dotted       (G.dotted      )
 #define pingaddr     (G.pingaddr    )
 #define rcvd_tbl     (G.rcvd_tbl    )
-void BUG_ping_globals_too_big(void);
 #define INIT_G() do { \
-	if (sizeof(G) > COMMON_BUFSIZE) \
-		BUG_ping_globals_too_big(); \
+	BUILD_BUG_ON(sizeof(G) > COMMON_BUFSIZE); \
 	datalen = DEFDATALEN; \
 	timeout = MAXWAIT; \
 	tmin = UINT_MAX; \
@@ -732,7 +730,6 @@ static void ping4(len_and_sockaddr *lsa)
 	}
 }
 #if ENABLE_PING6
-extern int BUG_bad_offsetof_icmp6_cksum(void);
 static void ping6(len_and_sockaddr *lsa)
 {
 	int sockopt;
@@ -769,8 +766,7 @@ static void ping6(len_and_sockaddr *lsa)
 	setsockopt_SOL_SOCKET_int(pingsock, SO_RCVBUF, sockopt);
 
 	sockopt = offsetof(struct icmp6_hdr, icmp6_cksum);
-	if (offsetof(struct icmp6_hdr, icmp6_cksum) != 2)
-		BUG_bad_offsetof_icmp6_cksum();
+	BUILD_BUG_ON(offsetof(struct icmp6_hdr, icmp6_cksum) != 2);
 	setsockopt_int(pingsock, SOL_RAW, IPV6_CHECKSUM, sockopt);
 
 	/* request ttl info to be returned in ancillary data */

networking/tc.c

@@ -64,15 +64,14 @@ struct globals {
 	uint32_t filter_proto;
 } FIX_ALIASING;
 #define G (*(struct globals*)&bb_common_bufsiz1)
-struct BUG_G_too_big {
-	char BUG_G_too_big[sizeof(G) <= COMMON_BUFSIZE ? 1 : -1];
-};
 #define filter_ifindex (G.filter_ifindex)
 #define filter_qdisc (G.filter_qdisc)
 #define filter_parent (G.filter_parent)
 #define filter_prio (G.filter_prio)
 #define filter_proto (G.filter_proto)
-#define INIT_G() do { } while (0)
+#define INIT_G() do { \
+	BUILD_BUG_ON(sizeof(G) > COMMON_BUFSIZE); \
+} while (0)
 
 /* Allocates a buffer containing the name of a class id.
  * The caller must free the returned memory.  */

networking/tftp.c

@@ -129,10 +129,9 @@ struct globals {
 #endif
 } FIX_ALIASING;
 #define G (*(struct globals*)&bb_common_bufsiz1)
-struct BUG_G_too_big {
-	char BUG_G_too_big[sizeof(G) <= COMMON_BUFSIZE ? 1 : -1];
-};
-#define INIT_G() do { } while (0)
+#define INIT_G() do { \
+	BUILD_BUG_ON(sizeof(G) > COMMON_BUFSIZE); \
+} while (0)
 
 #define G_error_pkt_reason (G.error_pkt[3])
 #define G_error_pkt_str    ((char*)(G.error_pkt + 4))

runit/runsv.c

@@ -49,16 +49,11 @@ static void gettimeofday_ns(struct timespec *ts)
 #else
 static void gettimeofday_ns(struct timespec *ts)
 {
-	if (sizeof(struct timeval) == sizeof(struct timespec)
-	 && sizeof(((struct timeval*)ts)->tv_usec) == sizeof(ts->tv_nsec)
-	) {
-		/* Cheat */
-		gettimeofday((void*)ts, NULL);
-		ts->tv_nsec *= 1000;
-	} else {
-		extern void BUG_need_to_implement_gettimeofday_ns(void);
-		BUG_need_to_implement_gettimeofday_ns();
-	}
+	BUILD_BUG_ON(sizeof(struct timeval) != sizeof(struct timespec));
+	BUILD_BUG_ON(sizeof(((struct timeval*)ts)->tv_usec) != sizeof(ts->tv_nsec));
+	/* Cheat */
+	gettimeofday((void*)ts, NULL);
+	ts->tv_nsec *= 1000;
 }
 #endif
 

util-linux/umount.c

@@ -82,11 +82,7 @@ int umount_main(int argc UNUSED_PARAM, char **argv)
 
 	// MNT_FORCE and MNT_DETACH (from linux/fs.h) must match
 	// OPT_FORCE and OPT_LAZY.
-	{
-		typedef char bug[
-			(OPT_FORCE != MNT_FORCE || OPT_LAZY != MNT_DETACH) ? -1 : 1
-		];
-	}
+	BUILD_BUG_ON(OPT_FORCE != MNT_FORCE || OPT_LAZY != MNT_DETACH);
 	doForce = opt & (OPT_FORCE|OPT_LAZY);
 
 	/* Get a list of mount points from mtab.  We read them all in now mostly