Cleaner impl. of DEFER

Makefile

@@ -68,11 +68,11 @@ nsjail.o: nsjail.h common.h cmdline.h log.h net.h subproc.h
 cmdline.o: cmdline.h common.h log.h util.h
 contain.o: contain.h common.h log.h mount.h net.h util.h uts.h
 log.o: log.h common.h
-net.o: net.h common.h log.h
 mount.o: mount.h common.h log.h
-user.o: user.h common.h log.h util.h
-subproc.o: subproc.h common.h contain.h log.h net.h sandbox.h user.h util.h
+net.o: net.h common.h log.h
 sandbox.o: sandbox.h common.h log.h seccomp/bpf-helper.h
+subproc.o: subproc.h common.h contain.h log.h net.h sandbox.h user.h util.h
+user.o: user.h common.h log.h util.h
 util.o: util.h common.h log.h
 uts.o: uts.h common.h log.h
 seccomp/bpf-helper.o: seccomp/bpf-helper.h

common.h

@@ -31,6 +31,7 @@
 
 #define ARRAYSIZE(array) (sizeof(array) / sizeof(*array))
 
+/* Go-style defer implementation */
 #define __STRMERGE(a, b) a##b
 #define _STRMERGE(a, b) __STRMERGE(a, b)
 
@@ -40,10 +41,12 @@ static void __attribute__ ((unused)) _clang_cleanup_func(void (^*dfunc) (void))
 	(*dfunc) ();
 }
 
-#define defer(a) void (^_STRMERGE(__df_, __COUNTER__))(void) __attribute__((cleanup(_clang_cleanup_func))) __attribute__((unused)) = ^{ a; }
+#define DEFER(a) void (^_STRMERGE(__defer_f_, __COUNTER__))(void) __attribute__((cleanup(_clang_cleanup_func))) __attribute__((unused)) = ^{ a; }
 #else
 #define __block
-#define defer(a) void _STRMERGE(_cleanup_func_, __LINE__)(void *_STRMERGE(_cleanup_unused_, __LINE__) __attribute__((unused))) { a; } ; int _STRMERGE(_cleanup_var_, __LINE__) __attribute__((cleanup(_STRMERGE(_cleanup_func_, __LINE__)))) __attribute__((unused))
+#define _DEFER(a, count) void _STRMERGE(__defer_f_, count)(void *_defer_arg __attribute__((unused))) { a; } ; \
+    int _STRMERGE(_defer_var_, count) __attribute__((cleanup(_STRMERGE(__defer_f_, count)))) __attribute__((unused))
+#define DEFER(a) _DEFER(a, __COUNTER__)
 #endif
 
 struct pids_t {

contain.c

@@ -204,7 +204,7 @@ static bool containMakeFdsCOEProc(void)
 		PLOG_D("opendir('/proc/self/fd')");
 		return false;
 	}
-	defer(closedir(dir));
+	DEFER(closedir(dir));
 	for (;;) {
 		errno = 0;
 		struct dirent *entry = readdir(dir);

net.c

@@ -62,7 +62,7 @@ bool netInitNsFromParent(struct nsjconf_t * nsjconf, int pid)
 		LOG_E("Could not allocate socket with nl_socket_alloc()");
 		return false;
 	}
-	defer(nl_socket_free(sk));
+	DEFER(nl_socket_free(sk));
 
 	int err;
 	if ((err = nl_connect(sk, NETLINK_ROUTE)) < 0) {
@@ -75,14 +75,14 @@ bool netInitNsFromParent(struct nsjconf_t * nsjconf, int pid)
 		LOG_E("rtnl_link_macvlan_alloc(): %s", nl_geterror(err));
 		return false;
 	}
-	defer(rtnl_link_put(rmv));
+	DEFER(rtnl_link_put(rmv));
 
 	struct nl_cache *link_cache;
 	if ((err = rtnl_link_alloc_cache(sk, AF_UNSPEC, &link_cache)) < 0) {
 		LOG_E("rtnl_link_alloc_cache(): %s", nl_geterror(err));
 		return false;
 	}
-	defer(nl_cache_free(link_cache));
+	DEFER(nl_cache_free(link_cache));
 
 	int master_index = rtnl_link_name2i(link_cache, nsjconf->iface);
 	if (master_index == 0) {
@@ -327,7 +327,7 @@ static bool netIfaceUp(const char *ifacename)
 		PLOG_E("socket(AF_INET, SOCK_STREAM, IPPROTO_IP)");
 		return false;
 	}
-	defer(close(sock));
+	DEFER(close(sock));
 
 	struct ifreq ifr;
 	memset(&ifr, '\0', sizeof(ifr));
@@ -360,7 +360,7 @@ static bool netConfigureVs(struct nsjconf_t *nsjconf)
 		PLOG_E("socket(AF_INET, SOCK_STREAM, IPPROTO_IP)");
 		return false;
 	}
-	defer(close(sock));
+	DEFER(close(sock));
 
 	if (inet_pton(AF_INET, nsjconf->iface_vs_ip, &addr) != 1) {
 		PLOG_E("Cannot convert '%s' into an IPv4 address", nsjconf->iface_vs_ip);

nsjail.c

@@ -115,7 +115,7 @@ static void nsjailListenMode(struct nsjconf_t *nsjconf)
 	if (listenfd == -1) {
 		return;
 	}
-	defer(close(listenfd));
+	DEFER(close(listenfd));
 	for (;;) {
 		if (nsjailSigFatal > 0) {
 			subprocKillAll(nsjconf);

subproc.c

@@ -248,7 +248,7 @@ void subprocRunChild(struct nsjconf_t *nsjconf, int fd_in, int fd_out, int fd_er
 		return;
 	}
 	int subproc_sock = sv[1];
-	defer(close(subproc_sock));
+	DEFER(close(subproc_sock));
 
 	pid_t pid = syscall(__NR_clone, (uintptr_t) flags, NULL, NULL, NULL, (uintptr_t) 0);
 	if (pid == 0) {

util.c

@@ -82,7 +82,7 @@ bool utilWriteBufToFile(char *filename, const void *buf, size_t len, int open_fl
 		PLOG_E("Couldn't open '%s' for R/O", filename);
 		return false;
 	}
-	defer(close(fd));
+	DEFER(close(fd));
 
 	if (utilWriteToFd(fd, buf, len) == false) {
 		PLOG_E("Couldn't write '%zu' bytes to file '%s' (fd='%d')", len, filename, fd);