util: introduce CMSG_FOREACH() macro and make use of it everywhere

It's only marginally shorter then the usual for() loop, but certainly
more readable.

15 files changed, 28 insertions, 21 deletions

diff --git a/src/core/manager.c b/src/core/manager.c
index 564fb5d579..eb80dd1b46 100644
--- a/src/core/manager.c
+++ b/src/core/manager.c
@@ -1546,7 +1546,7 @@ static int manager_dispatch_notify_fd(sd_event_source *source, int fd, uint32_t
                         return -errno;
                 }
 
-                for (cmsg = CMSG_FIRSTHDR(&msghdr); cmsg; cmsg = CMSG_NXTHDR(&msghdr, cmsg)) {
+                CMSG_FOREACH(cmsg, &msghdr) {
                         if (cmsg->cmsg_level == SOL_SOCKET && cmsg->cmsg_type == SCM_RIGHTS) {
 
                                 fd_array = (int*) CMSG_DATA(cmsg);
diff --git a/src/core/namespace.c b/src/core/namespace.c
index 01a817bf23..045321e1d4 100644
--- a/src/core/namespace.c
+++ b/src/core/namespace.c
@@ -696,12 +696,11 @@ int setup_netns(int netns_storage_socket[2]) {
         } else {
                 /* Yay, found something, so let's join the namespace */
 
-                for (cmsg = CMSG_FIRSTHDR(&mh); cmsg; cmsg = CMSG_NXTHDR(&mh, cmsg)) {
+                CMSG_FOREACH(cmsg, &mh)
                         if (cmsg->cmsg_level == SOL_SOCKET && cmsg->cmsg_type == SCM_RIGHTS) {
                                 assert(cmsg->cmsg_len == CMSG_LEN(sizeof(int)));
                                 netns = *(int*) CMSG_DATA(cmsg);
                         }
-                }
 
                 if (setns(netns, CLONE_NEWNET) < 0) {
                         r = -errno;
diff --git a/src/import/importd.c b/src/import/importd.c
index e2df44ad26..05a619ac0c 100644
--- a/src/import/importd.c
+++ b/src/import/importd.c
@@ -599,7 +599,7 @@ static int manager_on_notify(sd_event_source *s, int fd, uint32_t revents, void
 
         cmsg_close_all(&msghdr);
 
-        for (cmsg = CMSG_FIRSTHDR(&msghdr); cmsg; cmsg = CMSG_NXTHDR(&msghdr, cmsg)) {
+        CMSG_FOREACH(cmsg, &msghdr) {
                 if (cmsg->cmsg_level == SOL_SOCKET &&
                            cmsg->cmsg_type == SCM_CREDENTIALS &&
                            cmsg->cmsg_len == CMSG_LEN(sizeof(struct ucred))) {
diff --git a/src/journal/journald-server.c b/src/journal/journald-server.c
index 3353024f4e..32da8d61fc 100644
--- a/src/journal/journald-server.c
+++ b/src/journal/journald-server.c
@@ -1177,7 +1177,7 @@ int server_process_datagram(sd_event_source *es, int fd, uint32_t revents, void
                         return -errno;
                 }
 
-                for (cmsg = CMSG_FIRSTHDR(&msghdr); cmsg; cmsg = CMSG_NXTHDR(&msghdr, cmsg)) {
+                CMSG_FOREACH(cmsg, &msghdr) {
 
                         if (cmsg->cmsg_level == SOL_SOCKET &&
                             cmsg->cmsg_type == SCM_CREDENTIALS &&
diff --git a/src/libsystemd-network/sd-dhcp-client.c b/src/libsystemd-network/sd-dhcp-client.c
index 0193e42d65..6853038b67 100644
--- a/src/libsystemd-network/sd-dhcp-client.c
+++ b/src/libsystemd-network/sd-dhcp-client.c
@@ -1588,7 +1588,7 @@ static int client_receive_message_raw(sd_event_source *s, int fd,
         } else if ((size_t)len < sizeof(DHCPPacket))
                 return 0;
 
-        for (cmsg = CMSG_FIRSTHDR(&msg); cmsg; cmsg = CMSG_NXTHDR(&msg, cmsg)) {
+        CMSG_FOREACH(cmsg, &msg) {
                 if (cmsg->cmsg_level == SOL_PACKET &&
                     cmsg->cmsg_type == PACKET_AUXDATA &&
                     cmsg->cmsg_len == CMSG_LEN(sizeof(struct tpacket_auxdata))) {
diff --git a/src/libsystemd-network/sd-dhcp-server.c b/src/libsystemd-network/sd-dhcp-server.c
index a0a2320efa..cc5e032344 100644
--- a/src/libsystemd-network/sd-dhcp-server.c
+++ b/src/libsystemd-network/sd-dhcp-server.c
@@ -902,7 +902,7 @@ static int server_receive_message(sd_event_source *s, int fd,
         else if ((size_t)len < sizeof(DHCPMessage))
                 return 0;
 
-        for (cmsg = CMSG_FIRSTHDR(&msg); cmsg; cmsg = CMSG_NXTHDR(&msg, cmsg)) {
+        CMSG_FOREACH(cmsg, &msg) {
                 if (cmsg->cmsg_level == IPPROTO_IP &&
                     cmsg->cmsg_type == IP_PKTINFO &&
                     cmsg->cmsg_len == CMSG_LEN(sizeof(struct in_pktinfo))) {
diff --git a/src/libsystemd/sd-bus/bus-container.c b/src/libsystemd/sd-bus/bus-container.c
index f157c25bba..fa7a207448 100644
--- a/src/libsystemd/sd-bus/bus-container.c
+++ b/src/libsystemd/sd-bus/bus-container.c
@@ -222,7 +222,7 @@ int bus_container_connect_kernel(sd_bus *b) {
         if (recvmsg(pair[0], &mh, MSG_NOSIGNAL|MSG_CMSG_CLOEXEC) < 0)
                 return -errno;
 
-        for (cmsg = CMSG_FIRSTHDR(&mh); cmsg; cmsg = CMSG_NXTHDR(&mh, cmsg))
+        CMSG_FOREACH(cmsg, &mh)
                 if (cmsg->cmsg_level == SOL_SOCKET && cmsg->cmsg_type == SCM_RIGHTS) {
                         int *fds;
                         unsigned n_fds;
diff --git a/src/libsystemd/sd-bus/bus-socket.c b/src/libsystemd/sd-bus/bus-socket.c
index 9f3756f0c2..322d57ddbb 100644
--- a/src/libsystemd/sd-bus/bus-socket.c
+++ b/src/libsystemd/sd-bus/bus-socket.c
@@ -502,7 +502,6 @@ static int bus_socket_read_auth(sd_bus *b) {
                 struct cmsghdr cmsghdr;
                 uint8_t buf[CMSG_SPACE(sizeof(int) * BUS_FDS_MAX)];
         } control;
-        struct cmsghdr *cmsg;
         bool handle_cmsg = false;
 
         assert(b);
@@ -552,8 +551,10 @@ static int bus_socket_read_auth(sd_bus *b) {
 
         b->rbuffer_size += k;
 
-        if (handle_cmsg)
-                for (cmsg = CMSG_FIRSTHDR(&mh); cmsg; cmsg = CMSG_NXTHDR(&mh, cmsg))
+        if (handle_cmsg) {
+                struct cmsghdr *cmsg;
+
+                CMSG_FOREACH(cmsg, &mh)
                         if (cmsg->cmsg_level == SOL_SOCKET &&
                             cmsg->cmsg_type == SCM_RIGHTS) {
                                 int j;
@@ -567,6 +568,7 @@ static int bus_socket_read_auth(sd_bus *b) {
                         } else
                                 log_debug("Got unexpected auxiliary data with level=%d and type=%d",
                                           cmsg->cmsg_level, cmsg->cmsg_type);
+        }
 
         r = bus_socket_auth_verify(b);
         if (r != 0)
@@ -916,7 +918,6 @@ int bus_socket_read_message(sd_bus *bus) {
                 struct cmsghdr cmsghdr;
                 uint8_t buf[CMSG_SPACE(sizeof(int) * BUS_FDS_MAX)];
         } control;
-        struct cmsghdr *cmsg;
         bool handle_cmsg = false;
 
         assert(bus);
@@ -961,8 +962,10 @@ int bus_socket_read_message(sd_bus *bus) {
 
         bus->rbuffer_size += k;
 
-        if (handle_cmsg)
-                for (cmsg = CMSG_FIRSTHDR(&mh); cmsg; cmsg = CMSG_NXTHDR(&mh, cmsg))
+        if (handle_cmsg) {
+                struct cmsghdr *cmsg;
+
+                CMSG_FOREACH(cmsg, &mh)
                         if (cmsg->cmsg_level == SOL_SOCKET &&
                             cmsg->cmsg_type == SCM_RIGHTS) {
                                 int n, *f;
@@ -990,6 +993,7 @@ int bus_socket_read_message(sd_bus *bus) {
                         } else
                                 log_debug("Got unexpected auxiliary data with level=%d and type=%d",
                                           cmsg->cmsg_level, cmsg->cmsg_type);
+        }
 
         r = bus_socket_read_message_need(bus, &need);
         if (r < 0)
diff --git a/src/libsystemd/sd-rtnl/rtnl-message.c b/src/libsystemd/sd-rtnl/rtnl-message.c
index bab2a4ff08..9dcf7df559 100644
--- a/src/libsystemd/sd-rtnl/rtnl-message.c
+++ b/src/libsystemd/sd-rtnl/rtnl-message.c
@@ -1442,7 +1442,7 @@ static int socket_recv_message(int fd, struct iovec *iov, uint32_t *_group, bool
                 return (errno == EAGAIN || errno == EINTR) ? 0 : -errno;
         }
 
-        for (cmsg = CMSG_FIRSTHDR(&msg); cmsg; cmsg = CMSG_NXTHDR(&msg, cmsg)) {
+        CMSG_FOREACH(cmsg, &msg) {
                 if (cmsg->cmsg_level == SOL_SOCKET &&
                     cmsg->cmsg_type == SCM_CREDENTIALS &&
                     cmsg->cmsg_len == CMSG_LEN(sizeof(struct ucred))) {
diff --git a/src/resolve/resolved-dns-stream.c b/src/resolve/resolved-dns-stream.c
index 4c0b557bad..7f47e7223a 100644
--- a/src/resolve/resolved-dns-stream.c
+++ b/src/resolve/resolved-dns-stream.c
@@ -113,7 +113,8 @@ static int dns_stream_identify(DnsStream *s) {
 
         mh.msg_control = &control;
         mh.msg_controllen = sl;
-        for (cmsg = CMSG_FIRSTHDR(&mh); cmsg; cmsg = CMSG_NXTHDR(&mh, cmsg)) {
+
+        CMSG_FOREACH(cmsg, &mh) {
 
                 if (cmsg->cmsg_level == IPPROTO_IPV6) {
                         assert(s->peer.sa.sa_family == AF_INET6);
diff --git a/src/resolve/resolved-manager.c b/src/resolve/resolved-manager.c
index 52695376f0..7fc2803ddb 100644
--- a/src/resolve/resolved-manager.c
+++ b/src/resolve/resolved-manager.c
@@ -920,7 +920,7 @@ int manager_recv(Manager *m, int fd, DnsProtocol protocol, DnsPacket **ret) {
         } else
                 return -EAFNOSUPPORT;
 
-        for (cmsg = CMSG_FIRSTHDR(&mh); cmsg; cmsg = CMSG_NXTHDR(&mh, cmsg)) {
+        CMSG_FOREACH(cmsg, &mh) {
 
                 if (cmsg->cmsg_level == IPPROTO_IPV6) {
                         assert(p->family == AF_INET6);
diff --git a/src/shared/macro.h b/src/shared/macro.h
index 7ae1ed80b6..cc1c9e73c0 100644
--- a/src/shared/macro.h
+++ b/src/shared/macro.h
@@ -467,4 +467,7 @@ do {                                                                    \
         }                                                       \
         struct __useless_struct_to_allow_trailing_semicolon__
 
+#define CMSG_FOREACH(cmsg, mh)                                          \
+        for ((cmsg) = CMSG_FIRSTHDR(mh); (cmsg); (cmsg) = CMSG_NXTHDR((mh), (cmsg)))
+
 #include "log.h"
diff --git a/src/shared/util.c b/src/shared/util.c
index a20e7bb2ef..6f6906f877 100644
--- a/src/shared/util.c
+++ b/src/shared/util.c
@@ -5520,7 +5520,7 @@ int openpt_in_namespace(pid_t pid, int flags) {
         if (recvmsg(pair[0], &mh, MSG_NOSIGNAL|MSG_CMSG_CLOEXEC) < 0)
                 return -errno;
 
-        for (cmsg = CMSG_FIRSTHDR(&mh); cmsg; cmsg = CMSG_NXTHDR(&mh, cmsg))
+        CMSG_FOREACH(cmsg, &mh)
                 if (cmsg->cmsg_level == SOL_SOCKET && cmsg->cmsg_type == SCM_RIGHTS) {
                         int *fds;
                         unsigned n_fds;
@@ -5908,7 +5908,7 @@ void cmsg_close_all(struct msghdr *mh) {
 
         assert(mh);
 
-        for (cmsg = CMSG_FIRSTHDR(mh); cmsg; cmsg = CMSG_NXTHDR(mh, cmsg))
+        CMSG_FOREACH(cmsg, mh)
                 if (cmsg->cmsg_level == SOL_SOCKET && cmsg->cmsg_type == SCM_RIGHTS)
                         close_many((int*) CMSG_DATA(cmsg), (cmsg->cmsg_len - CMSG_LEN(0)) / sizeof(int));
 }
diff --git a/src/timesync/timesyncd-manager.c b/src/timesync/timesyncd-manager.c
index 88e9cf98ed..40e0fd31fe 100644
--- a/src/timesync/timesyncd-manager.c
+++ b/src/timesync/timesyncd-manager.c
@@ -528,7 +528,7 @@ static int manager_receive_response(sd_event_source *source, int fd, uint32_t re
         }
 
         recv_time = NULL;
-        for (cmsg = CMSG_FIRSTHDR(&msghdr); cmsg; cmsg = CMSG_NXTHDR(&msghdr, cmsg)) {
+        CMSG_FOREACH(cmsg, &msghdr) {
                 if (cmsg->cmsg_level != SOL_SOCKET)
                         continue;
 
diff --git a/src/udev/udevd.c b/src/udev/udevd.c
index 26aae89990..2affb5944a 100644
--- a/src/udev/udevd.c
+++ b/src/udev/udevd.c
@@ -875,7 +875,7 @@ static int on_worker(sd_event_source *s, int fd, uint32_t revents, void *userdat
                         continue;
                 }
 
-                for (cmsg = CMSG_FIRSTHDR(&msghdr); cmsg; cmsg = CMSG_NXTHDR(&msghdr, cmsg)) {
+                CMSG_FOREACH(cmsg, &msghdr) {
                         if (cmsg->cmsg_level == SOL_SOCKET &&
                             cmsg->cmsg_type == SCM_CREDENTIALS &&
                             cmsg->cmsg_len == CMSG_LEN(sizeof(struct ucred)))