macro: introduce new TAKE_FD() macro

This is similar to TAKE_PTR() but operates on file descriptors, and thus
assigns -1 to the fd parameter after returning it.

Removes 60 lines from our codebase. Pretty good too I think.

coccinelle/take-fd.cocci

@@ -0,0 +1,14 @@
+@@
+local idexpression p;
+expression q;
+@@
+- p = q;
+- q = -1;
+- return p;
++ return TAKE_FD(q);
+@@
+expression p, q;
+@@
+- p = q;
+- q = -1;
++ p = TAKE_FD(q);

src/basic/fd-util.c

@@ -484,10 +484,7 @@ int acquire_data_fd(const void *data, size_t size, unsigned flags) {
                 if (r < 0)
                         return r;
 
-                r = fd;
-                fd = -1;
-
-                return r;
+                return TAKE_FD(fd);
         }
 
 try_pipe:
@@ -524,10 +521,7 @@ try_pipe:
 
                 (void) fd_nonblock(pipefds[0], false);
 
-                r = pipefds[0];
-                pipefds[0] = -1;
-
-                return r;
+                return TAKE_FD(pipefds[0]);
         }
 
 try_dev_shm:

src/basic/fd-util.h

@@ -105,3 +105,11 @@ int rearrange_stdio(int original_input_fd, int original_output_fd, int original_
 static inline int make_null_stdio(void) {
         return rearrange_stdio(-1, -1, -1);
 }
+
+/* Like TAKE_PTR() but for file descriptors, resetting them to -1 */
+#define TAKE_FD(fd)                             \
+        ({                                      \
+                int _fd_ = (fd);                \
+                (fd) = -1;                      \
+                _fd_;                           \
+        })

src/basic/fs-util.c

@@ -730,8 +730,7 @@ int chase_symlinks(const char *path, const char *original_root, unsigned flags,
                         }
 
                         safe_close(fd);
-                        fd = fd_parent;
-                        fd_parent = -1;
+                        fd = TAKE_FD(fd_parent);
 
                         continue;
                 }
@@ -849,8 +848,7 @@ int chase_symlinks(const char *path, const char *original_root, unsigned flags,
 
                 /* And iterate again, but go one directory further down. */
                 safe_close(fd);
-                fd = child;
-                child = -1;
+                fd = TAKE_FD(child);
         }
 
         if (!done) {
@@ -864,16 +862,11 @@ int chase_symlinks(const char *path, const char *original_root, unsigned flags,
                 *ret = TAKE_PTR(done);
 
         if (flags & CHASE_OPEN) {
-                int q;
-
                 /* Return the O_PATH fd we currently are looking to the caller. It can translate it to a proper fd by
                  * opening /proc/self/fd/xyz. */
 
                 assert(fd >= 0);
-                q = fd;
-                fd = -1;
-
-                return q;
+                return TAKE_FD(fd);
         }
 
         return exists;

src/basic/memfd-util.c

@@ -168,8 +168,5 @@ int memfd_new_and_map(const char *name, size_t sz, void **p) {
         if (r < 0)
                 return r;
 
-        r = fd;
-        fd = -1;
-
-        return r;
+        return TAKE_FD(fd);
 }

src/basic/terminal-util.c

@@ -496,10 +496,7 @@ int acquire_terminal(
                 fd = safe_close(fd);
         }
 
-        r = fd;
-        fd = -1;
-
-        return r;
+        return TAKE_FD(fd);
 }
 
 int release_terminal(void) {

src/core/dynamic-user.c

@@ -319,10 +319,7 @@ static int pick_uid(char **suggested_paths, const char *name, uid_t *ret_uid) {
                 (void) make_uid_symlinks(candidate, name, true); /* also add direct lookup symlinks */
 
                 *ret_uid = candidate;
-                r = lock_fd;
-                lock_fd = -1;
-
-                return r;
+                return TAKE_FD(lock_fd);
 
         next:
                 ;

src/core/manager.c

@@ -844,8 +844,7 @@ static int manager_setup_notify(Manager *m) {
                 if (r < 0)
                         return log_error_errno(errno, "SO_PASSCRED failed: %m");
 
-                m->notify_fd = fd;
-                fd = -1;
+                m->notify_fd = TAKE_FD(fd);
 
                 log_debug("Using notification socket %s", m->notify_socket);
         }

src/core/socket.c

@@ -1238,10 +1238,7 @@ static int fifo_address_create(
                 goto fail;
         }
 
-        r = fd;
-        fd = -1;
-
-        return r;
+        return TAKE_FD(fd);
 
 fail:
         mac_selinux_create_file_clear();
@@ -1251,7 +1248,6 @@ fail:
 static int special_address_create(const char *path, bool writable) {
         _cleanup_close_ int fd = -1;
         struct stat st;
-        int r;
 
         assert(path);
 
@@ -1266,16 +1262,12 @@ static int special_address_create(const char *path, bool writable) {
         if (!S_ISREG(st.st_mode) && !S_ISCHR(st.st_mode))
                 return -EEXIST;
 
-        r = fd;
-        fd = -1;
-
-        return r;
+        return TAKE_FD(fd);
 }
 
 static int usbffs_address_create(const char *path) {
         _cleanup_close_ int fd = -1;
         struct stat st;
-        int r;
 
         assert(path);
 
@@ -1290,10 +1282,7 @@ static int usbffs_address_create(const char *path) {
         if (!S_ISREG(st.st_mode))
                 return -EEXIST;
 
-        r = fd;
-        fd = -1;
-
-        return r;
+        return TAKE_FD(fd);
 }
 
 static int mq_address_create(
@@ -1306,7 +1295,6 @@ static int mq_address_create(
         struct stat st;
         mode_t old_mask;
         struct mq_attr _attr, *attr = NULL;
-        int r;
 
         assert(path);
 
@@ -1338,10 +1326,7 @@ static int mq_address_create(
             st.st_gid != getgid())
                 return -EEXIST;
 
-        r = fd;
-        fd = -1;
-
-        return r;
+        return TAKE_FD(fd);
 }
 
 static int socket_symlink(Socket *s) {

src/import/export-raw.c

@@ -326,13 +326,10 @@ int raw_export_start(RawExport *e, const char *path, int fd, ImportCompressType
 
         /* Try to take a reflink snapshot of the file, if we can t make the export atomic */
         tfd = reflink_snapshot(sfd, path);
-        if (tfd >= 0) {
-                e->input_fd = tfd;
-                tfd = -1;
-        } else {
-                e->input_fd = sfd;
-                sfd = -1;
-        }
+        if (tfd >= 0)
+                e->input_fd = TAKE_FD(tfd);
+        else
+                e->input_fd = TAKE_FD(sfd);
 
         r = import_compress_init(&e->compress, compress);
         if (r < 0)

src/import/import-common.c

@@ -117,13 +117,9 @@ int import_fork_tar_x(const char *path, pid_t *ret) {
                 _exit(EXIT_FAILURE);
         }
 
-        pipefd[0] = safe_close(pipefd[0]);
-        r = pipefd[1];
-        pipefd[1] = -1;
-
         *ret = pid;
 
-        return r;
+        return TAKE_FD(pipefd[1]);
 }
 
 int import_fork_tar_c(const char *path, pid_t *ret) {
@@ -165,11 +161,7 @@ int import_fork_tar_c(const char *path, pid_t *ret) {
                 _exit(EXIT_FAILURE);
         }
 
-        pipefd[1] = safe_close(pipefd[1]);
-        r = pipefd[0];
-        pipefd[0] = -1;
-
         *ret = pid;
 
-        return r;
+        return TAKE_FD(pipefd[0]);
 }

src/import/import-raw.c

@@ -210,8 +210,7 @@ static int raw_import_maybe_convert_qcow2(RawImport *i) {
         free_and_replace(i->temp_path, t);
 
         safe_close(i->output_fd);
-        i->output_fd = converted_fd;
-        converted_fd = -1;
+        i->output_fd = TAKE_FD(converted_fd);
 
         return 1;
 }

src/import/importd.c

@@ -453,8 +453,7 @@ static int transfer_start(Transfer *t) {
         }
 
         pipefd[1] = safe_close(pipefd[1]);
-        t->log_fd = pipefd[0];
-        pipefd[0] = -1;
+        t->log_fd = TAKE_FD(pipefd[0]);
 
         t->stdin_fd = safe_close(t->stdin_fd);
 

src/import/pull-raw.c

@@ -272,8 +272,7 @@ static int raw_pull_maybe_convert_qcow2(RawPull *i) {
         free_and_replace(i->temp_path, t);
 
         safe_close(i->raw_job->disk_fd);
-        i->raw_job->disk_fd = converted_fd;
-        converted_fd = -1;
+        i->raw_job->disk_fd = TAKE_FD(converted_fd);
 
         return 1;
 }

src/journal/journal-send.c

@@ -441,9 +441,7 @@ _public_ int sd_journal_stream_fd(const char *identifier, int priority, int leve
         if (r < 0)
                 return r;
 
-        r = fd;
-        fd = -1;
-        return r;
+        return TAKE_FD(fd);
 }
 
 _public_ int sd_journal_print_with_location(int priority, const char *file, const char *line, const char *func, const char *format, ...) {

src/libsystemd-network/arp-util.c

@@ -103,10 +103,7 @@ int arp_network_bind_raw_socket(int ifindex, be32_t address, const struct ether_
         if (r < 0)
                 return -errno;
 
-        r = s;
-        s = -1;
-
-        return r;
+        return TAKE_FD(s);
 }
 
 static int arp_send_packet(int fd, int ifindex,

src/libsystemd-network/dhcp-network.c

@@ -123,10 +123,7 @@ static int _bind_raw_socket(int ifindex, union sockaddr_union *link,
         if (r < 0)
                 return -errno;
 
-        r = s;
-        s = -1;
-
-        return r;
+        return TAKE_FD(s);
 }
 
 int dhcp_network_bind_raw_socket(int ifindex, union sockaddr_union *link,
@@ -211,10 +208,7 @@ int dhcp_network_bind_udp_socket(int ifindex, be32_t address, uint16_t port) {
         if (r < 0)
                 return -errno;
 
-        r = s;
-        s = -1;
-
-        return r;
+        return TAKE_FD(s);
 }
 
 int dhcp_network_send_raw_socket(int s, const union sockaddr_union *link,

src/libsystemd-network/dhcp6-network.c

@@ -67,9 +67,7 @@ int dhcp6_network_bind_udp_socket(int index, struct in6_addr *local_address) {
         if (r < 0)
                 return -errno;
 
-        r = s;
-        s = -1;
-        return r;
+        return TAKE_FD(s);
 }
 
 int dhcp6_network_send_udp_socket(int s, struct in6_addr *server_address,

src/libsystemd-network/icmp6-util.c

@@ -98,9 +98,7 @@ static int icmp6_bind_router_message(const struct icmp6_filter *filter,
         if (r < 0)
                 return -errno;
 
-        r = s;
-        s = -1;
-        return r;
+        return TAKE_FD(s);
 }
 
 int icmp6_bind_router_solicitation(int index) {

src/libsystemd-network/lldp-network.c

@@ -92,8 +92,5 @@ int lldp_network_bind_raw_socket(int ifindex) {
         if (r < 0)
                 return -errno;
 
-        r = fd;
-        fd = -1;
-
-        return r;
+        return TAKE_FD(fd);
 }