diff options
Diffstat (limited to 'src/libelogind/sd-bus/bus-socket.c')
| -rw-r--r-- | src/libelogind/sd-bus/bus-socket.c | 279 |
1 files changed, 266 insertions, 13 deletions
diff --git a/src/libelogind/sd-bus/bus-socket.c b/src/libelogind/sd-bus/bus-socket.c index 5034d5147..74d90ecdf 100644 --- a/src/libelogind/sd-bus/bus-socket.c +++ b/src/libelogind/sd-bus/bus-socket.c @@ -32,9 +32,12 @@ #include "bus-socket.h" #include "fd-util.h" #include "format-util.h" +//#include "fs-util.h" #include "hexdecoct.h" +//#include "io-util.h" #include "macro.h" #include "missing.h" +//#include "path-util.h" #include "selinux-util.h" #include "signal-util.h" #include "stdio-util.h" @@ -688,30 +691,249 @@ int bus_socket_start_auth(sd_bus *b) { return bus_socket_start_auth_client(b); } +static int bus_socket_inotify_setup(sd_bus *b) { + _cleanup_free_ int *new_watches = NULL; + _cleanup_free_ char *absolute = NULL; + size_t n_allocated = 0, n = 0, done = 0, i; + unsigned max_follow = 32; + const char *p; + int wd, r; + + assert(b); + assert(b->watch_bind); + assert(b->sockaddr.sa.sa_family == AF_UNIX); + assert(b->sockaddr.un.sun_path[0] != 0); + + /* Sets up an inotify fd in case watch_bind is enabled: wait until the configured AF_UNIX file system socket + * appears before connecting to it. The implemented is pretty simplistic: we just subscribe to relevant changes + * to all prefix components of the path, and every time we get an event for that we try to reconnect again, + * without actually caring what precisely the event we got told us. If we still can't connect we re-subscribe + * to all relevant changes of anything in the path, so that our watches include any possibly newly created path + * components. */ + + if (b->inotify_fd < 0) { + b->inotify_fd = inotify_init1(IN_NONBLOCK|IN_CLOEXEC); + if (b->inotify_fd < 0) + return -errno; + } + + /* Make sure the path is NUL terminated */ + p = strndupa(b->sockaddr.un.sun_path, sizeof(b->sockaddr.un.sun_path)); + + /* Make sure the path is absolute */ + r = path_make_absolute_cwd(p, &absolute); + if (r < 0) + goto fail; + + /* Watch all parent directories, and don't mind any prefix that doesn't exist yet. For the innermost directory + * that exists we want to know when files are created or moved into it. For all parents of it we just care if + * they are removed or renamed. */ + + if (!GREEDY_REALLOC(new_watches, n_allocated, n + 1)) { + r = -ENOMEM; + goto fail; + } + + /* Start with the top-level directory, which is a bit simpler than the rest, since it can't be a symlink, and + * always exists */ + wd = inotify_add_watch(b->inotify_fd, "/", IN_CREATE|IN_MOVED_TO); + if (wd < 0) { + r = log_debug_errno(errno, "Failed to add inotify watch on /: %m"); + goto fail; + } else + new_watches[n++] = wd; + + for (;;) { + _cleanup_free_ char *component = NULL, *prefix = NULL, *destination = NULL; + size_t n_slashes, n_component; + char *c = NULL; + + n_slashes = strspn(absolute + done, "/"); + n_component = n_slashes + strcspn(absolute + done + n_slashes, "/"); + + if (n_component == 0) /* The end */ + break; + + component = strndup(absolute + done, n_component); + if (!component) { + r = -ENOMEM; + goto fail; + } + + /* A trailing slash? That's a directory, and not a socket then */ + if (path_equal(component, "/")) { + r = -EISDIR; + goto fail; + } + + /* A single dot? Let's eat this up */ + if (path_equal(component, "/.")) { + done += n_component; + continue; + } + + prefix = strndup(absolute, done + n_component); + if (!prefix) { + r = -ENOMEM; + goto fail; + } + + if (!GREEDY_REALLOC(new_watches, n_allocated, n + 1)) { + r = -ENOMEM; + goto fail; + } + + wd = inotify_add_watch(b->inotify_fd, prefix, IN_DELETE_SELF|IN_MOVE_SELF|IN_ATTRIB|IN_CREATE|IN_MOVED_TO|IN_DONT_FOLLOW); + log_debug("Added inotify watch for %s on bus %s: %i", prefix, strna(b->description), wd); + + if (wd < 0) { + if (IN_SET(errno, ENOENT, ELOOP)) + break; /* This component doesn't exist yet, or the path contains a cyclic symlink right now */ + + r = log_debug_errno(errno, "Failed to add inotify watch on %s: %m", isempty(prefix) ? "/" : prefix); + goto fail; + } else + new_watches[n++] = wd; + + /* Check if this is possibly a symlink. If so, let's follow it and watch it too. */ + r = readlink_malloc(prefix, &destination); + if (r == -EINVAL) { /* not a symlink */ + done += n_component; + continue; + } + if (r < 0) + goto fail; + + if (isempty(destination)) { /* Empty symlink target? Yuck! */ + r = -EINVAL; + goto fail; + } + + if (max_follow <= 0) { /* Let's make sure we don't follow symlinks forever */ + r = -ELOOP; + goto fail; + } + + if (path_is_absolute(destination)) { + /* For absolute symlinks we build the new path and start anew */ + c = strjoin(destination, absolute + done + n_component); + done = 0; + } else { + _cleanup_free_ char *t = NULL; + + /* For relative symlinks we replace the last component, and try again */ + t = strndup(absolute, done); + if (!t) + return -ENOMEM; + + c = strjoin(t, "/", destination, absolute + done + n_component); + } + if (!c) { + r = -ENOMEM; + goto fail; + } + + free(absolute); + absolute = c; + + max_follow--; + } + + /* And now, let's remove all watches from the previous iteration we don't need anymore */ + for (i = 0; i < b->n_inotify_watches; i++) { + bool found = false; + size_t j; + + for (j = 0; j < n; j++) + if (new_watches[j] == b->inotify_watches[i]) { + found = true; + break; + } + + if (found) + continue; + + (void) inotify_rm_watch(b->inotify_fd, b->inotify_watches[i]); + } + + free_and_replace(b->inotify_watches, new_watches); + b->n_inotify_watches = n; + + return 0; + +fail: + bus_close_inotify_fd(b); + return r; +} + int bus_socket_connect(sd_bus *b) { + bool inotify_done = false; int r; assert(b); - assert(b->input_fd < 0); - assert(b->output_fd < 0); - assert(b->sockaddr.sa.sa_family != AF_UNSPEC); - b->input_fd = socket(b->sockaddr.sa.sa_family, SOCK_STREAM|SOCK_CLOEXEC|SOCK_NONBLOCK, 0); - if (b->input_fd < 0) - return -errno; + for (;;) { + assert(b->input_fd < 0); + assert(b->output_fd < 0); + assert(b->sockaddr.sa.sa_family != AF_UNSPEC); - b->output_fd = b->input_fd; + b->input_fd = socket(b->sockaddr.sa.sa_family, SOCK_STREAM|SOCK_CLOEXEC|SOCK_NONBLOCK, 0); + if (b->input_fd < 0) + return -errno; - bus_socket_setup(b); + b->output_fd = b->input_fd; + bus_socket_setup(b); - r = connect(b->input_fd, &b->sockaddr.sa, b->sockaddr_size); - if (r < 0) { - if (errno == EINPROGRESS) - return 1; + if (connect(b->input_fd, &b->sockaddr.sa, b->sockaddr_size) < 0) { + if (errno == EINPROGRESS) { - return -errno; + /* If we have any inotify watches open, close them now, we don't need them anymore, as + * we have successfully initiated a connection */ + bus_close_inotify_fd(b); + + /* Note that very likely we are already in BUS_OPENING state here, as we enter it when + * we start parsing the address string. The only reason we set the state explicitly + * here, is to undo BUS_WATCH_BIND, in case we did the inotify magic. */ + b->state = BUS_OPENING; + return 1; + } + + if (IN_SET(errno, ENOENT, ECONNREFUSED) && /* ENOENT → unix socket doesn't exist at all; ECONNREFUSED → unix socket stale */ + b->watch_bind && + b->sockaddr.sa.sa_family == AF_UNIX && + b->sockaddr.un.sun_path[0] != 0) { + + /* This connection attempt failed, let's release the socket for now, and start with a + * fresh one when reconnecting. */ + bus_close_io_fds(b); + + if (inotify_done) { + /* inotify set up already, don't do it again, just return now, and remember + * that we are waiting for inotify events now. */ + b->state = BUS_WATCH_BIND; + return 1; + } + + /* This is a file system socket, and the inotify logic is enabled. Let's create the necessary inotify fd. */ + r = bus_socket_inotify_setup(b); + if (r < 0) + return r; + + /* Let's now try to connect a second time, because in theory there's otherwise a race + * here: the socket might have been created in the time between our first connect() and + * the time we set up the inotify logic. But let's remember that we set up inotify now, + * so that we don't do the connect() more than twice. */ + inotify_done = true; + + } else + return -errno; + } else + break; } + /* Yay, established, we don't need no inotify anymore! */ + bus_close_inotify_fd(b); + return bus_socket_start_auth(b); } @@ -1069,3 +1291,34 @@ int bus_socket_process_authenticating(sd_bus *b) { return bus_socket_read_auth(b); } + +int bus_socket_process_watch_bind(sd_bus *b) { + int r, q; + + assert(b); + assert(b->state == BUS_WATCH_BIND); + assert(b->inotify_fd >= 0); + + r = flush_fd(b->inotify_fd); + if (r <= 0) + return r; + + log_debug("Got inotify event on bus %s.", strna(b->description)); + + /* We flushed events out of the inotify fd. In that case, maybe the socket is valid now? Let's try to connect + * to it again */ + + r = bus_socket_connect(b); + if (r < 0) + return r; + + q = bus_attach_io_events(b); + if (q < 0) + return q; + + q = bus_attach_inotify_event(b); + if (q < 0) + return q; + + return r; +} |