2 * Copyright (c) 2008, 2009, 2010, 2011, 2012 Nicira, Inc.
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at:
8 * http://www.apache.org/licenses/LICENSE-2.0
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
18 #include "socket-util.h"
19 #include <arpa/inet.h>
30 #include <sys/resource.h>
31 #include <sys/socket.h>
35 #include "dynamic-string.h"
36 #include "fatal-signal.h"
40 #if AF_PACKET && __linux__
41 #include <linux/if_packet.h>
44 #include "netlink-protocol.h"
45 #include "netlink-socket.h"
48 VLOG_DEFINE_THIS_MODULE(socket_util);
50 /* #ifdefs make it a pain to maintain code: you have to try to build both ways.
51 * Thus, this file compiles all of the code regardless of the target, by
52 * writing "if (LINUX)" instead of "#ifdef __linux__". */
63 static int getsockopt_int(int fd, int level, int option, const char *optname,
66 /* Sets 'fd' to non-blocking mode. Returns 0 if successful, otherwise a
67 * positive errno value. */
69 set_nonblocking(int fd)
71 int flags = fcntl(fd, F_GETFL, 0);
73 if (fcntl(fd, F_SETFL, flags | O_NONBLOCK) != -1) {
76 VLOG_ERR("fcntl(F_SETFL) failed: %s", strerror(errno));
80 VLOG_ERR("fcntl(F_GETFL) failed: %s", strerror(errno));
86 set_dscp(int fd, uint8_t dscp)
93 if (setsockopt(fd, IPPROTO_IP, IP_TOS, &dscp, sizeof dscp)) {
101 rlim_is_finite(rlim_t limit)
103 if (limit == RLIM_INFINITY) {
107 #ifdef RLIM_SAVED_CUR /* FreeBSD 8.0 lacks RLIM_SAVED_CUR. */
108 if (limit == RLIM_SAVED_CUR) {
113 #ifdef RLIM_SAVED_MAX /* FreeBSD 8.0 lacks RLIM_SAVED_MAX. */
114 if (limit == RLIM_SAVED_MAX) {
122 /* Returns the maximum valid FD value, plus 1. */
126 static int max_fds = -1;
129 if (!getrlimit(RLIMIT_NOFILE, &r) && rlim_is_finite(r.rlim_cur)) {
130 max_fds = r.rlim_cur;
132 VLOG_WARN("failed to obtain fd limit, defaulting to 1024");
139 /* Translates 'host_name', which must be a string representation of an IP
140 * address, into a numeric IP address in '*addr'. Returns 0 if successful,
141 * otherwise a positive errno value. */
143 lookup_ip(const char *host_name, struct in_addr *addr)
145 if (!inet_aton(host_name, addr)) {
146 static struct vlog_rate_limit rl = VLOG_RATE_LIMIT_INIT(1, 5);
147 VLOG_ERR_RL(&rl, "\"%s\" is not a valid IP address", host_name);
153 /* Translates 'host_name', which must be a string representation of an IPv6
154 * address, into a numeric IPv6 address in '*addr'. Returns 0 if successful,
155 * otherwise a positive errno value. */
157 lookup_ipv6(const char *host_name, struct in6_addr *addr)
159 if (inet_pton(AF_INET6, host_name, addr) != 1) {
160 static struct vlog_rate_limit rl = VLOG_RATE_LIMIT_INIT(1, 5);
161 VLOG_ERR_RL(&rl, "\"%s\" is not a valid IPv6 address", host_name);
167 /* Translates 'host_name', which must be a host name or a string representation
168 * of an IP address, into a numeric IP address in '*addr'. Returns 0 if
169 * successful, otherwise a positive errno value.
171 * Most Open vSwitch code should not use this because it causes deadlocks:
172 * gethostbyname() sends out a DNS request but that starts a new flow for which
173 * OVS must set up a flow, but it can't because it's waiting for a DNS reply.
174 * The synchronous lookup also delays other activty. (Of course we can solve
175 * this but it doesn't seem worthwhile quite yet.) */
177 lookup_hostname(const char *host_name, struct in_addr *addr)
181 if (inet_aton(host_name, addr)) {
185 h = gethostbyname(host_name);
187 *addr = *(struct in_addr *) h->h_addr;
191 return (h_errno == HOST_NOT_FOUND ? ENOENT
192 : h_errno == TRY_AGAIN ? EAGAIN
193 : h_errno == NO_RECOVERY ? EIO
194 : h_errno == NO_ADDRESS ? ENXIO
198 /* Returns the error condition associated with socket 'fd' and resets the
199 * socket's error status. */
201 get_socket_error(int fd)
205 if (getsockopt_int(fd, SOL_SOCKET, SO_ERROR, "SO_ERROR", &error)) {
212 check_connection_completion(int fd)
218 pfd.events = POLLOUT;
220 retval = poll(&pfd, 1, 0);
221 } while (retval < 0 && errno == EINTR);
223 return get_socket_error(fd);
224 } else if (retval < 0) {
225 static struct vlog_rate_limit rl = VLOG_RATE_LIMIT_INIT(5, 10);
226 VLOG_ERR_RL(&rl, "poll: %s", strerror(errno));
233 /* Drain all the data currently in the receive queue of a datagram socket (and
234 * possibly additional data). There is no way to know how many packets are in
235 * the receive queue, but we do know that the total number of bytes queued does
236 * not exceed the receive buffer size, so we pull packets until none are left
237 * or we've read that many bytes. */
243 rcvbuf = get_socket_rcvbuf(fd);
249 /* In Linux, specifying MSG_TRUNC in the flags argument causes the
250 * datagram length to be returned, even if that is longer than the
251 * buffer provided. Thus, we can use a 1-byte buffer to discard the
252 * incoming datagram and still be able to account how many bytes were
253 * removed from the receive buffer.
255 * On other Unix-like OSes, MSG_TRUNC has no effect in the flags
257 char buffer[LINUX ? 1 : 2048];
258 ssize_t n_bytes = recv(fd, buffer, sizeof buffer,
259 MSG_TRUNC | MSG_DONTWAIT);
260 if (n_bytes <= 0 || n_bytes >= rcvbuf) {
268 /* Returns the size of socket 'sock''s receive buffer (SO_RCVBUF), or a
269 * negative errno value if an error occurs. */
271 get_socket_rcvbuf(int sock)
276 error = getsockopt_int(sock, SOL_SOCKET, SO_RCVBUF, "SO_RCVBUF", &rcvbuf);
277 return error ? -error : rcvbuf;
280 /* Reads and discards up to 'n' datagrams from 'fd', stopping as soon as no
281 * more data can be immediately read. ('fd' should therefore be in
282 * non-blocking mode.)*/
284 drain_fd(int fd, size_t n_packets)
286 for (; n_packets > 0; n_packets--) {
287 /* 'buffer' only needs to be 1 byte long in most circumstances. This
288 * size is defensive against the possibility that we someday want to
289 * use a Linux tap device without TUN_NO_PI, in which case a buffer
290 * smaller than sizeof(struct tun_pi) will give EINVAL on read. */
292 if (read(fd, buffer, sizeof buffer) <= 0) {
298 /* Stores in '*un' a sockaddr_un that refers to file 'name'. Stores in
299 * '*un_len' the size of the sockaddr_un. */
301 make_sockaddr_un__(const char *name, struct sockaddr_un *un, socklen_t *un_len)
303 un->sun_family = AF_UNIX;
304 ovs_strzcpy(un->sun_path, name, sizeof un->sun_path);
305 *un_len = (offsetof(struct sockaddr_un, sun_path)
306 + strlen (un->sun_path) + 1);
309 /* Stores in '*un' a sockaddr_un that refers to file 'name'. Stores in
310 * '*un_len' the size of the sockaddr_un.
312 * Returns 0 on success, otherwise a positive errno value. On success,
313 * '*dirfdp' is either -1 or a nonnegative file descriptor that the caller
314 * should close after using '*un' to bind or connect. On failure, '*dirfdp' is
317 make_sockaddr_un(const char *name, struct sockaddr_un *un, socklen_t *un_len,
320 enum { MAX_UN_LEN = sizeof un->sun_path - 1 };
323 if (strlen(name) > MAX_UN_LEN) {
324 static struct vlog_rate_limit rl = VLOG_RATE_LIMIT_INIT(1, 1);
327 /* 'name' is too long to fit in a sockaddr_un, but we have a
328 * workaround for that on Linux: shorten it by opening a file
329 * descriptor for the directory part of the name and indirecting
330 * through /proc/self/fd/<dirfd>/<basename>. */
335 dir = dir_name(name);
336 base = base_name(name);
338 dirfd = open(dir, O_DIRECTORY | O_RDONLY);
345 short_name = xasprintf("/proc/self/fd/%d/%s", dirfd, base);
349 if (strlen(short_name) <= MAX_UN_LEN) {
350 make_sockaddr_un__(short_name, un, un_len);
358 VLOG_WARN_RL(&rl, "Unix socket name %s is longer than maximum "
359 "%d bytes (even shortened)", name, MAX_UN_LEN);
361 /* 'name' is too long and we have no workaround. */
362 VLOG_WARN_RL(&rl, "Unix socket name %s is longer than maximum "
363 "%d bytes", name, MAX_UN_LEN);
368 make_sockaddr_un__(name, un, un_len);
373 /* Binds Unix domain socket 'fd' to a file with permissions 0700. */
375 bind_unix_socket(int fd, struct sockaddr *sun, socklen_t sun_len)
377 /* According to _Unix Network Programming_, umask should affect bind(). */
378 mode_t old_umask = umask(0077);
379 int error = bind(fd, sun, sun_len) ? errno : 0;
384 /* Creates a Unix domain socket in the given 'style' (either SOCK_DGRAM or
385 * SOCK_STREAM) that is bound to '*bind_path' (if 'bind_path' is non-null) and
386 * connected to '*connect_path' (if 'connect_path' is non-null). If 'nonblock'
387 * is true, the socket is made non-blocking.
389 * Returns the socket's fd if successful, otherwise a negative errno value. */
391 make_unix_socket(int style, bool nonblock,
392 const char *bind_path, const char *connect_path)
397 fd = socket(PF_UNIX, style, 0);
402 /* Set nonblocking mode right away, if we want it. This prevents blocking
403 * in connect(), if connect_path != NULL. (In turn, that's a corner case:
404 * it will only happen if style is SOCK_STREAM or SOCK_SEQPACKET, and only
405 * if a backlog of un-accepted connections has built up in the kernel.) */
407 int flags = fcntl(fd, F_GETFL, 0);
412 if (fcntl(fd, F_SETFL, flags | O_NONBLOCK) == -1) {
419 struct sockaddr_un un;
423 if (unlink(bind_path) && errno != ENOENT) {
424 VLOG_WARN("unlinking \"%s\": %s\n", bind_path, strerror(errno));
426 fatal_signal_add_file_to_unlink(bind_path);
428 error = make_sockaddr_un(bind_path, &un, &un_len, &dirfd);
430 error = bind_unix_socket(fd, (struct sockaddr *) &un, un_len);
441 struct sockaddr_un un;
445 error = make_sockaddr_un(connect_path, &un, &un_len, &dirfd);
447 && connect(fd, (struct sockaddr*) &un, un_len)
448 && errno != EINPROGRESS) {
462 if (error == EAGAIN) {
466 fatal_signal_unlink_file_now(bind_path);
473 get_unix_name_len(socklen_t sun_len)
475 return (sun_len >= offsetof(struct sockaddr_un, sun_path)
476 ? sun_len - offsetof(struct sockaddr_un, sun_path)
481 guess_netmask(ovs_be32 ip_)
483 uint32_t ip = ntohl(ip_);
484 return ((ip >> 31) == 0 ? htonl(0xff000000) /* Class A */
485 : (ip >> 30) == 2 ? htonl(0xffff0000) /* Class B */
486 : (ip >> 29) == 6 ? htonl(0xffffff00) /* Class C */
487 : htonl(0)); /* ??? */
490 /* Parses 'target', which should be a string in the format "<host>[:<port>]".
491 * <host> is required. If 'default_port' is nonzero then <port> is optional
492 * and defaults to 'default_port'.
494 * On success, returns true and stores the parsed remote address into '*sinp'.
495 * On failure, logs an error, stores zeros into '*sinp', and returns false. */
497 inet_parse_active(const char *target_, uint16_t default_port,
498 struct sockaddr_in *sinp)
500 char *target = xstrdup(target_);
501 char *save_ptr = NULL;
502 const char *host_name;
503 const char *port_string;
507 sinp->sin_family = AF_INET;
508 sinp->sin_port = htons(default_port);
511 host_name = strtok_r(target, ":", &save_ptr);
512 port_string = strtok_r(NULL, ":", &save_ptr);
514 VLOG_ERR("%s: bad peer name format", target_);
518 /* Look up IP, port. */
519 if (lookup_ip(host_name, &sinp->sin_addr)) {
522 if (port_string && atoi(port_string)) {
523 sinp->sin_port = htons(atoi(port_string));
524 } else if (!default_port) {
525 VLOG_ERR("%s: port number must be specified", target_);
533 memset(sinp, 0, sizeof *sinp);
539 /* Opens a non-blocking IPv4 socket of the specified 'style' and connects to
540 * 'target', which should be a string in the format "<host>[:<port>]". <host>
541 * is required. If 'default_port' is nonzero then <port> is optional and
542 * defaults to 'default_port'.
544 * 'style' should be SOCK_STREAM (for TCP) or SOCK_DGRAM (for UDP).
546 * On success, returns 0 (indicating connection complete) or EAGAIN (indicating
547 * connection in progress), in which case the new file descriptor is stored
548 * into '*fdp'. On failure, returns a positive errno value other than EAGAIN
549 * and stores -1 into '*fdp'.
551 * If 'sinp' is non-null, then on success the target address is stored into
554 * 'dscp' becomes the DSCP bits in the IP headers for the new connection. It
555 * should be in the range [0, 63] and will automatically be shifted to the
556 * appropriately place in the IP tos field. */
558 inet_open_active(int style, const char *target, uint16_t default_port,
559 struct sockaddr_in *sinp, int *fdp, uint8_t dscp)
561 struct sockaddr_in sin;
566 if (!inet_parse_active(target, default_port, &sin)) {
567 error = EAFNOSUPPORT;
571 /* Create non-blocking socket. */
572 fd = socket(AF_INET, style, 0);
574 VLOG_ERR("%s: socket: %s", target, strerror(errno));
578 error = set_nonblocking(fd);
583 /* The dscp bits must be configured before connect() to ensure that the TOS
584 * field is set during the connection establishment. If set after
585 * connect(), the handshake SYN frames will be sent with a TOS of 0. */
586 error = set_dscp(fd, dscp);
588 VLOG_ERR("%s: socket: %s", target, strerror(error));
593 error = connect(fd, (struct sockaddr *) &sin, sizeof sin) == 0 ? 0 : errno;
594 if (error == EINPROGRESS) {
599 if (!error || error == EAGAIN) {
603 } else if (fd >= 0) {
610 /* Parses 'target', which should be a string in the format "[<port>][:<ip>]":
612 * - If 'default_port' is -1, then <port> is required. Otherwise, if
613 * <port> is omitted, then 'default_port' is used instead.
615 * - If <port> (or 'default_port', if used) is 0, then no port is bound
616 * and the TCP/IP stack will select a port.
618 * - If <ip> is omitted then the IP address is wildcarded.
620 * If successful, stores the address into '*sinp' and returns true; otherwise
621 * zeros '*sinp' and returns false. */
623 inet_parse_passive(const char *target_, int default_port,
624 struct sockaddr_in *sinp)
626 char *target = xstrdup(target_);
627 char *string_ptr = target;
628 const char *host_name;
629 const char *port_string;
633 /* Address defaults. */
634 memset(sinp, 0, sizeof *sinp);
635 sinp->sin_family = AF_INET;
636 sinp->sin_addr.s_addr = htonl(INADDR_ANY);
637 sinp->sin_port = htons(default_port);
639 /* Parse optional port number. */
640 port_string = strsep(&string_ptr, ":");
641 if (port_string && str_to_int(port_string, 10, &port)) {
642 sinp->sin_port = htons(port);
643 } else if (default_port < 0) {
644 VLOG_ERR("%s: port number must be specified", target_);
648 /* Parse optional bind IP. */
649 host_name = strsep(&string_ptr, ":");
650 if (host_name && host_name[0] && lookup_ip(host_name, &sinp->sin_addr)) {
658 memset(sinp, 0, sizeof *sinp);
665 /* Opens a non-blocking IPv4 socket of the specified 'style', binds to
666 * 'target', and listens for incoming connections. Parses 'target' in the same
667 * way was inet_parse_passive().
669 * 'style' should be SOCK_STREAM (for TCP) or SOCK_DGRAM (for UDP).
671 * For TCP, the socket will have SO_REUSEADDR turned on.
673 * On success, returns a non-negative file descriptor. On failure, returns a
674 * negative errno value.
676 * If 'sinp' is non-null, then on success the bound address is stored into
679 * 'dscp' becomes the DSCP bits in the IP headers for the new connection. It
680 * should be in the range [0, 63] and will automatically be shifted to the
681 * appropriately place in the IP tos field. */
683 inet_open_passive(int style, const char *target, int default_port,
684 struct sockaddr_in *sinp, uint8_t dscp)
686 struct sockaddr_in sin;
688 unsigned int yes = 1;
690 if (!inet_parse_passive(target, default_port, &sin)) {
691 return -EAFNOSUPPORT;
694 /* Create non-blocking socket, set SO_REUSEADDR. */
695 fd = socket(AF_INET, style, 0);
698 VLOG_ERR("%s: socket: %s", target, strerror(error));
701 error = set_nonblocking(fd);
705 if (style == SOCK_STREAM
706 && setsockopt(fd, SOL_SOCKET, SO_REUSEADDR, &yes, sizeof yes) < 0) {
708 VLOG_ERR("%s: setsockopt(SO_REUSEADDR): %s", target, strerror(error));
713 if (bind(fd, (struct sockaddr *) &sin, sizeof sin) < 0) {
715 VLOG_ERR("%s: bind: %s", target, strerror(error));
719 /* The dscp bits must be configured before connect() to ensure that the TOS
720 * field is set during the connection establishment. If set after
721 * connect(), the handshake SYN frames will be sent with a TOS of 0. */
722 error = set_dscp(fd, dscp);
724 VLOG_ERR("%s: socket: %s", target, strerror(error));
729 if (style == SOCK_STREAM && listen(fd, 10) < 0) {
731 VLOG_ERR("%s: listen: %s", target, strerror(error));
736 socklen_t sin_len = sizeof sin;
737 if (getsockname(fd, (struct sockaddr *) &sin, &sin_len) < 0){
739 VLOG_ERR("%s: getsockname: %s", target, strerror(error));
742 if (sin.sin_family != AF_INET || sin_len != sizeof sin) {
743 error = EAFNOSUPPORT;
744 VLOG_ERR("%s: getsockname: invalid socket name", target);
757 /* Returns a readable and writable fd for /dev/null, if successful, otherwise
758 * a negative errno value. The caller must not close the returned fd (because
759 * the same fd will be handed out to subsequent callers). */
763 static int null_fd = -1;
765 null_fd = open("/dev/null", O_RDWR);
768 VLOG_ERR("could not open /dev/null: %s", strerror(error));
776 read_fully(int fd, void *p_, size_t size, size_t *bytes_read)
782 ssize_t retval = read(fd, p, size);
784 *bytes_read += retval;
787 } else if (retval == 0) {
789 } else if (errno != EINTR) {
797 write_fully(int fd, const void *p_, size_t size, size_t *bytes_written)
799 const uint8_t *p = p_;
803 ssize_t retval = write(fd, p, size);
805 *bytes_written += retval;
808 } else if (retval == 0) {
809 VLOG_WARN("write returned 0");
811 } else if (errno != EINTR) {
818 /* Given file name 'file_name', fsyncs the directory in which it is contained.
819 * Returns 0 if successful, otherwise a positive errno value. */
821 fsync_parent_dir(const char *file_name)
827 dir = dir_name(file_name);
828 fd = open(dir, O_RDONLY);
831 if (errno == EINVAL || errno == EROFS) {
832 /* This directory does not support synchronization. Not
833 * really an error. */
836 VLOG_ERR("%s: fsync failed (%s)", dir, strerror(error));
842 VLOG_ERR("%s: open failed (%s)", dir, strerror(error));
849 /* Obtains the modification time of the file named 'file_name' to the greatest
850 * supported precision. If successful, stores the mtime in '*mtime' and
851 * returns 0. On error, returns a positive errno value and stores zeros in
854 get_mtime(const char *file_name, struct timespec *mtime)
858 if (!stat(file_name, &s)) {
859 mtime->tv_sec = s.st_mtime;
861 #if HAVE_STRUCT_STAT_ST_MTIM_TV_NSEC
862 mtime->tv_nsec = s.st_mtim.tv_nsec;
863 #elif HAVE_STRUCT_STAT_ST_MTIMENSEC
864 mtime->tv_nsec = s.st_mtimensec;
871 mtime->tv_sec = mtime->tv_nsec = 0;
880 VLOG_FATAL("failed to create pipe (%s)", strerror(errno));
885 getsockopt_int(int fd, int level, int option, const char *optname, int *valuep)
887 static struct vlog_rate_limit rl = VLOG_RATE_LIMIT_INIT(5, 10);
893 if (getsockopt(fd, level, option, &value, &len)) {
895 VLOG_ERR_RL(&rl, "getsockopt(%s): %s", optname, strerror(error));
896 } else if (len != sizeof value) {
898 VLOG_ERR_RL(&rl, "getsockopt(%s): value is %u bytes (expected %zu)",
899 optname, (unsigned int) len, sizeof value);
904 *valuep = error ? 0 : value;
909 describe_sockaddr(struct ds *string, int fd,
910 int (*getaddr)(int, struct sockaddr *, socklen_t *))
912 struct sockaddr_storage ss;
913 socklen_t len = sizeof ss;
915 if (!getaddr(fd, (struct sockaddr *) &ss, &len)) {
916 if (ss.ss_family == AF_INET) {
917 struct sockaddr_in sin;
919 memcpy(&sin, &ss, sizeof sin);
920 ds_put_format(string, IP_FMT":%"PRIu16,
921 IP_ARGS(&sin.sin_addr.s_addr), ntohs(sin.sin_port));
922 } else if (ss.ss_family == AF_UNIX) {
923 struct sockaddr_un sun;
927 memcpy(&sun, &ss, sizeof sun);
928 maxlen = len - offsetof(struct sockaddr_un, sun_path);
929 null = memchr(sun.sun_path, '\0', maxlen);
930 ds_put_buffer(string, sun.sun_path,
931 null ? null - sun.sun_path : maxlen);
934 else if (ss.ss_family == AF_NETLINK) {
937 /* SO_PROTOCOL was introduced in 2.6.32. Support it regardless of the version
938 * of the Linux kernel headers in use at build time. */
940 #define SO_PROTOCOL 38
943 if (!getsockopt_int(fd, SOL_SOCKET, SO_PROTOCOL, "SO_PROTOCOL",
947 ds_put_cstr(string, "NETLINK_ROUTE");
950 case NETLINK_GENERIC:
951 ds_put_cstr(string, "NETLINK_GENERIC");
955 ds_put_format(string, "AF_NETLINK family %d", protocol);
959 ds_put_cstr(string, "AF_NETLINK");
963 #if AF_PACKET && __linux__
964 else if (ss.ss_family == AF_PACKET) {
965 struct sockaddr_ll sll;
967 memcpy(&sll, &ss, sizeof sll);
968 ds_put_cstr(string, "AF_PACKET");
969 if (sll.sll_ifindex) {
972 if (if_indextoname(sll.sll_ifindex, name)) {
973 ds_put_format(string, "(%s)", name);
975 ds_put_format(string, "(ifindex=%d)", sll.sll_ifindex);
978 if (sll.sll_protocol) {
979 ds_put_format(string, "(protocol=0x%"PRIu16")",
980 ntohs(sll.sll_protocol));
984 else if (ss.ss_family == AF_UNSPEC) {
985 ds_put_cstr(string, "AF_UNSPEC");
987 ds_put_format(string, "AF_%d", (int) ss.ss_family);
995 put_fd_filename(struct ds *string, int fd)
1001 linkname = xasprintf("/proc/self/fd/%d", fd);
1002 n = readlink(linkname, buf, sizeof buf);
1004 ds_put_char(string, ' ');
1005 ds_put_buffer(string, buf, n);
1006 if (n > sizeof buf) {
1007 ds_put_cstr(string, "...");
1014 /* Returns a malloc()'d string describing 'fd', for use in logging. */
1022 if (fstat(fd, &s)) {
1023 ds_put_format(&string, "fstat failed (%s)", strerror(errno));
1024 } else if (S_ISSOCK(s.st_mode)) {
1025 describe_sockaddr(&string, fd, getsockname);
1026 ds_put_cstr(&string, "<->");
1027 describe_sockaddr(&string, fd, getpeername);
1029 ds_put_cstr(&string, (isatty(fd) ? "tty"
1030 : S_ISDIR(s.st_mode) ? "directory"
1031 : S_ISCHR(s.st_mode) ? "character device"
1032 : S_ISBLK(s.st_mode) ? "block device"
1033 : S_ISREG(s.st_mode) ? "file"
1034 : S_ISFIFO(s.st_mode) ? "FIFO"
1035 : S_ISLNK(s.st_mode) ? "symbolic link"
1038 put_fd_filename(&string, fd);
1041 return ds_steal_cstr(&string);