2 * Routines for capture options setting
6 * Wireshark - Network traffic analyzer
7 * By Gerald Combs <gerald@wireshark.org>
8 * Copyright 1998 Gerald Combs
10 * This program is free software; you can redistribute it and/or
11 * modify it under the terms of the GNU General Public License
12 * as published by the Free Software Foundation; either version 2
13 * of the License, or (at your option) any later version.
15 * This program is distributed in the hope that it will be useful,
16 * but WITHOUT ANY WARRANTY; without even the implied warranty of
17 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
18 * GNU General Public License for more details.
20 * You should have received a copy of the GNU General Public License
21 * along with this program; if not, write to the Free Software
22 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
38 #ifdef HAVE_SYS_TYPES_H
39 # include <sys/types.h>
42 #ifdef HAVE_NETINET_IN_H
43 #include <netinet/in.h>
46 #ifdef HAVE_ARPA_INET_H
47 #include <arpa/inet.h>
50 #ifdef HAVE_SYS_SOCKET_H
51 #include <sys/socket.h> /* needed to define AF_ values on UNIX */
54 #ifdef HAVE_WINSOCK2_H
55 #include <winsock2.h> /* needed to define AF_ values on Windows */
58 #ifdef NEED_INET_V6DEFS_H
59 # include "inet_v6defs.h"
64 #include <epan/packet.h>
66 #include "capture_opts.h"
67 #include "ringbuffer.h"
68 #include "clopts_common.h"
69 #include "cmdarg_err.h"
71 #include "capture-pcap-util.h"
72 #include <wsutil/file_util.h>
74 static gboolean capture_opts_output_to_pipe(const char *save_file, gboolean *is_pipe);
78 capture_opts_init(capture_options *capture_opts, void *cf)
80 capture_opts->cf = cf;
81 capture_opts->cfilter = g_strdup(""); /* No capture filter string specified */
82 capture_opts->iface = NULL; /* Default is "pick the first interface" */
83 capture_opts->iface_descr = NULL;
84 #ifdef HAVE_PCAP_REMOTE
85 capture_opts->src_type = CAPTURE_IFLOCAL;
86 capture_opts->remote_host = NULL;
87 capture_opts->remote_port = NULL;
88 capture_opts->auth_type = CAPTURE_AUTH_NULL;
89 capture_opts->auth_username = NULL;
90 capture_opts->auth_password = NULL;
91 capture_opts->datatx_udp = FALSE;
92 capture_opts->nocap_rpcap = TRUE;
93 capture_opts->nocap_local = FALSE;
94 #ifdef HAVE_PCAP_SETSAMPLING
95 capture_opts->sampling_method = CAPTURE_SAMP_NONE;
96 capture_opts->sampling_param = 0;
100 capture_opts->buffer_size = 1; /* 1 MB */
102 capture_opts->has_snaplen = FALSE;
103 capture_opts->snaplen = WTAP_MAX_PACKET_SIZE; /* snapshot length - default is
104 infinite, in effect */
105 capture_opts->promisc_mode = TRUE; /* promiscuous mode is the default */
106 capture_opts->linktype = -1; /* the default linktype */
107 capture_opts->saving_to_file = FALSE;
108 capture_opts->save_file = NULL;
109 capture_opts->use_pcapng = FALSE; /* the default is pcap */
110 capture_opts->real_time_mode = TRUE;
111 capture_opts->show_info = TRUE;
112 capture_opts->quit_after_cap = FALSE;
113 capture_opts->restart = FALSE;
115 capture_opts->multi_files_on = FALSE;
116 capture_opts->has_file_duration = FALSE;
117 capture_opts->file_duration = 60; /* 1 min */
118 capture_opts->has_ring_num_files = FALSE;
119 capture_opts->ring_num_files = RINGBUFFER_MIN_NUM_FILES;
121 capture_opts->has_autostop_files = FALSE;
122 capture_opts->autostop_files = 1;
123 capture_opts->has_autostop_packets = FALSE;
124 capture_opts->autostop_packets = 0;
125 capture_opts->has_autostop_filesize = FALSE;
126 capture_opts->autostop_filesize = 1024; /* 1 MB */
127 capture_opts->has_autostop_duration = FALSE;
128 capture_opts->autostop_duration = 60; /* 1 min */
131 capture_opts->fork_child = -1; /* invalid process handle */
133 capture_opts->signal_pipe_write_fd = -1;
135 capture_opts->state = CAPTURE_STOPPED;
136 capture_opts->output_to_pipe = FALSE;
138 capture_opts->owner = getuid();
139 capture_opts->group = getgid();
144 /* log content of capture_opts */
146 capture_opts_log(const char *log_domain, GLogLevelFlags log_level, capture_options *capture_opts) {
147 g_log(log_domain, log_level, "CAPTURE OPTIONS :");
148 g_log(log_domain, log_level, "CFile : 0x%p", capture_opts->cf);
149 g_log(log_domain, log_level, "Filter : %s", capture_opts->cfilter);
150 g_log(log_domain, log_level, "Interface : %s", capture_opts->iface);
151 /* iface_descr may not been filled in and some C Libraries hate a null ptr for %s */
152 g_log(log_domain, log_level, "Interface Descr : %s",
153 capture_opts->iface_descr ? capture_opts->iface_descr : "<null>");
154 #ifdef HAVE_PCAP_REMOTE
155 g_log(log_domain, log_level, "Capture source : %s",
156 capture_opts->src_type == CAPTURE_IFLOCAL ? "Local interface" :
157 capture_opts->src_type == CAPTURE_IFREMOTE ? "Remote interface" :
159 if (capture_opts->src_type == CAPTURE_IFREMOTE) {
160 g_log(log_domain, log_level, "Remote host : %s", capture_opts->remote_host);
161 g_log(log_domain, log_level, "Remote port : %s", capture_opts->remote_port);
163 g_log(log_domain, log_level, "Authentication : %s",
164 capture_opts->auth_type == CAPTURE_AUTH_NULL ? "Null" :
165 capture_opts->auth_type == CAPTURE_AUTH_PWD ? "By username/password" :
167 if (capture_opts->auth_type == CAPTURE_AUTH_PWD) {
168 g_log(log_domain, log_level, "Auth username : %s", capture_opts->auth_password);
169 g_log(log_domain, log_level, "Auth password : <hidden>");
171 g_log(log_domain, log_level, "UDP data transfer : %u", capture_opts->datatx_udp);
172 g_log(log_domain, log_level, "No capture RPCAP : %u", capture_opts->nocap_rpcap);
173 g_log(log_domain, log_level, "No capture local : %u", capture_opts->nocap_local);
176 g_log(log_domain, log_level, "BufferSize : %u (MB)", capture_opts->buffer_size);
178 g_log(log_domain, log_level, "SnapLen (%u): %u", capture_opts->has_snaplen, capture_opts->snaplen);
179 g_log(log_domain, log_level, "Promisc : %u", capture_opts->promisc_mode);
180 g_log(log_domain, log_level, "LinkType : %d", capture_opts->linktype);
181 g_log(log_domain, log_level, "SavingToFile : %u", capture_opts->saving_to_file);
182 g_log(log_domain, log_level, "SaveFile : %s", (capture_opts->save_file) ? capture_opts->save_file : "");
183 g_log(log_domain, log_level, "Fileformat : %s", (capture_opts->use_pcapng) ? "PCAPNG" : "PCAP");
184 g_log(log_domain, log_level, "RealTimeMode : %u", capture_opts->real_time_mode);
185 g_log(log_domain, log_level, "ShowInfo : %u", capture_opts->show_info);
186 g_log(log_domain, log_level, "QuitAfterCap : %u", capture_opts->quit_after_cap);
188 g_log(log_domain, log_level, "MultiFilesOn : %u", capture_opts->multi_files_on);
189 g_log(log_domain, log_level, "FileDuration (%u): %u", capture_opts->has_file_duration, capture_opts->file_duration);
190 g_log(log_domain, log_level, "RingNumFiles (%u): %u", capture_opts->has_ring_num_files, capture_opts->ring_num_files);
192 g_log(log_domain, log_level, "AutostopFiles (%u): %u", capture_opts->has_autostop_files, capture_opts->autostop_files);
193 g_log(log_domain, log_level, "AutostopPackets (%u): %u", capture_opts->has_autostop_packets, capture_opts->autostop_packets);
194 g_log(log_domain, log_level, "AutostopFilesize(%u): %u (KB)", capture_opts->has_autostop_filesize, capture_opts->autostop_filesize);
195 g_log(log_domain, log_level, "AutostopDuration(%u): %u", capture_opts->has_autostop_duration, capture_opts->autostop_duration);
197 g_log(log_domain, log_level, "ForkChild : %d", capture_opts->fork_child);
199 g_log(log_domain, log_level, "SignalPipeWrite : %d", capture_opts->signal_pipe_write_fd);
204 * Given a string of the form "<autostop criterion>:<value>", as might appear
205 * as an argument to a "-a" option, parse it and set the criterion in
206 * question. Return an indication of whether it succeeded or failed
210 set_autostop_criterion(capture_options *capture_opts, const char *autostoparg)
214 colonp = strchr(autostoparg, ':');
222 * Skip over any white space (there probably won't be any, but
223 * as we allow it in the preferences file, we might as well
226 while (isspace((guchar)*p))
230 * Put the colon back, so if our caller uses, in an
231 * error message, the string they passed us, the message
237 if (strcmp(autostoparg,"duration") == 0) {
238 capture_opts->has_autostop_duration = TRUE;
239 capture_opts->autostop_duration = get_positive_int(p,"autostop duration");
240 } else if (strcmp(autostoparg,"filesize") == 0) {
241 capture_opts->has_autostop_filesize = TRUE;
242 capture_opts->autostop_filesize = get_positive_int(p,"autostop filesize");
243 } else if (strcmp(autostoparg,"files") == 0) {
244 capture_opts->multi_files_on = TRUE;
245 capture_opts->has_autostop_files = TRUE;
246 capture_opts->autostop_files = get_positive_int(p,"autostop files");
250 *colonp = ':'; /* put the colon back */
255 * Given a string of the form "<ring buffer file>:<duration>", as might appear
256 * as an argument to a "-b" option, parse it and set the arguments in
257 * question. Return an indication of whether it succeeded or failed
261 get_ring_arguments(capture_options *capture_opts, const char *arg)
263 gchar *p = NULL, *colonp;
265 colonp = strchr(arg, ':');
273 * Skip over any white space (there probably won't be any, but
274 * as we allow it in the preferences file, we might as well
277 while (isspace((guchar)*p))
281 * Put the colon back, so if our caller uses, in an
282 * error message, the string they passed us, the message
289 if (strcmp(arg,"files") == 0) {
290 capture_opts->has_ring_num_files = TRUE;
291 capture_opts->ring_num_files = get_natural_int(p, "number of ring buffer files");
292 } else if (strcmp(arg,"filesize") == 0) {
293 capture_opts->has_autostop_filesize = TRUE;
294 capture_opts->autostop_filesize = get_positive_int(p, "ring buffer filesize");
295 } else if (strcmp(arg,"duration") == 0) {
296 capture_opts->has_file_duration = TRUE;
297 capture_opts->file_duration = get_positive_int(p, "ring buffer duration");
300 *colonp = ':'; /* put the colon back */
304 #ifdef HAVE_PCAP_SETSAMPLING
306 * Given a string of the form "<sampling type>:<value>", as might appear
307 * as an argument to a "-m" option, parse it and set the arguments in
308 * question. Return an indication of whether it succeeded or failed
312 get_sampling_arguments(capture_options *capture_opts, const char *arg)
314 gchar *p = NULL, *colonp;
316 colonp = strchr(arg, ':');
323 while (isspace((guchar)*p))
330 if (strcmp(arg, "count") == 0) {
331 capture_opts->sampling_method = CAPTURE_SAMP_BY_COUNT;
332 capture_opts->sampling_param = get_positive_int(p, "sampling count");
333 } else if (strcmp(arg, "timer") == 0) {
334 capture_opts->sampling_method = CAPTURE_SAMP_BY_TIMER;
335 capture_opts->sampling_param = get_positive_int(p, "sampling timer");
342 #ifdef HAVE_PCAP_REMOTE
344 * Given a string of the form "<username>:<password>", as might appear
345 * as an argument to a "-A" option, parse it and set the arguments in
346 * question. Return an indication of whether it succeeded or failed
350 get_auth_arguments(capture_options *capture_opts, const char *arg)
352 gchar *p = NULL, *colonp;
354 colonp = strchr(arg, ':');
361 while (isspace((guchar)*p))
364 capture_opts->auth_type = CAPTURE_AUTH_PWD;
365 capture_opts->auth_username = g_strdup(arg);
366 capture_opts->auth_password = g_strdup(p);
373 capture_opts_add_iface_opt(capture_options *capture_opts, const char *optarg)
384 * If the argument is a number, treat it as an index into the list
385 * of adapters, as printed by "tshark -D".
387 * This should be OK on UNIX systems, as interfaces shouldn't have
388 * names that begin with digits. It can be useful on Windows, where
389 * more than one interface can have the same name.
391 adapter_index = strtol(optarg, &p, 10);
392 if (p != NULL && *p == '\0') {
393 if (adapter_index < 0) {
394 cmdarg_err("The specified adapter index is a negative number");
397 if (adapter_index > INT_MAX) {
398 cmdarg_err("The specified adapter index is too large (greater than %d)",
402 if (adapter_index == 0) {
403 cmdarg_err("There is no interface with that adapter index");
406 if_list = get_interface_list(&err, &err_str);
407 if (if_list == NULL) {
410 case CANT_GET_INTERFACE_LIST:
411 cmdarg_err("%s", err_str);
415 case NO_INTERFACES_FOUND:
416 cmdarg_err("There are no interfaces on which a capture can be done");
421 if_info = g_list_nth_data(if_list, adapter_index - 1);
422 if (if_info == NULL) {
423 cmdarg_err("There is no interface with that adapter index");
426 capture_opts->iface = g_strdup(if_info->name);
427 /* We don't set iface_descr here because doing so requires
428 * capture_ui_utils.c which requires epan/prefs.c which is
429 * probably a bit too much dependency for here...
431 free_interface_list(if_list);
433 capture_opts->iface = g_strdup(optarg);
440 capture_opts_add_opt(capture_options *capture_opts, int opt, const char *optarg, gboolean *start_capture)
445 case 'a': /* autostop criteria */
446 if (set_autostop_criterion(capture_opts, optarg) == FALSE) {
447 cmdarg_err("Invalid or unknown -a flag \"%s\"", optarg);
451 #ifdef HAVE_PCAP_REMOTE
453 if (get_auth_arguments(capture_opts, optarg) == FALSE) {
454 cmdarg_err("Invalid or unknown -A arg \"%s\"", optarg);
459 case 'b': /* Ringbuffer option */
460 capture_opts->multi_files_on = TRUE;
461 if (get_ring_arguments(capture_opts, optarg) == FALSE) {
462 cmdarg_err("Invalid or unknown -b arg \"%s\"", optarg);
467 case 'B': /* Buffer size */
468 capture_opts->buffer_size = get_positive_int(optarg, "buffer size");
471 case 'c': /* Capture n packets */
472 capture_opts->has_autostop_packets = TRUE;
473 capture_opts->autostop_packets = get_positive_int(optarg, "packet count");
475 case 'f': /* capture filter */
476 if (capture_opts->has_cfilter) {
477 cmdarg_err("More than one -f argument specified");
480 capture_opts->has_cfilter = TRUE;
481 g_free(capture_opts->cfilter);
482 capture_opts->cfilter = g_strdup(optarg);
484 case 'H': /* Hide capture info dialog box */
485 capture_opts->show_info = FALSE;
487 case 'i': /* Use interface x */
488 status = capture_opts_add_iface_opt(capture_opts, optarg);
493 case 'k': /* Start capture immediately */
494 *start_capture = TRUE;
496 /*case 'l':*/ /* Automatic scrolling in live capture mode */
497 #ifdef HAVE_PCAP_SETSAMPLING
499 if (get_sampling_arguments(capture_opts, optarg) == FALSE) {
500 cmdarg_err("Invalid or unknown -m arg \"%s\"", optarg);
505 case 'n': /* Use pcapng format */
506 capture_opts->use_pcapng = TRUE;
508 case 'p': /* Don't capture in promiscuous mode */
509 capture_opts->promisc_mode = FALSE;
511 case 'Q': /* Quit after capture (just capture to file) */
512 capture_opts->quit_after_cap = TRUE;
513 *start_capture = TRUE; /*** -Q implies -k !! ***/
515 #ifdef HAVE_PCAP_REMOTE
517 capture_opts->nocap_rpcap = FALSE;
520 case 's': /* Set the snapshot (capture) length */
521 capture_opts->has_snaplen = TRUE;
522 capture_opts->snaplen = get_natural_int(optarg, "snapshot length");
524 * Make a snapshot length of 0 equivalent to the maximum packet
525 * length, mirroring what tcpdump does.
527 if (capture_opts->snaplen == 0)
528 capture_opts->snaplen = WTAP_MAX_PACKET_SIZE;
530 case 'S': /* "Real-Time" mode: used for following file ala tail -f */
531 capture_opts->real_time_mode = TRUE;
533 #ifdef HAVE_PCAP_REMOTE
535 capture_opts->datatx_udp = TRUE;
538 case 'w': /* Write to capture file x */
539 capture_opts->saving_to_file = TRUE;
540 g_free(capture_opts->save_file);
541 #if defined _WIN32 && GLIB_CHECK_VERSION(2,6,0)
542 /* since GLib 2.6, we need to convert filenames to utf8 for Win32 */
543 capture_opts->save_file = g_locale_to_utf8(optarg, -1, NULL, NULL, NULL);
545 capture_opts->save_file = g_strdup(optarg);
547 status = capture_opts_output_to_pipe(capture_opts->save_file, &capture_opts->output_to_pipe);
549 case 'y': /* Set the pcap data link type */
550 capture_opts->linktype = linktype_name_to_val(optarg);
551 if (capture_opts->linktype == -1) {
552 cmdarg_err("The specified data link type \"%s\" isn't valid",
558 /* the caller is responsible to send us only the right opt's */
559 g_assert_not_reached();
566 * If you change the output format of this function, you MUST update
567 * capture_sync.c:sync_linktype_list_open() accordingly!
570 capture_opts_list_link_layer_types(capture_options *capture_opts, gboolean machine_readable)
572 gchar *err_str, *desc_str;
573 GList *lt_list, *lt_entry;
574 data_link_info_t *data_link_info;
576 /* Get the list of link-layer types for the capture device. */
577 lt_list = get_pcap_linktype_list(capture_opts->iface, &err_str);
578 if (lt_list == NULL) {
579 if (err_str != NULL) {
580 cmdarg_err("The list of data link types for the capture device \"%s\" could not be obtained (%s)."
581 "Please check to make sure you have sufficient permissions, and that\n"
582 "you have the proper interface or pipe specified.\n", capture_opts->iface, err_str);
585 cmdarg_err("The capture device \"%s\" has no data link types.", capture_opts->iface);
588 if (machine_readable) { /* tab-separated values to stdout */
589 for (lt_entry = lt_list; lt_entry != NULL; lt_entry = g_list_next(lt_entry)) {
590 data_link_info = lt_entry->data;
591 if (data_link_info->description != NULL)
592 desc_str = data_link_info->description;
594 desc_str = "(not supported)";
595 printf("%d\t%s\t%s\n", data_link_info->dlt, data_link_info->name,
599 cmdarg_err_cont("Data link types (use option -y to set):");
600 for (lt_entry = lt_list; lt_entry != NULL;
601 lt_entry = g_list_next(lt_entry)) {
602 data_link_info = lt_entry->data;
603 cmdarg_err_cont(" %s", data_link_info->name);
604 if (data_link_info->description != NULL)
605 cmdarg_err_cont(" (%s)", data_link_info->description);
607 cmdarg_err_cont(" (not supported)");
611 free_pcap_linktype_list(lt_list);
616 /* Return an ASCII-formatted list of interfaces. */
617 #define ADDRSTRLEN 46 /* Covers IPv4 & IPv6 */
619 capture_opts_list_interfaces(gboolean machine_readable)
629 char addr_str[ADDRSTRLEN];
631 if_list = get_interface_list(&err, &err_str);
632 if (if_list == NULL) {
634 case CANT_GET_INTERFACE_LIST:
635 cmdarg_err("%s", err_str);
639 case NO_INTERFACES_FOUND:
640 cmdarg_err("There are no interfaces on which a capture can be done");
646 i = 1; /* Interface id number */
647 for (if_entry = g_list_first(if_list); if_entry != NULL;
648 if_entry = g_list_next(if_entry)) {
649 if_info = if_entry->data;
650 printf("%d. %s", i++, if_info->name);
652 if (!machine_readable) {
653 /* Add the description if it exists */
654 if (if_info->description != NULL)
655 printf(" (%s)", if_info->description);
658 * Add the contents of the if_entry struct in a parseable format.
659 * Each if_entry element is tab-separated. Addresses are comma-
662 /* XXX - Make sure our description doesn't contain a tab */
663 if (if_info->description != NULL)
664 printf("\t%s\t", if_info->description);
668 for(ip_addr = g_slist_nth(if_info->ip_addr, 0); ip_addr != NULL;
669 ip_addr = g_slist_next(ip_addr)) {
670 if (ip_addr != g_slist_nth(if_info->ip_addr, 0))
673 if_addr = ip_addr->data;
674 switch(if_addr->type) {
676 if (inet_ntop(AF_INET, &if_addr->ip_addr.ip4_addr, addr_str,
678 printf("%s", addr_str);
680 printf("<unknown IPv4>");
684 if (inet_ntop(AF_INET6, &if_addr->ip_addr.ip6_addr,
685 addr_str, ADDRSTRLEN)) {
686 printf("%s", addr_str);
688 printf("<unknown IPv6>");
692 printf("<type unknown %u>", if_addr->type);
696 if (if_info->loopback)
697 printf("\tloopback");
704 free_interface_list(if_list);
710 void capture_opts_trim_snaplen(capture_options *capture_opts, int snaplen_min)
712 if (capture_opts->snaplen < 1)
713 capture_opts->snaplen = WTAP_MAX_PACKET_SIZE;
714 else if (capture_opts->snaplen < snaplen_min)
715 capture_opts->snaplen = snaplen_min;
719 void capture_opts_trim_ring_num_files(capture_options *capture_opts)
721 /* Check the value range of the ring_num_files parameter */
722 if (capture_opts->ring_num_files > RINGBUFFER_MAX_NUM_FILES)
723 capture_opts->ring_num_files = RINGBUFFER_MAX_NUM_FILES;
724 #if RINGBUFFER_MIN_NUM_FILES > 0
725 else if (capture_opts->ring_num_files < RINGBUFFER_MIN_NUM_FILES)
726 capture_opts->ring_num_files = RINGBUFFER_MIN_NUM_FILES;
731 gboolean capture_opts_trim_iface(capture_options *capture_opts, const char *capture_device)
739 /* Did the user specify an interface to use? */
740 if (capture_opts->iface == NULL) {
741 /* No - is a default specified in the preferences file? */
742 if (capture_device != NULL) {
744 capture_opts->iface = g_strdup(capture_device);
745 /* We don't set iface_descr here because doing so requires
746 * capture_ui_utils.c which requires epan/prefs.c which is
747 * probably a bit too much dependency for here...
750 /* No - pick the first one from the list of interfaces. */
751 if_list = get_interface_list(&err, &err_str);
752 if (if_list == NULL) {
755 case CANT_GET_INTERFACE_LIST:
756 cmdarg_err("%s", err_str);
760 case NO_INTERFACES_FOUND:
761 cmdarg_err("There are no interfaces on which a capture can be done");
766 if_info = if_list->data; /* first interface */
767 capture_opts->iface = g_strdup(if_info->name);
768 /* We don't set iface_descr here because doing so requires
769 * capture_ui_utils.c which requires epan/prefs.c which is
770 * probably a bit too much dependency for here...
772 free_interface_list(if_list);
782 #define S_IFIFO _S_IFIFO
785 #define S_ISFIFO(mode) (((mode) & S_IFMT) == S_IFIFO)
788 /* copied from filesystem.c */
789 static int capture_opts_test_for_fifo(const char *path)
793 if (ws_stat(path, &statb) < 0)
796 if (S_ISFIFO(statb.st_mode))
802 static gboolean capture_opts_output_to_pipe(const char *save_file, gboolean *is_pipe)
808 if (save_file != NULL) {
809 /* We're writing to a capture file. */
810 if (strcmp(save_file, "-") == 0) {
811 /* Writing to stdout. */
812 /* XXX - should we check whether it's a pipe? It's arguably
813 silly to do "-w - >output_file" rather than "-w output_file",
814 but by not checking we might be violating the Principle Of
815 Least Astonishment. */
818 /* not writing to stdout, test for a FIFO (aka named pipe) */
819 err = capture_opts_test_for_fifo(save_file);
822 case ENOENT: /* it doesn't exist, so we'll be creating it,
823 and it won't be a FIFO */
824 case 0: /* found it, but it's not a FIFO */
827 case ESPIPE: /* it is a FIFO */
831 default: /* couldn't stat it */
832 break; /* ignore: later attempt to open */
833 /* will generate a nice msg */
841 #endif /* HAVE_LIBPCAP */