Clean up handling of --capture-comment.

Don't store the comments in a capture_options structure, because that's
available only if we're being built with capture support, and
--capture-comment can be used in TShark when reading a capture file and
writing another capture file, with no live capture taking place.

This means we don't handle that option in capture_opts_add_opt(); handle
it in the programs that support it.

Support writing multiple comments in dumpcap when capturing.

These changes also fix builds without pcap, and makes --capture-comment
work in Wireshark when a capture is started from the command line with
-k.

Update the help messages to indicate that --capture-comment adds a
capture comment, it doesn't change any comment (much less "the" comment,
as there isn't necessarily a single comment).

Update the man pages:

- not to presume that only pcapng files support file comments (even if
that's true now, it might not be true in the future);
- to note that multiple instances of --capture-comment are supported,
and that multiple comments will be written, whether capturing or reading
one file and writing another;
- clarify that Wireshark doesn't *discard* SHB comments other than the
first one, even though it only displays the first one;

6 files changed, 39 insertions, 6 deletions

diff --git a/ui/capture.c b/ui/capture.c
index b88c86efdd..cff9d4ae6f 100644
--- a/ui/capture.c
+++ b/ui/capture.c
@@ -117,7 +117,9 @@ capture_callback_remove(capture_callback_t func, gpointer user_data)
  * @return TRUE if the capture starts successfully, FALSE otherwise.
  */
 gboolean
-capture_start(capture_options *capture_opts, capture_session *cap_session, info_data_t* cap_data, void(*update_cb)(void))
+capture_start(capture_options *capture_opts, GPtrArray *capture_comments,
+              capture_session *cap_session, info_data_t* cap_data,
+              void(*update_cb)(void))
 {
     GString *source;
 
@@ -128,7 +130,8 @@ capture_start(capture_options *capture_opts, capture_session *cap_session, info_
     cf_set_tempfile_source((capture_file *)cap_session->cf, source->str);
     g_string_free(source, TRUE);
     /* try to start the capture child process */
-    if (!sync_pipe_start(capture_opts, cap_session, cap_data, update_cb)) {
+    if (!sync_pipe_start(capture_opts, capture_comments, cap_session,
+                         cap_data, update_cb)) {
         /* We failed to start the capture child. */
         if(capture_opts->save_file != NULL) {
             g_free(capture_opts->save_file);
diff --git a/ui/capture.h b/ui/capture.h
index 6589dfc8e7..f02e18ed92 100644
--- a/ui/capture.h
+++ b/ui/capture.h
@@ -60,13 +60,17 @@ capture_input_init(capture_session *cap_session, capture_file *cf);
  * Start a capture session.
  *
  * @param capture_opts the numerous capture options
+ * @param capture_comments if not NULL, a GPtrArray * to a set of comments
+ *  to put in the capture file's Section Header Block if it's a pcapng file
  * @param cap_session the handle for the capture session
  * @param cap_data a struct with capture info data
  * @param update_cb update screen
  * @return TRUE if the capture starts successfully, FALSE otherwise.
  */
 extern gboolean
-capture_start(capture_options *capture_opts, capture_session *cap_session, info_data_t* cap_data, void(*update_cb)(void));
+capture_start(capture_options *capture_opts, GPtrArray *capture_comments,
+              capture_session *cap_session, info_data_t* cap_data,
+              void(*update_cb)(void));
 
 /** Stop a capture session (usually from a menu item). */
 extern void
diff --git a/ui/commandline.c b/ui/commandline.c
index 66a82493ab..66f7ebe111 100644
--- a/ui/commandline.c
+++ b/ui/commandline.c
@@ -173,8 +173,10 @@ commandline_print_usage(gboolean for_help_option) {
     fprintf(output, "\n");
     fprintf(output, "Output:\n");
     fprintf(output, "  -w <outfile|->           set the output filename (or '-' for stdout)\n");
+#ifdef HAVE_LIBPCAP
     fprintf(output, "  --capture-comment <comment>\n");
-    fprintf(output, "                           set the capture file comment, if supported\n");
+    fprintf(output, "                           add a capture file comment, if supported\n");
+#endif
 
     ws_log_print_usage(output);
 
@@ -197,6 +199,7 @@ commandline_print_usage(gboolean for_help_option) {
 }
 
 #define LONGOPT_FULL_SCREEN     LONGOPT_BASE_GUI+1
+#define LONGOPT_CAPTURE_COMMENT LONGOPT_BASE_GUI+2
 
 #define OPTSTRING OPTSTRING_CAPTURE_COMMON OPTSTRING_DISSECT_COMMON "C:g:HhjJ:klm:o:P:r:R:Svw:X:Y:z:"
 static const struct option long_options[] = {
@@ -206,6 +209,7 @@ static const struct option long_options[] = {
         {"display-filter", required_argument, NULL, 'Y' },
         {"version", no_argument, NULL, 'v'},
         {"fullscreen", no_argument, NULL, LONGOPT_FULL_SCREEN },
+        {"capture-comment", required_argument, NULL, LONGOPT_CAPTURE_COMMENT},
         LONGOPT_CAPTURE_COMMON
         LONGOPT_DISSECT_COMMON
         {0, 0, 0, 0 }
@@ -407,6 +411,7 @@ void commandline_other_options(int argc, char *argv[], gboolean opt_reset)
     global_commandline_info.list_link_layer_types = FALSE;
     global_commandline_info.list_timestamp_types = FALSE;
     global_commandline_info.quit_after_cap = getenv("WIRESHARK_QUIT_AFTER_CAPTURE") ? TRUE : FALSE;
+    global_commandline_info.capture_comments = NULL;
 #endif
     global_commandline_info.full_screen = FALSE;
 
@@ -587,6 +592,17 @@ void commandline_other_options(int argc, char *argv[], gboolean opt_reset)
             case LONGOPT_FULL_SCREEN:
                 global_commandline_info.full_screen = TRUE;
                 break;
+#ifdef HAVE_LIBPCAP
+            case LONGOPT_CAPTURE_COMMENT:  /* capture comment */
+                if (global_commandline_info.capture_comments == NULL) {
+                    global_commandline_info.capture_comments = g_ptr_array_new_with_free_func(g_free);
+                }
+                g_ptr_array_add(global_commandline_info.capture_comments, g_strdup(optarg));
+#else
+                capture_option_specified = TRUE;
+                arg_error = TRUE;
+#endif
+                break;
             default:
             case '?':        /* Bad flag - print usage message */
                 arg_error = TRUE;
diff --git a/ui/commandline.h b/ui/commandline.h
index de1ba65528..72eeefc4d7 100644
--- a/ui/commandline.h
+++ b/ui/commandline.h
@@ -27,6 +27,13 @@ typedef struct commandline_param_info
     gboolean list_timestamp_types;
     gboolean start_capture;
     gboolean quit_after_cap;
+
+    /*
+     * We currently don't support this as a way to add file comments
+     * to an existing capture file in Wireshark; we only support it
+     * for adding comments to live captures.
+     */
+    GPtrArray *capture_comments;
 #endif
     e_prefs *prefs_p;
     search_direction jump_backwards;
diff --git a/ui/qt/main.cpp b/ui/qt/main.cpp
index 975c0e21b5..efb55caad6 100644
--- a/ui/qt/main.cpp
+++ b/ui/qt/main.cpp
@@ -1034,7 +1034,9 @@ int main(int argc, char *qt_argv[])
             if (global_capture_opts.ifaces->len == 0)
                 collect_ifaces(&global_capture_opts);
             CaptureFile::globalCapFile()->window = main_w;
-            if (capture_start(&global_capture_opts, main_w->captureSession(), main_w->captureInfoData(), main_window_update)) {
+            if (capture_start(&global_capture_opts, global_commandline_info.capture_comments,
+                              main_w->captureSession(), main_w->captureInfoData(),
+                              main_window_update)) {
                 /* The capture started.  Open stat windows; we do so after creating
                    the main window, to avoid GTK warnings, and after successfully
                    opening the capture file, so we know we have something to compute
diff --git a/ui/qt/main_window_slots.cpp b/ui/qt/main_window_slots.cpp
index eed66d9ad9..0c18aece0d 100644
--- a/ui/qt/main_window_slots.cpp
+++ b/ui/qt/main_window_slots.cpp
@@ -868,7 +868,8 @@ void MainWindow::startCapture() {
 
     CaptureFile::globalCapFile()->window = this;
     info_data_.ui.ui = this;
-    if (capture_start(&global_capture_opts, &cap_session_, &info_data_, main_window_update)) {
+    if (capture_start(&global_capture_opts, NULL, &cap_session_, &info_data_,
+                      main_window_update)) {
         capture_options *capture_opts = cap_session_.capture_opts;
         GString *interface_names;