Customize 'permission denied' error.

Add Fedora-specific message to error output when dumpcap cannot be started

because of permissions.

diff --git a/capture_sync.c b/capture_sync.c

index 8c49ed2..65e242d 100644

--- a/capture_sync.c

+++ b/capture_sync.c

@@ -368,6 +368,7 @@ sync_pipe_start(capture_options *capture_opts, capture_session *cap_session)

     gchar *signal_pipe_name;

 #else

     char errmsg[1024+1];

+    const char *securitymsg = "";

     int sync_pipe[2];                       /* pipe used to send messages from child to parent */

     enum PIPES { PIPE_READ, PIPE_WRITE };   /* Constants 0 and 1 for PIPE_READ and PIPE_WRITE */

 #endif

@@ -638,8 +639,10 @@ sync_pipe_start(capture_options *capture_opts, capture_session *cap_session)

         dup2(sync_pipe[PIPE_WRITE], 2);

         ws_close(sync_pipe[PIPE_READ]);

         execv(argv[0], argv);

-        g_snprintf(errmsg, sizeof errmsg, "Couldn't run %s in child process: %s",

-                   argv[0], g_strerror(errno));

+        if (errno == EPERM || errno == EACCES)

+            securitymsg = "\nAre you a member of the 'wireshark' group? Try running\n'usermod -a -G wireshark _your_username_' as root.";

+        g_snprintf(errmsg, sizeof errmsg, "Couldn't run %s in child process: %s%s",

+            argv[0], g_strerror(errno), securitymsg);

         sync_pipe_errmsg_to_parent(2, errmsg, "");

         /* Exit with "_exit()", so that we don't close the connection

@@ -731,6 +734,7 @@ sync_pipe_open_command(char** argv, int *data_read_fd,

     PROCESS_INFORMATION pi;

 #else

     char errmsg[1024+1];

+    const char *securitymsg = "";

     int sync_pipe[2];                       /* pipe used to send messages from child to parent */

     int data_pipe[2];                       /* pipe used to send data from child to parent */

 #endif

@@ -865,8 +869,10 @@ sync_pipe_open_command(char** argv, int *data_read_fd,

         ws_close(sync_pipe[PIPE_READ]);

         ws_close(sync_pipe[PIPE_WRITE]);

         execv(argv[0], argv);

-        g_snprintf(errmsg, sizeof errmsg, "Couldn't run %s in child process: %s",

-                   argv[0], g_strerror(errno));

+        if (errno == EPERM || errno == EACCES)

+            securitymsg = "\nAre you a member of the 'wireshark' group? Try running\n'usermod -a -G wireshark _your_username_' as root.";

+        g_snprintf(errmsg, sizeof errmsg, "Couldn't run %s in child process: %s%s",

+            argv[0], g_strerror(errno), securitymsg);

         sync_pipe_errmsg_to_parent(2, errmsg, "");

         /* Exit with "_exit()", so that we don't close the connection