/*cellwriter -- a character recognition input methodCopyright (C) 2007 Michael Levin <risujin@risujin.org>This program is free software; you can redistribute it and/ormodify it under the terms of the GNU General Public Licenseas published by the Free Software Foundation; either version 2of the License, or (at your option) any later version.This program is distributed in the hope that it will be useful,but WITHOUT ANY WARRANTY; without even the implied warranty ofMERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See theGNU General Public License for more details.You should have received a copy of the GNU General Public Licensealong with this program; if not, write to the Free SoftwareFoundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.*/#include "config.h"#include "common.h"#include <sys/stat.h>#include <fcntl.h>#include <unistd.h>/*        Single-instance checks*/static SingleInstanceFunc on_dupe;static int fifo;static char *path;static gboolean check_dupe(void){        ssize_t len;        char buf[2];        if (fifo <= 0 || !on_dupe)                return FALSE;        len = read(fifo, buf, 1);        buf[1] = 0;        if (len > 0)                on_dupe(buf);        return TRUE;}void single_instance_cleanup(void){        if (fifo > 0)                close(fifo);        if (path && unlink(path) == -1)                log_errno("Failed to unlink program FIFO");}int single_instance_init(SingleInstanceFunc func, const char *str){        on_dupe = func;        path = g_build_filename(g_get_home_dir(), "." PACKAGE, "fifo", NULL);        /* If we can open the program FIFO in write-only mode then we must           have a reader process already running. We send it a one-byte junk           message to wake it up and quit. */        if ((fifo = open(path, O_WRONLY | O_NONBLOCK)) > 0) {                write(fifo, str, 1);                close(fifo);                return TRUE;        }        /* The FIFO can be left over from a previous instance if the program           crashes or is killed */        if (g_file_test(path, G_FILE_TEST_EXISTS)) {                g_debug("Program FIFO exists but is not opened on "                        "read-only side, deleting\n");                single_instance_cleanup();        }        /* Otherwise, create a read-only FIFO and poll for input */        fifo = 0;        if (mkfifo(path, S_IRUSR | S_IWUSR)) {                log_errno("Failed to create program FIFO");                return FALSE;        }        if ((fifo = open(path, O_RDONLY | O_NONBLOCK)) == -1) {                log_errno("Failed to open FIFO for reading");                return FALSE;        }        /* Setup the polling function */        g_timeout_add_full(G_PRIORITY_DEFAULT_IDLE, 1000,                           (GSourceFunc)check_dupe, NULL, NULL);        return FALSE;}