knotify.c

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#include "config.h"
#include "knotify.h"

#include <stdlib.h>
#include <stdio.h>
#include <stddef.h>
#include <dirent.h>
#include <string.h>
#include <libintl.h>

#ifdef WITH_KNOTIFY
#ifdef HAVE_GIO_GIO_H
#define INCLUDE_KDENOTIFY
#include <gio/gio.h>
#endif /* HAVE_GIO_GIO_H */
#endif /* WITH_KNOTIFY */

#include "output.h"
#include "len.h"
#include "char_to_int.h"
#include "check_path_exists.h"

#define UNUSED(x) (void)(x)     

#ifndef MIN
# define MIN(a,b) (((a) < (b)) ? (a) : (b))
#endif

int check(const struct dirent *e);
uid_t find_dbus_user(void);

static char *default_app = "kde";

int check(const struct dirent *e)
{
        if(strcmp(e->d_name, ".") == 0 || strcmp(e->d_name, "..") == 0)
                return 0;
        if(e->d_type == DT_DIR)
                return 1;
        return 0;
}

uid_t find_dbus_user(void)
{
        const char *machine_id_file = "/var/lib/dbus/machine-id";
        const char *search_string = "DBUS_SESSION_BUS_PID=";
        const int search_string_len = str_len(search_string);
        // get machine id from /var/lib/dbus/machine-id

        if(check_file_exists(machine_id_file, PATH_R) != 0)
                return (uid_t)0;

        char *machine_id = NULL;
        size_t n = 0;
        FILE *fp = fopen(machine_id_file, "r");
        getline(&machine_id, &n, fp);
        fclose(fp);

        if(machine_id[line_len(machine_id)] == '\n')
                machine_id[line_len(machine_id)] = '\0';

        // search for file /home/*/.dbus/session-bus/$machine_id-0
        struct dirent **dirs = NULL;
        int j, k;

        if((j = scandir("/home/", &dirs, check, NULL)) != -1)
        {
                k = 0;
                while(k < j)
                {
                        char *file = NULL;
                        asprintf(&file, "/home/%s/.dbus/session-bus/%s-0", dirs[k]->d_name, machine_id);
                        k++;
                        if(check_file_exists(file, PATH_R) != 0)
                                continue;

                        // read file
                        char *line = NULL;
                        n = 0;
                        ssize_t s;
                        fp = fopen(file, "r");

                        // read file /home/*/.dbus/session-bus/$machine_id-0
                        while((s = getline(&line, &n, fp)) != -1)
                        {
                                // search for a line starting with 'DBUS_SESSION_BUS_PID'
                                if(strncmp(line, search_string, search_string_len) == 0)
                                {
                                        // translate the 2nd part to a number
                                        pid_t pid = (pid_t)char_to_int(line + search_string_len, MIN(str_len(line), line_len(line)) - search_string_len, 10);
                                        char *proc_dir = NULL;
                                        // lookup the owner of this process id
                                        asprintf(&proc_dir, "/proc/%d/", pid);

                                        if(check_dir_exists(proc_dir, PATH_R) != 0)
                                        {
                                                free(proc_dir);
                                                proc_dir = NULL;
                                                continue;
                                        }

                                        struct stat st;
                                        if(stat(proc_dir, &st) != 0)
                                        {
                                                free(proc_dir);
                                                proc_dir = NULL;
                                                continue;
                                        }
                                        free(proc_dir);
                                        proc_dir = NULL;
                                        return st.st_uid;
                                }

                        }
                        free(line);
                        line = NULL;
                        n = 0;
                        fclose(fp);
                        fp = NULL;
                }
        }

        // return DBUS_SESSION_BUS_PID

        return (uid_t)0;
}

int kdenotify(char *app, char *title, char *text)
{
#ifdef INCLUDE_KDENOTIFY
        GError *error = NULL;

        if(app == NULL)
                app = default_app;
        if(text == NULL || title == NULL)
                return -1;

        unsigned int timeout = 5000; // duration of message in miliseconds

        if(getuid() == 0)
        {
                // get the dbus session user
                uid_t dbus_id = find_dbus_user();

                // change to the dbus session user
                debug(_("change effective user id to %d for dbus call"), dbus_id);
                seteuid(dbus_id);
        }

        g_type_init();
        GDBusProxy *proxy = g_dbus_proxy_new_for_bus_sync(G_BUS_TYPE_SESSION, G_DBUS_PROXY_FLAGS_NONE, NULL, "org.freedesktop.Notifications", "/org/freedesktop/Notifications",  "org.freedesktop.Notifications", NULL, &error);
        if(proxy == NULL)
        {
                error(_("Error creating proxy: %s"), error->message);
                g_error_free(error);
                return -1;
        }
        /*
         * s    application name
         * u    rplaces_id
         * s    app_icon
         * s    summary (/title)
         * s    message
         * as   actions
         * a{sv}        hints
         * i    timeout
         */

        GVariant *data = g_variant_new("(susssasa{sv}i)", app, 0, "", title, text, NULL, NULL, timeout);
        GVariant *res = g_dbus_proxy_call_sync(proxy, "org.freedesktop.Notifications.Notify", data, G_DBUS_CALL_FLAGS_NONE, -1, NULL, &error);
        if(res == NULL)
        {
                error(_("Error issuing call: %s"), error->message);
                g_error_free(error);
                return -1;
        }

        if(getuid() != geteuid())
        {
                debug(_("change effective user id back to root"));
                seteuid(0);
        }
#else
        UNUSED(app);
        UNUSED(title);
        UNUSED(text);
        UNUSED(default_app);
#endif /* INCLUDE_KDENOTIFY */
        return 0;
}