/*
 * sysfs.c
 * Utility functions for reading and writing sysfs properties and otherwise
 * interacting with the /sys filesystem.
 *
 * Copyright (C) 2009  Red Hat, Inc.
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of 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 of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 *
 * Author(s): David Cantrell <dcantrell@redhat.com>
 */

#include <stdio.h>
#include <stdarg.h>
#include <glib.h>
#include <libsysfs.h>

#include "sysfs.h"

/*
 * ARCH: all
 * Read the value of the specified property and return to the caller.  The
 * variable arguments are joined in to the sysfs path to read.  The caller
 * is responsible for freeing the returned value.
 */
gchar *read_sysfs_property(gchar *path, ...) {
    gchar *arg = NULL;
    va_list ap;
    gchar *value = NULL;
    gsize len = 0;
    GString *tmp = NULL;
    GError *e = NULL;

    if (path == NULL) {
        return NULL;
    }

    tmp = g_string_new(path);
    va_start(ap, path);

    /* join the variable arguments in to a path specification */
    while ((arg = va_arg(ap, char *)) != NULL) {
        if (g_str_has_suffix(tmp->str, "/")) {
            if (g_str_has_prefix(arg, "/")) {
                while (*arg != '/' && arg != '\0') {
                    arg++;
                }
            } else {
                g_string_append_printf(tmp, "/");
            }

            g_string_append_printf(tmp, arg);
        } else if (g_str_has_prefix(arg, "/")) {
            g_string_append_printf(tmp, arg);
        } else {
            g_string_append_printf(tmp, "/%s", arg);
        }
    }

    va_end(ap);

    if (!g_file_get_contents(tmp->str, &value, &len, &e)) {
        g_string_free(tmp, TRUE);
        return NULL;
    }

    g_string_free(tmp, TRUE);
    return value;
}

/*
 * ARCH: all
 * Write specified value to the given sysfs path.  The sysfs path is
 * constructed from all of the arguments following the first one.  The
 * first argument is the value to write.  All variadic arguments must be
 * strings.
 */
gboolean write_sysfs_property(gchar *value, ...) {
    gchar *arg = NULL;
    va_list ap;
    GString *tmp = g_string_new(NULL);
    GError *e = NULL;

    va_start(ap, value);

    while ((arg = va_arg(ap, char *)) != NULL) {
        if (tmp->len == 0) {
            g_string_append_printf(tmp, arg);
        } else if (g_str_has_suffix(tmp->str, "/")) {
            if (g_str_has_prefix(arg, "/")) {
                while (*arg != '/' && arg != '\0') {
                    arg++;
                }
            } else {
                g_string_append_printf(tmp, "/");
            }

            g_string_append_printf(tmp, arg);
        } else if (g_str_has_prefix(arg, "/")) {
            g_string_append_printf(tmp, arg);
        } else {
            g_string_append_printf(tmp, "/%s", arg);
        }
    }

    va_end(ap);

    if (!g_file_set_contents(tmp->str, value, -1, &e)) {
        g_string_free(tmp, TRUE);
        return FALSE;
    }

    g_string_free(tmp, TRUE);
    return TRUE;
}

/*
 * ARCH: all
 * Given a path and a bus component, look for that bus component in the
 * subdirectories of the specified path, return the fully composed bus
 * path.  Caller is responsible for freeing the returned path.
 */
gchar *sysfs_find_bus_by_component(gchar *root, gchar *component) {
    gchar *ret = NULL;
    const gchar *dir = NULL;
    GDir *dirs = NULL;
    GError *e = NULL;
    GString *tmp = NULL;

    if (root == NULL || component == NULL || sysfs_path_is_dir(root)) {
        return NULL;
    }

    if ((dirs = g_dir_open(root, 0, &e)) == NULL) {
        fprintf(stderr, "*** error opening %s: %s\n", root, e->message);
        return NULL;
    }

    tmp = g_string_new(NULL);

    while ((dir = g_dir_read_name(dirs)) != NULL) {
        g_string_printf(tmp, "%s/%s/%s", root, dir, component);

        if (!sysfs_path_is_dir(tmp->str)) {
            ret = g_strdup(tmp->str);
            break;
        }
    }

    g_dir_close(dirs);
    g_string_free(tmp, TRUE);
    return ret;
}