C语言之回调函数&模块化

这里解析weston代码的部分

/* 解析配置文件并回调 */
/* 配置文件格式

[shell]
background-image=/usr/share/backgrounds/bg.jpg
background-color=0xff002244
panel-color=0x90ff0000
locking=true

[launcher]
icon=/usr/share/icons/gnome/24x24/apps/utilities-terminal.png
path=/usr/bin/gnome-terminal

 */

/* 实例 */
static void launcher_section_done(void *data);

static const struct config_key shell_config_keys[] = {
    { "background-image", CONFIG_KEY_STRING, &key_background_image },
    { "background-type", CONFIG_KEY_STRING, &key_background_type },
    { "panel-color", CONFIG_KEY_UNSIGNED_INTEGER, &key_panel_color },
    { "background-color", CONFIG_KEY_UNSIGNED_INTEGER, &key_background_color },
    { "locking", CONFIG_KEY_BOOLEAN, &key_locking },
};

static const struct config_key launcher_config_keys[] = {
    { "icon", CONFIG_KEY_STRING, &key_launcher_icon },
    { "path", CONFIG_KEY_STRING, &key_launcher_path },
};

static const struct config_section config_sections[] = {
    { "shell",
      shell_config_keys, ARRAY_LENGTH(shell_config_keys) },
    { "launcher",
      launcher_config_keys, ARRAY_LENGTH(launcher_config_keys),
      launcher_section_done }
};

static void
launcher_section_done(void *data)
{
    struct desktop *desktop = data;
    struct output *output;

    if (key_launcher_icon == NULL || key_launcher_path == NULL) {
        fprintf(stderr, "invalid launcher section
");
        return;
    }

    wl_list_for_each(output, &desktop->outputs, link) {
        panel_add_launcher(output->panel,
                   key_launcher_icon, key_launcher_path);
    }

    free(key_launcher_icon);
    key_launcher_icon = NULL;
    free(key_launcher_path);
    key_launcher_path = NULL;
}


int main()
{
    config_file = config_file_path("weston.ini");
    ret = parse_config_file(config_file,
                config_sections, ARRAY_LENGTH(config_sections),
                &desktop);
    free(config_file);
}


/**以下为共享部分******shared/config-parser.c*************************/
static int
handle_key(const struct config_key *key, const char *value)
{
    char *end, *s;
    int i, len;
    unsigned int ui;
    
    switch (key->type) {
    case CONFIG_KEY_INTEGER:
        i = strtol(value, &end, 0);
        if (*end != '
') {
            fprintf(stderr, "invalid integer: %s
", value);
            return -1;
        }
        *(int *)key->data = i;
        return 0;

    case CONFIG_KEY_UNSIGNED_INTEGER:
        ui = strtoul(value, &end, 0);
        if (*end != '
') {
            fprintf(stderr, "invalid integer: %s
", value);
            return -1;
        }
        *(unsigned int *)key->data = ui;
        return 0;

    case CONFIG_KEY_STRING:
        len = strlen(value);
        while (len > 0 && isspace(value[len - 1]))
            len--;
        s = malloc(len + 1);
        if (s == NULL)
            return -1;
        memcpy(s, value, len);
        s[len] = '';
        *(char **)key->data = s;
        return 0;

    case CONFIG_KEY_BOOLEAN:
        if (strcmp(value, "false
") == 0)
            *(int *)key->data = 0;
        else if (strcmp(value, "true
") == 0)
            *(int *)key->data = 1;
        else {
            fprintf(stderr, "invalid bool: %s
", value);
            return -1;
        }
        return 0;

    default:
        assert(0);
        break;
    }

    return -1;
}

int
parse_config_file(const char *path,
          const struct config_section *sections, int num_sections,
          void *data)
{
    FILE *fp;
    char line[512], *p;
    const struct config_section *current = NULL;
    int i;

    fp = fopen(path, "r");
    if (fp == NULL) {
        fprintf(stderr, "couldn't open %s
", path);
        return -1;
    }

    while (fgets(line, sizeof line, fp)) {
        if (line[0] == '#' || line[0] == '
') {
            continue;
        } if (line[0] == '[') {
            p = strchr(&line[1], ']');
            if (!p || p[1] != '
') {
                fprintf(stderr, "malformed "
                    "section header: %s
", line);
                fclose(fp);
                return -1;
            }
            if (current && current->done)
                current->done(data);
            p[0] = '';
            for (i = 0; i < num_sections; i++) {
                if (strcmp(sections[i].name, &line[1]) == 0) {
                    current = &sections[i];
                    break;
                }
            }
            if (i == num_sections)
                current = NULL;
        } else if (p = strchr(line, '='), p != NULL) {
            if (current == NULL)
                continue;
            p[0] = '';
            for (i = 0; i < current->num_keys; i++) {
                if (strcmp(current->keys[i].name, line) == 0) {
                    if (handle_key(&current->keys[i], &p[1]) < 0) {
                        fclose(fp);
                        return -1;
                    }
                    break;
                }
            }
        } else {
            fprintf(stderr, "malformed config line: %s
", line);
            fclose(fp);
            return -1;
        }
    }

    if (current && current->done)
        current->done(data);

    fclose(fp);

    return 0;
}