isremovable.c

bool DeviceLister::isRemovable( const std::string& deviceName ) const
{
    struct stat info;
    int ret = stat(deviceName.c_str(), &info);
    if (ret != 0) {
        return false;
    }

    std::stringstream devPath;
    devPath << "/sys/dev/block/" << major(info.st_rdev) << ":" << minor(info.st_rdev);

    //this should link to /sys/devices/platform/..
    char linkPath[PATH_MAX + 1];
    if (realpath( devPath.str().c_str(), linkPath ) == NULL)
        return false;

    while (true)
    {
        bool hasRemovable = false;
        bool hasPartition  = false;

        std::unique_ptr<DIR, int(*)(DIR*)> dir( opendir( linkPath ), &closedir );
        if ( dir == nullptr ) {
            LOG_WARN( "can't  opendir", linkPath );
            return false;
        }


        dirent* result;
        while ( ( result = readdir( dir.get() ) ) != nullptr )
        {
            if ( strcmp( result->d_name, "removable" ) == 0 )
                hasRemovable  = true;
            else if ( strcmp( result->d_name, "partition" ) == 0 )
                hasPartition  = true;
            else
                continue;
        }

        if (hasRemovable)
        {
            std::stringstream removableFilePath;
            removableFilePath << linkPath << "/removable";
            std::unique_ptr<FILE, int(*)(FILE*)> removableFile( fopen( removableFilePath.str().c_str(), "r" ), &fclose );
            // Assume the file isn't removable by default
            if ( removableFile != nullptr )
            {
                char buff;
                if ( fread(&buff, sizeof(buff), 1, removableFile.get() ) == 1 ) {
                    return buff == '1';
                }
                return false;
            }
        }

        if (hasPartition)
        {
            char* lastSlash = strrchr(linkPath, '/');
            if (lastSlash == NULL)
                break;
            *lastSlash = '\0';
            continue;
        }

        break;
    }
    return false;
}