usb設備被多次掛載問題

發現系統啓動後，同一個usb設備被掛載了多次，導致文件管理器相關應用顯示出現問題。usb設備掛載的流程在android/system/vold/Volume.cpp中，由Volume::mountUdiskVol函數處理。在mount前判斷該設備是否已被掛載，可解決該問題：

bool isUsbDeviceMounted(const char *path) {
    char device[256];
    char mount_path[256];
    char rest[256];
    FILE *fp;
    char line[1024];


    if (!(fp = fopen("/proc/mounts", "r"))) {
        SLOGE("Error opening /proc/mounts (%s)", strerror(errno));
        return false;
    }


    while(fgets(line, sizeof(line), fp)) {
        line[strlen(line)-1] = '\0';
        sscanf(line, "%255s %255s %255s\n", device, mount_path, rest);
        if (!strcmp(device, path)) {
            fclose(fp);
            return true;
        }


    }

    fclose(fp);
    return false;
}

int Volume::mountUdiskVol() {
            ...
            for (it = mUdiskPartition->begin(); it != mUdiskPartition->end();it++)
            {
                imajor =(*it)->imajor;
                iminor =(*it)->iminor;

                sprintf(devicePath, "/dev/block/vold/%d:%d", imajor,iminor);
                if (isUsbDeviceMounted(devicePath))
                    continue;
                ...            
            }
           ...
}