Android媒体应用下不能将两个U盘间文件复制

一、现象

复制时提示只读文件。

二、原因

1.错误

shell@coconut:/mnt/usb $ ls -l
drwxrwxr-x media_rw media_rw          1970-01-01 08:00 1214-9D53
drwxrwxr-x media_rw media_rw          1970-01-01 08:00 4256-0C90

2.正确

130|shell@coconut:/mnt/usb $ ls -l
drwxrwxr-x system   sdcard_rw          2015-03-26 19:51 1214-9D53
drwxrwxr-x system   sdcard_rw          2015-03-26 19:50 4256-0C90

三、问题解决

在挂载参数上做改动

system/vold/Volume.cpp

int Volume::mountVol() {
  if (isFatFs) {
    if (Fat::doMount(devicePath, getMountpoint(), false, false, false,
                /*AID_MEDIA_RW*/AID_SYSTEM, /*AID_MEDIA_RW*/AID_SDCARD_RW, /*permMask*/0002, true)) { //modify by tank
      SLOGE("%s failed to mount via VFAT (%s)\n", devicePath, strerror(errno));
      isFatFs = false;
    } else {
      isExtFs = false;
      isExfatFs = false;
    }
  }
}

过滤log方法：logcat -s Vold MountService DirectVolume