I have an application that writes important data to the SDCard and encrypts it using AES, which later will be used by a desktop application. I have noticed that if I do not unmount the SDCard from the Settings menu sometimes the files don't get written at all, or are corrupted.
Is there anyway in Android 2.1 that I can unmount the SDCard programmatically? Because I'm pretty sure that from time to time the users will forget to do this, and I'll be the one fixing the problems and I really don't want this.
If this is not possible,what Linux command should I use to unmount the SDCard? Since the application will run on some tablets that have a rooted OS.
You should unmount what's using the sdcard in the proper order, for example
umount /mnt/sdcard/.android_secure
umount /mnt/sdcard
or, probably synchronizing the buffers with the filesystem would be enough
sync; sync
Related
I’m new to android´s app development; so far I was able to create text files on my device. The problem is when I try move the file to my PC I cannot find it. After research I now know that files saved in the internal memory are only available to the app and the external storage can be use to share files, but my device (moto G 1° gen) only have internal memory.
So the question is, is there a way to share files on my smartphone with my pc.?
Typically, devices with internal memory still have a partition set aside that emulates external storage. On any Android device I've had, the internal memory is mounted to /sdcard/ and if you insert an actual sdcard, it gets mounted to /sdcard2/. Anything you save in /sdcard/ should appear in Windows explorer when plugging the device in over USB.
Alternatively, you can also use adb to retrieve files outside of the /sdcard/ partition by using the command "adb.exe pull [source file] [destination directory(optional)]"
It may seem strange, but I wonder is an android app able to make the SD Card inside the device windows bootable? I thought of making the SD bootable and write ultimatebootcd to it. I did it through windows, but it would be so great if android can do it!
To make the SD card bootable, you have to modify the boot sector of the card. This can not be done from a standard Android application. If the Android device is rooted, it can almost certainly be done from a native Linux program, or an NDK program.
If the device is not rooted, you can probably not do what you want. As Chris Stratton commented, if the card is already made bootable, you could probably then change for instance what OS is booted up and how.
Say, there is startup code which loads and boots an OS, then you can change the configuration file for the bootloader. A starter: http://www.syslinux.org/wiki/index.php/Boot_an_Iso_image
I used Rufus and installed a syslynux on the SdCard from a PC running window 10.then I put the card back into the Moto phone. It's receiving files that I have moved from the internal storage to the card how ever I have not a chance to find out whether they Will open up In the PC or not.
Im working on "mount ntfs sdcard"
That is problem:
- If i mount sdcard to another folder than /mtn/sdcard then my sdcard working find
- If i mount it to /mnt/sdcard then android not except it : " The SDcard is not currently mounted"
In adb shell i type mount command and see that my SDcard is mounted to /mnt/sdcard
But infact SDcard folder cannot accessable.
I think android doesnt except mount ntfs sdcard on /mnt/sdcard because it programed to mount vfat sdcard on /mnt/sdcard.
Now the question: where i can find mounting code or mounting procedure of android when we insert SDcard? i want to modify it to accept ntfs sdcard.
P/S: im on GB 2.3.6
This is a very specific question, I doubt you will get an answer here. You might want to try to locate it yourself from the source code which could be found here:
https://sites.google.com/a/android.com/opensource/download
I did some googling and found this:
http://cateee.net/lkddb/web-lkddb/NTFS_FS.html, you might need to modify it.
On Android, the mounting of the sdcard is managed by the vold daemon.
If you want a stable system, you likely need to either get vold to manage your custom mount, remove vold from the system and do it's entire job yourself, or somehow get it and your custom solution to stay out of each other's way.
Lots of custom ROMs have used vold in different ways - to partition an sdcard and add a unix-style filesystem for storing apps, to put an entire alternate android installation on an sdcard or tablet internal storage area, etc. You might get some ideas by looking at those, reading their development discussion history, etc.
I want to have access to an ext4 partition, without using Data2SD yet, on the SD card of my HTC Vision running the Virtuous Unity 1.3.0 ROM. I modded my /system/etc/vold.fstab file from this:
dev_mount sdcard /mnt/sdcard auto /devices/platform/goldfish_mmc.0
/devices/platform/msm_sdcc.4/mmc_host/mmc2
To this:
#dev_mount sdcard /mnt/sdcard auto /devices/platform/goldfish_mmc.0
/devices/platform/msm_sdcc.4/mmc_host/mmc2
dev_mount sdcard /mnt/sdcard 1 /devices/platform/goldfish_mmc.0 /devices/platform/msm_sdcc.4/mmc_host/mmc2
dev_mount e4vol /mnt/sdcard2 2 /devices/platform/goldfish_mmc.0
/devices/platform/msm_sdcc.4/mmc_host/mmc2
So I can get my second partition, with label e4vol, mount and usable on my Android device. Two issues, and I think one obviously has to do with the other.
I have tried remounting the root read-write and creating the mount point /mnt/sdcard2, but it is gone on reboot. Seems like Android might have in the past created such mounts with mount.conf. Now it does not exist on Gingerbread ROMS. Thoughts?
Is this all I would have to do to get my second partition mounted in Android, or do I also need to create /sdcard2 like /sdcard? I presume both are created as symlinks by vold as specified in this conf file, but I have not had time to check yet.
I would ask forums, but this seems like a developer question and this is the most recent release of the OS. It seems to change a lot from version to version of the OS. Thanks in advance for your patience and help.
UPDATE: So, moved the test mount to sdcard, and it did not work, even with a persistent mount point. So, not sure where I am going wrong.
Maybe you'll have to have a look into /init.rc.
There are some "mkdir /mnt/..."-statements. You only have to add your "mkdir /mnt/sdcard2" and "ln -s /mnt/sdcard2 /sdcard2" to this file.
But be careful when editing this file!!!
I looked at the vold source up to including Icecream-Sandwich: it’s final mount() system call is hardcoded to the “vfat” file system type. – Even if you get it to try the mount, it would fail.
I myself actually want to mount my ext4 SD card to /sdcard, because I regularly suffer from SD card FAT file system corruptions (and I’m not the only one having those with Android).
The alternative is: modify the init/boot process to just mount the partition where you want, bypassing vold.
I've managed to simulate a fake sdcard on Android 2.2, so that when I don't have a real sdcard, applications that need sdcard will still work. To achieve this, I borrowed some code from the Android-x86 project's extended version of `vold', and did the following:
# dd if=/dev/zero of=/data/sdcard.img bs=1024 count=1 seek=1000000 (1GB image, a sparse file)
# busybox losetup /dev/block/loop7 /data/sdcard.img
# newfs_msdos /dev/block/loop7
The problem is, when a real sdcard is inserted, I wish to use both of them without switching back and forth between them - namely, a `dual sdcard setup' on a system which only allows one sdcard. How can this be achieved?
Personally I'm not quite familiar with the Android system (actually today is my second day working on an Android project). I was told that the 2.2 version only supports one sdcard mounted on "/mnt/sdcard", applications that read/write sdcard will follow this path. I'm not quite sure about this. Can someone please shed me some light on the Android sdcard limitations and how its presence affects applications?