Can't change file permissions with Root Explorer


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  1. pancake_old

    pancake_old Guest This Topic's Starter

    Yes, the phone is rooted ;)

    Specifically, when I go to /mnt/sdcard/download all the files are ---rwxr-x. When I long-click a file I can access a Permissions dialog, but any changes I make there are not actually reflected on the file system. Anyone know what might be going on?
     

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  2. pancake_old

    pancake_old Guest This Topic's Starter

    Bumping.. Can anyone please try this? I want to know if this is the expected behavior.

    Thanks!
     
  3. scary alien

    scary alien not really so scary Moderator

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    pancake,

    I've wondered the same things myself. I believe the issue is that the files you are trying to manipulate are on the /sdcard and there's clearly some mechanism for preventing the changing of the file's permission bits (probably to help prevent rooting, I'm guessing).

    I did a little manual test on my Droid Eris and my Droid X (got the same results on both; here's the results from my Droid X):

    d:\android-sdk-windows\tools>adb shell
    $ su
    su
    # cd /sdcard
    cd /sdcard
    # busybox touch testfile
    busybox touch testfile
    # ls -a -l testfile
    ls -a -l testfile
    ----rwxr-x system sdcard_rw 0 2010-11-18 23:19 testfile
    # chmod 777 testfile
    chmod 777 testfile
    # ls -a -l testfile
    ls -a -l testfile
    ----rwxr-x system sdcard_rw 0 2010-11-18 23:19 testfile
    # rm testfile
    rm testfile
    #


    Okay, now doing similar things on filesystems located under the root directory yields much different results (i.e., permission settings are honored):

    # cd /data/data
    cd /data/data
    # busybox touch testfile
    busybox touch testfile
    # ls -a -l testfile
    ls -a -l testfile
    -rw-rw-rw- root root 0 2010-11-18 23:19 testfile
    # chmod 777 testfile
    chmod 777 testfile
    # ls -a -l testfile
    ls -a -l testfile
    -rwxrwxrwx root root 0 2010-11-18 23:19 testfile
    # chmod 555 testfile
    chmod 555 testfile
    # ls -a -l testfile
    ls -a -l testfile
    -r-xr-xr-x root root 0 2010-11-18 23:19 testfile
    # chmod 500 testfile
    chmod 500 testfile
    # ls -a -l testfile
    ls -a -l testfile
    -r-x------ root root 0 2010-11-18 23:19 testfile
    # rm testfile
    rm testfile
    #


    Not a total answer, I know, but something...

    Cheers!
     
    pancake_old likes this.
  4. Android Al

    Android Al Active Member

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    It would appear that the sd card is formatted as FAT32 (pretty standard for a sd card). So you'll never get it to change permissions, as that is not supported with FAT32.
     
    pancake_old and scary alien like this.
  5. pancake_old

    pancake_old Guest This Topic's Starter

    Ahh, many thanks folks!
     
  6. scary alien

    scary alien not really so scary Moderator

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    After Android Al posted the information about FAT32 being the relevant piece of information above (thanks again, btw), I just had to know a little more about what is going on.

    I found a very good / interesting discussion about this here: Why no executables on FAT32 (SD card)? (Page 1) / General Discussion / EeeUser Forum (I know, its on an Asus EEE forum, but I think the concepts discussed are relevant to our Android phones).

    At the very least, it discusses some of the issues / reasons for this (noexec/fmask mount settings, execution bits, etc.). Not sure I understood all of it, but suffice to say that there are several things in place to keep the permissions from being monkeyed with ;).

    Cheers!
     

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