Android Enthusiasts

Firelord

16:00

@Izzy There is a name of the folder where adb saves the shared storage in its backup. I don't remember it. You may see this question asking about the location of the pictures.

Izzy

16:14

@Firelord I never include shared-storage with my ADB backups (makes no sense, just bloats them – I can copy SD card contents directly to back it up), so I don't remember the name either.

Apart from that, I usually make "app-based backups" – i.e. backup each app separately (Adebar generates those scripts for me). A bit nasty that one has to approve each of them separately – but that gives me the chance of a "selective restore" ;)

Firelord

@Izzy haha! And I told that user to wait patiently since I pinged a user to help out. I would never make the same mistake again. :)

Izzy

I'll take a look at the question and apologize on your behalf #D

Firelord

@Izzy Thanks! and I'm obliged to ping you again in 4 hours. :)

Izzy

@Firelord So you are, yes :)

Arielle

16:49

Hi people. First time here

Izzy

@Arielle Welcome to our chat-room!

Arielle

Thanks.

Izzy

It's usually quite silent in here (unless @Firelord and I have a hot discussion ;) – so don't wonder.

Might well be the calm before the storm :)

Arielle

Heh, okay. And sorry if this is a stupid question, but what happens when a bounty expires?

Firelord

@Arielle Hi! || @Izzy I took shared backup, so I updated OP about the location of images, possibly will be able to help out completely, so I won't complete my obligation now. :D

Izzy

16:56

@Firelord OK, thanks! That's the safe variant. I'm not sure whether I've kept that pretty large file.

@Arielle You won't get it back.

If you don't assing it explicitly, the highest rating answer given after the bounty was setup will be granted half of it.

Firelord

@Arielle I see you have three hours left here.

Izzy

Bounties are like lottery tickets: you might win (an answer) or not, but you never get your pay back :)

@Firelord Yes, but she cannot award it (no answer at all). And don't forget about the "grace period", usually giving her another 24h

Your chance maybe? ;)

What I find strange with that issue Arielle is having there: that the mount seems to "be hidden".

@Arielle you switched to root, mounted (card was there), went back to "normal user" (mount no longer showed the card). If at that moment you su again, does mount show the card again, or is it really gone?

Arielle

Yeah, the mount does show up again. It doesn't go away until I shut down, or umount it

Izzy

Well, that's real strange. So it is mounted, but doesn't show up with mount executed as user?

Arielle

That's right. Non-root users just ignore it and attempt to write through to rootfs, which fails because it's mounted as read-only.

Izzy

17:04

When mounted, can you check the mount-point with ls -l (to show its permissions in mounted state)?

Firelord

@Izzy Thinking the same

Izzy

@Arielle Huh? I had expected they'd get a "permission denied" – but never that!

Arielle

Well, probably because I changed permissions on the mount point while it wasn't mounted

Izzy

Either there is something mounted (then write there or give permission error), or not (write "through to /"). But never a mix of the two.

@Arielle I don't think so. When you run mount as root, what does it show where the card is mounted to?

Could you just copy-paste that one line here?

Arielle

Hold on, I'm plugging my phone in to run ADB on my PC

Izzy

17:07

Yupp

Next to look for is where the "normal users" (apps) are trying to write to.

I have a guess here: missing symlinks. Let's see when we've got the output.

Arielle

Apparently the ADB shell user is denied permission to /storage at all

Izzy

(though missing symlinks won't explain why it's not auto-mounted)

Firelord

@Arielle Permissions messed up.

Izzy

@Arielle Uh? Yeah, in that case: See @Firelord, quote: "Permissions messed up."

Arielle

`d---r-x--- root sdcard_r`
Those are the permissions on `/storage`

Izzy

17:11

All users should have at least read-access to /storage (and most likely also one level below that, if there is something)

Arielle

Apparently only the users in the sdcard_r group can access /storage

Firelord

No r for others is there.

Izzy

and no r for owner, very strange.

and no x for owner/others, so noone can cd into it.

Firelord

@Izzy Well I myself don't have r for the owner but it should be available for others.

Izzy

@Firelord well, if root is the owner, that might explain ("I'm root, I can" :)

Arielle

17:13

Okay, I did a chmod a+rx on storage

Izzy

And yes, agreed: there should at least be "rx" for group and others.

Firelord

@Izzy I'm not root, simple bash from ssh, and I can cd as well.

Izzy

@Arielle Who's "a"? Must that not be "o"?

Arielle

"a" is everyone - owner, group and others

Izzy

And wait: if it's group "sdcard_r", it might be OK as long as everyone is in that group (the name suggests somehow that others shall not be able to read here)

@Arielle Oh, OK – that shortcut I never use :)

Dangerous :)

Arielle

17:16

Now here comes the strange part: pastebin.com/Hz9hqtdU

Izzy

btw, while "not root", run groups to see whether adb is allowed here

@Arielle leaves me speechless.

Perms look all correct when ls -l as root. Shouldn't change when not root.

Arielle

Yeah, I really don't know what's the problem here

Izzy

Somethings really messed up there – but I've got no idea what. Wouldn't have thought that possible (that perms show differently for different users – either they're shown, or "permission denied" – but not that mix).

I'm not deep enough in system stuff to know what that might be.

Arielle

pastebin.com/TsW9hBxv

Izzy

Though I wouldn't wonder if it turned out to be something really trivial in the end...

Arielle

17:20

Apparently when I run mount as root, it also turns out to have some more mounts for /data/media

Firelord

@Izzy Those messed up permission on extsdcard are actually same on my device if Ext SD card isn't mounted, but root shows the other ones. If you mount SD card and make it available for others, then permissions are same everywhere.

I just unmounted Sd card, and got that d---------

Izzy

Yeah, because it's a designated mount point. But in our case here, the card is mounted.

Did you notice in the last pastebin, that a "non-root user" doesn't see anything at all from /storage?

Though "root" gets multiple entries here?

Arielle

Wait, yes, that's right. Maybe I should mount it to somewhere else

Izzy

And do not tell me that has to do with file-system permissions – as those have nothing to do with the mount command, which reads those information from a very different place

Firelord

@Arielle Even that wouldn't explain why mount can't see any /storage

Izzy

17:24

I can't remember ad-hoc where mount reads from, but can check that. Just a sec...

Adebar, where are you?

Arielle

Okay, I tried creating an extSdCard directory in the rootfs and... same thing. pastebin.com/csawWssj

Izzy

/proc/mounts it is.

Try cat /proc/mounts and see if that differs between root and not-root.

Arielle

It does. For some reason.

pastebin.com/gNV0FN7r

Izzy

Well, so basically if root reads a certain file it has different content? (looking at the pastebin now)

Arielle

Yeah.

And what's even more strange is that normal users can read from /storage/emulated/0 just fine

Even though it doesn't show up in /proc/mounts for them

Izzy

17:29

OK, that explains why output of the mount command differs. But not why it differs – if you know what I mean confused

Arielle

...Apparently it's a chain of symlinks.

Izzy

Just wanted to say that, yes.

emulated/0 points to the storage of the "main user".

Arielle

There's /storage/sdcard0 which points to /storage/emulated/legacy which points to /mnt/shell/emulated/0

Izzy

OK, sorry, but I've gotta go now. I'll read this later when home.

Arielle

See ya

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