ccl:temp-pathname on Android

[heller]

ccl:temp-pathname on Android returns things like #P"/tmp/tmp\\.4.JYCET1462". That's not terribly useful as /tmp does usually not exist or is not accessible from non-root applications.

[gb]

We're basically just returning what (#_tmpnam (%null-ptr)) returns, though you're right that trusting the Android C library is unwise. (And #_tmpnam has non-Android-specific problems.)

Does /data/local/tmp/ exist ?

[heller]

Does /data/local/tmp/ exist ?

Yes, it's there but I probably created that myself.

I'm trying to use SSHDriod, a ssh server from the Android market, to setup a shared filesystem. ssh-ing to the device puts me in the directory /data/data/berserker.android.apps.sshdroid/home and gives be a different uid as adb shell would use. I'd need to change permissions for /data/local/tmp and make it writable for everybody. Setting $TMPDIR so that ccl:temp-pathname can pick it up, would be the simplest solution for me.

[gb]

(In [15146]) Optionally use environment variables to initilize CCL's notion of some filesystem paths, if CCL:*TRUST-PATHS-FROM-ENVIRONMENT* is true (as it is by default.)

Specifically:

- on Unix systems (including Android), try to use the value of the

"HOME" environment variable to initialize (USER-HOMEDIR-PATHNAME).

- On Android (only) for now, make TEMP-PATHNAME try to use the value of

TMPDIR if the directory component of the value returned by #_tmpnam doesn't exist. (It seems to be "/tmp", which would make sense if /tmp existed on Android.)

It's possible that someone might have "HOME" set incorrectly, and that trusting (easily spoofed) environment variables opens security vulnerabilities. (The glibc docs mention the latter possibility, then note that env variables are usually used because of their convenience.)

Fixes ticket:892 and fixes ticket:893.