Leo Famulari <leo@famulari.name> skribis:

> On Wed, Dec 21, 2016 at 03:22:40AM -0500, Leo Famulari wrote:
>> I ran the guix-daemon with strace, and I see these relevant lines:
>> 
>> 15337 [pid 30675] mkdir("/home/leo/tmp/guix-build/guix-build-nmap-7.40.tar.bz2.drv-0", 0700) = 0
>> 15338 [pid 30675] getegid()                   = 0
>> 15339 [pid 30675] chown("/home/leo/tmp/guix-build/guix-build-nmap-7.40.tar.bz2.drv-0", -1, 0) = 0
>
> I believe this corresponds to the use of createTempDir() at
> nix/libstore/build.cc:1718. The path of the new directory is saved in
> the tmpDir variable.
>
>> 15438 [pid 30693] chdir("/tmp/guix-build-nmap-7.40.tar.bz2.drv-0") = -1 ENOENT (No such file or directory)
>
> And then later, at nix/libstore/build.cc:2204, we do this:
>
> 2204         if (chdir(tmpDirInSandbox.c_str()) == -1)
> 2205             throw SysError(format("changing into `%1%'") % tmpDir);
>
> It tries to change to the wrong directory (the new "out of band"
> downloader doesn't use a chroot, IIUC), and then prints a misleading
> error message. This explains the discrepancy between what we see in
> strace and on stderr.

Good catch!

AFAICS the flaw is that there’s one place where I wrote:

  if (useChroot && !isBuiltin(drv))

while several other places just do something like:

  if (useChroot)

Could the patch below solve the problem?