Fixes #824.

Functions like copyClosure() had 3 bool arguments, which creates a
severe risk of mixing up arguments.

Also, implement copyClosure() using copyPaths().

Call SetDllDirectory("") after sqlite3 init on cygwin

Cygwin sqlite3 is patched to call SetDllDirectory("/usr/bin") on init, which
affects the current process and is inherited by child processes.  It causes
DLLs to be loaded from /usr/bin/ before $PATH, which breaks all sorts of
things.  A typical failures would be header/lib version mismatches (e.g.
openssl when running checkPhase on openssh).  We'll just set it back to the
default value.

Note that this is a problem with the cygwin version of sqlite3 (currently
3.18.0).  nixpkgs doesn't have the problematic patch.

There's no reason to restrict this to Error exceptions. This shouldn't
matter to #1407 since the repl doesn't catch non-Error exceptions
anyway, but you never know...

Recently aws-sdk-cpp quietly switched to using S3 virtual host URIs
(https://github.com/aws/aws-sdk-cpp/commit/69d9c53882), i.e. it sends
requests to http://<bucket>.<region>.s3.amazonaws.com rather than
http://<region>.s3.amazonaws.com/<bucket>. However this interacts
badly with curl connection reuse. For example, if we do the following:

1) Check whether a bucket exists using GetBucketLocation.
2) If it doesn't, create it using CreateBucket.
3) Do operations on the bucket.

then 3) will fail for a minute or so with a NoSuchBucket exception,
presumably because the server being hit is a fallback for cases when
buckets don't exist.

Disabling the use of virtual hosts ensures that 3) succeeds
immediately. (I don't know what S3's consistency guarantees are for
bucket creation, but in practice buckets appear to be available
immediately.)

This is returned by recent versions. Also handle NO_SUCH_KEY even
though the library doesn't actually return that at the moment.

Newer versions of aws-sdk-cpp call CalculateDelayBeforeNextRetry()
even for non-retriable errors (like NoSuchKey) whih causes log spam in
hydra-queue-runner.

Sandboxes cannot be nested, so if Nix's build runs inside a sandbox,
it cannot use a sandbox itself. I don't see a clean way to detect
whether we're in a sandbox, so use a test-specific hack.

https://github.com/NixOS/nix/issues/1413

In particular, UF_IMMUTABLE (uchg) needs to be cleared to allow the
path to be garbage-collected or optimised.

See https://github.com/NixOS/nixpkgs/issues/25819.
+       the file from being garbage-collected.

(cherry picked from commit c20641ce)

(cherry picked from commit 0fb60e4e)

Untested, hopefully fixes #1406.

This broke "nix-store --serve".

This is mostly to ensure that when Nix is started on macOS via a
launchd service or sshd (for a remote build), it gets a certificate
bundle.

This fixes a build failure on OS X when using Hydra or Nix 1.12's
build-remote (since they don't copy the derivation to the build
machine).

Thus, instead of ‘--option <name> <value>’, you can write ‘--<name>
<value>’. So

  --option http-connections 100

becomes

  --http-connections 100

Apart from brevity, the difference is that it's not an error to set a
non-existent option via --option, but unrecognized arguments are
fatal.

Boolean options have special treatment: they're mapped to the
argument-less flags ‘--<name>’ and ‘--no-<name>’. E.g.

  --option auto-optimise-store false

becomes

  --no-auto-optimise-store

Even with "build-use-sandbox = false", we now use sandboxing with a
permissive profile that allows everything except the creation of
setuid/setgid binaries.

Add .editorconfig

- Automatically adjust editor to nix coding style
-> less nitpiks/styling issues in pull requests
-> profit(!)

see also nixpkgs' editorconfig: https://github.com/NixOS/nixpkgs/blob/master/.editorconfig

It appears that sometimes, listxattr() returns a different value for
the query case (i.e. when the buffer size is 0).

Also, add rules to allow fixed-output derivations to access the
network.

These rules are sufficient to build stdenvDarwin without any
__sandboxProfile magic.

This fixes

  Could not find any mach64 blobs in file ‘/usr/lib/libSystem.B.dylib’, continuing...

This doesn't work because the OS X sandbox cannot bind-mount
path to a different location.

The filename used was not unique and owned by the build user, so
builds could fail with

error: while setting up the build environment: cannot unlink ‘/nix/store/99i210ihnsjacajaw8r33fmgjvzpg6nr-bison-3.0.4.drv.sb’: Permission denied

runResolver() was barfing on directories like
/System/Library/Frameworks/Security.framework/Versions/Current/PlugIns. It
should probably do something sophisticated for frameworks, but let's
ignore them for now.

Issue #759.

Also, remove nix.conf from the sandbox since I don't really see a
legitimate reason for builders to access the Nix configuration.