Commit graph

177 commits

Author SHA1 Message Date
Eelco Dolstra d8306148e0
Suppress "copying 0 paths" message 2017-10-18 15:02:58 +02:00
Eelco Dolstra 6a888ec29a
copyStorePath(): Fill in missing narHash regardless of checkSigs
I don't remember what the reasoning was here, but security is provided
by the signatures, not by whether the hash is provided by the other
store.
2017-09-08 14:48:08 +02:00
Eelco Dolstra 2cc345b95f
Give activities a verbosity level again
And print them (separately from the progress bar) given sufficient -v
flags.
2017-08-28 19:13:24 +02:00
Eelco Dolstra c137c0a5eb
Allow activities to be nested
In particular, this allows more relevant activities ("substituting X")
to supersede inferior ones ("downloading X").
2017-08-25 17:49:40 +02:00
Eelco Dolstra 40bffe0a43
Progress indicator: Cleanup 2017-08-16 20:56:03 +02:00
Eelco Dolstra bf1f123b09
Progress indicator: Show number of active items 2017-08-16 20:56:03 +02:00
Eelco Dolstra 0e0dcf2c7e
Progress indicator: Unify "copying" and "substituting"
They're the same thing after all.

Example:

  $ nix build --store local?root=/tmp/nix nixpkgs.firefox-unwrapped
  [0/1 built, 49/98 copied, 16.3/92.8 MiB DL, 55.8/309.2 MiB copied] downloading 'https://cache.nixos.org/nar/0pl9li1jigcj2dany47hpmn0r3r48wc4nz48v5mqhh426lgz3bz6.nar.xz'
2017-08-16 20:56:03 +02:00
Eelco Dolstra b29b6feaba
nix copy: Improve progress indicator
It now shows the amount of data copied:

  [8/1038 copied, 160.4/1590.9 MiB copied] copying path '...'
2017-08-16 20:56:02 +02:00
Eelco Dolstra c5e4404580
nix copy: Revive progress bar 2017-08-16 20:56:02 +02:00
Jörg Thalheim 2fd8f8bb99 Replace Unicode quotes in user-facing strings by ASCII
Relevant RFC: NixOS/rfcs#4

$ ag -l | xargs sed -i -e "/\"/s/’/'/g;/\"/s/‘/'/g"
2017-07-30 12:32:45 +01:00
Eelco Dolstra 4ec6eb1fdf
Fix accidental printError 2017-07-17 11:38:15 +02:00
Eelco Dolstra 766ad5db3b
nix path-info: Show download sizes for binary cache stores
E.g.

  $ nix path-info --json --store https://cache.nixos.org nixpkgs.thunderbird -S
  ...
      "downloadHash": "sha256:1jlixpzi225wwa0f4xdrwrqgi47ip1qpj9p06fyxxg07sfmyi4q0",
      "downloadSize": 43047620,
      "closureDownloadSize": 84745960
    }
  ]
2017-07-14 18:29:10 +02:00
Eelco Dolstra 3908d3929c
nix path-info: Don't barf on invalid paths
Now you get

  [
    {
      "path": "/nix/store/fzvliz4j5xzvnd0w5zgw2l0ksqh578yk-bla",
      "valid": false
    }
  ]
2017-07-14 18:29:10 +02:00
Eelco Dolstra 42c5774e78
Sort substituters by priority
Fixes #1438.
2017-07-04 16:34:53 +02:00
Eelco Dolstra b7203e853e
getDefaultSubstituters(): Simplify initialisation
As shlevy pointed out, static variables in C++11 have thread-safe
initialisation.
2017-07-04 16:26:48 +02:00
Eelco Dolstra c0015e87af
Support base-64 hashes
Also simplify the Hash API.

Fixes #1437.
2017-07-04 15:07:41 +02:00
Eelco Dolstra fcca702a96
Replace a few bool flags with enums
Functions like copyClosure() had 3 bool arguments, which creates a
severe risk of mixing up arguments.

Also, implement copyClosure() using copyPaths().
2017-07-03 11:38:08 +02:00
Eelco Dolstra 6e01ecd112
Fix nix-copy-closure test
Fixes

  client# error: size mismatch importing path ‘/nix/store/ywf5fihjlxwijm6ygh6s0a353b5yvq4d-libidn2-0.16’; expected 0, got 120264

This is mostly an artifact of the NixOS VM test environment, where the
Nix database doesn't contain hashes/sizes.

http://hydra.nixos.org/build/53537471
2017-05-29 16:08:56 +02:00
Eelco Dolstra b01d62285c
Improve progress indicator 2017-05-16 16:09:57 +02:00
Eelco Dolstra 62d476c7ee
Fix typo 2017-05-11 14:02:03 +02:00
Eelco Dolstra 7689181e4f
Minor cleanup 2017-05-08 15:56:52 +02:00
Eelco Dolstra 3a5f04f48c
build-remote: Don't require signatures
This restores the old behaviour.
2017-05-01 20:03:25 +02:00
Eelco Dolstra 031d70e500
Support arbitrary store URIs in nix.machines
For backwards compatibility, if the URI is just a hostname, ssh://
(i.e. LegacySSHStore) is prepended automatically.

Also, all fields except the URI are now optional. For example, this is
a valid nix.machines file:

  local?root=/tmp/nix

This is useful for testing the remote build machinery since you don't
have to mess around with ssh.
2017-05-01 17:35:30 +02:00
Eelco Dolstra 0dddcf867a
Add a dummy Store::buildPaths() method
This default implementation of buildPaths() does nothing if all
requested paths are already valid, and throws an "unsupported
operation" error otherwise. This fixes a regression introduced by
c30330df6f in binary cache and legacy
SSH stores.
2017-05-01 13:43:34 +02:00
Eelco Dolstra ba9ad29fdb
Convert Settings to the new config system
This makes all config options self-documenting.

Unknown or unparseable config settings and --option flags now cause a
warning.
2017-04-13 20:53:23 +02:00
Eelco Dolstra 1860070548
Merge branch 'rework-options' of https://github.com/copumpkin/nix 2017-04-13 16:15:51 +02:00
Eelco Dolstra 2040240e23
Add a Config class to simplify adding configuration settings
The typical use is to inherit Config and add Setting<T> members:

  class MyClass : private Config
  {
    Setting<int> foo{this, 123, "foo", "the number of foos to use"};
    Setting<std::string> bar{this, "blabla", "bar", "the name of the bar"};

    MyClass() : Config(readConfigFile("/etc/my-app.conf"))
    {
      std::cout << foo << "\n"; // will print 123 unless overriden
    }
  };

Currently, this is used by Store and its subclasses for store
parameters. You now get a warning if you specify a non-existant store
parameter in a store URI.
2017-04-13 16:03:31 +02:00
Eelco Dolstra 95295482ea
Allow "auto" as a store URI
Using the empty string is likely to be ambiguous in some contexts.
2017-04-10 11:27:29 +02:00
Eelco Dolstra 256940fc48
nix-daemon: Disable path info cache
This is useless because the client also caches path info, and can
cause problems for long-running clients like hydra-queue-runner
(i.e. it may return cached info about paths that have been
garbage-collected).
2017-04-06 14:30:31 +02:00
Eelco Dolstra e1e49c58e1
Only use cache.nixos.org when the store is /nix/store
This is consistent with the behaviour of the old
download-from-binary-cache substituter.
2017-03-21 17:59:18 +01:00
Eelco Dolstra 4bb38591e5
Restore cache.nixos.org as the default substituter
Fixes #1283.
2017-03-21 15:06:46 +01:00
Eelco Dolstra c5b83d8913
copyPaths(): Use queryValidPaths() to reduce SSH latency 2017-03-16 13:50:01 +01:00
Eelco Dolstra 91d67692cf
copyPaths(): Don't query path info for a path the target already has
For example, this cuts "nix-copy-closure --from" on a NixOS system
closure from 15.9s to 0.5s.
2017-03-16 12:05:51 +01:00
Eelco Dolstra d3eb1cf3bb
build-remote: Don't use a SSH master
This is unnecessary because we make only one connection.
2017-03-03 19:23:20 +01:00
Dan Peebles e7cb2847ab Explicitly model all settings and fail on unrecognized ones
Previously, the Settings class allowed other code to query for string
properties, which led to a proliferation of code all over the place making
up new options without any sort of central registry of valid options. This
commit pulls all those options back into the central Settings class and
removes the public get() methods, to discourage future abuses like that.

Furthermore, because we know the full set of options ahead of time, we
now fail loudly if someone enters an unrecognized option, thus preventing
subtle typos. With some template fun, we could probably also dump the full
set of options (with documentation, defaults, etc.) to the command line,
but I'm not doing that yet here.
2017-02-22 20:19:25 -05:00
Eelco Dolstra f023f64f40
RemoteStore::addToStore(): Pass content-addressability assertion
... and use this in Downloader::downloadCached(). This fixes

  $ nix-build https://nixos.org/channels/nixos-16.09-small/nixexprs.tar.xz -A hello
  error: cannot import path ‘/nix/store/csfbp1s60dkgmk9f8g0zk0mwb7hzgabd-nixexprs.tar.xz’ because it lacks a valid signature
2017-02-22 16:58:00 +01:00
Eelco Dolstra 6f4682ad36
Merge branch 'nix-copy-closure-c++' of https://github.com/shlevy/nix 2017-02-07 20:47:45 +01:00
Eelco Dolstra f38224e924
copyStorePath(): Don't require signatures for "trusted" stores
For example, SSH stores could be trusted.
2017-02-07 19:29:21 +01:00
Eelco Dolstra fa07558a06
Provide default implementations for a couple of Store methods 2017-02-07 19:29:21 +01:00
Eelco Dolstra c2b0d8749f
exportReferencesGraph: Export more complete info in JSON format
This writes info about every path in the closure in the same format as
‘nix path-info --json’. Thus it also includes NAR hashes and sizes.

Example:

  [
    {
      "path": "/nix/store/10h6li26i7g6z3mdpvra09yyf10mmzdr-hello-2.10",
      "narHash": "sha256:0ckdc4z20kkmpqdilx0wl6cricxv90lh85xpv2qljppcmz6vzcxl",
      "narSize": 197648,
      "references": [
        "/nix/store/10h6li26i7g6z3mdpvra09yyf10mmzdr-hello-2.10",
        "/nix/store/27binbdy296qvjycdgr1535v8872vz3z-glibc-2.24"
      ],
      "closureSize": 20939776
    },
    {
      "path": "/nix/store/27binbdy296qvjycdgr1535v8872vz3z-glibc-2.24",
      "narHash": "sha256:1nfn3m3p98y1c0kd0brp80dn9n5mycwgrk183j17rajya0h7gax3",
      "narSize": 20742128,
      "references": [
        "/nix/store/27binbdy296qvjycdgr1535v8872vz3z-glibc-2.24"
      ],
      "closureSize": 20742128
    }
  ]

Fixes #1134.
2017-01-26 20:41:08 +01:00
Shea Levy bfa41eb671 nix-copy-closure: Implement in C++.
Tests fail currently because the database is not given proper hashes in the VM
2017-01-20 09:47:58 -05:00
Shea Levy 167d12b02c build-remote: Implement in C++ 2016-11-10 11:09:15 -05:00
Eelco Dolstra e4655b166c copyClosure() / copyStorePath(): Expose dontCheckSigs
Needed by Hydra.
2016-11-09 19:08:20 +01:00
Eelco Dolstra 4b8f1b0ec0 Merge branch 'ssh-store' of https://github.com/shlevy/nix 2016-11-09 18:57:22 +01:00
Eelco Dolstra 542ae5c8f8 BinaryCacheStore: Optionally write a NAR listing
The store parameter "write-nar-listing=1" will cause BinaryCacheStore
to write a file ‘<store-hash>.ls.xz’ for each ‘<store-hash>.narinfo’
added to the binary cache. This file contains an XZ-compressed JSON
file describing the contents of the NAR, excluding the contents of
regular files.

E.g.

  {
    "version": 1,
    "root": {
      "type": "directory",
      "entries": {
        "lib": {
          "type": "directory",
          "entries": {
            "Mcrt1.o": {
              "type": "regular",
              "size": 1288
            },
            "Scrt1.o": {
              "type": "regular",
              "size": 3920
            },
          }
        }
      }
      ...
    }
  }

(The actual file has no indentation.)

This is intended to speed up the NixOS channels programs index
generator [1], since fetching gazillions of large NARs from
cache.nixos.org is currently a bottleneck for updating the regular
(non-small) channel.

[1] https://github.com/NixOS/nixos-channel-scripts/blob/master/generate-programs-index.cc
2016-10-21 16:50:28 +02:00
Eelco Dolstra 844219f364 Store::queryValidPaths(): Use async queryPathInfo()
This allows the binary cache substituter to pipeline requests.
2016-10-07 19:43:36 +02:00
Eelco Dolstra c663b84573 Implement generic Store::queryValidPaths() 2016-10-07 19:20:47 +02:00
Eelco Dolstra 35db4f65a0 Add copyClosure utility function for Hydra 2016-10-07 19:15:25 +02:00
Eelco Dolstra c55bf085eb printMsg(lvlError, ...) -> printError(...) etc. 2016-09-21 16:54:53 +02:00
Eelco Dolstra 75989bdca7 Make computeFSClosure() single-threaded again
The fact that queryPathInfo() is synchronous meant that we needed a
thread for every concurrent binary cache lookup, even though they end
up being handled by the same download thread. Requiring hundreds of
threads is not a good idea. So now there is an asynchronous version of
queryPathInfo() that takes a callback function to process the
result. Similarly, enqueueDownload() now takes a callback rather than
returning a future.

Thus, a command like

  nix path-info --store https://cache.nixos.org/ -r /nix/store/slljrzwmpygy1daay14kjszsr9xix063-nixos-16.09beta231.dccf8c5

that returns 4941 paths now takes 1.87s using only 2 threads (the main
thread and the downloader thread). (This is with a prewarmed
CloudFront.)
2016-09-16 18:54:14 +02:00
Shea Levy 0f39633290 Factor out the unix domain socket-specific code from RemoteStore 2016-09-02 14:15:04 -04:00
Shea Levy 53b27ddce2 Factor a function to get the store type from a URI out of the main RegisterStoreImplementation 2016-09-02 06:39:29 -04:00
Shea Levy a91954f0c6 Merge openStore and openStoreAt with default arguments 2016-09-02 06:35:48 -04:00
Eelco Dolstra d961c29c9c Mark content-addressed paths in the Nix database and in .narinfo
This allows such paths to be imported without signatures.
2016-08-10 18:05:35 +02:00
Eelco Dolstra ee22a91ab8 makeFixedOutputPath(): Drop superfluous HashType argument 2016-07-26 21:25:52 +02:00
Eelco Dolstra 74dd603495 Re-implement negative binary cache lookup caching 2016-06-20 17:39:05 +02:00
Eelco Dolstra 812c0dfbe2 Allow setting the state directory as a store parameter
E.g. "local?store=/tmp/store&state=/tmp/var".
2016-06-02 16:02:48 +02:00
Eelco Dolstra 7850d3d279 Make the store directory a member variable of Store 2016-06-01 16:24:17 +02:00
Eelco Dolstra b66ab6cdbc Fix repair during substitution 2016-05-30 15:18:12 +02:00
Eelco Dolstra 538a64e8c3 Add a Store::addToStore() variant that accepts a NAR
As a side effect, this ensures that signatures are propagated when
copying paths between stores.

Also refactored import/export to make use of this.
2016-05-04 16:15:54 +02:00
Eelco Dolstra f435f82475 Remove OpenSSL-based signing 2016-05-04 11:01:48 +02:00
Eelco Dolstra dfebfc835f Add a copyStorePath() utility function 2016-05-04 11:01:48 +02:00
Eelco Dolstra 95d20dfde9 Allow parameters in store URIs
This is to allow store-specific configuration,
e.g. s3://my-cache?compression=bzip2&secret-key=/path/to/key.
2016-04-29 16:26:16 +02:00
Eelco Dolstra aa3bc3d5dc Eliminate the substituter mechanism
Substitution is now simply a Store -> Store copy operation, most
typically from BinaryCacheStore to LocalStore.
2016-04-29 13:57:08 +02:00
Eelco Dolstra 21ef1670b3 Fix test failures 2016-04-21 18:21:25 +02:00
Eelco Dolstra 7d14f5c331 Implement S3BinaryCacheStore::queryAllValidPaths()
This allows commands like "nix verify --all" or "nix path-info --all"
to work on S3 caches.

Unfortunately, this requires some ugly hackery: when querying the
contents of the bucket, we don't want to have to read every .narinfo
file. But the S3 bucket keys only include the hash part of each store
path, not the name part. So as a special exception
queryAllValidPaths() can now return store paths *without* the name
part, and queryPathInfo() accepts such store paths (returning a
ValidPathInfo object containing the full name).
2016-04-21 17:53:47 +02:00
Eelco Dolstra 451ebf24ce Cache path info lookups in SQLite
This re-implements the binary cache database in C++, allowing it to be
used by other Store backends, in particular the S3 backend.
2016-04-20 14:12:38 +02:00
Eelco Dolstra e0204f8d46 Move path info caching from BinaryCacheStore to Store
Caching path info is generally useful. For instance, it speeds up "nix
path-info -rS /run/current-system" (i.e. showing the closure sizes of
all paths in the closure of the current system) from 5.6s to 0.15s.

This also eliminates some APIs like Store::queryDeriver() and
Store::queryReferences().
2016-04-19 18:52:53 +02:00
Eelco Dolstra 05fbc606fc nix verify-paths: Add ‘--sigs-needed <N>’ flag
This specifies the number of distinct signatures required to consider
each path "trusted".

Also renamed ‘--no-sigs’ to ‘--no-trust’ for the flag that disables
verifying whether a path is trusted (since a path can also be trusted
if it has no signatures, but was built locally).
2016-04-07 15:16:57 +02:00
Eelco Dolstra b654381eb3 Add "nix sign-paths" command
E.g.

  $ nix sign-paths -k ./secret -r $(type -p geeqie)

signs geeqie and all its dependencies using the key in ./secret.
2016-04-05 16:39:29 +02:00
Eelco Dolstra 374198ad6d Move signature support from NarInfo to ValidPathInfo 2016-03-24 11:41:00 +01:00
Eelco Dolstra 11525377e1 Typos 2016-03-24 11:27:58 +01:00
Eelco Dolstra 0b907321cc Make store implementations pluggable
This for instance allows hydra-queue-runner to add the S3 backend
at runtime.
2016-02-29 16:11:11 +01:00
Eelco Dolstra 1042c10fd0 Add NAR / Store accessor abstraction
This is primary to allow hydra-queue-runner to extract files like
"nix-support/hydra-build-products" from NARs in binary caches.
2016-02-25 17:43:19 +01:00
Eelco Dolstra 28e7e29abd Eliminate reserveSpace flag 2016-02-24 17:44:55 +01:00
Eelco Dolstra 30e9d01516 openStoreAt(): Initialise the binary cache 2016-02-24 16:52:07 +01:00
Eelco Dolstra 263187a2ec Move BinaryCacheStore / LocalBinaryCacheStore from Hydra
So you can now do:

  $ NIX_REMOTE=file:///tmp/binary-cache nix-store -qR /nix/store/...
2016-02-24 14:48:16 +01:00
Eelco Dolstra 5ac27053e9 Rename ValidPathInfo::hash -> narHash for consistency 2016-02-16 11:49:12 +01:00
Eelco Dolstra c8f4d89a34 Expose the export magic value and move LocalStore::queryReferences to Store 2016-02-15 15:01:26 +01:00
Eelco Dolstra d089372565 Add function to extract hash part of a store path 2016-02-15 15:01:26 +01:00
Eelco Dolstra fd205fb6f8 ref<T>: Add cast operator 2016-02-11 15:32:48 +01:00
Eelco Dolstra fa7cd5369b StoreAPI -> Store
Calling a class an API is a bit redundant...
2016-02-04 14:48:42 +01:00
Eelco Dolstra c10c61449f Eliminate the "store" global variable
Also, move a few free-standing functions into StoreAPI and Derivation.

Also, introduce a non-nullable smart pointer, ref<T>, which is just a
wrapper around std::shared_ptr ensuring that the pointer is never
null. (For reference-counted values, this is better than passing a
"T&", because the latter doesn't maintain the refcount. Usually, the
caller will have a shared_ptr keeping the value alive, but that's not
always the case, e.g., when passing a reference to a std::thread via
std::bind.)
2016-02-04 14:28:26 +01:00
Eelco Dolstra 9e7c1a4bbd Use the daemon when we don't have write access to the Nix database 2016-01-31 10:28:48 +01:00
Eelco Dolstra eadb86f447 nix-collect-garbage: Revive --max-freed
Fixes #609.
2015-08-21 13:57:53 +02:00
Eelco Dolstra b3491c781c More cleanup 2015-07-20 01:16:16 +02:00
Eelco Dolstra 6bd2c7bb38 OCD: foreach -> C++11 ranged for 2015-07-17 20:13:56 +02:00
Eelco Dolstra 11849a320e Use proper quotes everywhere 2014-08-20 18:03:48 +02:00
Eelco Dolstra 1c2550a2ae boost::shared_ptr -> std::shared_ptr 2014-03-30 00:49:23 +01:00
Eelco Dolstra aeb810b01e Garbage collector: Don't follow symlinks arbitrarily
Only indirect roots (symlinks to symlinks to the Nix store) are now
supported.
2013-07-12 14:03:36 +02:00
Eelco Dolstra e94806d030 Merge branch 'master' into no-manifests 2012-08-27 11:09:07 -04:00
Eelco Dolstra 967d066d8e nix-store --gc: Make ‘--max-freed 0’ do the right thing
That is, delete almost nothing (it will still remove unused links from
/nix/store/.links).
2012-08-01 19:14:58 -04:00
Eelco Dolstra 97421eb5ec Refactor settings processing
Put all Nix configuration flags in a Settings object.
2012-07-30 19:55:41 -04:00
Eelco Dolstra 4bc4da331a Reserve some disk space for the garbage collector
We can't open a SQLite database if the disk is full.  Since this
prevents the garbage collector from running when it's most needed, we
reserve some dummy space that we can free just before doing a garbage
collection.  This actually revives some old code from the Berkeley DB
days.

Fixes #27.
2012-05-29 22:59:12 -04:00
Eelco Dolstra 8be1979f1a Remove the --max-links GC option
We don't need this anymore now that current filesystems support more
than 32,000 files in a directory.
2012-03-26 20:00:02 +02:00
Eelco Dolstra 5bbd693cae * Add an API function exportPaths() that provides the functionality of
‘nix-store --export’.
* Add a Perl module that provides the functionality of
  ‘nix-copy-closure --to’.  This is used by build-remote.pl so it no
  longer needs to start a separate nix-copy-closure process.  Also, it
  uses the Perl API to do the export, so it doesn't need to start a
  separate nix-store process either.  As a result, nix-copy-closure
  and build-remote.pl should no longer fail on very large closures due
  to an "Argument list too long" error.  (Note that having very many
  dependencies in a single derivation can still fail because the
  environment can become too large.  Can't be helped though.)
2011-11-23 15:13:37 +00:00
Eelco Dolstra b2027f70d9 * Fix a huuuuge security hole in the Nix daemon. It didn't check that
derivations added to the store by clients have "correct" output
  paths (meaning that the output paths are computed by hashing the
  derivation according to a certain algorithm).  This means that a
  malicious user could craft a special .drv file to build *any*
  desired path in the store with any desired contents (so long as the
  path doesn't already exist).  Then the attacker just needs to wait
  for a victim to come along and install the compromised path.

  For instance, if Alice (the attacker) knows that the latest Firefox
  derivation in Nixpkgs produces the path

    /nix/store/1a5nyfd4ajxbyy97r1fslhgrv70gj8a7-firefox-5.0.1

  then (provided this path doesn't already exist) she can craft a .drv
  file that creates that path (i.e., has it as one of its outputs),
  add it to the store using "nix-store --add", and build it with
  "nix-store -r".  So the fake .drv could write a Trojan to the
  Firefox path.  Then, if user Bob (the victim) comes along and does

    $ nix-env -i firefox
    $ firefox

  he executes the Trojan injected by Alice.

  The fix is to have the Nix daemon verify that derivation outputs are
  correct (in addValidPath()).  This required some refactoring to move
  the hash computation code to libstore.
2011-07-20 18:10:47 +00:00
Eelco Dolstra a3883cbd28 * Store the size of a store path in the database (to be precise, the
size of the NAR serialisation of the path, i.e., `nix-store --dump
  PATH').  This is useful for Hydra.
2010-11-16 17:11:46 +00:00
Eelco Dolstra 103cfee056 * Revert r19650 (implement gc-keep-outputs by looking for derivations
with the same name as the output) and instead use the
  DerivationOutputs table in the database, which is the correct way to
  to do things.
2010-02-22 11:44:17 +00:00
Eelco Dolstra 5388944e8d * Make the garbage collector do the right thing when `gc-keep-outputs'
is enabled by not depending on the deriver.
2010-01-25 16:04:32 +00:00