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#pragma once
#include "hash.hh"
#include "serialise.hh"
#include <string>
#include <map>
#include <memory>
namespace nix {
typedef std::map<Path, Path> Roots;
struct GCOptions
/* Garbage collector operation:
- `gcReturnLive': return the set of paths reachable from
(i.e. in the closure of) the roots.
- `gcReturnDead': return the set of paths not reachable from
the roots.
- `gcDeleteDead': actually delete the latter set.
- `gcDeleteSpecific': delete the paths listed in
`pathsToDelete', insofar as they are not reachable.
typedef enum {
} GCAction;
GCAction action;
/* If `ignoreLiveness' is set, then reachability from the roots is
ignored (dangerous!). However, the paths must still be
unreferenced *within* the store (i.e., there can be no other
store paths that depend on them). */
bool ignoreLiveness;
/* For `gcDeleteSpecific', the paths to delete. */
PathSet pathsToDelete;
/* Stop after at least `maxFreed' bytes have been freed. */
unsigned long long maxFreed;
struct GCResults
/* Depending on the action, the GC roots, or the paths that would
be or have been deleted. */
PathSet paths;
/* For `gcReturnDead', `gcDeleteDead' and `gcDeleteSpecific', the
number of bytes that would be or was freed. */
unsigned long long bytesFreed;
bytesFreed = 0;
struct SubstitutablePathInfo
Path deriver;
PathSet references;
unsigned long long downloadSize; /* 0 = unknown or inapplicable */
unsigned long long narSize; /* 0 = unknown */
typedef std::map<Path, SubstitutablePathInfo> SubstitutablePathInfos;
struct ValidPathInfo
Path path;
Path deriver;
Hash hash;
PathSet references;
time_t registrationTime = 0;
uint64_t narSize = 0; // 0 = unknown
uint64_t id; // internal use only
bool operator == (const ValidPathInfo & i) const
path == i.path
&& hash == i.hash
&& references == i.references;
typedef list<ValidPathInfo> ValidPathInfos;
enum BuildMode { bmNormal, bmRepair, bmCheck };
struct BuildResult
enum Status {
Built = 0,
TransientFailure, // possibly transient
} status = MiscFailure;
std::string errorMsg;
//time_t startTime = 0, stopTime = 0;
bool success() {
return status == Built || status == Substituted || status == AlreadyValid;
class StoreAPI
virtual ~StoreAPI() { }
/* Check whether a path is valid. */
virtual bool isValidPath(const Path & path) = 0;
/* Query which of the given paths is valid. */
virtual PathSet queryValidPaths(const PathSet & paths) = 0;
/* Query the set of all valid paths. */
virtual PathSet queryAllValidPaths() = 0;
/* Query information about a valid path. */
virtual ValidPathInfo queryPathInfo(const Path & path) = 0;
/* Query the hash of a valid path. */
virtual Hash queryPathHash(const Path & path) = 0;
/* Query the set of outgoing FS references for a store path. The
result is not cleared. */
virtual void queryReferences(const Path & path,
PathSet & references) = 0;
/* Queries the set of incoming FS references for a store path.
The result is not cleared. */
virtual void queryReferrers(const Path & path,
PathSet & referrers) = 0;
/* Query the deriver of a store path. Return the empty string if
no deriver has been set. */
virtual Path queryDeriver(const Path & path) = 0;
/* Return all currently valid derivations that have `path' as an
output. (Note that the result of `queryDeriver()' is the
derivation that was actually used to produce `path', which may
not exist anymore.) */
virtual PathSet queryValidDerivers(const Path & path) = 0;
/* Query the outputs of the derivation denoted by `path'. */
virtual PathSet queryDerivationOutputs(const Path & path) = 0;
/* Query the output names of the derivation denoted by `path'. */
virtual StringSet queryDerivationOutputNames(const Path & path) = 0;
/* Query the full store path given the hash part of a valid store
path, or "" if the path doesn't exist. */
virtual Path queryPathFromHashPart(const string & hashPart) = 0;
/* Query which of the given paths have substitutes. */
virtual PathSet querySubstitutablePaths(const PathSet & paths) = 0;
/* Query substitute info (i.e. references, derivers and download
sizes) of a set of paths. If a path does not have substitute
info, it's omitted from the resulting ‘infos’ map. */
virtual void querySubstitutablePathInfos(const PathSet & paths,
SubstitutablePathInfos & infos) = 0;
/* Copy the contents of a path to the store and register the
validity the resulting path. The resulting path is returned.
The function object `filter' can be used to exclude files (see
libutil/archive.hh). */
virtual Path addToStore(const string & name, const Path & srcPath,
bool recursive = true, HashType hashAlgo = htSHA256,
PathFilter & filter = defaultPathFilter, bool repair = false) = 0;
/* Like addToStore, but the contents written to the output path is
a regular file containing the given string. */
virtual Path addTextToStore(const string & name, const string & s,
const PathSet & references, bool repair = false) = 0;
/* Export a store path, that is, create a NAR dump of the store
path and append its references and its deriver. Optionally, a
cryptographic signature (created by OpenSSL) of the preceding
data is attached. */
virtual void exportPath(const Path & path, bool sign,
Sink & sink) = 0;
/* Import a sequence of NAR dumps created by exportPaths() into
the Nix store. */
virtual Paths importPaths(bool requireSignature, Source & source) = 0;
/* For each path, if it's a derivation, build it. Building a
derivation means ensuring that the output paths are valid. If
they are already valid, this is a no-op. Otherwise, validity
can be reached in two ways. First, if the output paths is
substitutable, then build the path that way. Second, the
output paths can be created by running the builder, after
recursively building any sub-derivations. For inputs that are
not derivations, substitute them. */
virtual void buildPaths(const PathSet & paths, BuildMode buildMode = bmNormal) = 0;
/* Ensure that a path is valid. If it is not currently valid, it
may be made valid by running a substitute (if defined for the
path). */
virtual void ensurePath(const Path & path) = 0;
/* Add a store path as a temporary root of the garbage collector.
The root disappears as soon as we exit. */
virtual void addTempRoot(const Path & path) = 0;
/* Add an indirect root, which is merely a symlink to `path' from
/nix/var/nix/gcroots/auto/<hash of `path'>. `path' is supposed
to be a symlink to a store path. The garbage collector will
automatically remove the indirect root when it finds that
`path' has disappeared. */
virtual void addIndirectRoot(const Path & path) = 0;
/* Acquire the global GC lock, then immediately release it. This
function must be called after registering a new permanent root,
but before exiting. Otherwise, it is possible that a running
garbage collector doesn't see the new root and deletes the
stuff we've just built. By acquiring the lock briefly, we
ensure that either:
- The collector is already running, and so we block until the
collector is finished. The collector will know about our
*temporary* locks, which should include whatever it is we
want to register as a permanent lock.
- The collector isn't running, or it's just started but hasn't
acquired the GC lock yet. In that case we get and release
the lock right away, then exit. The collector scans the
permanent root and sees our's.
In either case the permanent root is seen by the collector. */
virtual void syncWithGC() = 0;
/* Find the roots of the garbage collector. Each root is a pair
(link, storepath) where `link' is the path of the symlink
outside of the Nix store that point to `storePath'. */
virtual Roots findRoots() = 0;
/* Perform a garbage collection. */
virtual void collectGarbage(const GCOptions & options, GCResults & results) = 0;
/* Return the set of paths that have failed to build.*/
virtual PathSet queryFailedPaths() = 0;
/* Clear the "failed" status of the given paths. The special
value `*' causes all failed paths to be cleared. */
virtual void clearFailedPaths(const PathSet & paths) = 0;
/* Return a string representing information about the path that
can be loaded into the database using `nix-store --load-db' or
`nix-store --register-validity'. */
string makeValidityRegistration(const PathSet & paths,
bool showDerivers, bool showHash);
/* Optimise the disk space usage of the Nix store by hard-linking files
with the same contents. */
virtual void optimiseStore() = 0;
/* Check the integrity of the Nix store. Returns true if errors
remain. */
virtual bool verifyStore(bool checkContents, bool repair) = 0;
/* !!! These should be part of the store API, I guess. */
/* Throw an exception if `path' is not directly in the Nix store. */
void assertStorePath(const Path & path);
bool isInStore(const Path & path);
bool isStorePath(const Path & path);
/* Extract the name part of the given store path. */
string storePathToName(const Path & path);
void checkStoreName(const string & name);
/* Chop off the parts after the top-level store name, e.g.,
/nix/store/abcd-foo/bar => /nix/store/abcd-foo. */
Path toStorePath(const Path & path);
/* Follow symlinks until we end up with a path in the Nix store. */
Path followLinksToStore(const Path & path);
/* Same as followLinksToStore(), but apply toStorePath() to the
result. */
Path followLinksToStorePath(const Path & path);
/* Constructs a unique store path name. */
Path makeStorePath(const string & type,
const Hash & hash, const string & name);
Path makeOutputPath(const string & id,
const Hash & hash, const string & name);
Path makeFixedOutputPath(bool recursive,
HashType hashAlgo, Hash hash, string name);
/* This is the preparatory part of addToStore() and addToStoreFixed();
it computes the store path to which srcPath is to be copied.
Returns the store path and the cryptographic hash of the
contents of srcPath. */
std::pair<Path, Hash> computeStorePathForPath(const Path & srcPath,
bool recursive = true, HashType hashAlgo = htSHA256,
PathFilter & filter = defaultPathFilter);
/* Preparatory part of addTextToStore().
!!! Computation of the path should take the references given to
addTextToStore() into account, otherwise we have a (relatively
minor) security hole: a caller can register a source file with
bogus references. If there are too many references, the path may
not be garbage collected when it has to be (not really a problem,
the caller could create a root anyway), or it may be garbage
collected when it shouldn't be (more serious).
Hashing the references would solve this (bogus references would
simply yield a different store path, so other users wouldn't be
affected), but it has some backwards compatibility issues (the
hashing scheme changes), so I'm not doing that for now. */
Path computeStorePathForText(const string & name, const string & s,
const PathSet & references);
/* Remove the temporary roots file for this process. Any temporary
root becomes garbage after this point unless it has been registered
as a (permanent) root. */
void removeTempRoots();
/* Register a permanent GC root. */
Path addPermRoot(StoreAPI & store, const Path & storePath,
const Path & gcRoot, bool indirect, bool allowOutsideRootsDir = false);
/* Sort a set of paths topologically under the references relation.
If p refers to q, then p preceeds q in this list. */
Paths topoSortPaths(StoreAPI & store, const PathSet & paths);
/* For now, there is a single global store API object, but we'll
purify that in the future. */
extern std::shared_ptr<StoreAPI> store;
/* Factory method: open the Nix database, either through the local or
remote implementation. */
std::shared_ptr<StoreAPI> openStore(bool reserveSpace = true);
/* Display a set of paths in human-readable form (i.e., between quotes
and separated by commas). */
string showPaths(const PathSet & paths);
ValidPathInfo decodeValidPathInfo(std::istream & str,
bool hashGiven = false);
/* Export multiple paths in the format expected by ‘nix-store
--import’. */
void exportPaths(StoreAPI & store, const Paths & paths,
bool sign, Sink & sink);
MakeError(SubstError, Error)
MakeError(BuildError, Error) /* denotes a permanent build failure */