lix/src/libstore/profiles.hh
Alexander Bantyev 2384d36083
A setting to follow XDG Base Directory standard
XDG Base Directory is a standard for locations for storing various
files. Nix has a few files which seem to fit in the standard, but
currently use a custom location directly in the user's ~, polluting
it:

- ~/.nix-profile
- ~/.nix-defexpr
- ~/.nix-channels

This commit adds a config option (use-xdg-base-directories) to follow
the XDG spec and instead use the following locations:

- $XDG_STATE_HOME/nix/profile
- $XDG_STATE_HOME/nix/defexpr
- $XDG_STATE_HOME/nix/channels

If $XDG_STATE_HOME is not set, it is assumed to be ~/.local/state.

Co-authored-by: Théophane Hufschmitt <7226587+thufschmitt@users.noreply.github.com>
Co-authored-by: Tim Fenney <kodekata@gmail.com>
Co-authored-by: pasqui23 <pasqui23@users.noreply.github.com>
Co-authored-by: Artturin <Artturin@artturin.com>
Co-authored-by: John Ericson <Ericson2314@Yahoo.com>
2023-02-10 20:14:06 +04:00

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#pragma once
#include "types.hh"
#include "pathlocks.hh"
#include <time.h>
namespace nix {
class StorePath;
typedef uint64_t GenerationNumber;
struct Generation
{
GenerationNumber number;
Path path;
time_t creationTime;
};
typedef std::list<Generation> Generations;
/* Returns the list of currently present generations for the specified
profile, sorted by generation number. Also returns the number of
the current generation. */
std::pair<Generations, std::optional<GenerationNumber>> findGenerations(Path profile);
class LocalFSStore;
Path createGeneration(ref<LocalFSStore> store, Path profile, StorePath outPath);
void deleteGeneration(const Path & profile, GenerationNumber gen);
void deleteGenerations(const Path & profile, const std::set<GenerationNumber> & gensToDelete, bool dryRun);
void deleteGenerationsGreaterThan(const Path & profile, GenerationNumber max, bool dryRun);
void deleteOldGenerations(const Path & profile, bool dryRun);
void deleteGenerationsOlderThan(const Path & profile, time_t t, bool dryRun);
void deleteGenerationsOlderThan(const Path & profile, std::string_view timeSpec, bool dryRun);
void switchLink(Path link, Path target);
/* Roll back a profile to the specified generation, or to the most
recent one older than the current. */
void switchGeneration(
const Path & profile,
std::optional<GenerationNumber> dstGen,
bool dryRun);
/* Ensure exclusive access to a profile. Any command that modifies
the profile first acquires this lock. */
void lockProfile(PathLocks & lock, const Path & profile);
/* Optimistic locking is used by long-running operations like `nix-env
-i'. Instead of acquiring the exclusive lock for the entire
duration of the operation, we just perform the operation
optimistically (without an exclusive lock), and check at the end
whether the profile changed while we were busy (i.e., the symlink
target changed). If so, the operation is restarted. Restarting is
generally cheap, since the build results are still in the Nix
store. Most of the time, only the user environment has to be
rebuilt. */
std::string optimisticLockProfile(const Path & profile);
/* Creates and returns the path to a directory suitable for storing the users
profiles. */
Path profilesDir();
/* Resolve the default profile (~/.nix-profile by default, $XDG_STATE_HOME/
nix/profile if XDG Base Directory Support is enabled), and create if doesn't
exist */
Path getDefaultProfile();
}