#include "crypto.hh"
#include "fs-accessor.hh"
#include "globals.hh"
#include "store-api.hh"
#include "util.hh"
#include "nar-info-disk-cache.hh"
#include "thread-pool.hh"
#include "json.hh"
#include "url.hh"
#include "archive.hh"
#include "callback.hh"
namespace nix {
bool Store::isInStore(const Path & path) const
{
return isInDir(path, storeDir);
}
std::pair<StorePath, Path> Store::toStorePath(const Path & path) const
{
if (!isInStore(path))
throw Error("path '%1%' is not in the Nix store", path);
Path::size_type slash = path.find('/', storeDir.size() + 1);
if (slash == Path::npos)
return {parseStorePath(path), ""};
else
return {parseStorePath(std::string_view(path).substr(0, slash)), path.substr(slash)};
}
Path Store::followLinksToStore(std::string_view _path) const
{
Path path = absPath(std::string(_path));
while (!isInStore(path)) {
if (!isLink(path)) break;
string target = readLink(path);
path = absPath(target, dirOf(path));
}
if (!isInStore(path))
throw BadStorePath("path '%1%' is not in the Nix store", path);
return path;
}
StorePath Store::followLinksToStorePath(std::string_view path) const
{
return toStorePath(followLinksToStore(path)).first;
}
StorePathWithOutputs Store::followLinksToStorePathWithOutputs(std::string_view path) const
{
auto [path2, outputs] = nix::parsePathWithOutputs(path);
return StorePathWithOutputs { followLinksToStorePath(path2), std::move(outputs) };
}
/* Store paths have the following form:
<realized-path> = <store>/<h>-<name>
where
<store> = the location of the Nix store, usually /nix/store
<name> = a human readable name for the path, typically obtained
from the name attribute of the derivation, or the name of the
source file from which the store path is created. For derivation
outputs other than the default "out" output, the string "-<id>"
is suffixed to <name>.
<h> = base-32 representation of the first 160 bits of a SHA-256
hash of <s>; the hash part of the store name
<s> = the string "<type>:sha256:<h2>:<store>:<name>";
note that it includes the location of the store as well as the
name to make sure that changes to either of those are reflected
in the hash (e.g. you won't get /nix/store/<h>-name1 and
/nix/store/<h>-name2 with equal hash parts).
<type> = one of:
"text:<r1>:<r2>:...<rN>"
for plain text files written to the store using
addTextToStore(); <r1> ... <rN> are the store paths referenced
by this path, in the form described by <realized-path>
"source:<r1>:<r2>:...:<rN>:self"
for paths copied to the store using addToStore() when recursive
= true and hashAlgo = "sha256". Just like in the text case, we
can have the store paths referenced by the path.
Additionally, we can have an optional :self label to denote self
reference.
"output:<id>"
for either the outputs created by derivations, OR paths copied
to the store using addToStore() with recursive != true or
hashAlgo != "sha256" (in that case "source" is used; it's
silly, but it's done that way for compatibility). <id> is the
name of the output (usually, "out").
<h2> = base-16 representation of a SHA-256 hash of:
if <type> = "text:...":
the string written to the resulting store path
if <type> = "source":
the serialisation of the path from which this store path is
copied, as returned by hashPath()
if <type> = "output:<id>":
for non-fixed derivation outputs:
the derivation (see hashDerivationModulo() in
primops.cc)
for paths copied by addToStore() or produced by fixed-output
derivations:
the string "fixed:out:<rec><algo>:<hash>:", where
<rec> = "r:" for recursive (path) hashes, or "" for flat
(file) hashes
<algo> = "md5", "sha1" or "sha256"
<hash> = base-16 representation of the path or flat hash of
the contents of the path (or expected contents of the
path for fixed-output derivations)
Note that since an output derivation has always type output, while
something added by addToStore can have type output or source depending
on the hash, this means that the same input can be hashed differently
if added to the store via addToStore or via a derivation, in the sha256
recursive case.
It would have been nicer to handle fixed-output derivations under
"source", e.g. have something like "source:<rec><algo>", but we're
stuck with this for now...
The main reason for this way of computing names is to prevent name
collisions (for security). For instance, it shouldn't be feasible
to come up with a derivation whose output path collides with the
path for a copied source. The former would have a <s> starting with
"output:out:", while the latter would have a <s> starting with
"source:".
*/
StorePath Store::makeStorePath(std::string_view type,
std::string_view hash, std::string_view name) const
{
/* e.g., "source:sha256:1abc...:/nix/store:foo.tar.gz" */
string s = std::string { type }