lix/src/libstore/derivations.cc

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#include "derivations.hh"
#include "store-api.hh"
#include "globals.hh"
#include "util.hh"
#include "worker-protocol.hh"
#include "fs-accessor.hh"
#include "istringstream_nocopy.hh"
namespace nix {
// FIXME Put this somewhere?
template<class... Ts> struct overloaded : Ts... { using Ts::operator()...; };
template<class... Ts> overloaded(Ts...) -> overloaded<Ts...>;
StorePath DerivationOutput::path(const Store & store, std::string_view drvName) const
{
return std::visit(overloaded {
[](DerivationOutputInputAddressed doi) {
return doi.path;
},
[&](DerivationOutputFixed dof) {
return store.makeFixedOutputPath(dof.hash.method, dof.hash.hash, drvName);
}
}, output);
}
const StorePath BasicDerivation::findOutput(const Store & store, const string & id) const
{
auto i = outputs.find(id);
if (i == outputs.end())
throw Error("derivation has no output '%s'", id);
return i->second.path(store, name);
}
bool BasicDerivation::isBuiltin() const
{
return string(builder, 0, 8) == "builtin:";
}
StorePath writeDerivation(ref<Store> store,
const Derivation & drv, std::string_view name, RepairFlag repair)
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{
auto references = drv.inputSrcs;
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for (auto & i : drv.inputDrvs)
references.insert(i.first);
/* Note that the outputs of a derivation are *not* references
(that can be missing (of course) and should not necessarily be
held during a garbage collection). */
auto suffix = std::string(name) + drvExtension;
auto contents = drv.unparse(*store, false);
return settings.readOnlyMode
? store->computeStorePathForText(suffix, contents, references)
: store->addTextToStore(suffix, contents, references, repair);
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}
/* Read string `s' from stream `str'. */
static void expect(std::istream & str, const string & s)
{
char s2[s.size()];
str.read(s2, s.size());
if (string(s2, s.size()) != s)
throw FormatError("expected string '%1%'", s);
}
/* Read a C-style string from stream `str'. */
static string parseString(std::istream & str)
{
string res;
expect(str, "\"");
int c;
while ((c = str.get()) != '"')
if (c == '\\') {
c = str.get();
if (c == 'n') res += '\n';
else if (c == 'r') res += '\r';
else if (c == 't') res += '\t';
else res += c;
}
else res += c;
return res;
}
static Path parsePath(std::istream & str)
* Removed the `id' attribute hack. * Formalise the notion of fixed-output derivations, i.e., derivations for which a cryptographic hash of the output is known in advance. Changes to such derivations should not propagate upwards through the dependency graph. Previously this was done by specifying the hash component of the output path through the `id' attribute, but this is insecure since you can lie about it (i.e., you can specify any hash and then produce a completely different output). Now the responsibility for checking the output is moved from the builder to Nix itself. A fixed-output derivation can be created by specifying the `outputHash' and `outputHashAlgo' attributes, the latter taking values `md5', `sha1', and `sha256', and the former specifying the actual hash in hexadecimal or in base-32 (auto-detected by looking at the length of the attribute value). MD5 is included for compatibility but should be considered deprecated. * Removed the `drvPath' pseudo-attribute in derivation results. It's no longer necessary. * Cleaned up the support for multiple output paths in derivation store expressions. Each output now has a unique identifier (e.g., `out', `devel', `docs'). Previously there was no way to tell output paths apart at the store expression level. * `nix-hash' now has a flag `--base32' to specify that the hash should be printed in base-32 notation. * `fetchurl' accepts parameters `sha256' and `sha1' in addition to `md5'. * `nix-prefetch-url' now prints out a SHA-1 hash in base-32. (TODO: a flag to specify the hash.)
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{
string s = parseString(str);
* Removed the `id' attribute hack. * Formalise the notion of fixed-output derivations, i.e., derivations for which a cryptographic hash of the output is known in advance. Changes to such derivations should not propagate upwards through the dependency graph. Previously this was done by specifying the hash component of the output path through the `id' attribute, but this is insecure since you can lie about it (i.e., you can specify any hash and then produce a completely different output). Now the responsibility for checking the output is moved from the builder to Nix itself. A fixed-output derivation can be created by specifying the `outputHash' and `outputHashAlgo' attributes, the latter taking values `md5', `sha1', and `sha256', and the former specifying the actual hash in hexadecimal or in base-32 (auto-detected by looking at the length of the attribute value). MD5 is included for compatibility but should be considered deprecated. * Removed the `drvPath' pseudo-attribute in derivation results. It's no longer necessary. * Cleaned up the support for multiple output paths in derivation store expressions. Each output now has a unique identifier (e.g., `out', `devel', `docs'). Previously there was no way to tell output paths apart at the store expression level. * `nix-hash' now has a flag `--base32' to specify that the hash should be printed in base-32 notation. * `fetchurl' accepts parameters `sha256' and `sha1' in addition to `md5'. * `nix-prefetch-url' now prints out a SHA-1 hash in base-32. (TODO: a flag to specify the hash.)
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if (s.size() == 0 || s[0] != '/')
throw FormatError("bad path '%1%' in derivation", s);
return s;
* Removed the `id' attribute hack. * Formalise the notion of fixed-output derivations, i.e., derivations for which a cryptographic hash of the output is known in advance. Changes to such derivations should not propagate upwards through the dependency graph. Previously this was done by specifying the hash component of the output path through the `id' attribute, but this is insecure since you can lie about it (i.e., you can specify any hash and then produce a completely different output). Now the responsibility for checking the output is moved from the builder to Nix itself. A fixed-output derivation can be created by specifying the `outputHash' and `outputHashAlgo' attributes, the latter taking values `md5', `sha1', and `sha256', and the former specifying the actual hash in hexadecimal or in base-32 (auto-detected by looking at the length of the attribute value). MD5 is included for compatibility but should be considered deprecated. * Removed the `drvPath' pseudo-attribute in derivation results. It's no longer necessary. * Cleaned up the support for multiple output paths in derivation store expressions. Each output now has a unique identifier (e.g., `out', `devel', `docs'). Previously there was no way to tell output paths apart at the store expression level. * `nix-hash' now has a flag `--base32' to specify that the hash should be printed in base-32 notation. * `fetchurl' accepts parameters `sha256' and `sha1' in addition to `md5'. * `nix-prefetch-url' now prints out a SHA-1 hash in base-32. (TODO: a flag to specify the hash.)
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}
* Removed the `id' attribute hack. * Formalise the notion of fixed-output derivations, i.e., derivations for which a cryptographic hash of the output is known in advance. Changes to such derivations should not propagate upwards through the dependency graph. Previously this was done by specifying the hash component of the output path through the `id' attribute, but this is insecure since you can lie about it (i.e., you can specify any hash and then produce a completely different output). Now the responsibility for checking the output is moved from the builder to Nix itself. A fixed-output derivation can be created by specifying the `outputHash' and `outputHashAlgo' attributes, the latter taking values `md5', `sha1', and `sha256', and the former specifying the actual hash in hexadecimal or in base-32 (auto-detected by looking at the length of the attribute value). MD5 is included for compatibility but should be considered deprecated. * Removed the `drvPath' pseudo-attribute in derivation results. It's no longer necessary. * Cleaned up the support for multiple output paths in derivation store expressions. Each output now has a unique identifier (e.g., `out', `devel', `docs'). Previously there was no way to tell output paths apart at the store expression level. * `nix-hash' now has a flag `--base32' to specify that the hash should be printed in base-32 notation. * `fetchurl' accepts parameters `sha256' and `sha1' in addition to `md5'. * `nix-prefetch-url' now prints out a SHA-1 hash in base-32. (TODO: a flag to specify the hash.)
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static bool endOfList(std::istream & str)
{
if (str.peek() == ',') {
str.get();
return false;
}
if (str.peek() == ']') {
str.get();
return true;
}
return false;
}
static StringSet parseStrings(std::istream & str, bool arePaths)
{
StringSet res;
while (!endOfList(str))
res.insert(arePaths ? parsePath(str) : parseString(str));
return res;
}
static DerivationOutput parseDerivationOutput(const Store & store, istringstream_nocopy & str)
{
expect(str, ","); auto path = store.parseStorePath(parsePath(str));
expect(str, ","); auto hashAlgo = parseString(str);
expect(str, ","); const auto hash = parseString(str);
expect(str, ")");
if (hashAlgo != "") {
auto method = FileIngestionMethod::Flat;
if (string(hashAlgo, 0, 2) == "r:") {
method = FileIngestionMethod::Recursive;
hashAlgo = string(hashAlgo, 2);
}
const HashType hashType = parseHashType(hashAlgo);
return DerivationOutput {
.output = DerivationOutputFixed {
.hash = FixedOutputHash {
.method = std::move(method),
.hash = Hash(hash, hashType),
},
}
};
} else
return DerivationOutput {
.output = DerivationOutputInputAddressed {
.path = std::move(path),
}
};
}
static Derivation parseDerivation(const Store & store, const string & s, std::string_view name)
{
Derivation drv;
drv.name = name;
istringstream_nocopy str(s);
expect(str, "Derive([");
/* Parse the list of outputs. */
while (!endOfList(str)) {
expect(str, "("); std::string id = parseString(str);
auto output = parseDerivationOutput(store, str);
drv.outputs.emplace(std::move(id), std::move(output));
* Removed the `id' attribute hack. * Formalise the notion of fixed-output derivations, i.e., derivations for which a cryptographic hash of the output is known in advance. Changes to such derivations should not propagate upwards through the dependency graph. Previously this was done by specifying the hash component of the output path through the `id' attribute, but this is insecure since you can lie about it (i.e., you can specify any hash and then produce a completely different output). Now the responsibility for checking the output is moved from the builder to Nix itself. A fixed-output derivation can be created by specifying the `outputHash' and `outputHashAlgo' attributes, the latter taking values `md5', `sha1', and `sha256', and the former specifying the actual hash in hexadecimal or in base-32 (auto-detected by looking at the length of the attribute value). MD5 is included for compatibility but should be considered deprecated. * Removed the `drvPath' pseudo-attribute in derivation results. It's no longer necessary. * Cleaned up the support for multiple output paths in derivation store expressions. Each output now has a unique identifier (e.g., `out', `devel', `docs'). Previously there was no way to tell output paths apart at the store expression level. * `nix-hash' now has a flag `--base32' to specify that the hash should be printed in base-32 notation. * `fetchurl' accepts parameters `sha256' and `sha1' in addition to `md5'. * `nix-prefetch-url' now prints out a SHA-1 hash in base-32. (TODO: a flag to specify the hash.)
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}
/* Parse the list of input derivations. */
expect(str, ",[");
while (!endOfList(str)) {
expect(str, "(");
Path drvPath = parsePath(str);
expect(str, ",[");
drv.inputDrvs.insert_or_assign(store.parseStorePath(drvPath), parseStrings(str, false));
expect(str, ")");
}
expect(str, ",["); drv.inputSrcs = store.parseStorePathSet(parseStrings(str, true));
expect(str, ","); drv.platform = parseString(str);
expect(str, ","); drv.builder = parseString(str);
/* Parse the builder arguments. */
expect(str, ",[");
while (!endOfList(str))
drv.args.push_back(parseString(str));
/* Parse the environment variables. */
expect(str, ",[");
while (!endOfList(str)) {
expect(str, "("); string name = parseString(str);
expect(str, ","); string value = parseString(str);
expect(str, ")");
drv.env[name] = value;
}
expect(str, ")");
return drv;
}
Derivation readDerivation(const Store & store, const Path & drvPath, std::string_view name)
{
try {
return parseDerivation(store, readFile(drvPath), name);
} catch (FormatError & e) {
throw Error("error parsing derivation '%1%': %2%", drvPath, e.msg());
}
}
Derivation Store::derivationFromPath(const StorePath & drvPath)
{
ensurePath(drvPath);
return readDerivation(drvPath);
}
Derivation Store::readDerivation(const StorePath & drvPath)
{
auto accessor = getFSAccessor();
try {
return parseDerivation(*this, accessor->readFile(printStorePath(drvPath)), Derivation::nameFromPath(drvPath));
} catch (FormatError & e) {
throw Error("error parsing derivation '%s': %s", printStorePath(drvPath), e.msg());
}
}
static void printString(string & res, std::string_view s)
{
char buf[s.size() * 2 + 2];
char * p = buf;
*p++ = '"';
for (auto c : s)
if (c == '\"' || c == '\\') { *p++ = '\\'; *p++ = c; }
else if (c == '\n') { *p++ = '\\'; *p++ = 'n'; }
else if (c == '\r') { *p++ = '\\'; *p++ = 'r'; }
else if (c == '\t') { *p++ = '\\'; *p++ = 't'; }
else *p++ = c;
*p++ = '"';
res.append(buf, p - buf);
}
static void printUnquotedString(string & res, std::string_view s)
{
res += '"';
res.append(s);
res += '"';
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}
template<class ForwardIterator>
static void printStrings(string & res, ForwardIterator i, ForwardIterator j)
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{
res += '[';
bool first = true;
for ( ; i != j; ++i) {
if (first) first = false; else res += ',';
printString(res, *i);
}
res += ']';
}
template<class ForwardIterator>
static void printUnquotedStrings(string & res, ForwardIterator i, ForwardIterator j)
{
res += '[';
bool first = true;
for ( ; i != j; ++i) {
if (first) first = false; else res += ',';
printUnquotedString(res, *i);
}
res += ']';
}
string Derivation::unparse(const Store & store, bool maskOutputs,
std::map<std::string, StringSet> * actualInputs) const
{
string s;
s.reserve(65536);
s += "Derive([";
bool first = true;
for (auto & i : outputs) {
if (first) first = false; else s += ',';
s += '('; printUnquotedString(s, i.first);
s += ','; printUnquotedString(s, maskOutputs ? "" : store.printStorePath(i.second.path(store, name)));
if (auto hash = std::get_if<DerivationOutputFixed>(&i.second.output)) {
s += ','; printUnquotedString(s, hash->hash.printMethodAlgo());
s += ','; printUnquotedString(s, hash->hash.hash.to_string(Base16, false));
} else {
s += ','; printUnquotedString(s, "");
s += ','; printUnquotedString(s, "");
}
s += ')';
}
s += "],[";
first = true;
if (actualInputs) {
for (auto & i : *actualInputs) {
if (first) first = false; else s += ',';
s += '('; printUnquotedString(s, i.first);
s += ','; printUnquotedStrings(s, i.second.begin(), i.second.end());
s += ')';
}
} else {
for (auto & i : inputDrvs) {
if (first) first = false; else s += ',';
s += '('; printUnquotedString(s, store.printStorePath(i.first));
s += ','; printUnquotedStrings(s, i.second.begin(), i.second.end());
s += ')';
}
}
s += "],";
auto paths = store.printStorePathSet(inputSrcs); // FIXME: slow
printUnquotedStrings(s, paths.begin(), paths.end());
s += ','; printUnquotedString(s, platform);
s += ','; printString(s, builder);
s += ','; printStrings(s, args.begin(), args.end());
s += ",[";
first = true;
for (auto & i : env) {
if (first) first = false; else s += ',';
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s += '('; printString(s, i.first);
s += ','; printString(s, maskOutputs && outputs.count(i.first) ? "" : i.second);
s += ')';
}
s += "])";
return s;
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}
// FIXME: remove
bool isDerivation(const string & fileName)
{
return hasSuffix(fileName, drvExtension);
}
bool BasicDerivation::isFixedOutput() const
{
return outputs.size() == 1 &&
outputs.begin()->first == "out" &&
std::holds_alternative<DerivationOutputFixed>(outputs.begin()->second.output);
}
DrvHashes drvHashes;
/* Returns the hash of a derivation modulo fixed-output
subderivations. A fixed-output derivation is a derivation with one
output (`out') for which an expected hash and hash algorithm are
specified (using the `outputHash' and `outputHashAlgo'
attributes). We don't want changes to such derivations to
propagate upwards through the dependency graph, changing output
paths everywhere.
For instance, if we change the url in a call to the `fetchurl'
function, we do not want to rebuild everything depending on it
(after all, (the hash of) the file being downloaded is unchanged).
So the *output paths* should not change. On the other hand, the
*derivation paths* should change to reflect the new dependency
graph.
That's what this function does: it returns a hash which is just the
hash of the derivation ATerm, except that any input derivation
paths have been replaced by the result of a recursive call to this
function, and that for fixed-output derivations we return a hash of
its output path. */
Hash hashDerivationModulo(Store & store, const Derivation & drv, bool maskOutputs)
{
/* Return a fixed hash for fixed-output derivations. */
if (drv.isFixedOutput()) {
DerivationOutputs::const_iterator i = drv.outputs.begin();
auto hash = std::get<DerivationOutputFixed>(i->second.output);
return hashString(htSHA256, "fixed:out:"
+ hash.hash.printMethodAlgo() + ":"
+ hash.hash.hash.to_string(Base16, false) + ":"
+ store.printStorePath(i->second.path(store, drv.name)));
}
/* For other derivations, replace the inputs paths with recursive
calls to this function.*/
std::map<std::string, StringSet> inputs2;
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for (auto & i : drv.inputDrvs) {
auto h = drvHashes.find(i.first);
if (h == drvHashes.end()) {
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assert(store.isValidPath(i.first));
h = drvHashes.insert_or_assign(i.first, hashDerivationModulo(store,
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store.readDerivation(i.first), false)).first;
}
inputs2.insert_or_assign(h->second.to_string(Base16, false), i.second);
}
return hashString(htSHA256, drv.unparse(store, maskOutputs, &inputs2));
}
std::string StorePathWithOutputs::to_string(const Store & store) const
{
return outputs.empty()
? store.printStorePath(path)
: store.printStorePath(path) + "!" + concatStringsSep(",", outputs);
}
bool wantOutput(const string & output, const std::set<string> & wanted)
{
return wanted.empty() || wanted.find(output) != wanted.end();
}
StorePathSet BasicDerivation::outputPaths(const Store & store) const
{
StorePathSet paths;
for (auto & i : outputs)
paths.insert(i.second.path(store, name));
return paths;
}
static DerivationOutput readDerivationOutput(Source & in, const Store & store)
{
auto path = store.parseStorePath(readString(in));
auto hashAlgo = readString(in);
auto hash = readString(in);
if (hashAlgo != "") {
auto method = FileIngestionMethod::Flat;
if (string(hashAlgo, 0, 2) == "r:") {
method = FileIngestionMethod::Recursive;
hashAlgo = string(hashAlgo, 2);
}
auto hashType = parseHashType(hashAlgo);
return DerivationOutput {
.output = DerivationOutputFixed {
.hash = FixedOutputHash {
.method = std::move(method),
.hash = Hash(hash, hashType),
},
}
};
} else
return DerivationOutput {
.output = DerivationOutputInputAddressed {
.path = std::move(path),
}
};
}
StringSet BasicDerivation::outputNames() const
{
StringSet names;
for (auto & i : outputs)
names.insert(i.first);
return names;
}
std::string_view BasicDerivation::nameFromPath(const StorePath & drvPath) {
auto nameWithSuffix = drvPath.name();
constexpr std::string_view extension = ".drv";
assert(hasSuffix(nameWithSuffix, extension));
nameWithSuffix.remove_suffix(extension.size());
return nameWithSuffix;
}
Source & readDerivation(Source & in, const Store & store, BasicDerivation & drv, std::string_view name)
{
drv.name = name;
drv.outputs.clear();
auto nr = readNum<size_t>(in);
for (size_t n = 0; n < nr; n++) {
auto name = readString(in);
auto output = readDerivationOutput(in, store);
drv.outputs.emplace(std::move(name), std::move(output));
}
drv.inputSrcs = readStorePaths<StorePathSet>(store, in);
in >> drv.platform >> drv.builder;
drv.args = readStrings<Strings>(in);
nr = readNum<size_t>(in);
for (size_t n = 0; n < nr; n++) {
auto key = readString(in);
auto value = readString(in);
drv.env[key] = value;
}
return in;
}
void writeDerivation(Sink & out, const Store & store, const BasicDerivation & drv)
{
out << drv.outputs.size();
for (auto & i : drv.outputs) {
out << i.first
<< store.printStorePath(i.second.path(store, drv.name));
if (auto hash = std::get_if<DerivationOutputFixed>(&i.second.output)) {
out << hash->hash.printMethodAlgo()
<< hash->hash.hash.to_string(Base16, false);
} else {
out << "" << "";
}
}
writeStorePaths(store, out, drv.inputSrcs);
out << drv.platform << drv.builder << drv.args;
out << drv.env.size();
for (auto & i : drv.env)
out << i.first << i.second;
}
std::string hashPlaceholder(const std::string & outputName)
{
// FIXME: memoize?
return "/" + hashString(htSHA256, "nix-output:" + outputName).to_string(Base32, false);
}
}