fix/src/nix-build/nix-build.cc
Eelco Dolstra d4dcffd643
Add pure evaluation mode
In this mode, the following restrictions apply:

* The builtins currentTime, currentSystem and storePath throw an
  error.

* $NIX_PATH and -I are ignored.

* fetchGit and fetchMercurial require a revision hash.

* fetchurl and fetchTarball require a sha256 attribute.

* No file system access is allowed outside of the paths returned by
  fetch{Git,Mercurial,url,Tarball}. Thus 'nix build -f ./foo.nix' is
  not allowed.

Thus, the evaluation result is completely reproducible from the
command line arguments. E.g.

  nix build --pure-eval '(
    let
      nix = fetchGit { url = https://github.com/NixOS/nixpkgs.git; rev = "9c927de4b179a6dd210dd88d34bda8af4b575680"; };
      nixpkgs = fetchGit { url = https://github.com/NixOS/nixpkgs.git; ref = "release-17.09"; rev = "66b4de79e3841530e6d9c6baf98702aa1f7124e4"; };
    in (import (nix + "/release.nix") { inherit nix nixpkgs; }).build.x86_64-linux
  )'

The goal is to enable completely reproducible and traceable
evaluation. For example, a NixOS configuration could be fully
described by a single Git commit hash. 'nixos-rebuild' would do
something like

  nix build --pure-eval '(
    (import (fetchGit { url = file:///my-nixos-config; rev = "..."; })).system
  ')

where the Git repository /my-nixos-config would use further fetchGit
calls or Git externals to fetch Nixpkgs and whatever other
dependencies it has. Either way, the commit hash would uniquely
identify the NixOS configuration and allow it to reproduced.
2018-01-16 19:23:18 +01:00

501 lines
16 KiB
C++
Executable file

#include <cstring>
#include <fstream>
#include <iostream>
#include <regex>
#include <sstream>
#include <vector>
#include "store-api.hh"
#include "globals.hh"
#include "derivations.hh"
#include "affinity.hh"
#include "util.hh"
#include "shared.hh"
#include "eval.hh"
#include "eval-inline.hh"
#include "get-drvs.hh"
#include "common-eval-args.hh"
#include "attr-path.hh"
using namespace nix;
using namespace std::string_literals;
extern char * * environ;
/* Recreate the effect of the perl shellwords function, breaking up a
* string into arguments like a shell word, including escapes
*/
std::vector<string> shellwords(const string & s)
{
std::regex whitespace("^(\\s+).*");
auto begin = s.cbegin();
std::vector<string> res;
std::string cur;
enum state {
sBegin,
sQuote
};
state st = sBegin;
auto it = begin;
for (; it != s.cend(); ++it) {
if (st == sBegin) {
std::smatch match;
if (regex_search(it, s.cend(), match, whitespace)) {
cur.append(begin, it);
res.push_back(cur);
cur.clear();
it = match[1].second;
begin = it;
}
}
switch (*it) {
case '"':
cur.append(begin, it);
begin = it + 1;
st = st == sBegin ? sQuote : sBegin;
break;
case '\\':
/* perl shellwords mostly just treats the next char as part of the string with no special processing */
cur.append(begin, it);
begin = ++it;
break;
}
}
cur.append(begin, it);
if (!cur.empty()) res.push_back(cur);
return res;
}
void mainWrapped(int argc, char * * argv)
{
initNix();
initGC();
auto dryRun = false;
auto runEnv = std::regex_search(argv[0], std::regex("nix-shell$"));
auto pure = false;
auto fromArgs = false;
auto packages = false;
// Same condition as bash uses for interactive shells
auto interactive = isatty(STDIN_FILENO) && isatty(STDERR_FILENO);
Strings attrPaths;
Strings left;
RepairFlag repair = NoRepair;
Path gcRoot;
BuildMode buildMode = bmNormal;
bool readStdin = false;
auto shell = getEnv("SHELL", "/bin/sh");
std::string envCommand; // interactive shell
Strings envExclude;
auto myName = runEnv ? "nix-shell" : "nix-build";
auto inShebang = false;
std::string script;
std::vector<string> savedArgs;
AutoDelete tmpDir(createTempDir("", myName));
std::string outLink = "./result";
Strings args;
for (int i = 1; i < argc; ++i)
args.push_back(argv[i]);
// Heuristic to see if we're invoked as a shebang script, namely,
// if we have at least one argument, it's the name of an
// executable file, and it starts with "#!".
if (runEnv && argc > 1 && !std::regex_search(argv[1], std::regex("nix-shell"))) {
script = argv[1];
try {
auto lines = tokenizeString<Strings>(readFile(script), "\n");
if (std::regex_search(lines.front(), std::regex("^#!"))) {
lines.pop_front();
inShebang = true;
for (int i = 2; i < argc; ++i)
savedArgs.push_back(argv[i]);
args.clear();
for (auto line : lines) {
line = chomp(line);
std::smatch match;
if (std::regex_match(line, match, std::regex("^#!\\s*nix-shell (.*)$")))
for (const auto & word : shellwords(match[1].str()))
args.push_back(word);
}
}
} catch (SysError &) { }
}
struct MyArgs : LegacyArgs, MixEvalArgs
{
using LegacyArgs::LegacyArgs;
};
MyArgs myArgs(myName, [&](Strings::iterator & arg, const Strings::iterator & end) {
if (*arg == "--help") {
deletePath(tmpDir);
showManPage(myName);
}
else if (*arg == "--version")
printVersion(myName);
else if (*arg == "--add-drv-link")
; // obsolete
else if (*arg == "--no-out-link" || *arg == "--no-link")
outLink = (Path) tmpDir + "/result";
else if (*arg == "--attr" || *arg == "-A")
attrPaths.push_back(getArg(*arg, arg, end));
else if (*arg == "--drv-link")
getArg(*arg, arg, end); // obsolete
else if (*arg == "--out-link" || *arg == "-o")
outLink = getArg(*arg, arg, end);
else if (*arg == "--add-root")
gcRoot = getArg(*arg, arg, end);
else if (*arg == "--dry-run")
dryRun = true;
else if (*arg == "--repair") {
repair = Repair;
buildMode = bmRepair;
}
else if (*arg == "--hash")
buildMode = bmHash;
else if (*arg == "--run-env") // obsolete
runEnv = true;
else if (*arg == "--command" || *arg == "--run") {
if (*arg == "--run")
interactive = false;
envCommand = getArg(*arg, arg, end) + "\nexit";
}
else if (*arg == "--check")
buildMode = bmCheck;
else if (*arg == "--exclude")
envExclude.push_back(getArg(*arg, arg, end));
else if (*arg == "--expr" || *arg == "-E")
fromArgs = true;
else if (*arg == "--pure") pure = true;
else if (*arg == "--impure") pure = false;
else if (*arg == "--packages" || *arg == "-p")
packages = true;
else if (inShebang && *arg == "-i") {
auto interpreter = getArg(*arg, arg, end);
interactive = false;
auto execArgs = "";
// Überhack to support Perl. Perl examines the shebang and
// executes it unless it contains the string "perl" or "indir",
// or (undocumented) argv[0] does not contain "perl". Exploit
// the latter by doing "exec -a".
if (std::regex_search(interpreter, std::regex("perl")))
execArgs = "-a PERL";
std::ostringstream joined;
for (const auto & i : savedArgs)
joined << shellEscape(i) << ' ';
if (std::regex_search(interpreter, std::regex("ruby"))) {
// Hack for Ruby. Ruby also examines the shebang. It tries to
// read the shebang to understand which packages to read from. Since
// this is handled via nix-shell -p, we wrap our ruby script execution
// in ruby -e 'load' which ignores the shebangs.
envCommand = (format("exec %1% %2% -e 'load(\"%3%\") -- %4%") % execArgs % interpreter % script % joined.str()).str();
} else {
envCommand = (format("exec %1% %2% %3% %4%") % execArgs % interpreter % script % joined.str()).str();
}
}
else if (*arg == "-")
readStdin = true;
else if (*arg != "" && arg->at(0) == '-')
return false;
else
left.push_back(*arg);
return true;
});
myArgs.parseCmdline(args);
if (packages && fromArgs)
throw UsageError("'-p' and '-E' are mutually exclusive");
auto store = openStore();
EvalState state(myArgs.searchPath, store);
state.repair = repair;
Bindings & autoArgs = *myArgs.getAutoArgs(state);
if (packages) {
std::ostringstream joined;
joined << "with import <nixpkgs> { }; (pkgs.runCommandCC or pkgs.runCommand) \"shell\" { buildInputs = [ ";
for (const auto & i : left)
joined << '(' << i << ") ";
joined << "]; } \"\"";
fromArgs = true;
left = {joined.str()};
} else if (!fromArgs) {
if (left.empty() && runEnv && pathExists("shell.nix"))
left = {"shell.nix"};
if (left.empty())
left = {"default.nix"};
}
if (runEnv)
setenv("IN_NIX_SHELL", pure ? "pure" : "impure", 1);
DrvInfos drvs;
/* Parse the expressions. */
std::vector<Expr *> exprs;
if (readStdin)
exprs = {state.parseStdin()};
else
for (auto i : left) {
if (fromArgs)
exprs.push_back(state.parseExprFromString(i, absPath(".")));
else if (store->isStorePath(i) && std::regex_match(i, std::regex(".*\\.drv(!.*)?")))
drvs.push_back(DrvInfo(state, store, i));
else
/* If we're in a #! script, interpret filenames
relative to the script. */
exprs.push_back(state.parseExprFromFile(resolveExprPath(state.checkSourcePath(lookupFileArg(state,
inShebang && !packages ? absPath(i, absPath(dirOf(script))) : i)))));
}
/* Evaluate them into derivations. */
if (attrPaths.empty()) attrPaths = {""};
for (auto e : exprs) {
Value vRoot;
state.eval(e, vRoot);
for (auto & i : attrPaths) {
Value & v(*findAlongAttrPath(state, i, autoArgs, vRoot));
state.forceValue(v);
getDerivations(state, v, "", autoArgs, drvs, false);
}
}
auto buildPaths = [&](const PathSet & paths) {
/* Note: we do this even when !printMissing to efficiently
fetch binary cache data. */
unsigned long long downloadSize, narSize;
PathSet willBuild, willSubstitute, unknown;
store->queryMissing(paths,
willBuild, willSubstitute, unknown, downloadSize, narSize);
if (settings.printMissing)
printMissing(ref<Store>(store), willBuild, willSubstitute, unknown, downloadSize, narSize);
if (!dryRun)
store->buildPaths(paths, buildMode);
};
if (runEnv) {
if (drvs.size() != 1)
throw UsageError("nix-shell requires a single derivation");
auto & drvInfo = drvs.front();
auto drv = store->derivationFromPath(drvInfo.queryDrvPath());
PathSet pathsToBuild;
/* Figure out what bash shell to use. If $NIX_BUILD_SHELL
is not set, then build bashInteractive from
<nixpkgs>. */
auto shell = getEnv("NIX_BUILD_SHELL", "");
if (shell == "") {
try {
auto expr = state.parseExprFromString("(import <nixpkgs> {}).bashInteractive", absPath("."));
Value v;
state.eval(expr, v);
auto drv = getDerivation(state, v, false);
if (!drv)
throw Error("the 'bashInteractive' attribute in <nixpkgs> did not evaluate to a derivation");
pathsToBuild.insert(drv->queryDrvPath());
shell = drv->queryOutPath() + "/bin/bash";
} catch (Error & e) {
printError("warning: %s; will use bash from your environment", e.what());
shell = "bash";
}
}
// Build or fetch all dependencies of the derivation.
for (const auto & input : drv.inputDrvs)
if (std::all_of(envExclude.cbegin(), envExclude.cend(), [&](const string & exclude) { return !std::regex_search(input.first, std::regex(exclude)); }))
pathsToBuild.insert(input.first);
for (const auto & src : drv.inputSrcs)
pathsToBuild.insert(src);
buildPaths(pathsToBuild);
if (dryRun) return;
// Set the environment.
auto env = getEnv();
auto tmp = getEnv("TMPDIR", getEnv("XDG_RUNTIME_DIR", "/tmp"));
if (pure) {
std::set<string> keepVars{"HOME", "USER", "LOGNAME", "DISPLAY", "PATH", "TERM", "IN_NIX_SHELL", "TZ", "PAGER", "NIX_BUILD_SHELL", "SHLVL"};
decltype(env) newEnv;
for (auto & i : env)
if (keepVars.count(i.first))
newEnv.emplace(i);
env = newEnv;
// NixOS hack: prevent /etc/bashrc from sourcing /etc/profile.
env["__ETC_PROFILE_SOURCED"] = "1";
}
env["NIX_BUILD_TOP"] = env["TMPDIR"] = env["TEMPDIR"] = env["TMP"] = env["TEMP"] = tmp;
env["NIX_STORE"] = store->storeDir;
env["NIX_BUILD_CORES"] = std::to_string(settings.buildCores);
auto passAsFile = tokenizeString<StringSet>(get(drv.env, "passAsFile", ""));
bool keepTmp = false;
int fileNr = 0;
for (auto & var : drv.env)
if (passAsFile.count(var.first)) {
keepTmp = true;
string fn = ".attr-" + std::to_string(fileNr++);
Path p = (Path) tmpDir + "/" + fn;
writeFile(p, var.second);
env[var.first + "Path"] = p;
} else
env[var.first] = var.second;
restoreAffinity();
/* Run a shell using the derivation's environment. For
convenience, source $stdenv/setup to setup additional
environment variables and shell functions. Also don't
lose the current $PATH directories. */
auto rcfile = (Path) tmpDir + "/rc";
writeFile(rcfile, fmt(
(keepTmp ? "" : "rm -rf '%1%'; "s) +
"[ -n \"$PS1\" ] && [ -e ~/.bashrc ] && source ~/.bashrc; "
"%2%"
"dontAddDisableDepTrack=1; "
"[ -e $stdenv/setup ] && source $stdenv/setup; "
"%3%"
"set +e; "
R"s([ -n "$PS1" ] && PS1='\n\[\033[1;32m\][nix-shell:\w]\$\[\033[0m\] '; )s"
"if [ \"$(type -t runHook)\" = function ]; then runHook shellHook; fi; "
"unset NIX_ENFORCE_PURITY; "
"unset NIX_INDENT_MAKE; "
"shopt -u nullglob; "
"unset TZ; %4%"
"%5%",
(Path) tmpDir,
(pure ? "" : "p=$PATH; "),
(pure ? "" : "PATH=$PATH:$p; unset p; "),
(getenv("TZ") ? (string("export TZ='") + getenv("TZ") + "'; ") : ""),
envCommand));
Strings envStrs;
for (auto & i : env)
envStrs.push_back(i.first + "=" + i.second);
auto args = interactive
? Strings{"bash", "--rcfile", rcfile}
: Strings{"bash", rcfile};
auto envPtrs = stringsToCharPtrs(envStrs);
environ = envPtrs.data();
auto argPtrs = stringsToCharPtrs(args);
restoreSignals();
execvp(shell.c_str(), argPtrs.data());
throw SysError("executing shell '%s'", shell);
}
else {
PathSet pathsToBuild;
std::map<Path, Path> drvPrefixes;
std::map<Path, Path> resultSymlinks;
std::vector<Path> outPaths;
for (auto & drvInfo : drvs) {
auto drvPath = drvInfo.queryDrvPath();
auto outPath = drvInfo.queryOutPath();
auto outputName = drvInfo.queryOutputName();
if (outputName == "")
throw Error("derivation '%s' lacks an 'outputName' attribute", drvPath);
pathsToBuild.insert(drvPath + "!" + outputName);
std::string drvPrefix;
auto i = drvPrefixes.find(drvPath);
if (i != drvPrefixes.end())
drvPrefix = i->second;
else {
drvPrefix = outLink;
if (drvPrefixes.size())
drvPrefix += fmt("-%d", drvPrefixes.size() + 1);
drvPrefixes[drvPath] = drvPrefix;
}
std::string symlink = drvPrefix;
if (outputName != "out") symlink += "-" + outputName;
resultSymlinks[symlink] = outPath;
outPaths.push_back(outPath);
}
buildPaths(pathsToBuild);
if (dryRun) return;
for (auto & symlink : resultSymlinks)
if (auto store2 = store.dynamic_pointer_cast<LocalFSStore>())
store2->addPermRoot(symlink.second, absPath(symlink.first), true);
for (auto & path : outPaths)
std::cout << path << '\n';
}
}
int main(int argc, char * * argv)
{
return handleExceptions(argv[0], [&]() {
return mainWrapped(argc, argv);
});
}