diff options
| -rw-r--r-- | src/nix/repl.cc | 719 |
1 files changed, 719 insertions, 0 deletions
diff --git a/src/nix/repl.cc b/src/nix/repl.cc new file mode 100644 index 000000000000..71790eb481a7 --- /dev/null +++ b/src/nix/repl.cc @@ -0,0 +1,719 @@ +#include <nix/config.h> + +#include <iostream> +#include <cstdlib> + +#include <setjmp.h> + +#include <readline/readline.h> +#include <readline/history.h> + +#include "shared.hh" +#include "eval.hh" +#include "eval-inline.hh" +#include "store-api.hh" +#include "common-opts.hh" +#include "get-drvs.hh" +#include "derivations.hh" +#include "affinity.hh" +#include "globals.hh" + +using namespace std; +using namespace nix; + +#define ESC_RED "\033[31m" +#define ESC_GRE "\033[32m" +#define ESC_YEL "\033[33m" +#define ESC_BLU "\033[34;1m" +#define ESC_MAG "\033[35m" +#define ESC_CYA "\033[36m" +#define ESC_END "\033[0m" + +string programId = "nix-repl"; +const string historyFile = string(getenv("HOME")) + "/.nix-repl-history"; + +struct NixRepl +{ + string curDir; + EvalState state; + + Strings loadedFiles; + + const static int envSize = 32768; + StaticEnv staticEnv; + Env * env; + int displ; + StringSet varNames; + + StringSet completions; + StringSet::iterator curCompletion; + + NixRepl(const Strings & searchPath, nix::ref<Store> store); + void mainLoop(const Strings & files); + void completePrefix(string prefix); + bool getLine(string & input, const char * prompt); + Path getDerivationPath(Value & v); + bool processLine(string line); + void loadFile(const Path & path); + void initEnv(); + void reloadFiles(); + void addAttrsToScope(Value & attrs); + void addVarToScope(const Symbol & name, Value & v); + Expr * parseString(string s); + void evalString(string s, Value & v); + + typedef set<Value *> ValuesSeen; + std::ostream & printValue(std::ostream & str, Value & v, unsigned int maxDepth); + std::ostream & printValue(std::ostream & str, Value & v, unsigned int maxDepth, ValuesSeen & seen); +}; + + +void printHelp() +{ + cout << "Usage: nix-repl [--help] [--version] [-I path] paths...\n" + << "\n" + << "nix-repl is a simple read-eval-print loop (REPL) for the Nix package manager.\n" + << "\n" + << "Options:\n" + << " --help\n" + << " Prints out a summary of the command syntax and exits.\n" + << "\n" + << " --version\n" + << " Prints out the Nix version number on standard output and exits.\n" + << "\n" + << " -I path\n" + << " Add a path to the Nix expression search path. This option may be given\n" + << " multiple times. See the NIX_PATH environment variable for information on\n" + << " the semantics of the Nix search path. Paths added through -I take\n" + << " precedence over NIX_PATH.\n" + << "\n" + << " paths...\n" + << " A list of paths to files containing Nix expressions which nix-repl will\n" + << " load and add to its scope.\n" + << "\n" + << " A path surrounded in < and > will be looked up in the Nix expression search\n" + << " path, as in the Nix language itself.\n" + << "\n" + << " If an element of paths starts with http:// or https://, it is interpreted\n" + << " as the URL of a tarball that will be downloaded and unpacked to a temporary\n" + << " location. The tarball must include a single top-level directory containing\n" + << " at least a file named default.nix.\n" + << flush; +} + + +string removeWhitespace(string s) +{ + s = chomp(s); + size_t n = s.find_first_not_of(" \n\r\t"); + if (n != string::npos) s = string(s, n); + return s; +} + + +NixRepl::NixRepl(const Strings & searchPath, nix::ref<Store> store) + : state(searchPath, store) + , staticEnv(false, &state.staticBaseEnv) +{ + curDir = absPath("."); +} + + +void NixRepl::mainLoop(const Strings & files) +{ + string error = ANSI_RED "error:" ANSI_NORMAL " "; + std::cout << "Welcome to Nix version " << NIX_VERSION << ". Type :? for help." << std::endl << std::endl; + + for (auto & i : files) + loadedFiles.push_back(i); + + reloadFiles(); + if (!loadedFiles.empty()) std::cout << std::endl; + + // Allow nix-repl specific settings in .inputrc + rl_readline_name = "nix-repl"; + using_history(); + read_history(historyFile.c_str()); + + string input; + + while (true) { + // When continuing input from previous lines, don't print a prompt, just align to the same + // number of chars as the prompt. + const char * prompt = input.empty() ? "nix-repl> " : " "; + if (!getLine(input, prompt)) { + std::cout << std::endl; + break; + } + + try { + if (!removeWhitespace(input).empty() && !processLine(input)) return; + } catch (ParseError & e) { + if (e.msg().find("unexpected $end") != std::string::npos) { + // For parse errors on incomplete input, we continue waiting for the next line of + // input without clearing the input so far. + continue; + } else { + printMsg(lvlError, format(error + "%1%%2%") % (settings.showTrace ? e.prefix() : "") % e.msg()); + } + } catch (Error & e) { + printMsg(lvlError, format(error + "%1%%2%") % (settings.showTrace ? e.prefix() : "") % e.msg()); + } catch (Interrupted & e) { + printMsg(lvlError, format(error + "%1%%2%") % (settings.showTrace ? e.prefix() : "") % e.msg()); + } + + // We handled the current input fully, so we should clear it and read brand new input. + input.clear(); + std::cout << std::endl; + } +} + + +/* Apparently, the only way to get readline() to return on Ctrl-C + (SIGINT) is to use siglongjmp(). That's fucked up... */ +static sigjmp_buf sigintJmpBuf; + + +static void sigintHandler(int signo) +{ + siglongjmp(sigintJmpBuf, 1); +} + + +/* Oh, if only g++ had nested functions... */ +NixRepl * curRepl; + +char * completerThunk(const char * s, int state) +{ + string prefix(s); + + /* If the prefix has a slash in it, use readline's builtin filename + completer. */ + if (prefix.find('/') != string::npos) + return rl_filename_completion_function(s, state); + + /* Otherwise, return all symbols that start with the prefix. */ + if (state == 0) { + curRepl->completePrefix(s); + curRepl->curCompletion = curRepl->completions.begin(); + } + if (curRepl->curCompletion == curRepl->completions.end()) return 0; + return strdup((curRepl->curCompletion++)->c_str()); +} + + +bool NixRepl::getLine(string & input, const char * prompt) +{ + struct sigaction act, old; + act.sa_handler = sigintHandler; + sigfillset(&act.sa_mask); + act.sa_flags = 0; + if (sigaction(SIGINT, &act, &old)) + throw SysError("installing handler for SIGINT"); + + if (sigsetjmp(sigintJmpBuf, 1)) { + input.clear(); + } else { + curRepl = this; + rl_completion_entry_function = completerThunk; + + char * s = readline(prompt); + if (!s) return false; + input.append(s); + input.push_back('\n'); + if (!removeWhitespace(s).empty()) { + add_history(s); + append_history(1, 0); + } + free(s); + } + + _isInterrupted = 0; + + if (sigaction(SIGINT, &old, 0)) + throw SysError("restoring handler for SIGINT"); + + return true; +} + + +void NixRepl::completePrefix(string prefix) +{ + completions.clear(); + + size_t dot = prefix.rfind('.'); + + if (dot == string::npos) { + /* This is a variable name; look it up in the current scope. */ + StringSet::iterator i = varNames.lower_bound(prefix); + while (i != varNames.end()) { + if (string(*i, 0, prefix.size()) != prefix) break; + completions.insert(*i); + i++; + } + } else { + try { + /* This is an expression that should evaluate to an + attribute set. Evaluate it to get the names of the + attributes. */ + string expr(prefix, 0, dot); + string prefix2 = string(prefix, dot + 1); + + Expr * e = parseString(expr); + Value v; + e->eval(state, *env, v); + state.forceAttrs(v); + + for (auto & i : *v.attrs) { + string name = i.name; + if (string(name, 0, prefix2.size()) != prefix2) continue; + completions.insert(expr + "." + name); + } + + } catch (ParseError & e) { + // Quietly ignore parse errors. + } catch (EvalError & e) { + // Quietly ignore evaluation errors. + } catch (UndefinedVarError & e) { + // Quietly ignore undefined variable errors. + } + } +} + + +static int runProgram(const string & program, const Strings & args) +{ + std::vector<const char *> cargs; /* careful with c_str()! */ + cargs.push_back(program.c_str()); + for (Strings::const_iterator i = args.begin(); i != args.end(); ++i) + cargs.push_back(i->c_str()); + cargs.push_back(0); + + Pid pid; + pid = fork(); + if (pid == -1) throw SysError("forking"); + if (pid == 0) { + restoreAffinity(); + execvp(program.c_str(), (char * *) &cargs[0]); + _exit(1); + } + + return pid.wait(); +} + + +bool isVarName(const string & s) +{ + if (s.size() == 0) return false; + char c = s[0]; + if ((c >= '0' && c <= '9') || c == '-' || c == '\'') return false; + for (auto & i : s) + if (!((i >= 'a' && i <= 'z') || + (i >= 'A' && i <= 'Z') || + (i >= '0' && i <= '9') || + i == '_' || i == '-' || i == '\'')) + return false; + return true; +} + + +Path NixRepl::getDerivationPath(Value & v) { + DrvInfo drvInfo(state); + if (!getDerivation(state, v, drvInfo, false)) + throw Error("expression does not evaluate to a derivation, so I can't build it"); + Path drvPath = drvInfo.queryDrvPath(); + if (drvPath == "" || !state.store->isValidPath(drvPath)) + throw Error("expression did not evaluate to a valid derivation"); + return drvPath; +} + + +bool NixRepl::processLine(string line) +{ + if (line == "") return true; + + string command, arg; + + if (line[0] == ':') { + size_t p = line.find_first_of(" \n\r\t"); + command = string(line, 0, p); + if (p != string::npos) arg = removeWhitespace(string(line, p)); + } else { + arg = line; + } + + if (command == ":?" || command == ":help") { + cout << "The following commands are available:\n" + << "\n" + << " <expr> Evaluate and print expression\n" + << " <x> = <expr> Bind expression to variable\n" + << " :a <expr> Add attributes from resulting set to scope\n" + << " :b <expr> Build derivation\n" + << " :i <expr> Build derivation, then install result into current profile\n" + << " :l <path> Load Nix expression and add it to scope\n" + << " :p <expr> Evaluate and print expression recursively\n" + << " :q Exit nix-repl\n" + << " :r Reload all files\n" + << " :s <expr> Build dependencies of derivation, then start nix-shell\n" + << " :t <expr> Describe result of evaluation\n" + << " :u <expr> Build derivation, then start nix-shell\n"; + } + + else if (command == ":a" || command == ":add") { + Value v; + evalString(arg, v); + addAttrsToScope(v); + } + + else if (command == ":l" || command == ":load") { + state.resetFileCache(); + loadFile(arg); + } + + else if (command == ":r" || command == ":reload") { + state.resetFileCache(); + reloadFiles(); + } + + else if (command == ":t") { + Value v; + evalString(arg, v); + std::cout << showType(v) << std::endl; + + } else if (command == ":u") { + Value v, f, result; + evalString(arg, v); + evalString("drv: (import <nixpkgs> {}).runCommand \"shell\" { buildInputs = [ drv ]; } \"\"", f); + state.callFunction(f, v, result, Pos()); + + Path drvPath = getDerivationPath(result); + runProgram("nix-shell", Strings{drvPath}); + } + + else if (command == ":b" || command == ":i" || command == ":s") { + Value v; + evalString(arg, v); + Path drvPath = getDerivationPath(v); + + if (command == ":b") { + /* We could do the build in this process using buildPaths(), + but doing it in a child makes it easier to recover from + problems / SIGINT. */ + if (runProgram("nix-store", Strings{"-r", drvPath}) == 0) { + Derivation drv = readDerivation(drvPath); + std::cout << std::endl << "this derivation produced the following outputs:" << std::endl; + for (auto & i : drv.outputs) + std::cout << format(" %1% -> %2%") % i.first % i.second.path << std::endl; + } + } else if (command == ":i") { + runProgram("nix-env", Strings{"-i", drvPath}); + } else { + runProgram("nix-shell", Strings{drvPath}); + } + } + + else if (command == ":p" || command == ":print") { + Value v; + evalString(arg, v); + printValue(std::cout, v, 1000000000) << std::endl; + } + + else if (command == ":q" || command == ":quit") + return false; + + else if (command != "") + throw Error(format("unknown command ‘%1%’") % command); + + else { + size_t p = line.find('='); + string name; + if (p != string::npos && + p < line.size() && + line[p + 1] != '=' && + isVarName(name = removeWhitespace(string(line, 0, p)))) + { + Expr * e = parseString(string(line, p + 1)); + Value & v(*state.allocValue()); + v.type = tThunk; + v.thunk.env = env; + v.thunk.expr = e; + addVarToScope(state.symbols.create(name), v); + } else { + Value v; + evalString(line, v); + printValue(std::cout, v, 1) << std::endl; + } + } + + return true; +} + + +void NixRepl::loadFile(const Path & path) +{ + loadedFiles.remove(path); + loadedFiles.push_back(path); + Value v, v2; + state.evalFile(lookupFileArg(state, path), v); + Bindings & bindings(*state.allocBindings(0)); + state.autoCallFunction(bindings, v, v2); + addAttrsToScope(v2); +} + + +void NixRepl::initEnv() +{ + env = &state.allocEnv(envSize); + env->up = &state.baseEnv; + displ = 0; + staticEnv.vars.clear(); + + varNames.clear(); + for (auto & i : state.staticBaseEnv.vars) + varNames.insert(i.first); +} + + +void NixRepl::reloadFiles() +{ + initEnv(); + + Strings old = loadedFiles; + loadedFiles.clear(); + + bool first = true; + for (auto & i : old) { + if (!first) std::cout << std::endl; + first = false; + std::cout << format("Loading ‘%1%’...") % i << std::endl; + loadFile(i); + } +} + + +void NixRepl::addAttrsToScope(Value & attrs) +{ + state.forceAttrs(attrs); + for (auto & i : *attrs.attrs) + addVarToScope(i.name, *i.value); + std::cout << format("Added %1% variables.") % attrs.attrs->size() << std::endl; +} + + +void NixRepl::addVarToScope(const Symbol & name, Value & v) +{ + if (displ >= envSize) + throw Error("environment full; cannot add more variables"); + staticEnv.vars[name] = displ; + env->values[displ++] = &v; + varNames.insert((string) name); +} + + +Expr * NixRepl::parseString(string s) +{ + Expr * e = state.parseExprFromString(s, curDir, staticEnv); + return e; +} + + +void NixRepl::evalString(string s, Value & v) +{ + Expr * e = parseString(s); + e->eval(state, *env, v); + state.forceValue(v); +} + + +std::ostream & NixRepl::printValue(std::ostream & str, Value & v, unsigned int maxDepth) +{ + ValuesSeen seen; + return printValue(str, v, maxDepth, seen); +} + + +std::ostream & printStringValue(std::ostream & str, const char * string) { + str << "\""; + for (const char * i = string; *i; i++) + if (*i == '\"' || *i == '\\') str << "\\" << *i; + else if (*i == '\n') str << "\\n"; + else if (*i == '\r') str << "\\r"; + else if (*i == '\t') str << "\\t"; + else str << *i; + str << "\""; + return str; +} + + +// FIXME: lot of cut&paste from Nix's eval.cc. +std::ostream & NixRepl::printValue(std::ostream & str, Value & v, unsigned int maxDepth, ValuesSeen & seen) +{ + str.flush(); + checkInterrupt(); + + state.forceValue(v); + + switch (v.type) { + + case tInt: + str << ESC_CYA << v.integer << ESC_END; + break; + + case tBool: + str << ESC_CYA << (v.boolean ? "true" : "false") << ESC_END; + break; + + case tString: + str << ESC_YEL; + printStringValue(str, v.string.s); + str << ESC_END; + break; + + case tPath: + str << ESC_GRE << v.path << ESC_END; // !!! escaping? + break; + + case tNull: + str << ESC_CYA "null" ESC_END; + break; + + case tAttrs: { + seen.insert(&v); + + bool isDrv = state.isDerivation(v); + + if (isDrv) { + str << "«derivation "; + Bindings::iterator i = v.attrs->find(state.sDrvPath); + PathSet context; + Path drvPath = i != v.attrs->end() ? state.coerceToPath(*i->pos, *i->value, context) : "???"; + str << drvPath << "»"; + } + + else if (maxDepth > 0) { + str << "{ "; + + typedef std::map<string, Value *> Sorted; + Sorted sorted; + for (auto & i : *v.attrs) + sorted[i.name] = i.value; + + /* If this is a derivation, then don't show the + self-references ("all", "out", etc.). */ + StringSet hidden; + if (isDrv) { + hidden.insert("all"); + Bindings::iterator i = v.attrs->find(state.sOutputs); + if (i == v.attrs->end()) + hidden.insert("out"); + else { + state.forceList(*i->value); + for (unsigned int j = 0; j < i->value->listSize(); ++j) + hidden.insert(state.forceStringNoCtx(*i->value->listElems()[j])); + } + } + + for (auto & i : sorted) { + if (isVarName(i.first)) + str << i.first; + else + printStringValue(str, i.first.c_str()); + str << " = "; + if (hidden.find(i.first) != hidden.end()) + str << "«...»"; + else if (seen.find(i.second) != seen.end()) + str << "«repeated»"; + else + try { + printValue(str, *i.second, maxDepth - 1, seen); + } catch (AssertionError & e) { + str << ESC_RED "«error: " << e.msg() << "»" ESC_END; + } + str << "; "; + } + + str << "}"; + } else + str << "{ ... }"; + + break; + } + + case tList1: + case tList2: + case tListN: + seen.insert(&v); + + str << "[ "; + if (maxDepth > 0) + for (unsigned int n = 0; n < v.listSize(); ++n) { + if (seen.find(v.listElems()[n]) != seen.end()) + str << "«repeated»"; + else + try { + printValue(str, *v.listElems()[n], maxDepth - 1, seen); + } catch (AssertionError & e) { + str << ESC_RED "«error: " << e.msg() << "»" ESC_END; + } + str << " "; + } + else + str << "... "; + str << "]"; + break; + + case tLambda: { + std::ostringstream s; + s << v.lambda.fun->pos; + str << ESC_BLU "«lambda @ " << filterANSIEscapes(s.str()) << "»" ESC_END; + break; + } + + case tPrimOp: + str << ESC_MAG "«primop»" ESC_END; + break; + + case tPrimOpApp: + str << ESC_BLU "«primop-app»" ESC_END; + break; + + default: + str << ESC_RED "«unknown»" ESC_END; + break; + } + + return str; +} + + +int main(int argc, char * * argv) +{ + return handleExceptions(argv[0], [&]() { + initNix(); + initGC(); + + Strings files, searchPath; + + parseCmdLine(argc, argv, [&](Strings::iterator & arg, const Strings::iterator & end) { + if (*arg == "--version") + printVersion("nix-repl"); + else if (*arg == "--help") { + printHelp(); + // exit with 0 since user asked for help + _exit(0); + } + else if (parseSearchPathArg(arg, end, searchPath)) + ; + else if (*arg != "" && arg->at(0) == '-') + return false; + else + files.push_back(*arg); + return true; + }); + + NixRepl repl(searchPath, openStore()); + repl.mainLoop(files); + + write_history(historyFile.c_str()); + }); +} |