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#include "error.hh"
#include "file-system.hh"
#include "logging.hh"
#include <csignal>
#include <cstdio>
#include <iostream>
#include <string>
#include <string_view>
#include <cerrno>
#ifdef READLINE
#include <readline/history.h>
#include <readline/readline.h>
#else
// editline < 1.15.2 don't wrap their API for C++ usage
// (added in https://github.com/troglobit/editline/commit/91398ceb3427b730995357e9d120539fb9bb7461).
// This results in linker errors due to to name-mangling of editline C symbols.
// For compatibility with these versions, we wrap the API here
// (wrapping multiple times on newer versions is no problem).
extern "C" {
#include <editline.h>
}
#endif
#include "finally.hh"
#include "repl-interacter.hh"
namespace nix {
namespace {
// Used to communicate to NixRepl::getLine whether a signal occurred in ::readline.
volatile sig_atomic_t g_signal_received = 0;
void sigintHandler(int signo)
{
g_signal_received = signo;
}
};
static detail::ReplCompleterMixin * curRepl; // ugly
static char * completionCallback(char * s, int * match)
{
auto possible = curRepl->completePrefix(s);
if (possible.size() == 1) {
*match = 1;
auto * res = strdup(possible.begin()->c_str() + strlen(s));
if (!res)
throw Error("allocation failure");
return res;
} else if (possible.size() > 1) {
auto checkAllHaveSameAt = [&](size_t pos) {
auto & first = *possible.begin();
for (auto & p : possible) {
if (p.size() <= pos || p[pos] != first[pos])
return false;
}
return true;
};
size_t start = strlen(s);
size_t len = 0;
while (checkAllHaveSameAt(start + len))
++len;
if (len > 0) {
*match = 1;
auto * res = strdup(std::string(*possible.begin(), start, len).c_str());
if (!res)
throw Error("allocation failure");
return res;
}
}
*match = 0;
return nullptr;
}
static int listPossibleCallback(char * s, char *** avp)
{
auto possible = curRepl->completePrefix(s);
if (possible.size() > (INT_MAX / sizeof(char *)))
throw Error("too many completions");
int ac = 0;
char ** vp = nullptr;
auto check = [&](auto * p) {
if (!p) {
if (vp) {
while (--ac >= 0)
free(vp[ac]);
free(vp);
}
throw Error("allocation failure");
}
return p;
};
vp = check((char **) malloc(possible.size() * sizeof(char *)));
for (auto & p : possible)
vp[ac++] = check(strdup(p.c_str()));
*avp = vp;
return ac;
}
ReadlineLikeInteracter::Guard ReadlineLikeInteracter::init(detail::ReplCompleterMixin * repl)
{
// Allow nix-repl specific settings in .inputrc
rl_readline_name = "nix-repl";
try {
createDirs(dirOf(historyFile));
} catch (SysError & e) {
logWarning(e.info());
}
#ifndef READLINE
el_hist_size = 1000;
#endif
read_history(historyFile.c_str());
auto oldRepl = curRepl;
curRepl = repl;
Guard restoreRepl([oldRepl] { curRepl = oldRepl; });
#ifndef READLINE
rl_set_complete_func(completionCallback);
rl_set_list_possib_func(listPossibleCallback);
#endif
return restoreRepl;
}
static constexpr const char * promptForType(ReplPromptType promptType)
{
switch (promptType) {
case ReplPromptType::ReplPrompt:
return "nix-repl> ";
case ReplPromptType::ContinuationPrompt:
return " ";
}
assert(false);
}
bool ReadlineLikeInteracter::getLine(std::string & input, ReplPromptType promptType)
{
struct sigaction act, old;
sigset_t savedSignalMask, set;
auto setupSignals = [&]() {
act.sa_handler = sigintHandler;
sigfillset(&act.sa_mask);
act.sa_flags = 0;
if (sigaction(SIGINT, &act, &old))
throw SysError("installing handler for SIGINT");
sigemptyset(&set);
sigaddset(&set, SIGINT);
if (sigprocmask(SIG_UNBLOCK, &set, &savedSignalMask))
throw SysError("unblocking SIGINT");
};
auto restoreSignals = [&]() {
if (sigprocmask(SIG_SETMASK, &savedSignalMask, nullptr))
throw SysError("restoring signals");
if (sigaction(SIGINT, &old, 0))
throw SysError("restoring handler for SIGINT");
};
setupSignals();
char * s = readline(promptForType(promptType));
Finally doFree([&]() { free(s); });
restoreSignals();
if (g_signal_received) {
g_signal_received = 0;
input.clear();
return true;
}
if (!s)
return false;
this->writeHistory();
input += s;
input += '\n';
return true;
}
void ReadlineLikeInteracter::writeHistory()
{
int ret = write_history(historyFile.c_str());
int writeHistErr = errno;
if (ret == 0) {
return;
}
// If the open fails, editline returns EOF. If the close fails, editline
// forwards the return value of fclose(), which is EOF on error.
// readline however, returns the errno.
// So if we didn't get exactly EOF, then consider the return value the error
// code; otherwise use the errno we saved above.
// https://github.com/troglobit/editline/issues/66
if (ret != EOF) {
writeHistErr = ret;
}
// In any of these cases, we should explicitly ignore the error, but log
// them so the user isn't confused why their history is getting eaten.
std::string_view const errMsg(std::strerror(writeHistErr));
warn("ignoring error writing repl history to %s: %s", this->historyFile, errMsg);
}
ReadlineLikeInteracter::~ReadlineLikeInteracter()
{
this->writeHistory();
}
AutomationInteracter::Guard AutomationInteracter::init(detail::ReplCompleterMixin *)
{
return Guard([] {});
}
// ASCII ENQ character
constexpr const char * automationPrompt = "\x05";
bool AutomationInteracter::getLine(std::string & input, ReplPromptType promptType)
{
std::cout << std::unitbuf;
std::cout << automationPrompt;
if (!std::getline(std::cin, input)) {
// reset failure bits on EOF
std::cin.clear();
return false;
}
return true;
}
};
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