lix/src/libutil/error.cc
2021-01-25 12:50:57 +01:00

310 lines
8.1 KiB
C++

#include "error.hh"
#include <iostream>
#include <optional>
#include "serialise.hh"
#include <sstream>
namespace nix {
const std::string nativeSystem = SYSTEM;
BaseError & BaseError::addTrace(std::optional<ErrPos> e, hintformat hint)
{
err.traces.push_front(Trace { .pos = e, .hint = hint });
return *this;
}
// c++ std::exception descendants must have a 'const char* what()' function.
// This stringifies the error and caches it for use by what(), or similarly by msg().
const string & BaseError::calcWhat() const
{
if (what_.has_value())
return *what_;
else {
err.name = sname();
std::ostringstream oss;
showErrorInfo(oss, err, false);
what_ = oss.str();
return *what_;
}
}
std::optional<string> ErrorInfo::programName = std::nullopt;
std::ostream & operator<<(std::ostream & os, const hintformat & hf)
{
return os << hf.str();
}
string showErrPos(const ErrPos & errPos)
{
if (errPos.line > 0) {
if (errPos.column > 0) {
return fmt("%d:%d", errPos.line, errPos.column);
} else {
return fmt("%d", errPos.line);
}
}
else {
return "";
}
}
std::optional<LinesOfCode> getCodeLines(const ErrPos & errPos)
{
if (errPos.line <= 0)
return std::nullopt;
if (errPos.origin == foFile) {
LinesOfCode loc;
try {
// FIXME: when running as the daemon, make sure we don't
// open a file to which the client doesn't have access.
AutoCloseFD fd = open(errPos.file.c_str(), O_RDONLY | O_CLOEXEC);
if (!fd) return {};
// count the newlines.
int count = 0;
string line;
int pl = errPos.line - 1;
do
{
line = readLine(fd.get());
++count;
if (count < pl)
;
else if (count == pl)
loc.prevLineOfCode = line;
else if (count == pl + 1)
loc.errLineOfCode = line;
else if (count == pl + 2) {
loc.nextLineOfCode = line;
break;
}
} while (true);
return loc;
}
catch (EndOfFile & eof) {
if (loc.errLineOfCode.has_value())
return loc;
else
return std::nullopt;
}
catch (std::exception & e) {
return std::nullopt;
}
} else {
std::istringstream iss(errPos.file);
// count the newlines.
int count = 0;
string line;
int pl = errPos.line - 1;
LinesOfCode loc;
do
{
std::getline(iss, line);
++count;
if (count < pl)
{
;
}
else if (count == pl) {
loc.prevLineOfCode = line;
} else if (count == pl + 1) {
loc.errLineOfCode = line;
} else if (count == pl + 2) {
loc.nextLineOfCode = line;
break;
}
if (!iss.good())
break;
} while (true);
return loc;
}
}
// print lines of code to the ostream, indicating the error column.
void printCodeLines(std::ostream & out,
const string & prefix,
const ErrPos & errPos,
const LinesOfCode & loc)
{
// previous line of code.
if (loc.prevLineOfCode.has_value()) {
out << std::endl
<< fmt("%1% %|2$5d|| %3%",
prefix,
(errPos.line - 1),
*loc.prevLineOfCode);
}
if (loc.errLineOfCode.has_value()) {
// line of code containing the error.
out << std::endl
<< fmt("%1% %|2$5d|| %3%",
prefix,
(errPos.line),
*loc.errLineOfCode);
// error arrows for the column range.
if (errPos.column > 0) {
int start = errPos.column;
std::string spaces;
for (int i = 0; i < start; ++i) {
spaces.append(" ");
}
std::string arrows("^");
out << std::endl
<< fmt("%1% |%2%" ANSI_RED "%3%" ANSI_NORMAL,
prefix,
spaces,
arrows);
}
}
// next line of code.
if (loc.nextLineOfCode.has_value()) {
out << std::endl
<< fmt("%1% %|2$5d|| %3%",
prefix,
(errPos.line + 1),
*loc.nextLineOfCode);
}
}
void printAtPos(const ErrPos & pos, std::ostream & out)
{
if (pos) {
switch (pos.origin) {
case foFile: {
out << fmt(ANSI_BLUE "at " ANSI_YELLOW "%s:%s" ANSI_NORMAL ":", pos.file, showErrPos(pos));
break;
}
case foString: {
out << fmt(ANSI_BLUE "at " ANSI_YELLOW "«string»:%s" ANSI_NORMAL ":", showErrPos(pos));
break;
}
case foStdin: {
out << fmt(ANSI_BLUE "at " ANSI_YELLOW "«stdin»:%s" ANSI_NORMAL ":", showErrPos(pos));
break;
}
default:
throw Error("invalid FileOrigin in errPos");
}
}
}
static std::string indent(std::string_view indentFirst, std::string_view indentRest, std::string_view s)
{
std::string res;
bool first = true;
while (!s.empty()) {
auto end = s.find('\n');
if (!first) res += "\n";
res += chomp(std::string(first ? indentFirst : indentRest) + std::string(s.substr(0, end)));
first = false;
if (end == s.npos) break;
s = s.substr(end + 1);
}
return res;
}
std::ostream & showErrorInfo(std::ostream & out, const ErrorInfo & einfo, bool showTrace)
{
std::string prefix;
switch (einfo.level) {
case Verbosity::lvlError: {
prefix = ANSI_RED "error";
break;
}
case Verbosity::lvlNotice: {
prefix = ANSI_RED "note";
break;
}
case Verbosity::lvlWarn: {
prefix = ANSI_YELLOW "warning";
break;
}
case Verbosity::lvlInfo: {
prefix = ANSI_GREEN "info";
break;
}
case Verbosity::lvlTalkative: {
prefix = ANSI_GREEN "talk";
break;
}
case Verbosity::lvlChatty: {
prefix = ANSI_GREEN "chat";
break;
}
case Verbosity::lvlVomit: {
prefix = ANSI_GREEN "vomit";
break;
}
case Verbosity::lvlDebug: {
prefix = ANSI_YELLOW "debug";
break;
}
default:
assert(false);
}
// FIXME: show the program name as part of the trace?
if (einfo.programName && einfo.programName != ErrorInfo::programName)
prefix += fmt(" [%s]:" ANSI_NORMAL " ", einfo.programName.value_or(""));
else
prefix += ":" ANSI_NORMAL " ";
std::ostringstream oss;
oss << einfo.msg << "\n";
if (einfo.errPos.has_value() && *einfo.errPos) {
oss << "\n";
printAtPos(*einfo.errPos, oss);
auto loc = getCodeLines(*einfo.errPos);
// lines of code.
if (loc.has_value()) {
oss << "\n";
printCodeLines(oss, "", *einfo.errPos, *loc);
oss << "\n";
}
}
// traces
if (showTrace && !einfo.traces.empty()) {
for (auto iter = einfo.traces.rbegin(); iter != einfo.traces.rend(); ++iter) {
oss << "\n" << "" << iter->hint.str() << "\n";
if (iter->pos.has_value() && (*iter->pos)) {
auto pos = iter->pos.value();
oss << "\n";
printAtPos(pos, oss);
auto loc = getCodeLines(pos);
if (loc.has_value()) {
oss << "\n";
printCodeLines(oss, "", pos, *loc);
oss << "\n";
}
}
}
}
out << indent(prefix, std::string(filterANSIEscapes(prefix, true).size(), ' '), chomp(oss.str()));
return out;
}
}