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Don't interpret strings as format strings

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Ludo reported this error:

  unexpected Nix daemon error: boost::too_few_args: format-string refered to more arguments than were passed

coming from this line:

  printMsg(lvlError, run.program + ": " + string(err, 0, p));

The problem here is that the string ends up implicitly converted to a
Boost format() object, so % characters are treated specially.  I
always assumed (wrongly) that strings are converted to a format object
that outputs the string as-is.

Since this assumption appears in several places that may be hard to
grep for, I've added some C++ type hackery to ensures that the right
thing happens.  So you don't have to worry about % in statements like

  printMsg(lvlError, "foo: " + s);

or

  throw Error("foo: " + s);
This commit is contained in:
Eelco Dolstra 2014-03-28 16:59:26 +01:00
parent 24cb65efc3
commit 49009573bc
3 changed files with 32 additions and 23 deletions
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26
src/libutil/util.cc
View file

@ -25,22 +25,22 @@ extern char * * environ;
namespace nix {
BaseError::BaseError(const format & f, unsigned int status)
BaseError::BaseError(const FormatOrString & fs, unsigned int status)
: status(status)
{
err = f.str();
err = fs.s;
}
BaseError & BaseError::addPrefix(const format & f)
BaseError & BaseError::addPrefix(const FormatOrString & fs)
{
prefix_ = f.str() + prefix_;
prefix_ = fs.s + prefix_;
return *this;
}
SysError::SysError(const format & f)
: Error(format("%1%: %2%") % f.str() % strerror(errno))
SysError::SysError(const FormatOrString & fs)
: Error(format("%1%: %2%") % fs.s % strerror(errno))
, errNo(errno)
{
}
@ -417,14 +417,14 @@ static string escVerbosity(Verbosity level)
}
void Nest::open(Verbosity level, const format & f)
void Nest::open(Verbosity level, const FormatOrString & fs)
{
if (level <= verbosity) {
if (logType == ltEscapes)
std::cerr << "\033[" << escVerbosity(level) << "p"
<< f.str() << "\n";
<< fs.s << "\n";
else
printMsg_(level, f);
printMsg_(level, fs);
nest = true;
nestingLevel++;
}
@ -442,7 +442,7 @@ void Nest::close()
}
void printMsg_(Verbosity level, const format & f)
void printMsg_(Verbosity level, const FormatOrString & fs)
{
checkInterrupt();
if (level > verbosity) return;
@ -452,15 +452,15 @@ void printMsg_(Verbosity level, const format & f)
prefix += "| ";
else if (logType == ltEscapes && level != lvlInfo)
prefix = "\033[" + escVerbosity(level) + "s";
string s = (format("%1%%2%\n") % prefix % f.str()).str();
string s = (format("%1%%2%\n") % prefix % fs.s).str();
writeToStderr(s);
}
void warnOnce(bool & haveWarned, const format & f)
void warnOnce(bool & haveWarned, const FormatOrString & fs)
{
if (!haveWarned) {
printMsg(lvlError, format("warning: %1%") % f.str());
printMsg(lvlError, format("warning: %1%") % fs.s);
haveWarned = true;
}
}