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runProgram(): Distinguish between empty input and no input

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For example, if we call brotli with an empty input, it shouldn't read
from the caller's stdin.
This commit is contained in:
Eelco Dolstra 2017-03-15 14:40:47 +01:00
parent 042975ea8e
commit 25dff2b7db
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GPG key ID: 8170B4726D7198DE
5 changed files with 30 additions and 15 deletions
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33
src/libutil/util.cc
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@ -1,6 +1,7 @@
#include "util.hh"
#include "affinity.hh"
#include "sync.hh"
#include "finally.hh"
#include <cctype>
#include <cerrno>
@ -10,6 +11,7 @@
#include <iostream>
#include <sstream>
#include <thread>
#include <future>
#include <sys/wait.h>
#include <unistd.h>
@ -837,23 +839,21 @@ std::vector<char *> stringsToCharPtrs(const Strings & ss)
string runProgram(Path program, bool searchPath, const Strings & args,
const string & input)
const std::experimental::optional<std::string> & input)
{
checkInterrupt();
/* Create a pipe. */
Pipe out, in;
out.create();
if (!input.empty()) in.create();
if (input) in.create();
/* Fork. */
Pid pid = startProcess([&]() {
if (dup2(out.writeSide.get(), STDOUT_FILENO) == -1)
throw SysError("dupping stdout");
if (!input.empty()) {
if (dup2(in.readSide.get(), STDIN_FILENO) == -1)
throw SysError("dupping stdin");
}
if (input && dup2(in.readSide.get(), STDIN_FILENO) == -1)
throw SysError("dupping stdin");
Strings args_(args);
args_.push_front(program);
@ -872,10 +872,23 @@ string runProgram(Path program, bool searchPath, const Strings & args,
std::thread writerThread;
if (!input.empty()) {
std::promise<void> promise;
Finally doJoin([&]() {
if (writerThread.joinable())
writerThread.join();
});
if (input) {
in.readSide = -1;
writerThread = std::thread([&]() {
writeFull(in.writeSide.get(), input);
try {
writeFull(in.writeSide.get(), *input);
promise.set_value();
} catch (...) {
promise.set_exception(std::current_exception());
}
in.writeSide = -1;
});
}
@ -888,8 +901,8 @@ string runProgram(Path program, bool searchPath, const Strings & args,
throw ExecError(status, format("program ‘%1%’ %2%")
% program % statusToString(status));
if (!input.empty())
writerThread.join();
/* Wait for the writer thread to finish. */
if (input) promise.get_future().get();
return result;
}