Process stderr from substituters while doing have/info queries

This commit is contained in:
Eelco Dolstra 2013-06-07 15:02:14 +02:00
parent c5f9d0d080
commit 5959c591a0
4 changed files with 59 additions and 9 deletions

View file

@ -1007,10 +1007,6 @@ void LocalStore::startSubstituter(const Path & substituter, RunningSubstituter &
fromPipe.create();
errorPipe.create();
/* Hack: prevent substituters that write too much to stderr from
deadlocking our read() from stdout. */
fcntl(errorPipe.writeSide, F_SETFL, O_NONBLOCK);
setSubstituterEnv();
run.pid = maybeVfork();
@ -1038,20 +1034,65 @@ void LocalStore::startSubstituter(const Path & substituter, RunningSubstituter &
/* Parent. */
run.program = baseNameOf(substituter);
run.to = toPipe.writeSide.borrow();
run.from = run.fromBuf.fd = fromPipe.readSide.borrow();
run.error = errorPipe.readSide.borrow();
}
/* Read a line from the substituter's stdout, while also processing
its stderr. */
string LocalStore::getLineFromSubstituter(RunningSubstituter & run)
{
string s;
string res, err;
/* We might have stdout data left over from the last time. */
if (run.fromBuf.hasData()) goto haveData;
while (1) {
unsigned char c;
run.fromBuf(&c, 1);
if (c == '\n') return s;
s += c;
fd_set fds;
FD_ZERO(&fds);
FD_SET(run.from, &fds);
FD_SET(run.error, &fds);
/* Wait for data to appear on the substituter's stdout or
stderr. */
if (select(run.from > run.error ? run.from + 1 : run.error + 1, &fds, 0, 0, 0) == -1) {
if (errno == EINTR) continue;
throw SysError("waiting for input from the substituter");
}
/* Completely drain stderr before dealing with stdout. */
if (FD_ISSET(run.error, &fds)) {
char buf[4096];
ssize_t n = read(run.error, (unsigned char *) buf, sizeof(buf));
if (n == -1) {
if (errno == EINTR) continue;
throw SysError("reading from substituter's stderr");
}
if (n == 0) throw Error(format("substituter `%1%' died unexpectedly") % run.program);
err.append(buf, n);
string::size_type p;
while ((p = err.find('\n')) != string::npos) {
printMsg(lvlError, run.program + ": " + string(err, 0, p));
err = string(err, p + 1);
}
}
/* Read from stdout until we get a newline or the buffer is empty. */
else if (run.fromBuf.hasData() || FD_ISSET(run.from, &fds)) {
haveData:
do {
unsigned char c;
run.fromBuf(&c, 1);
if (c == '\n') {
if (!err.empty()) printMsg(lvlError, run.program + ": " + err);
return res;
}
res += c;
} while (run.fromBuf.hasData());
}
}
}

View file

@ -44,6 +44,7 @@ struct OptimiseStats
struct RunningSubstituter
{
Path program;
Pid pid;
AutoCloseFD to, from, error;
FdSource fromBuf;

View file

@ -90,6 +90,12 @@ size_t BufferedSource::read(unsigned char * data, size_t len)
}
bool BufferedSource::hasData()
{
return bufPosOut < bufPosIn;
}
size_t FdSource::readUnbuffered(unsigned char * data, size_t len)
{
ssize_t n;

View file

@ -63,6 +63,8 @@ struct BufferedSource : Source
/* Underlying read call, to be overriden. */
virtual size_t readUnbuffered(unsigned char * data, size_t len) = 0;
bool hasData();
};