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Runguard with less pipes.
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@meisterT
meisterT committed Nov 30, 2023
1 parent d66221b commit 170f0ec
Showing 1 changed file with 12 additions and 150 deletions.
162 changes: 12 additions & 150 deletions judge/runguard.c
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Original file line number Diff line number Diff line change
Expand Up @@ -161,7 +161,6 @@ static volatile sig_atomic_t received_signal = -1;

FILE *child_stdout;
FILE *child_stderr;
int child_pipefd[3][2];
int child_redirfd[3];

struct timeval progstarttime, starttime, endtime;
Expand Down Expand Up @@ -202,7 +201,7 @@ void warning(const char *format, ...)
va_list ap;
va_start(ap,format);

if ( ! be_quiet ) {
if ( true ) {
fprintf(stderr,"%s: warning: ",progname);
vfprintf(stderr,format,ap);
fprintf(stderr,"\n");
Expand All @@ -218,7 +217,7 @@ void verbose(const char *format, ...)
struct timeval currtime;
double runtime;

if ( ! be_quiet && be_verbose ) {
if ( true ) {
gettimeofday(&currtime,NULL);
runtime = (currtime.tv_sec - progstarttime.tv_sec ) +
(currtime.tv_usec - progstarttime.tv_usec)*1E-6;
Expand Down Expand Up @@ -883,92 +882,11 @@ void setrestrictions()
}
}

void pump_pipes(fd_set* readfds, size_t data_read[], size_t data_passed[])
{
char buf[BUF_SIZE];
ssize_t nread, nwritten;
size_t to_read, to_write;
int i;

/* Check to see if data is available and pass it on */
for(i=1; i<=2; i++) {
if ( child_pipefd[i][PIPE_OUT] != -1 &&
FD_ISSET(child_pipefd[i][PIPE_OUT], readfds) ) {

if (limit_streamsize && data_passed[i] == streamsize) {
/* Throw away data if we're at the output limit, but
still count how much data we consumed */
nread = read(child_pipefd[i][PIPE_OUT], buf, BUF_SIZE);
} else {
/* Otherwise copy the output to a file */
to_read = BUF_SIZE;
if (limit_streamsize) {
to_read = min(BUF_SIZE, streamsize-data_passed[i]);
}

if ( use_splice ) {
nread = splice(child_pipefd[i][PIPE_OUT], NULL,
child_redirfd[i], NULL,
to_read, SPLICE_F_MOVE | SPLICE_F_NONBLOCK);

if ( nread==-1 && errno==EINVAL ) {
use_splice = 0;
verbose("splice failed, switching to read/write");
/* Setting errno here to repeat the copy. */
errno = EAGAIN;
}
if ( nread==-1 && errno==EPIPE ) {
/* This happens when the child process has
exited and the pipe is closed. */
nread = 0;
errno = 0;
}
} else {
nread = read(child_pipefd[i][PIPE_OUT], buf, to_read);
if ( nread>0 ) {
to_write = nread;
while ( to_write>0 ) {
nwritten = write(child_redirfd[i], buf, to_write);
if ( nwritten==-1 ) {
nread = -1;
break;
}
to_write -= nwritten;
}
}
}

if ( nread>0 ) data_passed[i] += nread;

/* print message if we're at the streamsize limit */
if (limit_streamsize && data_passed[i] == streamsize) {
verbose("child fd %i limit reached",i);
}
}
if ( nread==-1 ) {
if (errno == EINTR || errno == EAGAIN || errno == EWOULDBLOCK) continue;
error(errno,"copying data fd %d",i);
}
if ( nread==0 ) {
/* EOF detected: close fd and indicate this with -1 */
if ( close(child_pipefd[i][PIPE_OUT])!=0 ) {
error(errno,"closing pipe for fd %d",i);
}
child_pipefd[i][PIPE_OUT] = -1;
continue;
}
data_read[i] += nread;
}
}

}

int main(int argc, char **argv)
{
sigset_t sigmask, emptymask;
fd_set readfds;
pid_t pid;
int i, r, nfds;
int i;
int ret;
FILE *fp;
char *oom_path;
Expand All @@ -981,7 +899,6 @@ int main(int argc, char **argv)
double tmpd;
size_t data_read[3];
size_t data_passed[3];
size_t total_data;
char str[256];

struct itimerval itimer;
Expand Down Expand Up @@ -1162,11 +1079,6 @@ int main(int argc, char **argv)
if ( ptr==NULL || runuid<=0 ) error(0,"illegal user specified: %d",runuid);
}

/* Setup pipes connecting to child stdout/err streams (ignore stdin). */
for(i=1; i<=2; i++) {
if ( pipe(child_pipefd[i])!=0 ) error(errno,"creating pipe for fd %d",i);
}

if ( sigemptyset(&emptymask)!=0 ) error(errno,"creating empty signal mask");

/* unmask all signals, except SIGCHLD: detected in pselect() below */
Expand Down Expand Up @@ -1247,20 +1159,6 @@ int main(int argc, char **argv)
setrestrictions();
verbose("setrestrictions() done");

/* Connect pipes to command (stdin/)stdout/stderr and close
* unneeded fd's. Do this after setting restrictions to let
* any messages not go to command stderr pipe. */
for(i=1; i<=2; i++) {
if ( dup2(child_pipefd[i][PIPE_IN],i)<0 ) {
error(errno,"redirecting child fd %d",i);
}
if ( close(child_pipefd[i][PIPE_IN] )!=0 ||
close(child_pipefd[i][PIPE_OUT])!=0 ) {
error(errno,"closing pipe for fd %d",i);
}
}
verbose("pipes closed in child");

/* And execute child command. */
execvp(cmdname,cmdargs);
error(errno,"cannot start `%s'",cmdname);
Expand All @@ -1278,11 +1176,7 @@ int main(int argc, char **argv)
if ( gettimeofday(&starttime,NULL) ) error(errno,"getting time");

/* Close unused file descriptors */
for(i=1; i<=2; i++) {
if ( close(child_pipefd[i][PIPE_IN])!=0 ) {
error(errno,"closing pipe for fd %i",i);
}
}
// TODO: we might want to close some fds here

/* Redirect child stdout/stderr to file */
for(i=1; i<=2; i++) {
Expand Down Expand Up @@ -1347,54 +1241,22 @@ int main(int argc, char **argv)
Initialize status here to quelch clang++ warning about
uninitialized value; it is set by the wait() call. */
status = 0;
/* We start using splice() to copy data from child to parent
I/O file descriptors. If that fails (not all I/O
source - dest combinations support it), then we revert to
using read()/write(). */
use_splice = 1;
while ( 1 ) {

FD_ZERO(&readfds);
nfds = -1;
for(i=1; i<=2; i++) {
if ( child_pipefd[i][PIPE_OUT]>=0 ) {
FD_SET(child_pipefd[i][PIPE_OUT],&readfds);
nfds = max(nfds,child_pipefd[i][PIPE_OUT]);
}
}

r = pselect(nfds+1, &readfds, NULL, NULL, NULL, &emptymask);
if ( r==-1 && errno!=EINTR ) error(errno,"waiting for child data");
/*
// TODO: fix this delay and use EPOLL as in runpipe?
nanosleep(&killdelay,NULL);
if ( received_SIGCHLD || received_signal == SIGALRM ) {
if ( (pid = wait(&status))<0 ) error(errno,"waiting on child");
if ( pid==child_pid ) break;
}

pump_pipes(&readfds, data_read, data_passed);
}

/* Reset pipe filedescriptors to use blocking I/O. */
FD_ZERO(&readfds);
for(i=1; i<=2; i++) {
if ( child_pipefd[i][PIPE_OUT]>=0 ) {
FD_SET(child_pipefd[i][PIPE_OUT],&readfds);
r = fcntl(child_pipefd[i][PIPE_OUT], F_GETFL);
if (r == -1) {
error(errno, "fcntl, getting flags");
}
r = fcntl(child_pipefd[i][PIPE_OUT], F_SETFL, r ^ O_NONBLOCK);
if (r == -1) {
error(errno, "fcntl, setting flags");
}
}
*/
if (child_pid == waitpid(child_pid, &status, WNOHANG)) {
break;
}
nanosleep(&cg_delete_delay,NULL);
}

do {
total_data = data_passed[1] + data_passed[2];
pump_pipes(&readfds, data_read, data_passed);
} while ( data_passed[1] + data_passed[2] > total_data );

/* Close the output files */
for(i=1; i<=2; i++) {
ret = close(child_redirfd[i]);
Expand Down

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