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playpen.c
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playpen.c
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#include <stdbool.h>
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <dirent.h>
#include <err.h>
#include <errno.h>
#include <fcntl.h>
#include <getopt.h>
#include <grp.h>
#include <linux/limits.h>
#include <pwd.h>
#include <unistd.h>
#include <sched.h>
#include <signal.h>
#include <sys/epoll.h>
#include <sys/mount.h>
#include <sys/prctl.h>
#include <sys/ptrace.h>
#include <sys/resource.h>
#include <sys/signalfd.h>
#include <sys/stat.h>
#include <sys/types.h>
#include <sys/timerfd.h>
#include <sys/reg.h>
#include <sys/wait.h>
#include <seccomp.h>
#include <systemd/sd-bus.h>
#include <systemd/sd-login.h>
#define SYSCALL_NAME_MAX 30
static void check(int rc) {
if (rc < 0) errx(EXIT_FAILURE, "%s", strerror(-rc));
}
__attribute__((format(printf, 2, 3))) static void check_posix(intmax_t rc, const char *fmt, ...) {
va_list args;
va_start(args, fmt);
if (rc == -1) verr(EXIT_FAILURE, fmt, args);
va_end(args);
}
__attribute__((format(printf, 2, 3))) static bool check_eagain(intmax_t rc, const char *fmt, ...) {
va_list args;
va_start(args, fmt);
if (rc == -1 && errno != EAGAIN) verr(EXIT_FAILURE, fmt, args);
va_end(args);
return rc == -1 && errno == EAGAIN;
}
static char *join_path(const char *left, const char *right) {
char *dst;
check_posix(asprintf(&dst, "%s/%s", left, right), "asprintf");
return dst;
}
static void mountx(const char *source, const char *target, const char *filesystemtype,
unsigned long mountflags, const void *data) {
check_posix(mount(source, target, filesystemtype, mountflags, data),
"mounting %s as %s (%s) failed", source, target, filesystemtype);
}
struct bind_list {
struct bind_list *next;
bool read_only;
char arg[];
};
static struct bind_list *bind_list_alloc(const char *arg, bool read_only) {
size_t len = strlen(arg);
struct bind_list *next = malloc(sizeof(struct bind_list) + len + 1);
if (!next) err(EXIT_FAILURE, "malloc");
next->next = NULL;
next->read_only = read_only;
strcpy(next->arg, arg);
return next;
}
static void bind_list_apply(const char *root, struct bind_list *list) {
for (; list; list = list->next) {
char *dst = join_path(root, list->arg);
// Only use MS_REC with writable mounts to work around a kernel bug:
// https://bugzilla.kernel.org/show_bug.cgi?id=24912
mountx(list->arg, dst, "bind", MS_BIND | (list->read_only ? 0 : MS_REC), NULL);
if (list->read_only)
mountx(list->arg, dst, "bind", MS_BIND|MS_REMOUNT|MS_RDONLY, NULL);
free(dst);
}
}
static void bind_list_free(struct bind_list *list) {
while (list) {
struct bind_list *next = list->next;
free(list);
list = next;
}
}
static const char *const systemd_bus_name = "org.freedesktop.systemd1";
static const char *const systemd_path_name = "/org/freedesktop/systemd1";
static const char *const manager_interface = "org.freedesktop.systemd1.Manager";
static void wait_for_unit(pid_t child_pid, const char *expected_name) {
for (;;) {
char *unit;
check(sd_pid_get_unit(child_pid, &unit));
bool equal = !strcmp(expected_name, unit);
free(unit);
if (equal) break;
}
}
static void start_scope_unit(sd_bus *connection, pid_t child_pid, long memory_limit,
char *devices, const char *unit_name) {
sd_bus_message *message = NULL;
check(sd_bus_message_new_method_call(connection, &message, systemd_bus_name, systemd_path_name,
manager_interface, "StartTransientUnit"));
check(sd_bus_message_append(message, "ss", unit_name, "fail"));
check(sd_bus_message_open_container(message, 'a', "(sv)"));
check(sd_bus_message_append(message, "(sv)", "PIDs", "au", 1, child_pid));
check(sd_bus_message_append(message, "(sv)", "Description", "s",
"Playpen application sandbox"));
check(sd_bus_message_append(message, "(sv)", "MemoryLimit", "t",
1024ULL * 1024ULL * (unsigned long long)memory_limit));
check(sd_bus_message_append(message, "(sv)", "DevicePolicy", "s", "strict"));
if (devices) {
check(sd_bus_message_open_container(message, 'r', "sv"));
check(sd_bus_message_append(message, "s", "DeviceAllow"));
check(sd_bus_message_open_container(message, 'v', "a(ss)"));
check(sd_bus_message_open_container(message, 'a', "(ss)"));
for (char *s_ptr = devices, *saveptr; ; s_ptr = NULL) {
const char *device = strtok_r(s_ptr, ",", &saveptr);
if (!device) break;
char *split = strchr(device, ':');
if (!split) errx(EXIT_FAILURE, "invalid device parameter `%s`", device);
*split = '\0';
sd_bus_message_append(message, "(ss)", device, split + 1);
}
check(sd_bus_message_close_container(message));
check(sd_bus_message_close_container(message));
check(sd_bus_message_close_container(message));
}
check(sd_bus_message_append(message, "(sv)", "CPUAccounting", "b", 1));
check(sd_bus_message_append(message, "(sv)", "BlockIOAccounting", "b", 1));
check(sd_bus_message_close_container(message));
check(sd_bus_message_append(message, "a(sa(sv))", 0));
sd_bus_error error = SD_BUS_ERROR_NULL;
int rc = sd_bus_call(connection, message, 0, &error, NULL);
if (rc < 0) errx(EXIT_FAILURE, "%s",
sd_bus_error_is_set(&error) ? error.message : strerror(-rc));
sd_bus_message_unref(message);
wait_for_unit(child_pid, unit_name);
}
static void stop_scope_unit(sd_bus *connection, const char *unit_name) {
sd_bus_error error = SD_BUS_ERROR_NULL;
int rc = sd_bus_call_method(connection, systemd_bus_name, systemd_path_name, manager_interface,
"StopUnit", &error, NULL, "ss", unit_name, "fail");
if (rc < 0) {
if (sd_bus_error_is_set(&error)) {
// NoSuchUnit errors are expected as the contained processes can die at any point.
if (strcmp(error.name, "org.freedesktop.systemd1.NoSuchUnit"))
errx(EXIT_FAILURE, "%s", error.message);
sd_bus_error_free(&error);
} else
errx(EXIT_FAILURE, "%s", strerror(-rc));
}
}
static void epoll_add(int epoll_fd, int fd, uint32_t events) {
struct epoll_event event = { .data.fd = fd, .events = events };
check_posix(epoll_ctl(epoll_fd, EPOLL_CTL_ADD, fd, &event), "epoll_ctl");
}
static void copy_to_stdstream(int in_fd, int out_fd) {
uint8_t buffer[BUFSIZ];
ssize_t n = read(in_fd, buffer, sizeof buffer);
if (check_eagain(n, "read")) return;
check_posix(write(out_fd, buffer, (size_t)n), "write");
}
static int get_syscall_nr(const char *name) {
int result = seccomp_syscall_resolve_name(name);
if (result == __NR_SCMP_ERROR) {
errx(EXIT_FAILURE, "non-existent syscall: %s", name);
}
return result;
}
_Noreturn static void usage(FILE *out) {
fprintf(out, "usage: %s [options] [root] [command ...]\n", program_invocation_short_name);
fputs("Options:\n"
" -h, --help display this help\n"
" -v, --version display version\n"
" -p, --mount-proc mount /proc in the container\n"
" --mount-dev mount /dev as devtmpfs in the container\n"
" -b, --bind bind mount a read-only directory in the container\n"
" -B, --bind-rw bind mount a directory in the container\n"
" -u, --user=USER the user to run the program as\n"
" -n, --hostname=NAME the hostname to set the container to\n"
" -t, --timeout=INTEGER how long the container is allowed to run\n"
" -m, --memory-limit=LIMIT the memory limit of the container\n"
" -d, --devices=LIST comma-separated whitelist of devices\n"
" -s, --syscalls=LIST comma-separated whitelist of syscalls\n"
" -S, --syscalls-file=PATH whitelist file containing one syscall name per line\n"
" -l, --learn=PATH allow unwhitelisted syscalls and append them to a file\n",
out);
exit(out == stderr ? EXIT_FAILURE : EXIT_SUCCESS);
}
static void set_non_blocking(int fd) {
int flags = fcntl(fd, F_GETFL, 0);
check_posix(flags, "fcntl");
check_posix(fcntl(fd, F_SETFL, flags | O_NONBLOCK), "fcntl");
}
// Mark any extra file descriptors `CLOEXEC`. Only `stdin`, `stdout` and `stderr` are left open.
static void prevent_leaked_file_descriptors() {
DIR *dir = opendir("/proc/self/fd");
if (!dir) err(EXIT_FAILURE, "opendir");
struct dirent *dp;
while ((dp = readdir(dir))) {
char *end;
int fd = (int)strtol(dp->d_name, &end, 10);
if (*end == '\0' && fd > 2 && fd != dirfd(dir)) {
check_posix(ioctl(fd, FIOCLEX), "ioctl");
}
}
closedir(dir);
}
static long strtolx_positive(const char *s, const char *what) {
char *end;
errno = 0;
long result = strtol(s, &end, 10);
if (errno) errx(EXIT_FAILURE, "%s is too large", what);
if (*end != '\0' || result < 0)
errx(EXIT_FAILURE, "%s must be a positive integer", what);
return result;
}
static void do_trace(const struct signalfd_siginfo *si, bool *trace_init, FILE *learn) {
int status;
if (waitpid((pid_t)si->ssi_pid, &status, WNOHANG) != (pid_t)si->ssi_pid)
errx(EXIT_FAILURE, "waitpid");
if (WIFEXITED(status) || WIFSIGNALED(status) || !WIFSTOPPED(status))
errx(EXIT_FAILURE, "unexpected ptrace event");
int inject_signal = 0;
if (*trace_init) {
int signal = WSTOPSIG(status);
if (signal != SIGTRAP || !(status & PTRACE_EVENT_SECCOMP))
inject_signal = signal;
else {
errno = 0;
#ifdef __x86_64__
long syscall = ptrace(PTRACE_PEEKUSER, si->ssi_pid, sizeof(long)*ORIG_RAX);
#else
long syscall = ptrace(PTRACE_PEEKUSER, si->ssi_pid, sizeof(long)*ORIG_EAX);
#endif
if (errno) err(EXIT_FAILURE, "ptrace");
char *name = seccomp_syscall_resolve_num_arch(SCMP_ARCH_NATIVE, (int)syscall);
if (!name) errx(EXIT_FAILURE, "seccomp_syscall_resolve_num_arch");
rewind(learn);
char line[SYSCALL_NAME_MAX];
while (fgets(line, sizeof line, learn)) {
char *pos;
if ((pos = strchr(line, '\n'))) *pos = '\0';
if (!strcmp(name, line)) {
name = NULL;
break;
}
}
if (name) {
fprintf(learn, "%s\n", name);
free(name);
}
}
} else {
check_posix(ptrace(PTRACE_SETOPTIONS, si->ssi_pid, 0, PTRACE_O_TRACESECCOMP), "ptrace");
*trace_init = true;
}
check_posix(ptrace(PTRACE_CONT, si->ssi_pid, 0, inject_signal), "ptrace");
}
static void handle_signal(int sig_fd, sd_bus *connection, const char *unit_name,
bool *trace_init, FILE *learn) {
struct signalfd_siginfo si;
ssize_t bytes_r = read(sig_fd, &si, sizeof(si));
check_posix(bytes_r, "read");
if (bytes_r != sizeof(si))
errx(EXIT_FAILURE, "read the wrong amount of bytes");
switch (si.ssi_signo) {
case SIGHUP:
case SIGINT:
case SIGTERM:
stop_scope_unit(connection, unit_name);
errx(EXIT_FAILURE, "interrupted, stopping early");
}
if (si.ssi_signo != SIGCHLD)
errx(EXIT_FAILURE, "got an unexpected signal");
switch (si.ssi_code) {
case CLD_EXITED:
if (si.ssi_status) {
warnx("application terminated with error code %d", si.ssi_status);
}
exit(si.ssi_status);
case CLD_KILLED:
case CLD_DUMPED:
errx(EXIT_FAILURE, "application terminated abnormally with signal %d (%s)",
si.ssi_status, strsignal(si.ssi_status));
case CLD_TRAPPED:
do_trace(&si, trace_init, learn);
case CLD_STOPPED:
default:
break;
}
}
int main(int argc, char **argv) {
prevent_leaked_file_descriptors();
bool mount_proc = false;
bool mount_dev = false;
const char *username = "nobody";
const char *hostname = "playpen";
long timeout = 0;
long memory_limit = 128;
struct bind_list *binds = NULL, *binds_tail = NULL;
char *devices = NULL;
char *syscalls = NULL;
const char *syscalls_file = NULL;
const char *learn_name = NULL;
static const struct option opts[] = {
{ "help", no_argument, 0, 'h' },
{ "version", no_argument, 0, 'v' },
{ "mount-proc", no_argument, 0, 'p' },
{ "mount-dev", no_argument, 0, 0x100 },
{ "bind", required_argument, 0, 'b' },
{ "bind-rw", required_argument, 0, 'B' },
{ "user", required_argument, 0, 'u' },
{ "hostname", required_argument, 0, 'n' },
{ "timeout", required_argument, 0, 't' },
{ "memory-limit", required_argument, 0, 'm' },
{ "devices", required_argument, 0, 'd' },
{ "syscalls", required_argument, 0, 's' },
{ "syscalls-file", required_argument, 0, 'S' },
{ "learn", required_argument, 0, 'l' },
{ 0, 0, 0, 0 }
};
for (;;) {
int opt = getopt_long(argc, argv, "hvpb:B:u:n:t:m:d:s:S:l:", opts, NULL);
if (opt == -1)
break;
switch (opt) {
case 'h':
usage(stdout);
case 'v':
printf("%s %s\n", program_invocation_short_name, VERSION);
return 0;
case 'p':
mount_proc = true;
break;
case 0x100:
mount_dev = true;
break;
case 'b':
case 'B':
if (binds) {
binds_tail->next = bind_list_alloc(optarg, opt == 'b');
binds_tail = binds_tail->next;
} else {
binds = binds_tail = bind_list_alloc(optarg, opt == 'b');
}
break;
case 'u':
username = optarg;
break;
case 'n':
hostname = optarg;
break;
case 't':
timeout = strtolx_positive(optarg, "timeout");
break;
case 'm':
memory_limit = strtolx_positive(optarg, "memory limit");
break;
case 'd':
devices = optarg;
break;
case 's':
syscalls = optarg;
break;
case 'S':
syscalls_file = optarg;
break;
case 'l':
learn_name = optarg;
break;
default:
usage(stderr);
}
}
if (argc - optind < 2) {
usage(stderr);
}
const char *root = argv[optind];
optind++;
scmp_filter_ctx ctx = seccomp_init(learn_name ? SCMP_ACT_TRACE(0) : SCMP_ACT_KILL);
if (!ctx) errx(EXIT_FAILURE, "seccomp_init");
if (syscalls_file) {
char name[SYSCALL_NAME_MAX];
FILE *file = fopen(syscalls_file, "r");
if (!file) err(EXIT_FAILURE, "failed to open syscalls file: %s", syscalls_file);
while (fgets(name, sizeof name, file)) {
char *pos;
if ((pos = strchr(name, '\n'))) *pos = '\0';
check(seccomp_rule_add(ctx, SCMP_ACT_ALLOW, get_syscall_nr(name), 0));
}
fclose(file);
}
check(seccomp_rule_add(ctx, SCMP_ACT_ALLOW, __NR_execve, 0));
if (syscalls) {
for (char *s_ptr = syscalls, *saveptr; ; s_ptr = NULL) {
const char *syscall = strtok_r(s_ptr, ",", &saveptr);
if (!syscall) break;
check(seccomp_rule_add(ctx, SCMP_ACT_ALLOW, get_syscall_nr(syscall), 0));
}
}
int epoll_fd = epoll_create1(EPOLL_CLOEXEC);
check_posix(epoll_fd, "epoll_create1");
sigset_t mask;
sigemptyset(&mask);
sigaddset(&mask, SIGCHLD);
sigaddset(&mask, SIGHUP);
sigaddset(&mask, SIGINT);
sigaddset(&mask, SIGTERM);
check_posix(sigprocmask(SIG_BLOCK, &mask, NULL), "sigprocmask");
int sig_fd = signalfd(-1, &mask, SFD_CLOEXEC);
check_posix(sig_fd, "signalfd");
epoll_add(epoll_fd, sig_fd, EPOLLIN);
int pipe_in[2];
int pipe_out[2];
int pipe_err[2];
check_posix(pipe(pipe_in), "pipe");
check_posix(pipe(pipe_out), "pipe");
set_non_blocking(pipe_out[0]);
check_posix(pipe(pipe_err), "pipe");
set_non_blocking(pipe_err[0]);
int rc = epoll_ctl(epoll_fd, EPOLL_CTL_ADD, STDIN_FILENO,
&(struct epoll_event){ .data.fd = STDIN_FILENO, .events = EPOLLIN });
if (rc == -1 && errno != EPERM) err(EXIT_FAILURE, "epoll_ctl");
const bool stdin_non_epoll = rc == -1;
epoll_add(epoll_fd, pipe_out[0], EPOLLIN);
epoll_add(epoll_fd, pipe_err[0], EPOLLIN);
epoll_add(epoll_fd, pipe_in[1], EPOLLET | EPOLLOUT);
unsigned long flags = SIGCHLD|CLONE_NEWIPC|CLONE_NEWNS|CLONE_NEWPID|CLONE_NEWUTS|CLONE_NEWNET;
pid_t pid = (pid_t)syscall(__NR_clone, flags, NULL);
check_posix(pid, "clone");
if (pid == 0) {
dup2(pipe_in[0], STDIN_FILENO);
close(pipe_in[0]);
close(pipe_in[1]);
dup2(pipe_out[1], STDOUT_FILENO);
close(pipe_out[0]);
close(pipe_out[1]);
dup2(pipe_err[1], STDERR_FILENO);
close(pipe_err[0]);
close(pipe_err[1]);
// Kill this process if the parent dies. This is not a replacement for killing the sandboxed
// processes via a control group as it is not inherited by child processes, but is more
// robust when the sandboxed process is not allowed to fork.
check_posix(prctl(PR_SET_PDEATHSIG, SIGKILL), "prctl");
// Wait until the scope unit is set up before moving on. This also ensures that the parent
// didn't die before `prctl` was called.
uint8_t ready;
check_posix(read(STDIN_FILENO, &ready, sizeof ready), "read");
check_posix(sethostname(hostname, strlen(hostname)), "sethostname");
// avoid propagating mounts to or from the parent's mount namespace
mountx(NULL, "/", NULL, MS_PRIVATE|MS_REC, NULL);
// turn directory into a bind mount
mountx(root, root, "bind", MS_BIND|MS_REC, NULL);
// re-mount as read-only
mountx(root, root, "bind", MS_BIND|MS_REMOUNT|MS_RDONLY|MS_REC, NULL);
if (mount_proc) {
char *mnt = join_path(root, "proc");
mountx(NULL, mnt, "proc", MS_NOSUID|MS_NOEXEC|MS_NODEV, NULL);
free(mnt);
}
if (mount_dev) {
char *mnt = join_path(root, "dev");
mountx(NULL, mnt, "devtmpfs", MS_NOSUID|MS_NOEXEC, NULL);
free(mnt);
}
char *shm = join_path(root, "dev/shm");
if (mount(NULL, shm, "tmpfs", MS_NOSUID|MS_NODEV, NULL) == -1) {
if (errno != ENOENT) {
err(EXIT_FAILURE, "mounting /dev/shm failed");
}
}
free(shm);
char *tmp = join_path(root, "tmp");
if (mount(NULL, tmp, "tmpfs", MS_NOSUID|MS_NODEV, NULL) == -1) {
if (errno != ENOENT) {
err(EXIT_FAILURE, "mounting /tmp failed");
}
}
free(tmp);
bind_list_apply(root, binds);
// preserve a reference to the target directory
check_posix(chdir(root), "chdir");
// make the working directory into the root of the mount namespace
mountx(".", "/", NULL, MS_MOVE, NULL);
// chroot into the root of the mount namespace
check_posix(chroot("."), "chroot into `%s` failed", root);
check_posix(chdir("/"), "entering chroot `%s` failed", root);
errno = 0;
struct passwd *pw = getpwnam(username);
if (!pw) {
if (errno) {
err(EXIT_FAILURE, "getpwnam");
} else {
errx(EXIT_FAILURE, "no passwd entry for username %s", username);
}
}
mountx(NULL, pw->pw_dir, "tmpfs", MS_NOSUID|MS_NODEV, NULL);
// switch to the user's home directory as a login shell would
check_posix(chdir(pw->pw_dir), "chdir");
// create a new session
check_posix(setsid(), "setsid");
check_posix(initgroups(username, pw->pw_gid), "initgroups");
check_posix(setresgid(pw->pw_gid, pw->pw_gid, pw->pw_gid), "setresgid");
check_posix(setresuid(pw->pw_uid, pw->pw_uid, pw->pw_uid), "setresuid");
char path[] = "PATH=/usr/local/bin:/usr/bin:/bin";
char *env[] = {path, NULL, NULL, NULL, NULL};
if ((asprintf(env + 1, "HOME=%s", pw->pw_dir) < 0 ||
asprintf(env + 2, "USER=%s", username) < 0 ||
asprintf(env + 3, "LOGNAME=%s", username) < 0)) {
errx(EXIT_FAILURE, "asprintf");
}
if (learn_name) check_posix(ptrace(PTRACE_TRACEME, 0, NULL, NULL), "ptrace");
check(seccomp_load(ctx));
check_posix(execvpe(argv[optind], argv + optind, env), "execvpe");
}
bind_list_free(binds);
seccomp_release(ctx);
FILE *learn = NULL;
if (learn_name) {
learn = fopen(learn_name, "a+");
if (!learn) err(EXIT_FAILURE, "fopen");
}
sd_bus *connection;
check(sd_bus_open_system(&connection));
char unit_name[100];
snprintf(unit_name, sizeof unit_name, "playpen-%u.scope", getpid());
start_scope_unit(connection, pid, memory_limit, devices, unit_name);
// Inform the child that the scope unit has been created.
check_posix(write(pipe_in[1], &(uint8_t) { 0 }, 1), "write");
set_non_blocking(pipe_in[1]);
int timer_fd = -1;
if (timeout) {
timer_fd = timerfd_create(CLOCK_MONOTONIC, TFD_CLOEXEC);
check_posix(timer_fd, "timerfd_create");
epoll_add(epoll_fd, timer_fd, EPOLLIN);
struct itimerspec spec = { .it_value = { .tv_sec = timeout } };
check_posix(timerfd_settime(timer_fd, 0, &spec, NULL), "timerfd_settime");
}
uint8_t stdin_buffer[PIPE_BUF];
ssize_t stdin_bytes_read = 0;
bool trace_init = false;
for (;;) {
struct epoll_event events[4];
int n_event = epoll_wait(epoll_fd, events, 4, -1);
if (n_event < 0) {
if (errno == EINTR)
continue;
err(EXIT_FAILURE, "epoll_wait");
}
for (int i = 0; i < n_event; ++i) {
struct epoll_event *evt = &events[i];
if (evt->events & EPOLLERR) {
close(evt->data.fd);
continue;
}
if (evt->events & EPOLLIN) {
if (evt->data.fd == timer_fd) {
warnx("timeout triggered!");
stop_scope_unit(connection, unit_name);
return EXIT_FAILURE;
} else if (evt->data.fd == sig_fd) {
handle_signal(sig_fd, connection, unit_name, &trace_init, learn);
} else if (evt->data.fd == pipe_out[0]) {
copy_to_stdstream(pipe_out[0], STDOUT_FILENO);
} else if (evt->data.fd == pipe_err[0]) {
copy_to_stdstream(pipe_err[0], STDERR_FILENO);
} else if (evt->data.fd == STDIN_FILENO) {
stdin_bytes_read = read(STDIN_FILENO, stdin_buffer, sizeof stdin_buffer);
check_posix(stdin_bytes_read, "read");
if (stdin_bytes_read == 0) {
check_posix(epoll_ctl(epoll_fd, EPOLL_CTL_DEL, STDIN_FILENO, NULL),
"epoll_ctl");
close(STDIN_FILENO);
close(pipe_in[1]);
continue;
}
ssize_t bytes_written = write(pipe_in[1], stdin_buffer, (size_t)stdin_bytes_read);
if (check_eagain(bytes_written, "write")) {
check_posix(epoll_ctl(epoll_fd, EPOLL_CTL_DEL, STDIN_FILENO, NULL),
"epoll_ctl");
continue;
}
stdin_bytes_read = 0;
continue;
}
}
// the child process is ready for more input
if (evt->events & EPOLLOUT && evt->data.fd == pipe_in[1]) {
// deal with previously buffered data
if (stdin_bytes_read > 0) {
ssize_t bytes_written = write(pipe_in[1], stdin_buffer, (size_t)stdin_bytes_read);
if (check_eagain(bytes_written, "write")) continue;
stdin_bytes_read = 0;
if (!stdin_non_epoll) {
epoll_add(epoll_fd, STDIN_FILENO, EPOLLIN); // accept more data
}
}
if (stdin_non_epoll) {
// drain stdin until a write would block
for (;;) {
stdin_bytes_read = read(STDIN_FILENO, stdin_buffer, sizeof stdin_buffer);
check_posix(stdin_bytes_read, "read");
ssize_t bytes_written = write(pipe_in[1], stdin_buffer,
(size_t)stdin_bytes_read);
if (check_eagain(bytes_written, "write")) break;
if (stdin_bytes_read < (ssize_t)sizeof stdin_buffer) {
close(STDIN_FILENO);
close(pipe_in[1]);
break;
}
}
continue;
}
}
if (evt->events & EPOLLHUP) {
if (evt->data.fd == STDIN_FILENO) {
close(pipe_in[1]);
check_posix(epoll_ctl(epoll_fd, EPOLL_CTL_DEL, STDIN_FILENO, NULL),
"epoll_ctl");
}
close(evt->data.fd);
}
}
}
}