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bnoordhuisbnoordhuis
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src: restore stdio on program exit
Record the state of the stdio file descriptors on start-up and restore them to that state on exit. This should prevent issues where node.js sometimes leaves stdio in raw or non-blocking mode. This is a reworked version of commit c2c9c0c from May 2018 that was reverted in commit 14dc17d from June 2018. The revert was a little light on details but I infer that the problem was caused by a missing call to `uv_tty_reset_mode()`. Apropos the NOLINT comments: cpplint doesn't understand do/while statements, it thinks they're while statements without a body. Fixes: nodejs#14752 Fixes: nodejs#21020 Original-PR-URL: nodejs#20592
1 parent 3293bbf commit 256614a

4 files changed

Lines changed: 91 additions & 8 deletions

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‎src/node.cc‎

Lines changed: 88 additions & 6 deletions
Original file line numberDiff line numberDiff line change
@@ -103,6 +103,7 @@
103103
#else
104104
#include <pthread.h>
105105
#include <sys/resource.h> // getrlimit, setrlimit
106+
#include <termios.h> // tcgetattr, tcsetattr
106107
#include <unistd.h> // STDIN_FILENO, STDERR_FILENO
107108
#endif
108109

@@ -191,7 +192,7 @@ void WaitForInspectorDisconnect(Environment* env) {
191192

192193
#ifdef __POSIX__
193194
void SignalExit(int signo, siginfo_t* info, void* ucontext) {
194-
uv_tty_reset_mode();
195+
ResetStdio();
195196
raise(signo);
196197
}
197198
#endif // __POSIX__
@@ -451,7 +452,7 @@ void TrapWebAssemblyOrContinue(int signo, siginfo_t* info, void* ucontext) {
451452
if (prev != nullptr) {
452453
prev(signo, info, ucontext);
453454
} else {
454-
uv_tty_reset_mode();
455+
ResetStdio();
455456
raise(signo);
456457
}
457458
}
@@ -481,6 +482,16 @@ void RegisterSignalHandler(int signal,
481482

482483
#endif // __POSIX__
483484

485+
#ifdef __POSIX__
486+
static struct {
487+
int flags;
488+
bool isatty;
489+
struct stat stat;
490+
struct termios termios;
491+
} stdio[1 + STDERR_FILENO];
492+
#endif // __POSIX__
493+
494+
484495
inline void PlatformInit() {
485496
#ifdef __POSIX__
486497
#if HAVE_INSPECTOR
@@ -491,16 +502,18 @@ inline void PlatformInit() {
491502
#endif // HAVE_INSPECTOR
492503

493504
// Make sure file descriptors 0-2 are valid before we start logging anything.
494-
for (int fd = STDIN_FILENO; fd <= STDERR_FILENO; fd += 1) {
495-
struct stat ignored;
496-
if (fstat(fd, &ignored) == 0)
505+
for (auto& s : stdio) {
506+
const int fd = &s - stdio;
507+
if (fstat(fd, &s.stat) == 0)
497508
continue;
498509
// Anything but EBADF means something is seriously wrong. We don't
499510
// have to special-case EINTR, fstat() is not interruptible.
500511
if (errno != EBADF)
501512
ABORT();
502513
if (fd != open("/dev/null", O_RDWR))
503514
ABORT();
515+
if (fstat(fd, &s.stat) != 0)
516+
ABORT();
504517
}
505518

506519
#if HAVE_INSPECTOR
@@ -523,6 +536,27 @@ inline void PlatformInit() {
523536
}
524537
#endif // !NODE_SHARED_MODE
525538

539+
// Record the state of the stdio file descriptors so we can restore it
540+
// on exit. Needs to happen before installing signal handlers because
541+
// they make use of that information.
542+
for (auto& s : stdio) {
543+
const int fd = &s - stdio;
544+
int err;
545+
546+
do
547+
s.flags = fcntl(fd, F_GETFL);
548+
while (s.flags == -1 && errno == EINTR); // NOLINT
549+
CHECK_NE(s.flags, -1);
550+
551+
if (!isatty(fd)) continue;
552+
s.isatty = true;
553+
554+
do
555+
err = tcgetattr(fd, &s.termios);
556+
while (err == -1 && errno == EINTR); // NOLINT
557+
CHECK_EQ(err, 0);
558+
}
559+
526560
RegisterSignalHandler(SIGINT, SignalExit, true);
527561
RegisterSignalHandler(SIGTERM, SignalExit, true);
528562

@@ -576,6 +610,54 @@ inline void PlatformInit() {
576610
#endif // _WIN32
577611
}
578612

613+
614+
// Safe to call more than once and from signal handlers.
615+
void ResetStdio() {
616+
uv_tty_reset_mode();
617+
#ifdef __POSIX__
618+
for (auto& s : stdio) {
619+
const int fd = &s - stdio;
620+
621+
struct stat tmp;
622+
if (-1 == fstat(fd, &tmp)) {
623+
CHECK_EQ(errno, EBADF); // Program closed file descriptor.
624+
continue;
625+
}
626+
627+
bool is_same_file =
628+
(s.stat.st_dev == tmp.st_dev && s.stat.st_ino == tmp.st_ino);
629+
if (!is_same_file) continue; // Program reopened file descriptor.
630+
631+
int flags;
632+
do
633+
flags = fcntl(fd, F_GETFL);
634+
while (flags == -1 && errno == EINTR); // NOLINT
635+
CHECK_NE(flags, -1);
636+
637+
// Restore the O_NONBLOCK flag if it changed.
638+
if (O_NONBLOCK & (flags ^ s.flags)) {
639+
flags &= ~O_NONBLOCK;
640+
flags |= s.flags & O_NONBLOCK;
641+
642+
int err;
643+
do
644+
err = fcntl(fd, F_SETFL, flags);
645+
while (err == -1 && errno == EINTR); // NOLINT
646+
CHECK_NE(err, -1);
647+
}
648+
649+
if (s.isatty) {
650+
int err;
651+
do
652+
err = tcsetattr(fd, TCSANOW, &s.termios);
653+
while (err == -1 && errno == EINTR); // NOLINT
654+
CHECK_NE(err, -1);
655+
}
656+
}
657+
#endif // __POSIX__
658+
}
659+
660+
579661
int ProcessGlobalArgs(std::vector<std::string>* args,
580662
std::vector<std::string>* exec_args,
581663
std::vector<std::string>* errors,
@@ -831,7 +913,7 @@ void Init(int* argc,
831913
}
832914

833915
InitializationResult InitializeOncePerProcess(int argc, char** argv) {
834-
atexit([] () { uv_tty_reset_mode(); });
916+
atexit(ResetStdio);
835917
PlatformInit();
836918
per_process::node_start_time = uv_hrtime();
837919

‎src/node_errors.cc‎

Lines changed: 1 addition & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -229,7 +229,7 @@ void AppendExceptionLine(Environment* env,
229229
Mutex::ScopedLock lock(per_process::tty_mutex);
230230
env->set_printed_error(true);
231231

232-
uv_tty_reset_mode();
232+
ResetStdio();
233233
PrintErrorString("\n%s", source.c_str());
234234
return;
235235
}

‎src/node_internals.h‎

Lines changed: 1 addition & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -91,6 +91,7 @@ void PrintCaughtException(v8::Isolate* isolate,
9191
const v8::TryCatch& try_catch);
9292

9393
void WaitForInspectorDisconnect(Environment* env);
94+
void ResetStdio(); // Safe to call more than once and from signal handlers.
9495
#ifdef __POSIX__
9596
void SignalExit(int signal, siginfo_t* info, void* ucontext);
9697
#endif

‎src/node_main_instance.cc‎

Lines changed: 1 addition & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -145,7 +145,7 @@ int NodeMainInstance::Run() {
145145

146146
env->set_can_call_into_js(false);
147147
env->stop_sub_worker_contexts();
148-
uv_tty_reset_mode();
148+
ResetStdio();
149149
env->RunCleanup();
150150
RunAtExit(env.get());
151151

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