// Copyright 2009 the V8 project authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#include <errno.h>
#include <fcntl.h>
#include <signal.h>
#include <stdlib.h>
#include <string.h>
#include <sys/stat.h>
#include <sys/time.h>
#include <sys/types.h>
#include <sys/wait.h>
#include <unistd.h>
#include "src/d8.h"
#if !V8_OS_NACL
#include <sys/select.h>
#endif
namespace v8 {
// If the buffer ends in the middle of a UTF-8 sequence then we return
// the length of the string up to but not including the incomplete UTF-8
// sequence. If the buffer ends with a valid UTF-8 sequence then we
// return the whole buffer.
static int LengthWithoutIncompleteUtf8(char* buffer, int len) {
int answer = len;
// 1-byte encoding.
static const int kUtf8SingleByteMask = 0x80;
static const int kUtf8SingleByteValue = 0x00;
// 2-byte encoding.
static const int kUtf8TwoByteMask = 0xe0;
static const int kUtf8TwoByteValue = 0xc0;
// 3-byte encoding.
static const int kUtf8ThreeByteMask = 0xf0;
static const int kUtf8ThreeByteValue = 0xe0;
// 4-byte encoding.
static const int kUtf8FourByteMask = 0xf8;
static const int kUtf8FourByteValue = 0xf0;
// Subsequent bytes of a multi-byte encoding.
static const int kMultiByteMask = 0xc0;
static const int kMultiByteValue = 0x80;
int multi_byte_bytes_seen = 0;
while (answer > 0) {
int c = buffer[answer - 1];
// Ends in valid single-byte sequence?
if ((c & kUtf8SingleByteMask) == kUtf8SingleByteValue) return answer;
// Ends in one or more subsequent bytes of a multi-byte value?
if ((c & kMultiByteMask) == kMultiByteValue) {
multi_byte_bytes_seen++;
answer--;
} else {
if ((c & kUtf8TwoByteMask) == kUtf8TwoByteValue) {
if (multi_byte_bytes_seen >= 1) {
return answer + 2;
}
return answer - 1;
} else if ((c & kUtf8ThreeByteMask) == kUtf8ThreeByteValue) {
if (multi_byte_bytes_seen >= 2) {
return answer + 3;
}
return answer - 1;
} else if ((c & kUtf8FourByteMask) == kUtf8FourByteValue) {
if (multi_byte_bytes_seen >= 3) {
return answer + 4;
}
return answer - 1;
} else {
return answer; // Malformed UTF-8.
}
}
}
return 0;
}
// Suspends the thread until there is data available from the child process.
// Returns false on timeout, true on data ready.
static bool WaitOnFD(int fd,
int read_timeout,
int total_timeout,
const struct timeval& start_time) {
fd_set readfds, writefds, exceptfds;
struct timeval timeout;
int gone = 0;
if (total_timeout != -1) {
struct timeval time_now;
gettimeofday(&time_now, NULL);
int seconds = time_now.tv_sec - start_time.tv_sec;
gone = seconds * 1000 + (time_now.tv_usec - start_time.tv_usec) / 1000;
if (gone >= total_timeout) return false;
}
FD_ZERO(&readfds);
FD_ZERO(&writefds);
FD_ZERO(&exceptfds);
FD_SET(fd, &readfds);
FD_SET(fd, &exceptfds);
if (read_timeout == -1 ||
(total_timeout != -1 && total_timeout - gone < read_timeout)) {
read_timeout = total_timeout - gone;
}
timeout.tv_usec = (read_timeout % 1000) * 1000;
timeout.tv_sec = read_timeout / 1000;
#if V8_OS_NACL
// PNaCL has no support for select.
int number_of_fds_ready = -1;
#else
int number_of_fds_ready = select(fd + 1,
&readfds,
&writefds,
&exceptfds,
read_timeout != -1 ? &timeout : NULL);
#endif
return number_of_fds_ready == 1;
}
// Checks whether we ran out of time on the timeout. Returns true if we ran out
// of time, false if we still have time.
static bool TimeIsOut(const struct timeval& start_time, const int& total_time) {
if (total_time == -1) return false;
struct timeval time_now;
gettimeofday(&time_now, NULL);
// Careful about overflow.
int seconds = time_now.tv_sec - start_time.tv_sec;
if (seconds > 100) {
if (seconds * 1000 > total_time) return true;
return false;
}
int useconds = time_now.tv_usec - start_time.tv_usec;
if (seconds * 1000000 + useconds > total_time * 1000) {
return true;
}
return false;
}
// A utility class that does a non-hanging waitpid on the child process if we
// bail out of the System() function early. If you don't ever do a waitpid on
// a subprocess then it turns into one of those annoying 'zombie processes'.
class ZombieProtector {
public:
explicit ZombieProtector(int pid): pid_(pid) { }
~ZombieProtector() { if (pid_ != 0) waitpid(pid_, NULL, 0); }
void ChildIsDeadNow() { pid_ = 0; }
private:
int pid_;
};
// A utility class that closes a file descriptor when it goes out of scope.
class OpenFDCloser {
public:
explicit OpenFDCloser(int fd): fd_(fd) { }
~OpenFDCloser() { close(fd_); }
private:
int fd_;
};
// A utility class that takes the array of command arguments and puts then in an
// array of new[]ed UTF-8 C strings. Deallocates them again when it goes out of
// scope.
class ExecArgs {
public:
ExecArgs() {
exec_args_[0] = NULL;
}
bool Init(Isolate* isolate, Handle<Value> arg0, Handle<Array> command_args) {
String::Utf8Value prog(arg0);
if (*prog == NULL) {
const char* message =
"os.system(): String conversion of program name failed";
isolate->ThrowException(String::NewFromUtf8(isolate, message));
return false;
}
int len = prog.length() + 3;
char* c_arg = new char[len];
snprintf(c_arg, len, "%s", *prog);
exec_args_[0] = c_arg;
int i = 1;
for (unsigned j = 0; j < command_args->Length(); i++, j++) {
Handle<Value> arg(command_args->Get(Integer::New(isolate, j)));
String::Utf8Value utf8_arg(arg);
if (*utf8_arg == NULL) {
exec_args_[i] = NULL; // Consistent state for destructor.
const char* message =
"os.system(): String conversion of argument failed.";
isolate->ThrowException(String::NewFromUtf8(isolate, message));
return false;
}
int len = utf8_arg.length() + 1;
char* c_arg = new char[len];
snprintf(c_arg, len, "%s", *utf8_arg);
exec_args_[i] = c_arg;
}
exec_args_[i] = NULL;
return true;
}
~ExecArgs() {
for (unsigned i = 0; i < kMaxArgs; i++) {
if (exec_args_[i] == NULL) {
return;
}
delete [] exec_args_[i];
exec_args_[i] = 0;
}
}
static const unsigned kMaxArgs = 1000;
char* const* arg_array() const { return exec_args_; }
const char* arg0() const { return exec_args_[0]; }
private:
char* exec_args_[kMaxArgs + 1];
};
// Gets the optional timeouts from the arguments to the system() call.
static bool GetTimeouts(const v8::FunctionCallbackInfo<v8::Value>& args,
int* read_timeout,
int* total_timeout) {
if (args.Length() > 3) {
if (args[3]->IsNumber()) {
*total_timeout = args[3]->Int32Value();
} else {
args.GetIsolate()->ThrowException(String::NewFromUtf8(
args.GetIsolate(), "system: Argument 4 must be a number"));
return false;
}
}
if (args.Length() > 2) {
if (args[2]->IsNumber()) {
*read_timeout = args[2]->Int32Value();
} else {
args.GetIsolate()->ThrowException(String::NewFromUtf8(
args.GetIsolate(), "system: Argument 3 must be a number"));
return false;
}
}
return true;
}
static const int kReadFD = 0;
static const int kWriteFD = 1;
// This is run in the child process after fork() but before exec(). It normally
// ends with the child process being replaced with the desired child program.
// It only returns if an error occurred.
static void ExecSubprocess(int* exec_error_fds,
int* stdout_fds,
const ExecArgs& exec_args) {
close(exec_error_fds[kReadFD]); // Don't need this in the child.
close(stdout_fds[kReadFD]); // Don't need this in the child.
close(1); // Close stdout.
dup2(stdout_fds[kWriteFD], 1); // Dup pipe fd to stdout.
close(stdout_fds[kWriteFD]); // Don't need the original fd now.
fcntl(exec_error_fds[kWriteFD], F_SETFD, FD_CLOEXEC);
execvp(exec_args.arg0(), exec_args.arg_array());
// Only get here if the exec failed. Write errno to the parent to tell
// them it went wrong. If it went well the pipe is closed.
int err = errno;
int bytes_written;
do {
bytes_written = write(exec_error_fds[kWriteFD], &err, sizeof(err));
} while (bytes_written == -1 && errno == EINTR);
// Return (and exit child process).
}
// Runs in the parent process. Checks that the child was able to exec (closing
// the file desriptor), or reports an error if it failed.
static bool ChildLaunchedOK(Isolate* isolate, int* exec_error_fds) {
int bytes_read;
int err;
do {
bytes_read = read(exec_error_fds[kReadFD], &err, sizeof(err));
} while (bytes_read == -1 && errno == EINTR);
if (bytes_read != 0) {
isolate->ThrowException(String::NewFromUtf8(isolate, strerror(err)));
return false;
}
return true;
}
// Accumulates the output from the child in a string handle. Returns true if it
// succeeded or false if an exception was thrown.
static Handle<Value> GetStdout(Isolate* isolate,
int child_fd,
const struct timeval& start_time,
int read_timeout,
int total_timeout) {
Handle<String> accumulator = String::Empty(isolate);
int fullness = 0;
static const int kStdoutReadBufferSize = 4096;
char buffer[kStdoutReadBufferSize];
if (fcntl(child_fd, F_SETFL, O_NONBLOCK) != 0) {
return isolate->ThrowException(
String::NewFromUtf8(isolate, strerror(errno)));
}
int bytes_read;
do {
bytes_read = read(child_fd,
buffer + fullness,
kStdoutReadBufferSize - fullness);
if (bytes_read == -1) {
if (errno == EAGAIN) {
if (!WaitOnFD(child_fd,
read_timeout,
total_timeout,
start_time) ||
(TimeIsOut(start_time, total_timeout))) {
return isolate->ThrowException(
String::NewFromUtf8(isolate, "Timed out waiting for output"));
}
continue;
} else if (errno == EINTR) {
continue;
} else {
break;
}
}
if (bytes_read + fullness > 0) {
int length = bytes_read == 0 ?
bytes_read + fullness :
LengthWithoutIncompleteUtf8(buffer, bytes_read + fullness);
Handle<String> addition =
String::NewFromUtf8(isolate, buffer, String::kNormalString, length);
accumulator = String::Concat(accumulator, addition);
fullness = bytes_read + fullness - length;
memcpy(buffer, buffer + length, fullness);
}
} while (bytes_read != 0);
return accumulator;
}
// Modern Linux has the waitid call, which is like waitpid, but more useful
// if you want a timeout. If we don't have waitid we can't limit the time
// waiting for the process to exit without losing the information about
// whether it exited normally. In the common case this doesn't matter because
// we don't get here before the child has closed stdout and most programs don't
// do that before they exit.
//
// We're disabling usage of waitid in Mac OS X because it doens't work for us:
// a parent process hangs on waiting while a child process is already a zombie.
// See http://code.google.com/p/v8/issues/detail?id=401.
#if defined(WNOWAIT) && !defined(ANDROID) && !defined(__APPLE__) \
&& !defined(__NetBSD__)
#if !defined(__FreeBSD__)
#define HAS_WAITID 1
#endif
#endif
// Get exit status of child.
static bool WaitForChild(Isolate* isolate,
int pid,
ZombieProtector& child_waiter, // NOLINT
const struct timeval& start_time,
int read_timeout,
int total_timeout) {
#ifdef HAS_WAITID
siginfo_t child_info;
child_info.si_pid = 0;
int useconds = 1;
// Wait for child to exit.
while (child_info.si_pid == 0) {
waitid(P_PID, pid, &child_info, WEXITED | WNOHANG | WNOWAIT);
usleep(useconds);
if (useconds < 1000000) useconds <<= 1;
if ((read_timeout != -1 && useconds / 1000 > read_timeout) ||
(TimeIsOut(start_time, total_timeout))) {
isolate->ThrowException(String::NewFromUtf8(
isolate, "Timed out waiting for process to terminate"));
kill(pid, SIGINT);
return false;
}
}
if (child_info.si_code == CLD_KILLED) {
char message[999];
snprintf(message,
sizeof(message),
"Child killed by signal %d",
child_info.si_status);
isolate->ThrowException(String::NewFromUtf8(isolate, message));
return false;
}
if (child_info.si_code == CLD_EXITED && child_info.si_status != 0) {
char message[999];
snprintf(message,
sizeof(message),
"Child exited with status %d",
child_info.si_status);
isolate->ThrowException(String::NewFromUtf8(isolate, message));
return false;
}
#else // No waitid call.
int child_status;
waitpid(pid, &child_status, 0); // We hang here if the child doesn't exit.
child_waiter.ChildIsDeadNow();
if (WIFSIGNALED(child_status)) {
char message[999];
snprintf(message,
sizeof(message),
"Child killed by signal %d",
WTERMSIG(child_status));
isolate->ThrowException(String::NewFromUtf8(isolate, message));
return false;
}
if (WEXITSTATUS(child_status) != 0) {
char message[999];
int exit_status = WEXITSTATUS(child_status);
snprintf(message,
sizeof(message),
"Child exited with status %d",
exit_status);
isolate->ThrowException(String::NewFromUtf8(isolate, message));
return false;
}
#endif // No waitid call.
return true;
}
// Implementation of the system() function (see d8.h for details).
void Shell::System(const v8::FunctionCallbackInfo<v8::Value>& args) {
HandleScope scope(args.GetIsolate());
int read_timeout = -1;
int total_timeout = -1;
if (!GetTimeouts(args, &read_timeout, &total_timeout)) return;
Handle<Array> command_args;
if (args.Length() > 1) {
if (!args[1]->IsArray()) {
args.GetIsolate()->ThrowException(String::NewFromUtf8(
args.GetIsolate(), "system: Argument 2 must be an array"));
return;
}
command_args = Handle<Array>::Cast(args[1]);
} else {
command_args = Array::New(args.GetIsolate(), 0);
}
if (command_args->Length() > ExecArgs::kMaxArgs) {
args.GetIsolate()->ThrowException(String::NewFromUtf8(
args.GetIsolate(), "Too many arguments to system()"));
return;
}
if (args.Length() < 1) {
args.GetIsolate()->ThrowException(String::NewFromUtf8(
args.GetIsolate(), "Too few arguments to system()"));
return;
}
struct timeval start_time;
gettimeofday(&start_time, NULL);
ExecArgs exec_args;
if (!exec_args.Init(args.GetIsolate(), args[0], command_args)) {
return;
}
int exec_error_fds[2];
int stdout_fds[2];
if (pipe(exec_error_fds) != 0) {
args.GetIsolate()->ThrowException(
String::NewFromUtf8(args.GetIsolate(), "pipe syscall failed."));
return;
}
if (pipe(stdout_fds) != 0) {
args.GetIsolate()->ThrowException(
String::NewFromUtf8(args.GetIsolate(), "pipe syscall failed."));
return;
}
pid_t pid = fork();
if (pid == 0) { // Child process.
ExecSubprocess(exec_error_fds, stdout_fds, exec_args);
exit(1);
}
// Parent process. Ensure that we clean up if we exit this function early.
ZombieProtector child_waiter(pid);
close(exec_error_fds[kWriteFD]);
close(stdout_fds[kWriteFD]);
OpenFDCloser error_read_closer(exec_error_fds[kReadFD]);
OpenFDCloser stdout_read_closer(stdout_fds[kReadFD]);
if (!ChildLaunchedOK(args.GetIsolate(), exec_error_fds)) return;
Handle<Value> accumulator = GetStdout(args.GetIsolate(),
stdout_fds[kReadFD],
start_time,
read_timeout,
total_timeout);
if (accumulator->IsUndefined()) {
kill(pid, SIGINT); // On timeout, kill the subprocess.
args.GetReturnValue().Set(accumulator);
return;
}
if (!WaitForChild(args.GetIsolate(),
pid,
child_waiter,
start_time,
read_timeout,
total_timeout)) {
return;
}
args.GetReturnValue().Set(accumulator);
}
void Shell::ChangeDirectory(const v8::FunctionCallbackInfo<v8::Value>& args) {
if (args.Length() != 1) {
const char* message = "chdir() takes one argument";
args.GetIsolate()->ThrowException(
String::NewFromUtf8(args.GetIsolate(), message));
return;
}
String::Utf8Value directory(args[0]);
if (*directory == NULL) {
const char* message = "os.chdir(): String conversion of argument failed.";
args.GetIsolate()->ThrowException(
String::NewFromUtf8(args.GetIsolate(), message));
return;
}
if (chdir(*directory) != 0) {
args.GetIsolate()->ThrowException(
String::NewFromUtf8(args.GetIsolate(), strerror(errno)));
return;
}
}
void Shell::SetUMask(const v8::FunctionCallbackInfo<v8::Value>& args) {
if (args.Length() != 1) {
const char* message = "umask() takes one argument";
args.GetIsolate()->ThrowException(
String::NewFromUtf8(args.GetIsolate(), message));
return;
}
if (args[0]->IsNumber()) {
#if V8_OS_NACL
// PNaCL has no support for umask.
int previous = 0;
#else
int previous = umask(args[0]->Int32Value());
#endif
args.GetReturnValue().Set(previous);
return;
} else {
const char* message = "umask() argument must be numeric";
args.GetIsolate()->ThrowException(
String::NewFromUtf8(args.GetIsolate(), message));
return;
}
}
static bool CheckItsADirectory(Isolate* isolate, char* directory) {
struct stat stat_buf;
int stat_result = stat(directory, &stat_buf);
if (stat_result != 0) {
isolate->ThrowException(String::NewFromUtf8(isolate, strerror(errno)));
return false;
}
if ((stat_buf.st_mode & S_IFDIR) != 0) return true;
isolate->ThrowException(String::NewFromUtf8(isolate, strerror(EEXIST)));
return false;
}
// Returns true for success. Creates intermediate directories as needed. No
// error if the directory exists already.
static bool mkdirp(Isolate* isolate, char* directory, mode_t mask) {
int result = mkdir(directory, mask);
if (result == 0) return true;
if (errno == EEXIST) {
return CheckItsADirectory(isolate, directory);
} else if (errno == ENOENT) { // Intermediate path element is missing.
char* last_slash = strrchr(directory, '/');
if (last_slash == NULL) {
isolate->ThrowException(String::NewFromUtf8(isolate, strerror(errno)));
return false;
}
*last_slash = 0;
if (!mkdirp(isolate, directory, mask)) return false;
*last_slash = '/';
result = mkdir(directory, mask);
if (result == 0) return true;
if (errno == EEXIST) {
return CheckItsADirectory(isolate, directory);
}
isolate->ThrowException(String::NewFromUtf8(isolate, strerror(errno)));
return false;
} else {
isolate->ThrowException(String::NewFromUtf8(isolate, strerror(errno)));
return false;
}
}
void Shell::MakeDirectory(const v8::FunctionCallbackInfo<v8::Value>& args) {
mode_t mask = 0777;
if (args.Length() == 2) {
if (args[1]->IsNumber()) {
mask = args[1]->Int32Value();
} else {
const char* message = "mkdirp() second argument must be numeric";
args.GetIsolate()->ThrowException(
String::NewFromUtf8(args.GetIsolate(), message));
return;
}
} else if (args.Length() != 1) {
const char* message = "mkdirp() takes one or two arguments";
args.GetIsolate()->ThrowException(
String::NewFromUtf8(args.GetIsolate(), message));
return;
}
String::Utf8Value directory(args[0]);
if (*directory == NULL) {
const char* message = "os.mkdirp(): String conversion of argument failed.";
args.GetIsolate()->ThrowException(
String::NewFromUtf8(args.GetIsolate(), message));
return;
}
mkdirp(args.GetIsolate(), *directory, mask);
}
void Shell::RemoveDirectory(const v8::FunctionCallbackInfo<v8::Value>& args) {
if (args.Length() != 1) {
const char* message = "rmdir() takes one or two arguments";
args.GetIsolate()->ThrowException(
String::NewFromUtf8(args.GetIsolate(), message));
return;
}
String::Utf8Value directory(args[0]);
if (*directory == NULL) {
const char* message = "os.rmdir(): String conversion of argument failed.";
args.GetIsolate()->ThrowException(
String::NewFromUtf8(args.GetIsolate(), message));
return;
}
rmdir(*directory);
}
void Shell::SetEnvironment(const v8::FunctionCallbackInfo<v8::Value>& args) {
if (args.Length() != 2) {
const char* message = "setenv() takes two arguments";
args.GetIsolate()->ThrowException(
String::NewFromUtf8(args.GetIsolate(), message));
return;
}
String::Utf8Value var(args[0]);
String::Utf8Value value(args[1]);
if (*var == NULL) {
const char* message =
"os.setenv(): String conversion of variable name failed.";
args.GetIsolate()->ThrowException(
String::NewFromUtf8(args.GetIsolate(), message));
return;
}
if (*value == NULL) {
const char* message =
"os.setenv(): String conversion of variable contents failed.";
args.GetIsolate()->ThrowException(
String::NewFromUtf8(args.GetIsolate(), message));
return;
}
setenv(*var, *value, 1);
}
void Shell::UnsetEnvironment(const v8::FunctionCallbackInfo<v8::Value>& args) {
if (args.Length() != 1) {
const char* message = "unsetenv() takes one argument";
args.GetIsolate()->ThrowException(
String::NewFromUtf8(args.GetIsolate(), message));
return;
}
String::Utf8Value var(args[0]);
if (*var == NULL) {
const char* message =
"os.setenv(): String conversion of variable name failed.";
args.GetIsolate()->ThrowException(
String::NewFromUtf8(args.GetIsolate(), message));
return;
}
unsetenv(*var);
}
void Shell::AddOSMethods(Isolate* isolate, Handle<ObjectTemplate> os_templ) {
os_templ->Set(String::NewFromUtf8(isolate, "system"),
FunctionTemplate::New(isolate, System));
os_templ->Set(String::NewFromUtf8(isolate, "chdir"),
FunctionTemplate::New(isolate, ChangeDirectory));
os_templ->Set(String::NewFromUtf8(isolate, "setenv"),
FunctionTemplate::New(isolate, SetEnvironment));
os_templ->Set(String::NewFromUtf8(isolate, "unsetenv"),
FunctionTemplate::New(isolate, UnsetEnvironment));
os_templ->Set(String::NewFromUtf8(isolate, "umask"),
FunctionTemplate::New(isolate, SetUMask));
os_templ->Set(String::NewFromUtf8(isolate, "mkdirp"),
FunctionTemplate::New(isolate, MakeDirectory));
os_templ->Set(String::NewFromUtf8(isolate, "rmdir"),
FunctionTemplate::New(isolate, RemoveDirectory));
}
} // namespace v8