Current File : /home/vacivi36/vittasync.vacivitta.com.br/vittasync/node/deps/uv/src/unix/process.c
/* Copyright Joyent, Inc. and other Node contributors. All rights reserved.
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to
* deal in the Software without restriction, including without limitation the
* rights to use, copy, modify, merge, publish, distribute, sublicense, and/or
* sell copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in
* all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
* FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
* IN THE SOFTWARE.
*/
#include "uv.h"
#include "internal.h"
#include <stdio.h>
#include <stdlib.h>
#include <assert.h>
#include <errno.h>
#include <signal.h>
#include <string.h>
#include <sys/types.h>
#include <sys/wait.h>
#include <unistd.h>
#include <fcntl.h>
#include <poll.h>
#if defined(__APPLE__)
# include <spawn.h>
# include <paths.h>
# include <sys/kauth.h>
# include <sys/types.h>
# include <sys/sysctl.h>
# include <dlfcn.h>
# include <crt_externs.h>
# include <xlocale.h>
# define environ (*_NSGetEnviron())
/* macOS 10.14 back does not define this constant */
# ifndef POSIX_SPAWN_SETSID
# define POSIX_SPAWN_SETSID 1024
# endif
#else
extern char **environ;
#endif
#if defined(__linux__)
# include <grp.h>
#endif
#if defined(__MVS__)
# include "zos-base.h"
#endif
#if defined(__APPLE__) || \
defined(__DragonFly__) || \
defined(__FreeBSD__) || \
defined(__NetBSD__) || \
defined(__OpenBSD__)
#include <sys/event.h>
#else
#define UV_USE_SIGCHLD
#endif
#ifdef UV_USE_SIGCHLD
static void uv__chld(uv_signal_t* handle, int signum) {
assert(signum == SIGCHLD);
uv__wait_children(handle->loop);
}
int uv__process_init(uv_loop_t* loop) {
int err;
err = uv_signal_init(loop, &loop->child_watcher);
if (err)
return err;
uv__handle_unref(&loop->child_watcher);
loop->child_watcher.flags |= UV_HANDLE_INTERNAL;
return 0;
}
#else
int uv__process_init(uv_loop_t* loop) {
memset(&loop->child_watcher, 0, sizeof(loop->child_watcher));
return 0;
}
#endif
void uv__wait_children(uv_loop_t* loop) {
uv_process_t* process;
int exit_status;
int term_signal;
int status;
int options;
pid_t pid;
struct uv__queue pending;
struct uv__queue* q;
struct uv__queue* h;
uv__queue_init(&pending);
h = &loop->process_handles;
q = uv__queue_head(h);
while (q != h) {
process = uv__queue_data(q, uv_process_t, queue);
q = uv__queue_next(q);
#ifndef UV_USE_SIGCHLD
if ((process->flags & UV_HANDLE_REAP) == 0)
continue;
options = 0;
process->flags &= ~UV_HANDLE_REAP;
loop->nfds--;
#else
options = WNOHANG;
#endif
do
pid = waitpid(process->pid, &status, options);
while (pid == -1 && errno == EINTR);
#ifdef UV_USE_SIGCHLD
if (pid == 0) /* Not yet exited */
continue;
#endif
if (pid == -1) {
if (errno != ECHILD)
abort();
/* The child died, and we missed it. This probably means someone else
* stole the waitpid from us. Handle this by not handling it at all. */
continue;
}
assert(pid == process->pid);
process->status = status;
uv__queue_remove(&process->queue);
uv__queue_insert_tail(&pending, &process->queue);
}
h = &pending;
q = uv__queue_head(h);
while (q != h) {
process = uv__queue_data(q, uv_process_t, queue);
q = uv__queue_next(q);
uv__queue_remove(&process->queue);
uv__queue_init(&process->queue);
uv__handle_stop(process);
if (process->exit_cb == NULL)
continue;
exit_status = 0;
if (WIFEXITED(process->status))
exit_status = WEXITSTATUS(process->status);
term_signal = 0;
if (WIFSIGNALED(process->status))
term_signal = WTERMSIG(process->status);
process->exit_cb(process, exit_status, term_signal);
}
assert(uv__queue_empty(&pending));
}
/*
* Used for initializing stdio streams like options.stdin_stream. Returns
* zero on success. See also the cleanup section in uv_spawn().
*/
#if !(defined(__APPLE__) && (TARGET_OS_TV || TARGET_OS_WATCH))
/* execvp is marked __WATCHOS_PROHIBITED __TVOS_PROHIBITED, so must be
* avoided. Since this isn't called on those targets, the function
* doesn't even need to be defined for them.
*/
static int uv__process_init_stdio(uv_stdio_container_t* container, int fds[2]) {
int mask;
int fd;
mask = UV_IGNORE | UV_CREATE_PIPE | UV_INHERIT_FD | UV_INHERIT_STREAM;
switch (container->flags & mask) {
case UV_IGNORE:
return 0;
case UV_CREATE_PIPE:
assert(container->data.stream != NULL);
if (container->data.stream->type != UV_NAMED_PIPE)
return UV_EINVAL;
else
return uv_socketpair(SOCK_STREAM, 0, fds, 0, 0);
case UV_INHERIT_FD:
case UV_INHERIT_STREAM:
if (container->flags & UV_INHERIT_FD)
fd = container->data.fd;
else
fd = uv__stream_fd(container->data.stream);
if (fd == -1)
return UV_EINVAL;
fds[1] = fd;
return 0;
default:
assert(0 && "Unexpected flags");
return UV_EINVAL;
}
}
static int uv__process_open_stream(uv_stdio_container_t* container,
int pipefds[2]) {
int flags;
int err;
if (!(container->flags & UV_CREATE_PIPE) || pipefds[0] < 0)
return 0;
err = uv__close(pipefds[1]);
if (err != 0)
abort();
pipefds[1] = -1;
uv__nonblock(pipefds[0], 1);
flags = 0;
if (container->flags & UV_WRITABLE_PIPE)
flags |= UV_HANDLE_READABLE;
if (container->flags & UV_READABLE_PIPE)
flags |= UV_HANDLE_WRITABLE;
return uv__stream_open(container->data.stream, pipefds[0], flags);
}
static void uv__process_close_stream(uv_stdio_container_t* container) {
if (!(container->flags & UV_CREATE_PIPE)) return;
uv__stream_close(container->data.stream);
}
static void uv__write_int(int fd, int val) {
ssize_t n;
do
n = write(fd, &val, sizeof(val));
while (n == -1 && errno == EINTR);
/* The write might have failed (e.g. if the parent process has died),
* but we have nothing left but to _exit ourself now too. */
_exit(127);
}
static void uv__write_errno(int error_fd) {
uv__write_int(error_fd, UV__ERR(errno));
}
static void uv__process_child_init(const uv_process_options_t* options,
int stdio_count,
int (*pipes)[2],
int error_fd) {
sigset_t signewset;
int close_fd;
int use_fd;
int fd;
int n;
/* Reset signal disposition first. Use a hard-coded limit because NSIG is not
* fixed on Linux: it's either 32, 34 or 64, depending on whether RT signals
* are enabled. We are not allowed to touch RT signal handlers, glibc uses
* them internally.
*/
for (n = 1; n < 32; n += 1) {
if (n == SIGKILL || n == SIGSTOP)
continue; /* Can't be changed. */
#if defined(__HAIKU__)
if (n == SIGKILLTHR)
continue; /* Can't be changed. */
#endif
if (SIG_ERR != signal(n, SIG_DFL))
continue;
uv__write_errno(error_fd);
}
if (options->flags & UV_PROCESS_DETACHED)
setsid();
/* First duplicate low numbered fds, since it's not safe to duplicate them,
* they could get replaced. Example: swapping stdout and stderr; without
* this fd 2 (stderr) would be duplicated into fd 1, thus making both
* stdout and stderr go to the same fd, which was not the intention. */
for (fd = 0; fd < stdio_count; fd++) {
use_fd = pipes[fd][1];
if (use_fd < 0 || use_fd >= fd)
continue;
#ifdef F_DUPFD_CLOEXEC /* POSIX 2008 */
pipes[fd][1] = fcntl(use_fd, F_DUPFD_CLOEXEC, stdio_count);
#else
pipes[fd][1] = fcntl(use_fd, F_DUPFD, stdio_count);
#endif
if (pipes[fd][1] == -1)
uv__write_errno(error_fd);
#ifndef F_DUPFD_CLOEXEC /* POSIX 2008 */
n = uv__cloexec(pipes[fd][1], 1);
if (n)
uv__write_int(error_fd, n);
#endif
}
for (fd = 0; fd < stdio_count; fd++) {
close_fd = -1;
use_fd = pipes[fd][1];
if (use_fd < 0) {
if (fd >= 3)
continue;
else {
/* Redirect stdin, stdout and stderr to /dev/null even if UV_IGNORE is
* set. */
uv__close_nocheckstdio(fd); /* Free up fd, if it happens to be open. */
use_fd = open("/dev/null", fd == 0 ? O_RDONLY : O_RDWR);
close_fd = use_fd;
if (use_fd < 0)
uv__write_errno(error_fd);
}
}
if (fd == use_fd) {
if (close_fd == -1) {
n = uv__cloexec(use_fd, 0);
if (n)
uv__write_int(error_fd, n);
}
}
else {
fd = dup2(use_fd, fd);
}
if (fd == -1)
uv__write_errno(error_fd);
if (fd <= 2 && close_fd == -1)
uv__nonblock_fcntl(fd, 0);
if (close_fd >= stdio_count)
uv__close(close_fd);
}
if (options->cwd != NULL && chdir(options->cwd))
uv__write_errno(error_fd);
if (options->flags & (UV_PROCESS_SETUID | UV_PROCESS_SETGID)) {
/* When dropping privileges from root, the `setgroups` call will
* remove any extraneous groups. If we don't call this, then
* even though our uid has dropped, we may still have groups
* that enable us to do super-user things. This will fail if we
* aren't root, so don't bother checking the return value, this
* is just done as an optimistic privilege dropping function.
*/
SAVE_ERRNO(setgroups(0, NULL));
}
if ((options->flags & UV_PROCESS_SETGID) && setgid(options->gid))
uv__write_errno(error_fd);
if ((options->flags & UV_PROCESS_SETUID) && setuid(options->uid))
uv__write_errno(error_fd);
if (options->env != NULL)
environ = options->env;
/* Reset signal mask just before exec. */
sigemptyset(&signewset);
if (sigprocmask(SIG_SETMASK, &signewset, NULL) != 0)
abort();
#ifdef __MVS__
execvpe(options->file, options->args, environ);
#else
execvp(options->file, options->args);
#endif
uv__write_errno(error_fd);
}
#if defined(__APPLE__)
typedef struct uv__posix_spawn_fncs_tag {
struct {
int (*addchdir_np)(const posix_spawn_file_actions_t *, const char *);
} file_actions;
} uv__posix_spawn_fncs_t;
static uv_once_t posix_spawn_init_once = UV_ONCE_INIT;
static uv__posix_spawn_fncs_t posix_spawn_fncs;
static int posix_spawn_can_use_setsid;
static void uv__spawn_init_posix_spawn_fncs(void) {
/* Try to locate all non-portable functions at runtime */
posix_spawn_fncs.file_actions.addchdir_np =
dlsym(RTLD_DEFAULT, "posix_spawn_file_actions_addchdir_np");
}
static void uv__spawn_init_can_use_setsid(void) {
int which[] = {CTL_KERN, KERN_OSRELEASE};
unsigned major;
unsigned minor;
unsigned patch;
char buf[256];
size_t len;
len = sizeof(buf);
if (sysctl(which, ARRAY_SIZE(which), buf, &len, NULL, 0))
return;
/* NULL specifies to use LC_C_LOCALE */
if (3 != sscanf_l(buf, NULL, "%u.%u.%u", &major, &minor, &patch))
return;
posix_spawn_can_use_setsid = (major >= 19); /* macOS Catalina */
}
static void uv__spawn_init_posix_spawn(void) {
/* Init handles to all potentially non-defined functions */
uv__spawn_init_posix_spawn_fncs();
/* Init feature detection for POSIX_SPAWN_SETSID flag */
uv__spawn_init_can_use_setsid();
}
static int uv__spawn_set_posix_spawn_attrs(
posix_spawnattr_t* attrs,
const uv__posix_spawn_fncs_t* posix_spawn_fncs,
const uv_process_options_t* options) {
int err;
unsigned int flags;
sigset_t signal_set;
err = posix_spawnattr_init(attrs);
if (err != 0) {
/* If initialization fails, no need to de-init, just return */
return err;
}
if (options->flags & (UV_PROCESS_SETUID | UV_PROCESS_SETGID)) {
/* kauth_cred_issuser currently requires exactly uid == 0 for these
* posixspawn_attrs (set_groups_np, setuid_np, setgid_np), which deviates
* from the normal specification of setuid (which also uses euid), and they
* are also undocumented syscalls, so we do not use them. */
err = ENOSYS;
goto error;
}
/* Set flags for spawn behavior
* 1) POSIX_SPAWN_CLOEXEC_DEFAULT: (Apple Extension) All descriptors in the
* parent will be treated as if they had been created with O_CLOEXEC. The
* only fds that will be passed on to the child are those manipulated by
* the file actions
* 2) POSIX_SPAWN_SETSIGDEF: Signals mentioned in spawn-sigdefault in the
* spawn attributes will be reset to behave as their default
* 3) POSIX_SPAWN_SETSIGMASK: Signal mask will be set to the value of
* spawn-sigmask in attributes
* 4) POSIX_SPAWN_SETSID: Make the process a new session leader if a detached
* session was requested. */
flags = POSIX_SPAWN_CLOEXEC_DEFAULT |
POSIX_SPAWN_SETSIGDEF |
POSIX_SPAWN_SETSIGMASK;
if (options->flags & UV_PROCESS_DETACHED) {
/* If running on a version of macOS where this flag is not supported,
* revert back to the fork/exec flow. Otherwise posix_spawn will
* silently ignore the flag. */
if (!posix_spawn_can_use_setsid) {
err = ENOSYS;
goto error;
}
flags |= POSIX_SPAWN_SETSID;
}
err = posix_spawnattr_setflags(attrs, flags);
if (err != 0)
goto error;
/* Reset all signal the child to their default behavior */
sigfillset(&signal_set);
err = posix_spawnattr_setsigdefault(attrs, &signal_set);
if (err != 0)
goto error;
/* Reset the signal mask for all signals */
sigemptyset(&signal_set);
err = posix_spawnattr_setsigmask(attrs, &signal_set);
if (err != 0)
goto error;
return err;
error:
(void) posix_spawnattr_destroy(attrs);
return err;
}
static int uv__spawn_set_posix_spawn_file_actions(
posix_spawn_file_actions_t* actions,
const uv__posix_spawn_fncs_t* posix_spawn_fncs,
const uv_process_options_t* options,
int stdio_count,
int (*pipes)[2]) {
int fd;
int fd2;
int use_fd;
int err;
err = posix_spawn_file_actions_init(actions);
if (err != 0) {
/* If initialization fails, no need to de-init, just return */
return err;
}
/* Set the current working directory if requested */
if (options->cwd != NULL) {
if (posix_spawn_fncs->file_actions.addchdir_np == NULL) {
err = ENOSYS;
goto error;
}
err = posix_spawn_fncs->file_actions.addchdir_np(actions, options->cwd);
if (err != 0)
goto error;
}
/* Do not return ENOSYS after this point, as we may mutate pipes. */
/* First duplicate low numbered fds, since it's not safe to duplicate them,
* they could get replaced. Example: swapping stdout and stderr; without
* this fd 2 (stderr) would be duplicated into fd 1, thus making both
* stdout and stderr go to the same fd, which was not the intention. */
for (fd = 0; fd < stdio_count; fd++) {
use_fd = pipes[fd][1];
if (use_fd < 0 || use_fd >= fd)
continue;
use_fd = stdio_count;
for (fd2 = 0; fd2 < stdio_count; fd2++) {
/* If we were not setting POSIX_SPAWN_CLOEXEC_DEFAULT, we would need to
* also consider whether fcntl(fd, F_GETFD) returned without the
* FD_CLOEXEC flag set. */
if (pipes[fd2][1] == use_fd) {
use_fd++;
fd2 = 0;
}
}
err = posix_spawn_file_actions_adddup2(
actions,
pipes[fd][1],
use_fd);
assert(err != ENOSYS);
if (err != 0)
goto error;
pipes[fd][1] = use_fd;
}
/* Second, move the descriptors into their respective places */
for (fd = 0; fd < stdio_count; fd++) {
use_fd = pipes[fd][1];
if (use_fd < 0) {
if (fd >= 3)
continue;
else {
/* If ignored, redirect to (or from) /dev/null, */
err = posix_spawn_file_actions_addopen(
actions,
fd,
"/dev/null",
fd == 0 ? O_RDONLY : O_RDWR,
0);
assert(err != ENOSYS);
if (err != 0)
goto error;
continue;
}
}
if (fd == use_fd)
err = posix_spawn_file_actions_addinherit_np(actions, fd);
else
err = posix_spawn_file_actions_adddup2(actions, use_fd, fd);
assert(err != ENOSYS);
if (err != 0)
goto error;
/* Make sure the fd is marked as non-blocking (state shared between child
* and parent). */
uv__nonblock_fcntl(use_fd, 0);
}
/* Finally, close all the superfluous descriptors */
for (fd = 0; fd < stdio_count; fd++) {
use_fd = pipes[fd][1];
if (use_fd < stdio_count)
continue;
/* Check if we already closed this. */
for (fd2 = 0; fd2 < fd; fd2++) {
if (pipes[fd2][1] == use_fd)
break;
}
if (fd2 < fd)
continue;
err = posix_spawn_file_actions_addclose(actions, use_fd);
assert(err != ENOSYS);
if (err != 0)
goto error;
}
return 0;
error:
(void) posix_spawn_file_actions_destroy(actions);
return err;
}
char* uv__spawn_find_path_in_env(char** env) {
char** env_iterator;
const char path_var[] = "PATH=";
/* Look for an environment variable called PATH in the
* provided env array, and return its value if found */
for (env_iterator = env; *env_iterator != NULL; env_iterator++) {
if (strncmp(*env_iterator, path_var, sizeof(path_var) - 1) == 0) {
/* Found "PATH=" at the beginning of the string */
return *env_iterator + sizeof(path_var) - 1;
}
}
return NULL;
}
static int uv__spawn_resolve_and_spawn(const uv_process_options_t* options,
posix_spawnattr_t* attrs,
posix_spawn_file_actions_t* actions,
pid_t* pid) {
const char *p;
const char *z;
const char *path;
size_t l;
size_t k;
int err;
int seen_eacces;
path = NULL;
err = -1;
seen_eacces = 0;
/* Short circuit for erroneous case */
if (options->file == NULL)
return ENOENT;
/* The environment for the child process is that of the parent unless overridden
* by options->env */
char** env = environ;
if (options->env != NULL)
env = options->env;
/* If options->file contains a slash, posix_spawn/posix_spawnp should behave
* the same, and do not involve PATH resolution at all. The libc
* `posix_spawnp` provided by Apple is buggy (since 10.15), so we now emulate it
* here, per https://github.com/libuv/libuv/pull/3583. */
if (strchr(options->file, '/') != NULL) {
do
err = posix_spawn(pid, options->file, actions, attrs, options->args, env);
while (err == EINTR);
return err;
}
/* Look for the definition of PATH in the provided env */
path = uv__spawn_find_path_in_env(env);
/* The following resolution logic (execvpe emulation) is copied from
* https://git.musl-libc.org/cgit/musl/tree/src/process/execvp.c
* and adapted to work for our specific usage */
/* If no path was provided in env, use the default value
* to look for the executable */
if (path == NULL)
path = _PATH_DEFPATH;
k = strnlen(options->file, NAME_MAX + 1);
if (k > NAME_MAX)
return ENAMETOOLONG;
l = strnlen(path, PATH_MAX - 1) + 1;
for (p = path;; p = z) {
/* Compose the new process file from the entry in the PATH
* environment variable and the actual file name */
char b[PATH_MAX + NAME_MAX];
z = strchr(p, ':');
if (!z)
z = p + strlen(p);
if ((size_t)(z - p) >= l) {
if (!*z++)
break;
continue;
}
memcpy(b, p, z - p);
b[z - p] = '/';
memcpy(b + (z - p) + (z > p), options->file, k + 1);
/* Try to spawn the new process file. If it fails with ENOENT, the
* new process file is not in this PATH entry, continue with the next
* PATH entry. */
do
err = posix_spawn(pid, b, actions, attrs, options->args, env);
while (err == EINTR);
switch (err) {
case EACCES:
seen_eacces = 1;
break; /* continue search */
case ENOENT:
case ENOTDIR:
break; /* continue search */
default:
return err;
}
if (!*z++)
break;
}
if (seen_eacces)
return EACCES;
return err;
}
static int uv__spawn_and_init_child_posix_spawn(
const uv_process_options_t* options,
int stdio_count,
int (*pipes)[2],
pid_t* pid,
const uv__posix_spawn_fncs_t* posix_spawn_fncs) {
int err;
posix_spawnattr_t attrs;
posix_spawn_file_actions_t actions;
err = uv__spawn_set_posix_spawn_attrs(&attrs, posix_spawn_fncs, options);
if (err != 0)
goto error;
/* This may mutate pipes. */
err = uv__spawn_set_posix_spawn_file_actions(&actions,
posix_spawn_fncs,
options,
stdio_count,
pipes);
if (err != 0) {
(void) posix_spawnattr_destroy(&attrs);
goto error;
}
/* Try to spawn options->file resolving in the provided environment
* if any */
err = uv__spawn_resolve_and_spawn(options, &attrs, &actions, pid);
assert(err != ENOSYS);
/* Destroy the actions/attributes */
(void) posix_spawn_file_actions_destroy(&actions);
(void) posix_spawnattr_destroy(&attrs);
error:
/* In an error situation, the attributes and file actions are
* already destroyed, only the happy path requires cleanup */
return UV__ERR(err);
}
#endif
static int uv__spawn_and_init_child_fork(const uv_process_options_t* options,
int stdio_count,
int (*pipes)[2],
int error_fd,
pid_t* pid) {
sigset_t signewset;
sigset_t sigoldset;
/* Start the child with most signals blocked, to avoid any issues before we
* can reset them, but allow program failures to exit (and not hang). */
sigfillset(&signewset);
sigdelset(&signewset, SIGKILL);
sigdelset(&signewset, SIGSTOP);
sigdelset(&signewset, SIGTRAP);
sigdelset(&signewset, SIGSEGV);
sigdelset(&signewset, SIGBUS);
sigdelset(&signewset, SIGILL);
sigdelset(&signewset, SIGSYS);
sigdelset(&signewset, SIGABRT);
if (pthread_sigmask(SIG_BLOCK, &signewset, &sigoldset) != 0)
abort();
*pid = fork();
if (*pid == 0) {
/* Fork succeeded, in the child process */
uv__process_child_init(options, stdio_count, pipes, error_fd);
abort();
}
if (pthread_sigmask(SIG_SETMASK, &sigoldset, NULL) != 0)
abort();
if (*pid == -1)
/* Failed to fork */
return UV__ERR(errno);
/* Fork succeeded, in the parent process */
return 0;
}
static int uv__spawn_and_init_child(
uv_loop_t* loop,
const uv_process_options_t* options,
int stdio_count,
int (*pipes)[2],
pid_t* pid) {
int signal_pipe[2] = { -1, -1 };
int status;
int err;
int exec_errorno;
ssize_t r;
#if defined(__APPLE__)
uv_once(&posix_spawn_init_once, uv__spawn_init_posix_spawn);
/* Special child process spawn case for macOS Big Sur (11.0) onwards
*
* Big Sur introduced a significant performance degradation on a call to
* fork/exec when the process has many pages mmaped in with MAP_JIT, like, say
* a javascript interpreter. Electron-based applications, for example,
* are impacted; though the magnitude of the impact depends on how much the
* app relies on subprocesses.
*
* On macOS, though, posix_spawn is implemented in a way that does not
* exhibit the problem. This block implements the forking and preparation
* logic with posix_spawn and its related primitives. It also takes advantage of
* the macOS extension POSIX_SPAWN_CLOEXEC_DEFAULT that makes impossible to
* leak descriptors to the child process. */
err = uv__spawn_and_init_child_posix_spawn(options,
stdio_count,
pipes,
pid,
&posix_spawn_fncs);
/* The posix_spawn flow will return UV_ENOSYS if any of the posix_spawn_x_np
* non-standard functions is both _needed_ and _undefined_. In those cases,
* default back to the fork/execve strategy. For all other errors, just fail. */
if (err != UV_ENOSYS)
return err;
#endif
/* This pipe is used by the parent to wait until
* the child has called `execve()`. We need this
* to avoid the following race condition:
*
* if ((pid = fork()) > 0) {
* kill(pid, SIGTERM);
* }
* else if (pid == 0) {
* execve("/bin/cat", argp, envp);
* }
*
* The parent sends a signal immediately after forking.
* Since the child may not have called `execve()` yet,
* there is no telling what process receives the signal,
* our fork or /bin/cat.
*
* To avoid ambiguity, we create a pipe with both ends
* marked close-on-exec. Then, after the call to `fork()`,
* the parent polls the read end until it EOFs or errors with EPIPE.
*/
err = uv__make_pipe(signal_pipe, 0);
if (err)
return err;
/* Acquire write lock to prevent opening new fds in worker threads */
uv_rwlock_wrlock(&loop->cloexec_lock);
err = uv__spawn_and_init_child_fork(options, stdio_count, pipes, signal_pipe[1], pid);
/* Release lock in parent process */
uv_rwlock_wrunlock(&loop->cloexec_lock);
uv__close(signal_pipe[1]);
if (err == 0) {
do
r = read(signal_pipe[0], &exec_errorno, sizeof(exec_errorno));
while (r == -1 && errno == EINTR);
if (r == 0)
; /* okay, EOF */
else if (r == sizeof(exec_errorno)) {
do
err = waitpid(*pid, &status, 0); /* okay, read errorno */
while (err == -1 && errno == EINTR);
assert(err == *pid);
err = exec_errorno;
} else if (r == -1 && errno == EPIPE) {
/* Something unknown happened to our child before spawn */
do
err = waitpid(*pid, &status, 0); /* okay, got EPIPE */
while (err == -1 && errno == EINTR);
assert(err == *pid);
err = UV_EPIPE;
} else
abort();
}
uv__close_nocheckstdio(signal_pipe[0]);
return err;
}
#endif /* ISN'T TARGET_OS_TV || TARGET_OS_WATCH */
int uv_spawn(uv_loop_t* loop,
uv_process_t* process,
const uv_process_options_t* options) {
#if defined(__APPLE__) && (TARGET_OS_TV || TARGET_OS_WATCH)
/* fork is marked __WATCHOS_PROHIBITED __TVOS_PROHIBITED. */
return UV_ENOSYS;
#else
int pipes_storage[8][2];
int (*pipes)[2];
int stdio_count;
pid_t pid;
int err;
int exec_errorno;
int i;
assert(options->file != NULL);
assert(!(options->flags & ~(UV_PROCESS_DETACHED |
UV_PROCESS_SETGID |
UV_PROCESS_SETUID |
UV_PROCESS_WINDOWS_FILE_PATH_EXACT_NAME |
UV_PROCESS_WINDOWS_HIDE |
UV_PROCESS_WINDOWS_HIDE_CONSOLE |
UV_PROCESS_WINDOWS_HIDE_GUI |
UV_PROCESS_WINDOWS_VERBATIM_ARGUMENTS)));
uv__handle_init(loop, (uv_handle_t*)process, UV_PROCESS);
uv__queue_init(&process->queue);
process->status = 0;
stdio_count = options->stdio_count;
if (stdio_count < 3)
stdio_count = 3;
err = UV_ENOMEM;
pipes = pipes_storage;
if (stdio_count > (int) ARRAY_SIZE(pipes_storage))
pipes = uv__malloc(stdio_count * sizeof(*pipes));
if (pipes == NULL)
goto error;
for (i = 0; i < stdio_count; i++) {
pipes[i][0] = -1;
pipes[i][1] = -1;
}
for (i = 0; i < options->stdio_count; i++) {
err = uv__process_init_stdio(options->stdio + i, pipes[i]);
if (err)
goto error;
}
#ifdef UV_USE_SIGCHLD
uv_signal_start(&loop->child_watcher, uv__chld, SIGCHLD);
#endif
/* Spawn the child */
exec_errorno = uv__spawn_and_init_child(loop, options, stdio_count, pipes, &pid);
#if 0
/* This runs into a nodejs issue (it expects initialized streams, even if the
* exec failed).
* See https://github.com/libuv/libuv/pull/3107#issuecomment-782482608 */
if (exec_errorno != 0)
goto error;
#endif
/* Activate this handle if exec() happened successfully, even if we later
* fail to open a stdio handle. This ensures we can eventually reap the child
* with waitpid. */
if (exec_errorno == 0) {
#ifndef UV_USE_SIGCHLD
struct kevent event;
EV_SET(&event, pid, EVFILT_PROC, EV_ADD | EV_ONESHOT, NOTE_EXIT, 0, 0);
if (kevent(loop->backend_fd, &event, 1, NULL, 0, NULL)) {
if (errno != ESRCH)
abort();
/* Process already exited. Call waitpid on the next loop iteration. */
process->flags |= UV_HANDLE_REAP;
loop->flags |= UV_LOOP_REAP_CHILDREN;
}
/* This prevents uv__io_poll() from bailing out prematurely, being unaware
* that we added an event here for it to react to. We will decrement this
* again after the waitpid call succeeds. */
loop->nfds++;
#endif
process->pid = pid;
process->exit_cb = options->exit_cb;
uv__queue_insert_tail(&loop->process_handles, &process->queue);
uv__handle_start(process);
}
for (i = 0; i < options->stdio_count; i++) {
err = uv__process_open_stream(options->stdio + i, pipes[i]);
if (err == 0)
continue;
while (i--)
uv__process_close_stream(options->stdio + i);
goto error;
}
if (pipes != pipes_storage)
uv__free(pipes);
return exec_errorno;
error:
if (pipes != NULL) {
for (i = 0; i < stdio_count; i++) {
if (i < options->stdio_count)
if (options->stdio[i].flags & (UV_INHERIT_FD | UV_INHERIT_STREAM))
continue;
if (pipes[i][0] != -1)
uv__close_nocheckstdio(pipes[i][0]);
if (pipes[i][1] != -1)
uv__close_nocheckstdio(pipes[i][1]);
}
if (pipes != pipes_storage)
uv__free(pipes);
}
return err;
#endif
}
int uv_process_kill(uv_process_t* process, int signum) {
return uv_kill(process->pid, signum);
}
int uv_kill(int pid, int signum) {
if (kill(pid, signum)) {
#if defined(__MVS__)
/* EPERM is returned if the process is a zombie. */
siginfo_t infop;
if (errno == EPERM &&
waitid(P_PID, pid, &infop, WNOHANG | WNOWAIT | WEXITED) == 0)
return 0;
#endif
return UV__ERR(errno);
} else
return 0;
}
void uv__process_close(uv_process_t* handle) {
uv__queue_remove(&handle->queue);
uv__handle_stop(handle);
#ifdef UV_USE_SIGCHLD
if (uv__queue_empty(&handle->loop->process_handles))
uv_signal_stop(&handle->loop->child_watcher);
#endif
}
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