* Copyright 2017-2019, Jérôme Duval, jerome.duval@gmail.com
* Distributed under the terms of the MIT License.
*/
#include <spawn.h>
#include <errno.h>
#include <signal.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <libroot_private.h>
#include <signal_defs.h>
#include <syscalls.h>
enum action_type {
file_action_open,
file_action_close,
file_action_dup2,
file_action_chdir,
file_action_fchdir
};
struct _file_action {
enum action_type type;
int fd;
union {
struct {
char* path;
int oflag;
mode_t mode;
} open_action;
struct {
int srcfd;
} dup2_action;
struct {
char* path;
} chdir_action;
} action;
};
struct _posix_spawnattr {
short flags;
pid_t pgroup;
sigset_t sigdefault;
sigset_t sigmask;
};
struct _posix_spawn_file_actions {
int size;
int count;
_file_action *actions;
};
static int
posix_spawn_file_actions_extend(struct _posix_spawn_file_actions *actions)
{
int newsize = actions->size + 4;
void *newactions = realloc(actions->actions,
newsize * sizeof(struct _file_action));
if (newactions == NULL)
return ENOMEM;
actions->actions = (struct _file_action*)newactions;
actions->size = newsize;
return 0;
}
int
posix_spawn_file_actions_init(posix_spawn_file_actions_t *_file_actions)
{
posix_spawn_file_actions_t actions = (posix_spawn_file_actions_t)malloc(
sizeof(struct _posix_spawn_file_actions));
if (actions == NULL)
return ENOMEM;
memset(actions, 0, sizeof(*actions));
*_file_actions = actions;
return 0;
}
int
posix_spawn_file_actions_destroy(posix_spawn_file_actions_t *_actions)
{
struct _posix_spawn_file_actions* actions = _actions != NULL ? *_actions : NULL;
if (actions == NULL)
return EINVAL;
for (int i = 0; i < actions->count; i++) {
struct _file_action *action = &actions->actions[i];
if (action->type == file_action_open)
free(action->action.open_action.path);
else if (action->type == file_action_chdir)
free(action->action.chdir_action.path);
}
free(actions);
return 0;
}
int
posix_spawn_file_actions_addopen(posix_spawn_file_actions_t *_actions,
int fildes, const char *path, int oflag, mode_t mode)
{
struct _posix_spawn_file_actions* actions = _actions != NULL ? *_actions : NULL;
if (actions == NULL)
return EINVAL;
if (fildes < 0 || fildes >= sysconf(_SC_OPEN_MAX))
return EBADF;
char* npath = strdup(path);
if (npath == NULL)
return ENOMEM;
if (actions->count == actions->size
&& posix_spawn_file_actions_extend(actions) != 0) {
free(npath);
return ENOMEM;
}
struct _file_action *action = &actions->actions[actions->count];
action->type = file_action_open;
action->fd = fildes;
action->action.open_action.path = npath;
action->action.open_action.oflag = oflag;
action->action.open_action.mode = mode;
actions->count++;
return 0;
}
int
posix_spawn_file_actions_addclose(posix_spawn_file_actions_t *_actions,
int fildes)
{
struct _posix_spawn_file_actions* actions = _actions != NULL ? *_actions : NULL;
if (actions == NULL)
return EINVAL;
if (fildes < 0 || fildes >= sysconf(_SC_OPEN_MAX))
return EBADF;
if (actions->count == actions->size
&& posix_spawn_file_actions_extend(actions) != 0) {
return ENOMEM;
}
struct _file_action *action = &actions->actions[actions->count];
action->type = file_action_close;
action->fd = fildes;
actions->count++;
return 0;
}
int
posix_spawn_file_actions_adddup2(posix_spawn_file_actions_t *_actions,
int fildes, int newfildes)
{
struct _posix_spawn_file_actions* actions = _actions != NULL ? *_actions : NULL;
if (actions == NULL)
return EINVAL;
if (fildes < 0 || fildes >= sysconf(_SC_OPEN_MAX))
return EBADF;
if (actions->count == actions->size
&& posix_spawn_file_actions_extend(actions) != 0) {
return ENOMEM;
}
struct _file_action *action = &actions->actions[actions->count];
action->type = file_action_dup2;
action->fd = newfildes;
action->action.dup2_action.srcfd = fildes;
actions->count++;
return 0;
}
extern "C" int
posix_spawn_file_actions_addchdir_np(posix_spawn_file_actions_t *_actions,
const char *path)
{
struct _posix_spawn_file_actions* actions = _actions != NULL ? *_actions : NULL;
if (actions == NULL)
return EINVAL;
char* npath = strdup(path);
if (npath == NULL)
return ENOMEM;
if (actions->count == actions->size
&& posix_spawn_file_actions_extend(actions) != 0) {
free(npath);
return ENOMEM;
}
struct _file_action *action = &actions->actions[actions->count];
action->type = file_action_chdir;
action->fd = -1;
action->action.chdir_action.path = npath;
actions->count++;
return 0;
}
extern "C" int
posix_spawn_file_actions_addfchdir_np(posix_spawn_file_actions_t *_actions,
int fildes)
{
struct _posix_spawn_file_actions* actions = _actions != NULL ? *_actions : NULL;
if (actions == NULL)
return EINVAL;
if (fildes < 0 || fildes >= sysconf(_SC_OPEN_MAX))
return EBADF;
if (actions->count == actions->size
&& posix_spawn_file_actions_extend(actions) != 0) {
return ENOMEM;
}
struct _file_action *action = &actions->actions[actions->count];
action->type = file_action_fchdir;
action->fd = fildes;
actions->count++;
return 0;
}
int
posix_spawnattr_init(posix_spawnattr_t *_attr)
{
posix_spawnattr_t attr = (posix_spawnattr_t)malloc(
sizeof(struct _posix_spawnattr));
if (attr == NULL)
return ENOMEM;
memset(attr, 0, sizeof(*attr));
*_attr = attr;
return 0;
}
int
posix_spawnattr_destroy(posix_spawnattr_t *_attr)
{
struct _posix_spawnattr* attr = _attr != NULL ? *_attr : NULL;
if (attr == NULL)
return EINVAL;
free(attr);
return 0;
}
int
posix_spawnattr_getflags(const posix_spawnattr_t *_attr, short *flags)
{
struct _posix_spawnattr *attr;
if (_attr == NULL || (attr = *_attr) == NULL || flags == NULL)
return EINVAL;
*flags = attr->flags;
return 0;
}
int
posix_spawnattr_setflags(posix_spawnattr_t *_attr, short flags)
{
struct _posix_spawnattr *attr;
if (_attr == NULL || (attr = *_attr) == NULL)
return EINVAL;
if ((flags & ~(POSIX_SPAWN_RESETIDS | POSIX_SPAWN_SETPGROUP
| POSIX_SPAWN_SETSIGDEF | POSIX_SPAWN_SETSIGMASK
| POSIX_SPAWN_SETSID)) != 0) {
return EINVAL;
}
attr->flags = flags;
return 0;
}
int
posix_spawnattr_getpgroup(const posix_spawnattr_t *_attr, pid_t *pgroup)
{
struct _posix_spawnattr *attr;
if (_attr == NULL || (attr = *_attr) == NULL || pgroup == NULL)
return EINVAL;
*pgroup = attr->pgroup;
return 0;
}
int
posix_spawnattr_setpgroup(posix_spawnattr_t *_attr, pid_t pgroup)
{
struct _posix_spawnattr *attr;
if (_attr == NULL || (attr = *_attr) == NULL)
return EINVAL;
attr->pgroup = pgroup;
return 0;
}
int
posix_spawnattr_getsigdefault(const posix_spawnattr_t *_attr, sigset_t *sigdefault)
{
struct _posix_spawnattr *attr;
if (_attr == NULL || (attr = *_attr) == NULL || sigdefault == NULL)
return EINVAL;
memcpy(sigdefault, &attr->sigdefault, sizeof(sigset_t));
return 0;
}
int
posix_spawnattr_setsigdefault(posix_spawnattr_t *_attr,
const sigset_t *sigdefault)
{
struct _posix_spawnattr *attr;
if (_attr == NULL || (attr = *_attr) == NULL || sigdefault == NULL)
return EINVAL;
memcpy(&attr->sigdefault, sigdefault, sizeof(sigset_t));
return 0;
}
int
posix_spawnattr_getsigmask(const posix_spawnattr_t *_attr, sigset_t *sigmask)
{
struct _posix_spawnattr *attr;
if (_attr == NULL || (attr = *_attr) == NULL || sigmask == NULL)
return EINVAL;
memcpy(sigmask, &attr->sigmask, sizeof(sigset_t));
return 0;
}
int
posix_spawnattr_setsigmask(posix_spawnattr_t *_attr, const sigset_t *sigmask)
{
struct _posix_spawnattr *attr;
if (_attr == NULL || (attr = *_attr) == NULL || sigmask == NULL)
return EINVAL;
memcpy(&attr->sigmask, sigmask, sizeof(sigset_t));
return 0;
}
static int
process_spawnattr(const posix_spawnattr_t *_attr)
{
if (_attr == NULL)
return 0;
struct _posix_spawnattr *attr = *_attr;
if (attr == NULL)
return EINVAL;
if ((attr->flags & POSIX_SPAWN_SETSIGMASK) != 0)
sigprocmask(SIG_SETMASK, &attr->sigmask, NULL);
if ((attr->flags & POSIX_SPAWN_SETSIGDEF) != 0) {
struct sigaction action;
action.sa_handler = SIG_DFL;
action.sa_flags = 0;
action.sa_userdata = NULL;
sigemptyset(&action.sa_mask);
for (int i = 1; i <= MAX_SIGNAL_NUMBER; i++) {
if (sigismember(&attr->sigdefault, i) == 1
&& sigaction(i, &action, NULL) != 0) {
return errno;
}
}
}
if ((attr->flags & POSIX_SPAWN_RESETIDS) != 0) {
if (setegid(getgid()) != 0)
return errno;
if (seteuid(getuid()) != 0)
return errno;
}
if ((attr->flags & POSIX_SPAWN_SETSID) != 0) {
if (setsid() != 0)
return errno;
}
if ((attr->flags & POSIX_SPAWN_SETPGROUP) != 0) {
if (setpgid(0, attr->pgroup) != 0)
return errno;
}
return 0;
}
static int
process_file_actions(const posix_spawn_file_actions_t *_actions, int *errfd)
{
if (_actions == NULL)
return 0;
struct _posix_spawn_file_actions* actions = *_actions;
if (actions == NULL)
return EINVAL;
for (int i = 0; i < actions->count; i++) {
struct _file_action *action = &actions->actions[i];
if (action->fd == *errfd) {
int newfd = dup(action->fd);
if (newfd == -1)
return errno;
close(action->fd);
fcntl(newfd, F_SETFD, FD_CLOEXEC);
*errfd = newfd;
}
if (action->type == file_action_close) {
if (close(action->fd) != 0)
return errno;
} else if (action->type == file_action_open) {
int fd = open(action->action.open_action.path,
action->action.open_action.oflag,
action->action.open_action.mode);
if (fd == -1)
return errno;
if (fd != action->fd) {
if (dup2(fd, action->fd) == -1)
return errno;
if (close(fd) != 0)
return errno;
}
} else if (action->type == file_action_dup2) {
if (dup2(action->action.dup2_action.srcfd, action->fd) == -1)
return errno;
} else if (action->type == file_action_chdir) {
if (chdir(action->action.chdir_action.path) == -1)
return errno;
} else if (action->type == file_action_fchdir) {
if (fchdir(action->fd) == -1)
return errno;
}
}
return 0;
}
static int
spawn_using_fork(pid_t *_pid, const char *path,
const posix_spawn_file_actions_t *actions,
const posix_spawnattr_t *attrp, char *const argv[], char *const envp[],
bool envpath)
{
int err = 0;
int fds[2];
pid_t pid;
if (pipe(fds) != 0)
return errno;
if (fcntl(fds[0], F_SETFD, FD_CLOEXEC) != 0
|| fcntl(fds[1], F_SETFD, FD_CLOEXEC) != 0) {
goto fail;
}
pid = vfork();
if (pid == -1)
goto fail;
if (pid != 0) {
if (_pid != NULL)
*_pid = pid;
close(fds[1]);
read(fds[0], &err, sizeof(err));
if (err != 0)
waitpid(pid, NULL, WNOHANG);
close(fds[0]);
return err;
}
close(fds[0]);
err = process_spawnattr(attrp);
if (err == 0)
err = process_file_actions(actions, &fds[1]);
if (err != 0)
goto fail_child;
if (envpath)
execvpe(path, argv, envp != NULL ? envp : environ);
else
execve(path, argv, envp != NULL ? envp : environ);
err = errno;
fail_child:
write(fds[1], &err, sizeof(err));
close(fds[1]);
_exit(127);
fail:
err = errno;
close(fds[0]);
close(fds[1]);
return err;
}
static int
spawn_using_load_image(pid_t *_pid, const char *_path,
char *const argv[], char *const envp[], bool envpath)
{
const char* path;
if (!envpath || strchr(_path, '/') != NULL) {
path = _path;
} else {
char* buffer = (char*)alloca(B_PATH_NAME_LENGTH);
status_t status = __look_up_in_path(_path, buffer);
if (status != B_OK)
return status;
path = buffer;
}
int32 argCount = 0;
while (argv[argCount] != NULL)
argCount++;
thread_id thread = __load_image_at_path(path, argCount, (const char**)argv,
(const char**)(envp != NULL ? envp : environ));
if (thread < 0)
return thread;
*_pid = thread;
return resume_thread(thread);
}
static int
do_posix_spawn(pid_t *_pid, const char *path,
const posix_spawn_file_actions_t *actions,
const posix_spawnattr_t *attrp, char *const argv[], char *const envp[],
bool envpath)
{
if ((actions == NULL || (*actions)->count == 0)
&& (attrp == NULL || (*attrp)->flags == 0)) {
return spawn_using_load_image(_pid, path, argv, envp, envpath);
} else {
return spawn_using_fork(_pid, path, actions, attrp, argv, envp,
envpath);
}
}
int
posix_spawn(pid_t *pid, const char *path,
const posix_spawn_file_actions_t *file_actions,
const posix_spawnattr_t *attrp, char *const argv[], char *const envp[])
{
return do_posix_spawn(pid, path, file_actions, attrp, argv, envp, false);
}
int
posix_spawnp(pid_t *pid, const char *file,
const posix_spawn_file_actions_t *file_actions,
const posix_spawnattr_t *attrp, char *const argv[],
char *const envp[])
{
return do_posix_spawn(pid, file, file_actions, attrp, argv, envp, true);
}
B_DEFINE_WEAK_ALIAS(posix_spawn_file_actions_addchdir_np, posix_spawn_file_actions_addchdir);
B_DEFINE_WEAK_ALIAS(posix_spawn_file_actions_addfchdir_np, posix_spawn_file_actions_addfchdir);
