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posixsubprocess.rs
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237 lines (211 loc) · 7.03 KB
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use crate::vm::{
builtins::PyListRef,
function::ArgSequence,
stdlib::{os::PyPathLike, posix},
{PyObjectRef, PyResult, TryFromObject, VirtualMachine},
};
use nix::{errno::Errno, unistd};
#[cfg(not(target_os = "redox"))]
use std::ffi::CStr;
#[cfg(not(target_os = "redox"))]
use std::os::unix::io::AsRawFd;
use std::{
convert::Infallible as Never,
ffi::CString,
io::{self, prelude::*},
};
use unistd::{Gid, Uid};
pub(crate) use _posixsubprocess::make_module;
#[pymodule]
mod _posixsubprocess {
use super::{exec, CStrPathLike, ForkExecArgs, ProcArgs};
use crate::vm::{convert::IntoPyException, PyResult, VirtualMachine};
#[pyfunction]
fn fork_exec(args: ForkExecArgs, vm: &VirtualMachine) -> PyResult<libc::pid_t> {
if args.preexec_fn.is_some() {
return Err(vm.new_not_implemented_error("preexec_fn not supported yet".to_owned()));
}
let cstrs_to_ptrs = |cstrs: &[CStrPathLike]| {
cstrs
.iter()
.map(|s| s.s.as_ptr())
.chain(std::iter::once(std::ptr::null()))
.collect::<Vec<_>>()
};
let argv = cstrs_to_ptrs(&args.args);
let argv = &argv;
let envp = args.env_list.as_ref().map(|s| cstrs_to_ptr
8000
s(s));
let envp = envp.as_deref();
match unsafe { nix::unistd::fork() }.map_err(|err| err.into_pyexception(vm))? {
nix::unistd::ForkResult::Child => exec(&args, ProcArgs { argv, envp }),
nix::unistd::ForkResult::Parent { child } => Ok(child.as_raw()),
}
}
}
macro_rules! gen_args {
($($field:ident: $t:ty),*$(,)?) => {
#[derive(FromArgs)]
struct ForkExecArgs {
$(#[pyarg(positional)] $field: $t,)*
}
};
}
struct CStrPathLike {
s: CString,
}
impl TryFromObject for CStrPathLike {
fn try_from_object(vm: &VirtualMachine, obj: PyObjectRef) -> PyResult<Self> {
let s = PyPathLike::try_from_object(vm, obj)?.into_cstring(vm)?;
Ok(CStrPathLike { s })
}
}
gen_args! {
args: ArgSequence<CStrPathLike> /* list */, exec_list: ArgSequence<CStrPathLike> /* list */,
close_fds: bool, fds_to_keep: ArgSequence<i32>,
cwd: Option<CStrPathLike>, env_list: Option<ArgSequence<CStrPathLike>>,
p2cread: i32, p2cwrite: i32, c2pread: i32, c2pwrite: i32,
errread: i32, errwrite: i32, errpipe_read: i32, errpipe_write: i32,
restore_signals: bool, call_setsid: bool,
gid: Option<Option<Gid>>, groups_list: Option<PyListRef>, uid: Option<Option<Uid>>, child_umask: i32,
preexec_fn: Option<PyObjectRef>,
}
// can't reallocate inside of exec(), so we reallocate prior to fork() and pass this along
struct ProcArgs<'a> {
argv: &'a [*const libc::c_char],
envp: Option<&'a [*const libc::c_char]>,
}
fn exec(args: &ForkExecArgs, procargs: ProcArgs) -> ! {
match exec_inner(args, procargs) {
Ok(x) => match x {},
Err(e) => {
let buf: &mut [u8] = &mut [0; 256];
let mut cur = io::Cursor::new(&mut *buf);
// TODO: check if reached preexec, if not then have "noexec" after
let _ = write!(cur, "OSError:{}:", e as i32);
let pos = cur.position();
let _ = unistd::write(args.errpipe_write, &buf[..pos as usize]);
std::process::exit(255)
}
}
}
fn exec_inner(args: &ForkExecArgs, procargs: ProcArgs) -> nix::Result<Never> {
for &fd in args.fds_to_keep.as_slice() {
if fd != args.errpipe_write {
posix::raw_set_inheritable(fd, true)?
}
}
for &fd in &[args.p2cwrite, args.c2pread, args.errread] {
if fd != -1 {
unistd::close(fd)?;
}
}
unistd::close(args.errpipe_read)?;
let c2pwrite = if args.c2pwrite == 0 {
let fd = unistd::dup(args.c2pwrite)?;
posix::raw_set_inheritable(fd, true)?;
fd
} else {
args.c2pwrite
};
let mut errwrite = args.errwrite;
while errwrite == 0 || errwrite == 1 {
errwrite = unistd::dup(errwrite)?;
posix::raw_set_inheritable(errwrite, true)?;
}
let dup_into_stdio = |fd, io_fd| {
if fd == io_fd {
posix::raw_set_inheritable(fd, true)
} else if fd != -1 {
unistd::dup2(fd, io_fd).map(drop)
} else {
Ok(())
}
};
dup_into_stdio(args.p2cread, 0)?;
dup_into_stdio(c2pwrite, 1)?;
dup_into_stdio(errwrite, 2)?;
if let Some(ref cwd) = args.cwd {
unistd::chdir(cwd.s.as_c_str())?
}
if args.child_umask >= 0 {
// TODO: umask(child_umask);
}
if args.restore_signals {
// TODO: restore signals SIGPIPE, SIGXFZ, SIGXFSZ to SIG_DFL
}
if args.call_setsid {
#[cfg(not(target_os = "redox"))]
unistd::setsid()?;
}
if let Some(_groups_list) = args.groups_list.as_ref() {
// TODO: setgroups
// unistd::setgroups(groups_size, groups);
}
if let Some(_gid) = args.gid.as_ref() {
// TODO: setgid
// unistd::setregid(gid, gid)?;
}
if let Some(_uid) = args.uid.as_ref() {
// TODO: setuid
// unistd::setreuid(uid, uid)?;
}
if args.close_fds {
#[cfg(not(target_os = "redox"))]
close_fds(3, &args.fds_to_keep)?;
}
let mut first_err = None;
for exec in args.exec_list.as_slice() {
if let Some(envp) = procargs.envp {
unsafe { libc::execve(exec.s.as_ptr(), procargs.argv.as_ptr(), envp.as_ptr()) };
} else {
unsafe { libc::execv(exec.s.as_ptr(), procargs.argv.as_ptr()) };
}
let e = Errno::last();
if e != Errno::ENOENT && e != Errno::ENOTDIR && first_err.is_none() {
first_err = Some(e)
}
}
Err(first_err.unwrap_or_else(Errno::last))
}
#[cfg(not(target_os = "redox"))]
fn close_fds(above: i32, keep: &[i32]) -> nix::Result<()> {
use nix::{dir::Dir, fcntl::OFlag};
// TODO: close fds by brute force if readdir doesn't work:
// https://github.com/python/cpython/blob/3.8/Modules/_posixsubprocess.c#L220
let path = unsafe { CStr::from_bytes_with_nul_unchecked(FD_DIR_NAME) };
let mut dir = Dir::open(
path,
OFlag::O_RDONLY | OFlag::O_DIRECTORY,
nix::sys::stat::Mode::empty(),
)?;
let dirfd = dir.as_raw_fd();
for e in dir.iter() {
if let Some(fd) = pos_int_from_ascii(e?.file_name()) {
if fd != dirfd && fd > above && !keep.contains(&fd) {
unistd::close(fd)?
}
}
}
Ok(())
}
#[cfg(any(
target_os = "dragonfly",
target_os = "freebsd",
target_os = "netbsd",
target_os = "openbsd",
target_vendor = "apple",
))]
const FD_DIR_NAME: &[u8] = b"/dev/fd\0";
#[cfg(any(target_os = "linux", target_os = "android"))]
const FD_DIR_NAME: &[u8] = b"/proc/self/fd\0";
#[cfg(not(target_os = "redox"))]
fn pos_int_from_ascii(name: &CStr) -> Option<i32> {
let mut num = 0;
for c in name.to_bytes() {
if !c.is_ascii_digit() {
return None;
}
num = num * 10 + i32::from(c - b'0')
}
Some(num)
}