1 // Copyright 2014-2015 The Rust Project Developers. See the COPYRIGHT
2 // file at the top-level directory of this distribution and at
3 // http://rust-lang.org/COPYRIGHT.
5 // Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
6 // http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
7 // <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
8 // option. This file may not be copied, modified, or distributed
9 // except according to those terms.
11 use io
::{self, Error, ErrorKind}
;
12 use libc
::{self, c_int, gid_t, pid_t, uid_t}
;
16 use sys
::process
::process_common
::*;
18 ////////////////////////////////////////////////////////////////////////////////
20 ////////////////////////////////////////////////////////////////////////////////
23 pub fn spawn(&mut self, default: Stdio
, needs_stdin
: bool
)
24 -> io
::Result
<(Process
, StdioPipes
)> {
27 const CLOEXEC_MSG_FOOTER
: &'
static [u8] = b
"NOEX";
29 let envp
= self.capture_env();
32 return Err(io
::Error
::new(ErrorKind
::InvalidInput
,
33 "nul byte found in provided data"));
36 let (ours
, theirs
) = self.setup_io(default, needs_stdin
)?
;
38 if let Some(ret
) = self.posix_spawn(&theirs
, envp
.as_ref())?
{
39 return Ok((ret
, ours
))
42 let (input
, output
) = sys
::pipe
::anon_pipe()?
;
45 match cvt(libc
::fork())?
{
48 let err
= self.do_exec(theirs
, envp
.as_ref());
49 let errno
= err
.raw_os_error().unwrap_or(libc
::EINVAL
) as u32;
55 CLOEXEC_MSG_FOOTER
[0], CLOEXEC_MSG_FOOTER
[1],
56 CLOEXEC_MSG_FOOTER
[2], CLOEXEC_MSG_FOOTER
[3]
58 // pipe I/O up to PIPE_BUF bytes should be atomic, and then
59 // we want to be sure we *don't* run at_exit destructors as
60 // we're being torn down regardless
61 assert
!(output
.write(&bytes
).is_ok());
68 let mut p
= Process { pid: pid, status: None }
;
70 let mut bytes
= [0; 8];
72 // loop to handle EINTR
74 match input
.read(&mut bytes
) {
75 Ok(0) => return Ok((p
, ours
)),
77 assert
!(combine(CLOEXEC_MSG_FOOTER
) == combine(&bytes
[4.. 8]),
78 "Validation on the CLOEXEC pipe failed: {:?}", bytes
);
79 let errno
= combine(&bytes
[0.. 4]);
80 assert
!(p
.wait().is_ok(),
81 "wait() should either return Ok or panic");
82 return Err(Error
::from_raw_os_error(errno
))
84 Err(ref e
) if e
.kind() == ErrorKind
::Interrupted
=> {}
86 assert
!(p
.wait().is_ok(),
87 "wait() should either return Ok or panic");
88 panic
!("the CLOEXEC pipe failed: {:?}", e
)
90 Ok(..) => { // pipe I/O up to PIPE_BUF bytes should be atomic
91 assert
!(p
.wait().is_ok(),
92 "wait() should either return Ok or panic");
93 panic
!("short read on the CLOEXEC pipe")
98 fn combine(arr
: &[u8]) -> i32 {
99 let a
= arr
[0] as u32;
100 let b
= arr
[1] as u32;
101 let c
= arr
[2] as u32;
102 let d
= arr
[3] as u32;
104 ((a
<< 24) | (b
<< 16) | (c
<< 8) | (d
<< 0)) as i32
108 pub fn exec(&mut self, default: Stdio
) -> io
::Error
{
109 let envp
= self.capture_env();
112 return io
::Error
::new(ErrorKind
::InvalidInput
,
113 "nul byte found in provided data")
116 match self.setup_io(default, true) {
117 Ok((_
, theirs
)) => unsafe { self.do_exec(theirs, envp.as_ref()) }
,
122 // And at this point we've reached a special time in the life of the
123 // child. The child must now be considered hamstrung and unable to
124 // do anything other than syscalls really. Consider the following
127 // 1. Thread A of process 1 grabs the malloc() mutex
128 // 2. Thread B of process 1 forks(), creating thread C
129 // 3. Thread C of process 2 then attempts to malloc()
130 // 4. The memory of process 2 is the same as the memory of
131 // process 1, so the mutex is locked.
133 // This situation looks a lot like deadlock, right? It turns out
134 // that this is what pthread_atfork() takes care of, which is
135 // presumably implemented across platforms. The first thing that
136 // threads to *before* forking is to do things like grab the malloc
137 // mutex, and then after the fork they unlock it.
139 // Despite this information, libnative's spawn has been witnessed to
140 // deadlock on both macOS and FreeBSD. I'm not entirely sure why, but
141 // all collected backtraces point at malloc/free traffic in the
142 // child spawned process.
144 // For this reason, the block of code below should contain 0
145 // invocations of either malloc of free (or their related friends).
147 // As an example of not having malloc/free traffic, we don't close
148 // this file descriptor by dropping the FileDesc (which contains an
149 // allocation). Instead we just close it manually. This will never
150 // have the drop glue anyway because this code never returns (the
151 // child will either exec() or invoke libc::exit)
155 maybe_envp
: Option
<&CStringArray
>
157 use sys
::{self, cvt_r}
;
160 ($e
:expr
) => (match $e
{
166 if let Some(fd
) = stdio
.stdin
.fd() {
167 t
!(cvt_r(|| libc
::dup2(fd
, libc
::STDIN_FILENO
)));
169 if let Some(fd
) = stdio
.stdout
.fd() {
170 t
!(cvt_r(|| libc
::dup2(fd
, libc
::STDOUT_FILENO
)));
172 if let Some(fd
) = stdio
.stderr
.fd() {
173 t
!(cvt_r(|| libc
::dup2(fd
, libc
::STDERR_FILENO
)));
176 if cfg
!(not(any(target_os
= "l4re"))) {
177 if let Some(u
) = self.get_gid() {
178 t
!(cvt(libc
::setgid(u
as gid_t
)));
180 if let Some(u
) = self.get_uid() {
181 // When dropping privileges from root, the `setgroups` call
182 // will remove any extraneous groups. If we don't call this,
183 // then even though our uid has dropped, we may still have
184 // groups that enable us to do super-user things. This will
185 // fail if we aren't root, so don't bother checking the
186 // return value, this is just done as an optimistic
187 // privilege dropping function.
188 let _
= libc
::setgroups(0, ptr
::null());
190 t
!(cvt(libc
::setuid(u
as uid_t
)));
193 if let Some(ref cwd
) = *self.get_cwd() {
194 t
!(cvt(libc
::chdir(cwd
.as_ptr())));
196 if let Some(envp
) = maybe_envp
{
197 *sys
::os
::environ() = envp
.as_ptr();
200 // emscripten has no signal support.
201 #[cfg(not(any(target_os = "emscripten")))]
204 // Reset signal handling so the child process starts in a
205 // standardized state. libstd ignores SIGPIPE, and signal-handling
206 // libraries often set a mask. Child processes inherit ignored
207 // signals and the signal mask from their parent, but most
208 // UNIX programs do not reset these things on their own, so we
209 // need to clean things up now to avoid confusing the program
210 // we're about to run.
211 let mut set
: libc
::sigset_t
= mem
::uninitialized();
212 if cfg
!(target_os
= "android") {
213 // Implementing sigemptyset allow us to support older Android
214 // versions. See the comment about Android and sig* functions in
216 libc
::memset(&mut set
as *mut _
as *mut _
,
218 mem
::size_of
::<libc
::sigset_t
>());
220 t
!(cvt(libc
::sigemptyset(&mut set
)));
222 t
!(cvt(libc
::pthread_sigmask(libc
::SIG_SETMASK
, &set
,
224 let ret
= sys
::signal(libc
::SIGPIPE
, libc
::SIG_DFL
);
225 if ret
== libc
::SIG_ERR
{
226 return io
::Error
::last_os_error()
230 for callback
in self.get_closures().iter_mut() {
234 libc
::execvp(self.get_argv()[0], self.get_argv().as_ptr());
235 io
::Error
::last_os_error()
238 #[cfg(not(any(target_os = "macos", target_os = "freebsd",
239 all(target_os
= "linux", target_env
= "gnu"))))]
240 fn posix_spawn(&mut self, _
: &ChildPipes
, _
: Option
<&CStringArray
>)
241 -> io
::Result
<Option
<Process
>>
246 // Only support platforms for which posix_spawn() can return ENOENT
248 #[cfg(any(target_os = "macos", target_os = "freebsd",
249 all(target_os
= "linux", target_env
= "gnu")))]
250 fn posix_spawn(&mut self, stdio
: &ChildPipes
, envp
: Option
<&CStringArray
>)
251 -> io
::Result
<Option
<Process
>>
256 if self.get_cwd().is_some() ||
257 self.get_gid().is_some() ||
258 self.get_uid().is_some() ||
259 self.env_saw_path() ||
260 self.get_closures().len() != 0 {
264 // Only glibc 2.24+ posix_spawn() supports returning ENOENT directly.
265 #[cfg(all(target_os = "linux", target_env = "gnu"))]
267 if let Some(version
) = sys
::os
::glibc_version() {
268 if version
< (2, 24) {
276 let mut p
= Process { pid: 0, status: None }
;
278 struct PosixSpawnFileActions(libc
::posix_spawn_file_actions_t
);
280 impl Drop
for PosixSpawnFileActions
{
283 libc
::posix_spawn_file_actions_destroy(&mut self.0);
288 struct PosixSpawnattr(libc
::posix_spawnattr_t
);
290 impl Drop
for PosixSpawnattr
{
293 libc
::posix_spawnattr_destroy(&mut self.0);
299 let mut file_actions
= PosixSpawnFileActions(mem
::uninitialized());
300 let mut attrs
= PosixSpawnattr(mem
::uninitialized());
302 libc
::posix_spawnattr_init(&mut attrs
.0);
303 libc
::posix_spawn_file_actions_init(&mut file_actions
.0);
305 if let Some(fd
) = stdio
.stdin
.fd() {
306 cvt(libc
::posix_spawn_file_actions_adddup2(&mut file_actions
.0,
308 libc
::STDIN_FILENO
))?
;
310 if let Some(fd
) = stdio
.stdout
.fd() {
311 cvt(libc
::posix_spawn_file_actions_adddup2(&mut file_actions
.0,
313 libc
::STDOUT_FILENO
))?
;
315 if let Some(fd
) = stdio
.stderr
.fd() {
316 cvt(libc
::posix_spawn_file_actions_adddup2(&mut file_actions
.0,
318 libc
::STDERR_FILENO
))?
;
321 let mut set
: libc
::sigset_t
= mem
::uninitialized();
322 cvt(libc
::sigemptyset(&mut set
))?
;
323 cvt(libc
::posix_spawnattr_setsigmask(&mut attrs
.0,
325 cvt(libc
::sigaddset(&mut set
, libc
::SIGPIPE
))?
;
326 cvt(libc
::posix_spawnattr_setsigdefault(&mut attrs
.0,
329 let flags
= libc
::POSIX_SPAWN_SETSIGDEF
|
330 libc
::POSIX_SPAWN_SETSIGMASK
;
331 cvt(libc
::posix_spawnattr_setflags(&mut attrs
.0, flags
as _
))?
;
333 let envp
= envp
.map(|c
| c
.as_ptr())
334 .unwrap_or(*sys
::os
::environ() as *const _
);
335 let ret
= libc
::posix_spawnp(
340 self.get_argv().as_ptr() as *const _
,
346 Err(io
::Error
::from_raw_os_error(ret
))
352 ////////////////////////////////////////////////////////////////////////////////
354 ////////////////////////////////////////////////////////////////////////////////
356 /// The unique id of the process (this should never be negative).
359 status
: Option
<ExitStatus
>,
363 pub fn id(&self) -> u32 {
367 pub fn kill(&mut self) -> io
::Result
<()> {
368 // If we've already waited on this process then the pid can be recycled
369 // and used for another process, and we probably shouldn't be killing
370 // random processes, so just return an error.
371 if self.status
.is_some() {
372 Err(Error
::new(ErrorKind
::InvalidInput
,
373 "invalid argument: can't kill an exited process"))
375 cvt(unsafe { libc::kill(self.pid, libc::SIGKILL) }
).map(|_
| ())
379 pub fn wait(&mut self) -> io
::Result
<ExitStatus
> {
381 if let Some(status
) = self.status
{
384 let mut status
= 0 as c_int
;
385 cvt_r(|| unsafe { libc::waitpid(self.pid, &mut status, 0) }
)?
;
386 self.status
= Some(ExitStatus
::new(status
));
387 Ok(ExitStatus
::new(status
))
390 pub fn try_wait(&mut self) -> io
::Result
<Option
<ExitStatus
>> {
391 if let Some(status
) = self.status
{
392 return Ok(Some(status
))
394 let mut status
= 0 as c_int
;
395 let pid
= cvt(unsafe {
396 libc
::waitpid(self.pid
, &mut status
, libc
::WNOHANG
)
401 self.status
= Some(ExitStatus
::new(status
));
402 Ok(Some(ExitStatus
::new(status
)))