bjoernager/rust
bjoernager/rust
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This commit is contained in:
Alex Crichton 2015-02-19 18:35:52 -08:00
parent 522d09dfec
commit 6686f7aa47
41 changed files with 20 additions and 5242 deletions
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258
src/libstd/sys/unix/process.rs
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@ -12,8 +12,6 @@ use prelude::v1::*;
use self::Req::*;
use collections::HashMap;
#[cfg(stage0)]
use collections::hash_map::Hasher;
use ffi::CString;
use hash::Hash;
use old_io::process::{ProcessExit, ExitStatus, ExitSignal};
@ -64,223 +62,6 @@ impl Process {
mkerr_libc(r)
}
#[cfg(stage0)]
pub fn spawn<K, V, C, P>(cfg: &C, in_fd: Option<P>,
out_fd: Option<P>, err_fd: Option<P>)
-> IoResult<Process>
where C: ProcessConfig<K, V>, P: AsInner<FileDesc>,
K: BytesContainer + Eq + Hash<Hasher>, V: BytesContainer
{
use libc::funcs::posix88::unistd::{fork, dup2, close, chdir, execvp};
mod rustrt {
extern {
pub fn rust_unset_sigprocmask();
}
}
#[cfg(all(target_os = "android", target_arch = "aarch64"))]
unsafe fn getdtablesize() -> c_int {
libc::sysconf(libc::consts::os::sysconf::_SC_OPEN_MAX) as c_int
}
#[cfg(not(all(target_os = "android", target_arch = "aarch64")))]
unsafe fn getdtablesize() -> c_int {
libc::funcs::bsd44::getdtablesize()
}
unsafe fn set_cloexec(fd: c_int) {
let ret = c::ioctl(fd, c::FIOCLEX);
assert_eq!(ret, 0);
}
let dirp = cfg.cwd().map(|c| c.as_ptr()).unwrap_or(ptr::null());
// temporary until unboxed closures land
let cfg = unsafe {
mem::transmute::<&ProcessConfig<K,V>,&'static ProcessConfig<K,V>>(cfg)
};
with_envp(cfg.env(), move|envp: *const c_void| {
with_argv(cfg.program(), cfg.args(), move|argv: *const *const libc::c_char| unsafe {
let (input, mut output) = try!(sys::os::pipe());
// We may use this in the child, so perform allocations before the
// fork
let devnull = b"/dev/null\0";
set_cloexec(output.fd());
let pid = fork();
if pid < 0 {
return Err(super::last_error())
} else if pid > 0 {
#[inline]
fn combine(arr: &[u8]) -> i32 {
let a = arr[0] as u32;
let b = arr[1] as u32;
let c = arr[2] as u32;
let d = arr[3] as u32;
((a << 24) | (b << 16) | (c << 8) | (d << 0)) as i32
}
let p = Process{ pid: pid };
drop(output);
let mut bytes = [0; 8];
return match input.read(&mut bytes) {
Ok(8) => {
assert!(combine(CLOEXEC_MSG_FOOTER) == combine(&bytes[4.. 8]),
"Validation on the CLOEXEC pipe failed: {:?}", bytes);
let errno = combine(&bytes[0.. 4]);
assert!(p.wait(0).is_ok(), "wait(0) should either return Ok or panic");
Err(super::decode_error(errno))
}
Err(ref e) if e.kind == EndOfFile => Ok(p),
Err(e) => {
assert!(p.wait(0).is_ok(), "wait(0) should either return Ok or panic");
panic!("the CLOEXEC pipe failed: {:?}", e)
},
Ok(..) => { // pipe I/O up to PIPE_BUF bytes should be atomic
assert!(p.wait(0).is_ok(), "wait(0) should either return Ok or panic");
panic!("short read on the CLOEXEC pipe")
}
};
}
// And at this point we've reached a special time in the life of the
// child. The child must now be considered hamstrung and unable to
// do anything other than syscalls really. Consider the following
// scenario:
//
// 1. Thread A of process 1 grabs the malloc() mutex
// 2. Thread B of process 1 forks(), creating thread C
// 3. Thread C of process 2 then attempts to malloc()
// 4. The memory of process 2 is the same as the memory of
// process 1, so the mutex is locked.
//
// This situation looks a lot like deadlock, right? It turns out
// that this is what pthread_atfork() takes care of, which is
// presumably implemented across platforms. The first thing that
// threads to *before* forking is to do things like grab the malloc
// mutex, and then after the fork they unlock it.
//
// Despite this information, libnative's spawn has been witnessed to
// deadlock on both OSX and FreeBSD. I'm not entirely sure why, but
// all collected backtraces point at malloc/free traffic in the
// child spawned process.
//
// For this reason, the block of code below should contain 0
// invocations of either malloc of free (or their related friends).
//
// As an example of not having malloc/free traffic, we don't close
// this file descriptor by dropping the FileDesc (which contains an
// allocation). Instead we just close it manually. This will never
// have the drop glue anyway because this code never returns (the
// child will either exec() or invoke libc::exit)
let _ = libc::close(input.fd());
fn fail(output: &mut FileDesc) -> ! {
let errno = sys::os::errno() as u32;
let bytes = [
(errno >> 24) as u8,
(errno >> 16) as u8,
(errno >> 8) as u8,
(errno >> 0) as u8,
CLOEXEC_MSG_FOOTER[0], CLOEXEC_MSG_FOOTER[1],
CLOEXEC_MSG_FOOTER[2], CLOEXEC_MSG_FOOTER[3]
];
// pipe I/O up to PIPE_BUF bytes should be atomic
assert!(output.write(&bytes).is_ok());
unsafe { libc::_exit(1) }
}
rustrt::rust_unset_sigprocmask();
// If a stdio file descriptor is set to be ignored (via a -1 file
// descriptor), then we don't actually close it, but rather open
// up /dev/null into that file descriptor. Otherwise, the first file
// descriptor opened up in the child would be numbered as one of the
// stdio file descriptors, which is likely to wreak havoc.
let setup = |src: Option<P>, dst: c_int| {
let src = match src {
None => {
let flags = if dst == libc::STDIN_FILENO {
libc::O_RDONLY
} else {
libc::O_RDWR
};
libc::open(devnull.as_ptr() as *const _, flags, 0)
}
Some(obj) => {
let fd = obj.as_inner().fd();
// Leak the memory and the file descriptor. We're in the
// child now an all our resources are going to be
// cleaned up very soon
mem::forget(obj);
fd
}
};
src != -1 && retry(|| dup2(src, dst)) != -1
};
if !setup(in_fd, libc::STDIN_FILENO) { fail(&mut output) }
if !setup(out_fd, libc::STDOUT_FILENO) { fail(&mut output) }
if !setup(err_fd, libc::STDERR_FILENO) { fail(&mut output) }
// close all other fds
for fd in (3..getdtablesize()).rev() {
if fd != output.fd() {
let _ = close(fd as c_int);
}
}
match cfg.gid() {
Some(u) => {
if libc::setgid(u as libc::gid_t) != 0 {
fail(&mut output);
}
}
None => {}
}
match cfg.uid() {
Some(u) => {
// 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.
extern {
fn setgroups(ngroups: libc::c_int,
ptr: *const libc::c_void) -> libc::c_int;
}
let _ = setgroups(0, ptr::null());
if libc::setuid(u as libc::uid_t) != 0 {
fail(&mut output);
}
}
None => {}
}
if cfg.detach() {
// Don't check the error of setsid because it fails if we're the
// process leader already. We just forked so it shouldn't return
// error, but ignore it anyway.
let _ = libc::setsid();
}
if !dirp.is_null() && chdir(dirp) == -1 {
fail(&mut output);
}
if !envp.is_null() {
*sys::os::environ() = envp as *const _;
}
let _ = execvp(*argv, argv as *mut _);
fail(&mut output);
})
})
}
#[cfg(not(stage0))]
pub fn spawn<K, V, C, P>(cfg: &C, in_fd: Option<P>,
out_fd: Option<P>, err_fd: Option<P>)
-> IoResult<Process>
@ -766,45 +547,6 @@ fn with_argv<T,F>(prog: &CString, args: &[CString],
cb(ptrs.as_ptr())
}
#[cfg(stage0)]
fn with_envp<K,V,T,F>(env: Option<&HashMap<K, V>>,
cb: F)
-> T
where F : FnOnce(*const c_void) -> T,
K : BytesContainer + Eq + Hash<Hasher>,
V : BytesContainer
{
// On posixy systems we can pass a char** for envp, which is a
// null-terminated array of "k=v\0" strings. Since we must create
// these strings locally, yet expose a raw pointer to them, we
// create a temporary vector to own the CStrings that outlives the
// call to cb.
match env {
Some(env) => {
let mut tmps = Vec::with_capacity(env.len());
for pair in env {
let mut kv = Vec::new();
kv.push_all(pair.0.container_as_bytes());
kv.push('=' as u8);
kv.push_all(pair.1.container_as_bytes());
kv.push(0); // terminating null
tmps.push(kv);
}
// As with `with_argv`, this is unsafe, since cb could leak the pointers.
let mut ptrs: Vec<*const libc::c_char> =
tmps.iter()
.map(|tmp| tmp.as_ptr() as *const libc::c_char)
.collect();
ptrs.push(ptr::null());
cb(ptrs.as_ptr() as *const c_void)
}
_ => cb(ptr::null())
}
}
#[cfg(not(stage0))]
fn with_envp<K,V,T,F>(env: Option<&HashMap<K, V>>,
cb: F)
-> T