diff --git a/src/libstd/process.rs b/src/libstd/process.rs index 52f5965db80..9929593ffcb 100644 --- a/src/libstd/process.rs +++ b/src/libstd/process.rs @@ -340,7 +340,7 @@ fn setup_io(io: &StdioImp, fd: libc::c_int, readable: bool) (Some(AnonPipe::from_fd(fd)), None) } Piped => { - let (reader, writer) = try!(unsafe { pipe2::anon_pipe() }); + let (reader, writer) = try!(pipe2::anon_pipe()); if readable { (Some(reader), Some(writer)) } else { diff --git a/src/libstd/sys/unix/c.rs b/src/libstd/sys/unix/c.rs index 282e5668e6e..aa4bf821207 100644 --- a/src/libstd/sys/unix/c.rs +++ b/src/libstd/sys/unix/c.rs @@ -159,6 +159,8 @@ extern { pub fn utimes(filename: *const libc::c_char, times: *const libc::timeval) -> libc::c_int; pub fn gai_strerror(errcode: libc::c_int) -> *const libc::c_char; + pub fn setgroups(ngroups: libc::c_int, + ptr: *const libc::c_void) -> libc::c_int; } #[cfg(any(target_os = "macos", target_os = "ios"))] diff --git a/src/libstd/sys/unix/fs2.rs b/src/libstd/sys/unix/fs2.rs index 20b1aac8f45..ac121f1c82e 100644 --- a/src/libstd/sys/unix/fs2.rs +++ b/src/libstd/sys/unix/fs2.rs @@ -205,13 +205,17 @@ impl OpenOptions { impl File { pub fn open(path: &Path, opts: &OpenOptions) -> io::Result { + let path = try!(cstr(path)); + File::open_c(&path, opts) + } + + pub fn open_c(path: &CStr, opts: &OpenOptions) -> io::Result { let flags = opts.flags | match (opts.read, opts.write) { (true, true) => libc::O_RDWR, (false, true) => libc::O_WRONLY, (true, false) | (false, false) => libc::O_RDONLY, }; - let path = try!(cstr(path)); let fd = try!(cvt_r(|| unsafe { libc::open(path.as_ptr(), flags, opts.mode) })); @@ -220,6 +224,8 @@ impl File { Ok(File(fd)) } + pub fn into_fd(self) -> FileDesc { self.0 } + pub fn file_attr(&self) -> io::Result { let mut stat: libc::stat = unsafe { mem::zeroed() }; try!(cvt(unsafe { libc::fstat(self.0.raw(), &mut stat) })); diff --git a/src/libstd/sys/unix/pipe2.rs b/src/libstd/sys/unix/pipe2.rs index 2fd4d6dd311..e9d8c69fefb 100644 --- a/src/libstd/sys/unix/pipe2.rs +++ b/src/libstd/sys/unix/pipe2.rs @@ -20,11 +20,10 @@ use libc; pub struct AnonPipe(FileDesc); -pub unsafe fn anon_pipe() -> io::Result<(AnonPipe, AnonPipe)> { +pub fn anon_pipe() -> io::Result<(AnonPipe, AnonPipe)> { let mut fds = [0; 2]; - if libc::pipe(fds.as_mut_ptr()) == 0 { - Ok((AnonPipe::from_fd(fds[0]), - AnonPipe::from_fd(fds[1]))) + if unsafe { libc::pipe(fds.as_mut_ptr()) == 0 } { + Ok((AnonPipe::from_fd(fds[0]), AnonPipe::from_fd(fds[1]))) } else { Err(io::Error::last_os_error()) } @@ -45,7 +44,7 @@ impl AnonPipe { self.0.write(buf) } - pub fn raw(&self) -> libc::c_int { - self.0.raw() + pub fn into_fd(self) -> FileDesc { + self.0 } } diff --git a/src/libstd/sys/unix/process2.rs b/src/libstd/sys/unix/process2.rs index 60f00c80b4a..dc6897fec8e 100644 --- a/src/libstd/sys/unix/process2.rs +++ b/src/libstd/sys/unix/process2.rs @@ -13,14 +13,14 @@ use os::unix::prelude::*; use collections::HashMap; use env; -use ffi::{OsString, OsStr, CString}; +use ffi::{OsString, OsStr, CString, CStr}; use fmt; use io::{self, Error, ErrorKind}; use libc::{self, pid_t, c_void, c_int, gid_t, uid_t}; -use mem; use ptr; use sys::pipe2::AnonPipe; use sys::{self, retry, c, cvt}; +use sys::fs2::{File, OpenOptions}; //////////////////////////////////////////////////////////////////////////////// // Command @@ -128,221 +128,178 @@ impl Process { } pub fn spawn(cfg: &Command, - in_fd: Option, out_fd: Option, err_fd: Option) - -> io::Result - { - use libc::funcs::posix88::unistd::{fork, dup2, close, chdir, execvp}; + in_fd: Option, + out_fd: Option, + err_fd: Option) -> io::Result { + let dirp = cfg.cwd.as_ref().map(|c| c.as_ptr()).unwrap_or(ptr::null()); - mod rustrt { - extern { - pub fn rust_unset_sigprocmask(); + let (envp, _a, _b) = make_envp(cfg.env.as_ref()); + let (argv, _a) = make_argv(&cfg.program, &cfg.args); + let (input, output) = try!(sys::pipe2::anon_pipe()); + + let pid = unsafe { + match libc::fork() { + 0 => { + drop(input); + Process::child_after_fork(cfg, output, argv, envp, dirp, + in_fd, out_fd, err_fd) + } + n if n < 0 => return Err(Error::last_os_error()), + n => n, + } + }; + + let p = Process{ pid: pid }; + drop(output); + let mut bytes = [0; 8]; + + // loop to handle EINTR + loop { + match input.read(&mut bytes) { + Ok(0) => return Ok(p), + 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().is_ok(), + "wait() should either return Ok or panic"); + return Err(Error::from_raw_os_error(errno)) + } + Err(ref e) if e.kind() == ErrorKind::Interrupted => {} + Err(e) => { + assert!(p.wait().is_ok(), + "wait() 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().is_ok(), + "wait() should either return Ok or panic"); + panic!("short read on the CLOEXEC pipe") + } } } - unsafe fn set_cloexec(fd: c_int) { - let ret = c::ioctl(fd, c::FIOCLEX); - assert_eq!(ret, 0); + 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 + } + } + + // 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) + unsafe fn child_after_fork(cfg: &Command, + mut output: AnonPipe, + argv: *const *const libc::c_char, + envp: *const libc::c_void, + dirp: *const libc::c_char, + in_fd: Option, + out_fd: Option, + err_fd: Option) -> ! { + fn fail(output: &mut AnonPipe) -> ! { + 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, and then we want + // to be sure we *don't* run at_exit destructors as we're being torn + // down regardless + assert!(output.write(&bytes).is_ok()); + unsafe { libc::_exit(1) } } - #[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 - } + // If a stdio file descriptor is set to be ignored, 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, dst: c_int| { + src.map(|p| p.into_fd()).or_else(|| { + let mut opts = OpenOptions::new(); + opts.read(dst == libc::STDIN_FILENO); + opts.write(dst != libc::STDIN_FILENO); + let devnull = CStr::from_ptr(b"/dev/null\0".as_ptr() + as *const _); + File::open_c(devnull, &opts).ok().map(|f| f.into_fd()) + }).map(|fd| { + fd.unset_cloexec(); + retry(|| libc::dup2(fd.raw(), dst)) != -1 + }).unwrap_or(false) + }; - #[cfg(not(all(target_os = "android", target_arch = "aarch64")))] - unsafe fn getdtablesize() -> c_int { - libc::funcs::bsd44::getdtablesize() - } + 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) } - let dirp = cfg.cwd.as_ref().map(|c| c.as_ptr()).unwrap_or(ptr::null()); - - with_envp(cfg.env.as_ref(), |envp: *const c_void| { - with_argv(&cfg.program, &cfg.args, |argv: *const *const libc::c_char| unsafe { - let (input, mut output) = try!(sys::pipe2::anon_pipe()); - - // We may use this in the child, so perform allocations before the - // fork - let devnull = b"/dev/null\0"; - - set_cloexec(output.raw()); - - let pid = fork(); - if pid < 0 { - return Err(Error::last_os_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]; - - // loop to handle EINTER - loop { - 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().is_ok(), - "wait() should either return Ok or panic"); - return Err(Error::from_raw_os_error(errno)) - } - Ok(0) => return Ok(p), - Err(ref e) if e.kind() == ErrorKind::Interrupted => {} - Err(e) => { - assert!(p.wait().is_ok(), - "wait() 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().is_ok(), - "wait() 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.raw()); - - fn fail(output: &mut AnonPipe) -> ! { - 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, 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, 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.raw(); - // 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.raw() { - 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 _); + if let Some(u) = cfg.gid { + if libc::setgid(u as libc::gid_t) != 0 { fail(&mut output); - }) - }) + } + } + if let Some(u) = cfg.uid { + // 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. + let _ = c::setgroups(0, ptr::null()); + + if libc::setuid(u as libc::uid_t) != 0 { + fail(&mut output); + } + } + 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() && libc::chdir(dirp) == -1 { + fail(&mut output); + } + if !envp.is_null() { + *sys::os::environ() = envp as *const _; + } + let _ = libc::execvp(*argv, argv as *mut _); + fail(&mut output) } pub fn wait(&self) -> io::Result { @@ -364,8 +321,8 @@ impl Process { } } -fn with_argv(prog: &CString, args: &[CString], cb: F) -> T - where F : FnOnce(*const *const libc::c_char) -> T +fn make_argv(prog: &CString, args: &[CString]) + -> (*const *const libc::c_char, Vec<*const libc::c_char>) { let mut ptrs: Vec<*const libc::c_char> = Vec::with_capacity(args.len()+1); @@ -380,40 +337,38 @@ fn with_argv(prog: &CString, args: &[CString], cb: F) -> T // Add a terminating null pointer (required by libc). ptrs.push(ptr::null()); - cb(ptrs.as_ptr()) + (ptrs.as_ptr(), ptrs) } -fn with_envp(env: Option<&HashMap>, cb: F) -> T - where F : FnOnce(*const c_void) -> T +fn make_envp(env: Option<&HashMap>) + -> (*const c_void, Vec>, Vec<*const libc::c_char>) { // 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()); + if let Some(env) = env { + let mut tmps = Vec::with_capacity(env.len()); - for pair in env { - let mut kv = Vec::new(); - kv.push_all(pair.0.as_bytes()); - kv.push('=' as u8); - kv.push_all(pair.1.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) + for pair in env { + let mut kv = Vec::new(); + kv.push_all(pair.0.as_bytes()); + kv.push('=' as u8); + kv.push_all(pair.1.as_bytes()); + kv.push(0); // terminating null + tmps.push(kv); } - _ => cb(ptr::null()) + + 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()); + + (ptrs.as_ptr() as *const _, tmps, ptrs) + } else { + (0 as *const _, Vec::new(), Vec::new()) } } diff --git a/src/libstd/sys/windows/pipe2.rs b/src/libstd/sys/windows/pipe2.rs index 229481e3d57..ed41c959782 100644 --- a/src/libstd/sys/windows/pipe2.rs +++ b/src/libstd/sys/windows/pipe2.rs @@ -22,22 +22,24 @@ pub struct AnonPipe { fd: c_int } -pub unsafe fn anon_pipe() -> io::Result<(AnonPipe, AnonPipe)> { +pub fn anon_pipe() -> io::Result<(AnonPipe, AnonPipe)> { // Windows pipes work subtly differently than unix pipes, and their // inheritance has to be handled in a different way that I do not // fully understand. Here we explicitly make the pipe non-inheritable, // which means to pass it to a subprocess they need to be duplicated // first, as in std::run. let mut fds = [0; 2]; - match libc::pipe(fds.as_mut_ptr(), 1024 as ::libc::c_uint, - (libc::O_BINARY | libc::O_NOINHERIT) as c_int) { - 0 => { - assert!(fds[0] != -1 && fds[0] != 0); - assert!(fds[1] != -1 && fds[1] != 0); + unsafe { + match libc::pipe(fds.as_mut_ptr(), 1024 as ::libc::c_uint, + (libc::O_BINARY | libc::O_NOINHERIT) as c_int) { + 0 => { + assert!(fds[0] != -1 && fds[0] != 0); + assert!(fds[1] != -1 && fds[1] != 0); - Ok((AnonPipe::from_fd(fds[0]), AnonPipe::from_fd(fds[1]))) + Ok((AnonPipe::from_fd(fds[0]), AnonPipe::from_fd(fds[1]))) + } + _ => Err(io::Error::last_os_error()), } - _ => Err(io::Error::last_os_error()), } }