src/libstd/sys/unix/os.rs

   1 // Copyright 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.
   4 //
   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.
  10
  11 //! Implementation of `std::os` functionality for unix systems
  12
  13 #![allow(unused_imports)] // lots of cfg code here
  14
  15 use os::unix::prelude::*;
  16
  17 use error::Error as StdError;
  18 use ffi::{CString, CStr, OsString, OsStr};
  19 use fmt;
  20 use io;
  21 use iter;
  22 use libc::{self, c_int, c_char, c_void};
  23 use marker::PhantomData;
  24 use mem;
  25 use memchr;
  26 use path::{self, PathBuf};
  27 use ptr;
  28 use slice;
  29 use str;
  30 use sys_common::mutex::Mutex;
  31 use sys::cvt;
  32 use sys::fd;
  33 use vec;
  34
  35 const TMPBUF_SZ: usize = 128;
  36 static ENV_LOCK: Mutex = Mutex::new();
  37
  38
  39 extern {
  40     #[cfg(not(target_os = "dragonfly"))]
  41     #[cfg_attr(any(target_os = "linux", target_os = "emscripten"),
  42                link_name = "__errno_location")]
  43     #[cfg_attr(any(target_os = "bitrig",
  44                    target_os = "netbsd",
  45                    target_os = "openbsd",
  46                    target_os = "android",
  47                    target_env = "newlib"),
  48                link_name = "__errno")]
  49     #[cfg_attr(target_os = "solaris", link_name = "___errno")]
  50     #[cfg_attr(any(target_os = "macos",
  51                    target_os = "ios",
  52                    target_os = "freebsd"),
  53                link_name = "__error")]
  54     #[cfg_attr(target_os = "haiku", link_name = "_errnop")]
  55     fn errno_location() -> *mut c_int;
  56 }
  57
  58 /// Returns the platform-specific value of errno
  59 #[cfg(not(target_os = "dragonfly"))]
  60 pub fn errno() -> i32 {
  61     unsafe {
  62         (*errno_location()) as i32
  63     }
  64 }
  65
  66 /// Sets the platform-specific value of errno
  67 #[cfg(target_os = "solaris")] // only needed for readdir so far
  68 pub fn set_errno(e: i32) {
  69     unsafe {
  70         *errno_location() = e as c_int
  71     }
  72 }
  73
  74 #[cfg(target_os = "dragonfly")]
  75 pub fn errno() -> i32 {
  76     extern {
  77         #[thread_local]
  78         static errno: c_int;
  79     }
  80
  81     errno as i32
  82 }
  83
  84 /// Gets a detailed string description for the given error number.
  85 pub fn error_string(errno: i32) -> String {
  86     extern {
  87         #[cfg_attr(any(target_os = "linux", target_env = "newlib"),
  88                    link_name = "__xpg_strerror_r")]
  89         fn strerror_r(errnum: c_int, buf: *mut c_char,
  90                       buflen: libc::size_t) -> c_int;
  91     }
  92
  93     let mut buf = [0 as c_char; TMPBUF_SZ];
  94
  95     let p = buf.as_mut_ptr();
  96     unsafe {
  97         if strerror_r(errno as c_int, p, buf.len() as libc::size_t) < 0 {
  98             panic!("strerror_r failure");
  99         }
 100
 101         let p = p as *const _;
 102         str::from_utf8(CStr::from_ptr(p).to_bytes()).unwrap().to_owned()
 103     }
 104 }
 105
 106 pub fn getcwd() -> io::Result<PathBuf> {
 107     let mut buf = Vec::with_capacity(512);
 108     loop {
 109         unsafe {
 110             let ptr = buf.as_mut_ptr() as *mut libc::c_char;
 111             if !libc::getcwd(ptr, buf.capacity() as libc::size_t).is_null() {
 112                 let len = CStr::from_ptr(buf.as_ptr() as *const libc::c_char).to_bytes().len();
 113                 buf.set_len(len);
 114                 buf.shrink_to_fit();
 115                 return Ok(PathBuf::from(OsString::from_vec(buf)));
 116             } else {
 117                 let error = io::Error::last_os_error();
 118                 if error.raw_os_error() != Some(libc::ERANGE) {
 119                     return Err(error);
 120                 }
 121             }
 122
 123             // Trigger the internal buffer resizing logic of `Vec` by requiring
 124             // more space than the current capacity.
 125             let cap = buf.capacity();
 126             buf.set_len(cap);
 127             buf.reserve(1);
 128         }
 129     }
 130 }
 131
 132 pub fn chdir(p: &path::Path) -> io::Result<()> {
 133     let p: &OsStr = p.as_ref();
 134     let p = CString::new(p.as_bytes())?;
 135     unsafe {
 136         match libc::chdir(p.as_ptr()) == (0 as c_int) {
 137             true => Ok(()),
 138             false => Err(io::Error::last_os_error()),
 139         }
 140     }
 141 }
 142
 143 pub struct SplitPaths<'a> {
 144     iter: iter::Map<slice::Split<'a, u8, fn(&u8) -> bool>,
 145                     fn(&'a [u8]) -> PathBuf>,
 146 }
 147
 148 pub fn split_paths(unparsed: &OsStr) -> SplitPaths {
 149     fn bytes_to_path(b: &[u8]) -> PathBuf {
 150         PathBuf::from(<OsStr as OsStrExt>::from_bytes(b))
 151     }
 152     fn is_colon(b: &u8) -> bool { *b == b':' }
 153     let unparsed = unparsed.as_bytes();
 154     SplitPaths {
 155         iter: unparsed.split(is_colon as fn(&u8) -> bool)
 156                       .map(bytes_to_path as fn(&[u8]) -> PathBuf)
 157     }
 158 }
 159
 160 impl<'a> Iterator for SplitPaths<'a> {
 161     type Item = PathBuf;
 162     fn next(&mut self) -> Option<PathBuf> { self.iter.next() }
 163     fn size_hint(&self) -> (usize, Option<usize>) { self.iter.size_hint() }
 164 }
 165
 166 #[derive(Debug)]
 167 pub struct JoinPathsError;
 168
 169 pub fn join_paths<I, T>(paths: I) -> Result<OsString, JoinPathsError>
 170     where I: Iterator<Item=T>, T: AsRef<OsStr>
 171 {
 172     let mut joined = Vec::new();
 173     let sep = b':';
 174
 175     for (i, path) in paths.enumerate() {
 176         let path = path.as_ref().as_bytes();
 177         if i > 0 { joined.push(sep) }
 178         if path.contains(&sep) {
 179             return Err(JoinPathsError)
 180         }
 181         joined.extend_from_slice(path);
 182     }
 183     Ok(OsStringExt::from_vec(joined))
 184 }
 185
 186 impl fmt::Display for JoinPathsError {
 187     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
 188         "path segment contains separator `:`".fmt(f)
 189     }
 190 }
 191
 192 impl StdError for JoinPathsError {
 193     fn description(&self) -> &str { "failed to join paths" }
 194 }
 195
 196 #[cfg(target_os = "freebsd")]
 197 pub fn current_exe() -> io::Result<PathBuf> {
 198     unsafe {
 199         let mut mib = [libc::CTL_KERN as c_int,
 200                        libc::KERN_PROC as c_int,
 201                        libc::KERN_PROC_PATHNAME as c_int,
 202                        -1 as c_int];
 203         let mut sz: libc::size_t = 0;
 204         cvt(libc::sysctl(mib.as_mut_ptr(), mib.len() as ::libc::c_uint,
 205                          ptr::null_mut(), &mut sz, ptr::null_mut(),
 206                          0 as libc::size_t))?;
 207         if sz == 0 {
 208             return Err(io::Error::last_os_error())
 209         }
 210         let mut v: Vec<u8> = Vec::with_capacity(sz as usize);
 211         cvt(libc::sysctl(mib.as_mut_ptr(), mib.len() as ::libc::c_uint,
 212                          v.as_mut_ptr() as *mut libc::c_void, &mut sz,
 213                          ptr::null_mut(), 0 as libc::size_t))?;
 214         if sz == 0 {
 215             return Err(io::Error::last_os_error());
 216         }
 217         v.set_len(sz as usize - 1); // chop off trailing NUL
 218         Ok(PathBuf::from(OsString::from_vec(v)))
 219     }
 220 }
 221
 222 #[cfg(target_os = "dragonfly")]
 223 pub fn current_exe() -> io::Result<PathBuf> {
 224     ::fs::read_link("/proc/curproc/file")
 225 }
 226
 227 #[cfg(target_os = "netbsd")]
 228 pub fn current_exe() -> io::Result<PathBuf> {
 229     ::fs::read_link("/proc/curproc/exe")
 230 }
 231
 232 #[cfg(any(target_os = "bitrig", target_os = "openbsd"))]
 233 pub fn current_exe() -> io::Result<PathBuf> {
 234     unsafe {
 235         let mut mib = [libc::CTL_KERN,
 236                        libc::KERN_PROC_ARGS,
 237                        libc::getpid(),
 238                        libc::KERN_PROC_ARGV];
 239         let mib = mib.as_mut_ptr();
 240         let mut argv_len = 0;
 241         cvt(libc::sysctl(mib, 4, ptr::null_mut(), &mut argv_len,
 242                          ptr::null_mut(), 0))?;
 243         let mut argv = Vec::<*const libc::c_char>::with_capacity(argv_len as usize);
 244         cvt(libc::sysctl(mib, 4, argv.as_mut_ptr() as *mut _,
 245                          &mut argv_len, ptr::null_mut(), 0))?;
 246         argv.set_len(argv_len as usize);
 247         if argv[0].is_null() {
 248             return Err(io::Error::new(io::ErrorKind::Other,
 249                                       "no current exe available"))
 250         }
 251         let argv0 = CStr::from_ptr(argv[0]).to_bytes();
 252         if argv0[0] == b'.' || argv0.iter().any(|b| *b == b'/') {
 253             ::fs::canonicalize(OsStr::from_bytes(argv0))
 254         } else {
 255             Ok(PathBuf::from(OsStr::from_bytes(argv0)))
 256         }
 257     }
 258 }
 259
 260 #[cfg(any(target_os = "linux", target_os = "android", target_os = "emscripten"))]
 261 pub fn current_exe() -> io::Result<PathBuf> {
 262     ::fs::read_link("/proc/self/exe")
 263 }
 264
 265 #[cfg(any(target_os = "macos", target_os = "ios"))]
 266 pub fn current_exe() -> io::Result<PathBuf> {
 267     extern {
 268         fn _NSGetExecutablePath(buf: *mut libc::c_char,
 269                                 bufsize: *mut u32) -> libc::c_int;
 270     }
 271     unsafe {
 272         let mut sz: u32 = 0;
 273         _NSGetExecutablePath(ptr::null_mut(), &mut sz);
 274         if sz == 0 { return Err(io::Error::last_os_error()); }
 275         let mut v: Vec<u8> = Vec::with_capacity(sz as usize);
 276         let err = _NSGetExecutablePath(v.as_mut_ptr() as *mut i8, &mut sz);
 277         if err != 0 { return Err(io::Error::last_os_error()); }
 278         v.set_len(sz as usize - 1); // chop off trailing NUL
 279         Ok(PathBuf::from(OsString::from_vec(v)))
 280     }
 281 }
 282
 283 #[cfg(any(target_os = "solaris"))]
 284 pub fn current_exe() -> io::Result<PathBuf> {
 285     extern {
 286         fn getexecname() -> *const c_char;
 287     }
 288     unsafe {
 289         let path = getexecname();
 290         if path.is_null() {
 291             Err(io::Error::last_os_error())
 292         } else {
 293             let filename = CStr::from_ptr(path).to_bytes();
 294             let path = PathBuf::from(<OsStr as OsStrExt>::from_bytes(filename));
 295
 296             // Prepend a current working directory to the path if
 297             // it doesn't contain an absolute pathname.
 298             if filename[0] == b'/' {
 299                 Ok(path)
 300             } else {
 301                 getcwd().map(|cwd| cwd.join(path))
 302             }
 303         }
 304     }
 305 }
 306
 307 #[cfg(target_os = "haiku")]
 308 pub fn current_exe() -> io::Result<PathBuf> {
 309     // Use Haiku's image info functions
 310     #[repr(C)]
 311     struct image_info {
 312         id: i32,
 313         type_: i32,
 314         sequence: i32,
 315         init_order: i32,
 316         init_routine: *mut libc::c_void,    // function pointer
 317         term_routine: *mut libc::c_void,    // function pointer
 318         device: libc::dev_t,
 319         node: libc::ino_t,
 320         name: [libc::c_char; 1024],         // MAXPATHLEN
 321         text: *mut libc::c_void,
 322         data: *mut libc::c_void,
 323         text_size: i32,
 324         data_size: i32,
 325         api_version: i32,
 326         abi: i32,
 327     }
 328
 329     unsafe {
 330         extern {
 331             fn _get_next_image_info(team_id: i32, cookie: *mut i32,
 332                 info: *mut image_info, size: i32) -> i32;
 333         }
 334
 335         let mut info: image_info = mem::zeroed();
 336         let mut cookie: i32 = 0;
 337         // the executable can be found at team id 0
 338         let result = _get_next_image_info(0, &mut cookie, &mut info,
 339             mem::size_of::<image_info>() as i32);
 340         if result != 0 {
 341             use io::ErrorKind;
 342             Err(io::Error::new(ErrorKind::Other, "Error getting executable path"))
 343         } else {
 344             let name = CStr::from_ptr(info.name.as_ptr()).to_bytes();
 345             Ok(PathBuf::from(OsStr::from_bytes(name)))
 346         }
 347     }
 348 }
 349
 350 pub struct Args {
 351     iter: vec::IntoIter<OsString>,
 352     _dont_send_or_sync_me: PhantomData<*mut ()>,
 353 }
 354
 355 impl Iterator for Args {
 356     type Item = OsString;
 357     fn next(&mut self) -> Option<OsString> { self.iter.next() }
 358     fn size_hint(&self) -> (usize, Option<usize>) { self.iter.size_hint() }
 359 }
 360
 361 impl ExactSizeIterator for Args {
 362     fn len(&self) -> usize { self.iter.len() }
 363 }
 364
 365 impl DoubleEndedIterator for Args {
 366     fn next_back(&mut self) -> Option<OsString> { self.iter.next_back() }
 367 }
 368
 369 /// Returns the command line arguments
 370 ///
 371 /// Returns a list of the command line arguments.
 372 #[cfg(target_os = "macos")]
 373 pub fn args() -> Args {
 374     extern {
 375         // These functions are in crt_externs.h.
 376         fn _NSGetArgc() -> *mut c_int;
 377         fn _NSGetArgv() -> *mut *mut *mut c_char;
 378     }
 379
 380     let vec = unsafe {
 381         let (argc, argv) = (*_NSGetArgc() as isize,
 382                             *_NSGetArgv() as *const *const c_char);
 383         (0.. argc as isize).map(|i| {
 384             let bytes = CStr::from_ptr(*argv.offset(i)).to_bytes().to_vec();
 385             OsStringExt::from_vec(bytes)
 386         }).collect::<Vec<_>>()
 387     };
 388     Args {
 389         iter: vec.into_iter(),
 390         _dont_send_or_sync_me: PhantomData,
 391     }
 392 }
 393
 394 // As _NSGetArgc and _NSGetArgv aren't mentioned in iOS docs
 395 // and use underscores in their names - they're most probably
 396 // are considered private and therefore should be avoided
 397 // Here is another way to get arguments using Objective C
 398 // runtime
 399 //
 400 // In general it looks like:
 401 // res = Vec::new()
 402 // let args = [[NSProcessInfo processInfo] arguments]
 403 // for i in (0..[args count])
 404 //      res.push([args objectAtIndex:i])
 405 // res
 406 #[cfg(target_os = "ios")]
 407 pub fn args() -> Args {
 408     use mem;
 409
 410     extern {
 411         fn sel_registerName(name: *const libc::c_uchar) -> Sel;
 412         fn objc_msgSend(obj: NsId, sel: Sel, ...) -> NsId;
 413         fn objc_getClass(class_name: *const libc::c_uchar) -> NsId;
 414     }
 415
 416     #[link(name = "Foundation", kind = "framework")]
 417     #[link(name = "objc")]
 418     #[cfg(not(cargobuild))]
 419     extern {}
 420
 421     type Sel = *const libc::c_void;
 422     type NsId = *const libc::c_void;
 423
 424     let mut res = Vec::new();
 425
 426     unsafe {
 427         let process_info_sel = sel_registerName("processInfo\0".as_ptr());
 428         let arguments_sel = sel_registerName("arguments\0".as_ptr());
 429         let utf8_sel = sel_registerName("UTF8String\0".as_ptr());
 430         let count_sel = sel_registerName("count\0".as_ptr());
 431         let object_at_sel = sel_registerName("objectAtIndex:\0".as_ptr());
 432
 433         let klass = objc_getClass("NSProcessInfo\0".as_ptr());
 434         let info = objc_msgSend(klass, process_info_sel);
 435         let args = objc_msgSend(info, arguments_sel);
 436
 437         let cnt: usize = mem::transmute(objc_msgSend(args, count_sel));
 438         for i in 0..cnt {
 439             let tmp = objc_msgSend(args, object_at_sel, i);
 440             let utf_c_str: *const libc::c_char =
 441                 mem::transmute(objc_msgSend(tmp, utf8_sel));
 442             let bytes = CStr::from_ptr(utf_c_str).to_bytes();
 443             res.push(OsString::from(str::from_utf8(bytes).unwrap()))
 444         }
 445     }
 446
 447     Args { iter: res.into_iter(), _dont_send_or_sync_me: PhantomData }
 448 }
 449
 450 #[cfg(any(target_os = "linux",
 451           target_os = "android",
 452           target_os = "freebsd",
 453           target_os = "dragonfly",
 454           target_os = "bitrig",
 455           target_os = "netbsd",
 456           target_os = "openbsd",
 457           target_os = "solaris",
 458           target_os = "nacl",
 459           target_os = "emscripten",
 460           target_os = "haiku"))]
 461 pub fn args() -> Args {
 462     use sys_common;
 463     let bytes = sys_common::args::clone().unwrap_or(Vec::new());
 464     let v: Vec<OsString> = bytes.into_iter().map(|v| {
 465         OsStringExt::from_vec(v)
 466     }).collect();
 467     Args { iter: v.into_iter(), _dont_send_or_sync_me: PhantomData }
 468 }
 469
 470 pub struct Env {
 471     iter: vec::IntoIter<(OsString, OsString)>,
 472     _dont_send_or_sync_me: PhantomData<*mut ()>,
 473 }
 474
 475 impl Iterator for Env {
 476     type Item = (OsString, OsString);
 477     fn next(&mut self) -> Option<(OsString, OsString)> { self.iter.next() }
 478     fn size_hint(&self) -> (usize, Option<usize>) { self.iter.size_hint() }
 479 }
 480
 481 #[cfg(target_os = "macos")]
 482 pub unsafe fn environ() -> *mut *const *const c_char {
 483     extern { fn _NSGetEnviron() -> *mut *const *const c_char; }
 484     _NSGetEnviron()
 485 }
 486
 487 #[cfg(not(target_os = "macos"))]
 488 pub unsafe fn environ() -> *mut *const *const c_char {
 489     extern { static mut environ: *const *const c_char; }
 490     &mut environ
 491 }
 492
 493 /// Returns a vector of (variable, value) byte-vector pairs for all the
 494 /// environment variables of the current process.
 495 pub fn env() -> Env {
 496     unsafe {
 497         ENV_LOCK.lock();
 498         let mut environ = *environ();
 499         if environ == ptr::null() {
 500             ENV_LOCK.unlock();
 501             panic!("os::env() failure getting env string from OS: {}",
 502                    io::Error::last_os_error());
 503         }
 504         let mut result = Vec::new();
 505         while *environ != ptr::null() {
 506             if let Some(key_value) = parse(CStr::from_ptr(*environ).to_bytes()) {
 507                 result.push(key_value);
 508             }
 509             environ = environ.offset(1);
 510         }
 511         let ret = Env {
 512             iter: result.into_iter(),
 513             _dont_send_or_sync_me: PhantomData,
 514         };
 515         ENV_LOCK.unlock();
 516         return ret
 517     }
 518
 519     fn parse(input: &[u8]) -> Option<(OsString, OsString)> {
 520         // Strategy (copied from glibc): Variable name and value are separated
 521         // by an ASCII equals sign '='. Since a variable name must not be
 522         // empty, allow variable names starting with an equals sign. Skip all
 523         // malformed lines.
 524         if input.is_empty() {
 525             return None;
 526         }
 527         let pos = memchr::memchr(b'=', &input[1..]).map(|p| p + 1);
 528         pos.map(|p| (
 529             OsStringExt::from_vec(input[..p].to_vec()),
 530             OsStringExt::from_vec(input[p+1..].to_vec()),
 531         ))
 532     }
 533 }
 534
 535 pub fn getenv(k: &OsStr) -> io::Result<Option<OsString>> {
 536     // environment variables with a nul byte can't be set, so their value is
 537     // always None as well
 538     let k = CString::new(k.as_bytes())?;
 539     unsafe {
 540         ENV_LOCK.lock();
 541         let s = libc::getenv(k.as_ptr()) as *const _;
 542         let ret = if s.is_null() {
 543             None
 544         } else {
 545             Some(OsStringExt::from_vec(CStr::from_ptr(s).to_bytes().to_vec()))
 546         };
 547         ENV_LOCK.unlock();
 548         return Ok(ret)
 549     }
 550 }
 551
 552 pub fn setenv(k: &OsStr, v: &OsStr) -> io::Result<()> {
 553     let k = CString::new(k.as_bytes())?;
 554     let v = CString::new(v.as_bytes())?;
 555
 556     unsafe {
 557         ENV_LOCK.lock();
 558         let ret = cvt(libc::setenv(k.as_ptr(), v.as_ptr(), 1)).map(|_| ());
 559         ENV_LOCK.unlock();
 560         return ret
 561     }
 562 }
 563
 564 pub fn unsetenv(n: &OsStr) -> io::Result<()> {
 565     let nbuf = CString::new(n.as_bytes())?;
 566
 567     unsafe {
 568         ENV_LOCK.lock();
 569         let ret = cvt(libc::unsetenv(nbuf.as_ptr())).map(|_| ());
 570         ENV_LOCK.unlock();
 571         return ret
 572     }
 573 }
 574
 575 pub fn page_size() -> usize {
 576     unsafe {
 577         libc::sysconf(libc::_SC_PAGESIZE) as usize
 578     }
 579 }
 580
 581 pub fn temp_dir() -> PathBuf {
 582     ::env::var_os("TMPDIR").map(PathBuf::from).unwrap_or_else(|| {
 583         if cfg!(target_os = "android") {
 584             PathBuf::from("/data/local/tmp")
 585         } else {
 586             PathBuf::from("/tmp")
 587         }
 588     })
 589 }
 590
 591 pub fn home_dir() -> Option<PathBuf> {
 592     return ::env::var_os("HOME").or_else(|| unsafe {
 593         fallback()
 594     }).map(PathBuf::from);
 595
 596     #[cfg(any(target_os = "android",
 597               target_os = "ios",
 598               target_os = "nacl",
 599               target_os = "emscripten"))]
 600     unsafe fn fallback() -> Option<OsString> { None }
 601     #[cfg(not(any(target_os = "android",
 602                   target_os = "ios",
 603                   target_os = "nacl",
 604                   target_os = "emscripten")))]
 605     unsafe fn fallback() -> Option<OsString> {
 606         #[cfg(not(target_os = "solaris"))]
 607         unsafe fn getpwduid_r(me: libc::uid_t, passwd: &mut libc::passwd,
 608                               buf: &mut Vec<c_char>) -> Option<()> {
 609             let mut result = ptr::null_mut();
 610             match libc::getpwuid_r(me, passwd, buf.as_mut_ptr(),
 611                                    buf.capacity() as libc::size_t,
 612                                    &mut result) {
 613                 0 if !result.is_null() => Some(()),
 614                 _ => None
 615             }
 616         }
 617
 618         #[cfg(target_os = "solaris")]
 619         unsafe fn getpwduid_r(me: libc::uid_t, passwd: &mut libc::passwd,
 620                               buf: &mut Vec<c_char>) -> Option<()> {
 621             // getpwuid_r semantics is different on Illumos/Solaris:
 622             // http://illumos.org/man/3c/getpwuid_r
 623             let result = libc::getpwuid_r(me, passwd, buf.as_mut_ptr(),
 624                                           buf.capacity() as libc::size_t);
 625             if result.is_null() { None } else { Some(()) }
 626         }
 627
 628         let amt = match libc::sysconf(libc::_SC_GETPW_R_SIZE_MAX) {
 629             n if n < 0 => 512 as usize,
 630             n => n as usize,
 631         };
 632         let mut buf = Vec::with_capacity(amt);
 633         let mut passwd: libc::passwd = mem::zeroed();
 634
 635         if getpwduid_r(libc::getuid(), &mut passwd, &mut buf).is_some() {
 636             let ptr = passwd.pw_dir as *const _;
 637             let bytes = CStr::from_ptr(ptr).to_bytes().to_vec();
 638             Some(OsStringExt::from_vec(bytes))
 639         } else {
 640             None
 641         }
 642     }
 643 }
 644
 645 pub fn exit(code: i32) -> ! {
 646     unsafe { libc::exit(code as c_int) }
 647 }