src/tools.rs

   1 //! Tools and utilities
   2 //!
   3 //! This is a collection of small and useful tools.
   4 use failure::*;
   5 use nix::unistd;
   6 use nix::sys::stat;
   7 use nix::{convert_ioctl_res, request_code_read, ioc};
   8
   9 use lazy_static::lazy_static;
  10
  11 use std::fs::{File, OpenOptions};
  12 use std::io::Write;
  13 use std::path::Path;
  14 use std::io::Read;
  15 use std::io::ErrorKind;
  16 use std::time::Duration;
  17 use std::any::Any;
  18
  19 use std::os::unix::io::{AsRawFd, FromRawFd, IntoRawFd, RawFd};
  20
  21 use std::collections::HashMap;
  22
  23 use serde_json::Value;
  24
  25 use proxmox::tools::vec;
  26
  27 pub mod async_mutex;
  28 pub mod timer;
  29 pub mod wrapped_reader_stream;
  30 #[macro_use]
  31 pub mod common_regex;
  32 pub mod ticket;
  33 pub mod borrow;
  34 pub mod fs;
  35 pub mod tty;
  36 pub mod signalfd;
  37 pub mod daemon;
  38 pub mod procfs;
  39 pub mod acl;
  40 pub mod xattr;
  41 pub mod futures;
  42
  43 mod process_locker;
  44 pub use process_locker::*;
  45
  46 #[macro_use]
  47 mod file_logger;
  48 pub use file_logger::*;
  49
  50 mod broadcast_future;
  51 pub use broadcast_future::*;
  52
  53 /// Macro to write error-handling blocks (like perl eval {})
  54 ///
  55 /// #### Example:
  56 /// ```
  57 /// # #[macro_use] extern crate proxmox_backup;
  58 /// # use failure::*;
  59 /// # let some_condition = false;
  60 /// let result = try_block!({
  61 ///     if (some_condition) {
  62 ///         bail!("some error");
  63 ///     }
  64 ///     Ok(())
  65 /// })
  66 /// .map_err(|e| format_err!("my try block returned an error - {}", e));
  67 /// ```
  68
  69 #[macro_export]
  70 macro_rules! try_block {
  71     { $($token:tt)* } => {{ (|| -> Result<_,_> { $($token)* })() }}
  72 }
  73
  74
  75 /// The `BufferedRead` trait provides a single function
  76 /// `buffered_read`. It returns a reference to an internal buffer. The
  77 /// purpose of this traid is to avoid unnecessary data copies.
  78 pub trait BufferedRead {
  79     /// This functions tries to fill the internal buffers, then
  80     /// returns a reference to the available data. It returns an empty
  81     /// buffer if `offset` points to the end of the file.
  82     fn buffered_read(&mut self, offset: u64) -> Result<&[u8], Error>;
  83 }
  84
  85 /// Directly map a type into a binary buffer. This is mostly useful
  86 /// for reading structured data from a byte stream (file). You need to
  87 /// make sure that the buffer location does not change, so please
  88 /// avoid vec resize while you use such map.
  89 ///
  90 /// This function panics if the buffer is not large enough.
  91 pub fn map_struct<T>(buffer: &[u8]) -> Result<&T, Error> {
  92     if buffer.len() < ::std::mem::size_of::<T>() {
  93         bail!("unable to map struct - buffer too small");
  94     }
  95     Ok(unsafe { & * (buffer.as_ptr() as *const T) })
  96 }
  97
  98 /// Directly map a type into a mutable binary buffer. This is mostly
  99 /// useful for writing structured data into a byte stream (file). You
 100 /// need to make sure that the buffer location does not change, so
 101 /// please avoid vec resize while you use such map.
 102 ///
 103 /// This function panics if the buffer is not large enough.
 104 pub fn map_struct_mut<T>(buffer: &mut [u8]) -> Result<&mut T, Error> {
 105     if buffer.len() < ::std::mem::size_of::<T>() {
 106         bail!("unable to map struct - buffer too small");
 107     }
 108     Ok(unsafe { &mut * (buffer.as_ptr() as *mut T) })
 109 }
 110
 111 pub fn file_read_firstline<P: AsRef<Path>>(path: P) -> Result<String, Error> {
 112
 113     let path = path.as_ref();
 114
 115     try_block!({
 116         let file = std::fs::File::open(path)?;
 117
 118         use std::io::{BufRead, BufReader};
 119
 120         let mut reader = BufReader::new(file);
 121
 122         let mut line = String::new();
 123
 124         let _ = reader.read_line(&mut line)?;
 125
 126         Ok(line)
 127     }).map_err(|err: Error| format_err!("unable to read {:?} - {}", path, err))
 128 }
 129
 130 pub fn file_get_contents<P: AsRef<Path>>(path: P) -> Result<Vec<u8>, Error> {
 131
 132     let path = path.as_ref();
 133
 134     try_block!({
 135         std::fs::read(path)
 136     }).map_err(|err| format_err!("unable to read {:?} - {}", path, err))
 137 }
 138
 139 pub fn file_get_json<P: AsRef<Path>>(path: P, default: Option<Value>) -> Result<Value, Error> {
 140
 141     let path = path.as_ref();
 142
 143     let raw = match std::fs::read(path) {
 144         Ok(v) => v,
 145         Err(err) => {
 146             if err.kind() ==  std::io::ErrorKind::NotFound {
 147                 if let Some(v) = default {
 148                     return Ok(v);
 149                 }
 150             }
 151             bail!("unable to read json {:?} - {}", path, err);
 152         }
 153     };
 154
 155     try_block!({
 156         let data = String::from_utf8(raw)?;
 157         let json = serde_json::from_str(&data)?;
 158         Ok(json)
 159     }).map_err(|err: Error| format_err!("unable to parse json from {:?} - {}", path, err))
 160 }
 161
 162 /// Atomically write a file
 163 ///
 164 /// We first create a temporary file, which is then renamed.
 165 pub fn file_set_contents<P: AsRef<Path>>(
 166     path: P,
 167     data: &[u8],
 168     perm: Option<stat::Mode>,
 169 ) -> Result<(), Error> {
 170     file_set_contents_full(path, data, perm, None, None)
 171 }
 172
 173 /// Atomically write a file with owner and group
 174 pub fn file_set_contents_full<P: AsRef<Path>>(
 175     path: P,
 176     data: &[u8],
 177     perm: Option<stat::Mode>,
 178     owner: Option<unistd::Uid>,
 179     group: Option<unistd::Gid>,
 180 ) -> Result<(), Error> {
 181
 182     let path = path.as_ref();
 183
 184     // Note: we use mkstemp heŕe, because this worka with different
 185     // processes, threads, and even tokio tasks.
 186     let mut template = path.to_owned();
 187     template.set_extension("tmp_XXXXXX");
 188     let (fd, tmp_path) = match unistd::mkstemp(&template) {
 189         Ok((fd, path)) => (fd, path),
 190         Err(err) => bail!("mkstemp {:?} failed: {}", template, err),
 191     };
 192
 193     let tmp_path = tmp_path.as_path();
 194
 195     let mode : stat::Mode = perm.unwrap_or(stat::Mode::from(
 196         stat::Mode::S_IRUSR | stat::Mode::S_IWUSR |
 197         stat::Mode::S_IRGRP | stat::Mode::S_IROTH
 198     ));
 199
 200     if perm != None {
 201         if let Err(err) = stat::fchmod(fd, mode) {
 202             let _ = unistd::unlink(tmp_path);
 203             bail!("fchmod {:?} failed: {}", tmp_path, err);
 204         }
 205     }
 206
 207     if owner != None || group != None {
 208         if let Err(err) = fchown(fd, owner, group) {
 209             let _ = unistd::unlink(tmp_path);
 210             bail!("fchown {:?} failed: {}", tmp_path, err);
 211         }
 212     }
 213
 214     let mut file = unsafe { File::from_raw_fd(fd) };
 215
 216     if let Err(err) = file.write_all(data) {
 217         let _ = unistd::unlink(tmp_path);
 218         bail!("write failed: {}", err);
 219     }
 220
 221     if let Err(err) = std::fs::rename(tmp_path, path) {
 222         let _ = unistd::unlink(tmp_path);
 223         bail!("Atomic rename failed for file {:?} - {}", path, err);
 224     }
 225
 226     Ok(())
 227 }
 228
 229 /// Create a file lock using fntl. This function allows you to specify
 230 /// a timeout if you want to avoid infinite blocking.
 231 pub fn lock_file<F: AsRawFd>(
 232     file: &mut F,
 233     exclusive: bool,
 234     timeout: Option<Duration>,
 235 ) -> Result<(), Error> {
 236     let lockarg =
 237         if exclusive {
 238             nix::fcntl::FlockArg::LockExclusive
 239         } else {
 240             nix::fcntl::FlockArg::LockShared
 241         };
 242
 243     let timeout = match timeout {
 244         None => {
 245             nix::fcntl::flock(file.as_raw_fd(), lockarg)?;
 246             return Ok(());
 247         }
 248         Some(t) => t,
 249     };
 250
 251     // unblock the timeout signal temporarily
 252     let _sigblock_guard = timer::unblock_timeout_signal();
 253
 254     // setup a timeout timer
 255     let mut timer = timer::Timer::create(
 256         timer::Clock::Realtime,
 257         timer::TimerEvent::ThisThreadSignal(timer::SIGTIMEOUT))?;
 258
 259     timer.arm(timer::TimerSpec::new()
 260         .value(Some(timeout))
 261         .interval(Some(Duration::from_millis(10))))?;
 262
 263     nix::fcntl::flock(file.as_raw_fd(), lockarg)?;
 264     Ok(())
 265 }
 266
 267 /// Open or create a lock file (append mode). Then try to
 268 /// aquire a lock using `lock_file()`.
 269 pub fn open_file_locked<P: AsRef<Path>>(path: P, timeout: Duration)
 270     -> Result<File, Error>
 271 {
 272     let path = path.as_ref();
 273     let mut file =
 274         match OpenOptions::new()
 275             .create(true)
 276             .append(true)
 277             .open(path)
 278         {
 279             Ok(file) => file,
 280             Err(err) => bail!("Unable to open lock {:?} - {}",
 281                               path, err),
 282         };
 283     match lock_file(&mut file, true, Some(timeout)) {
 284         Ok(_) => Ok(file),
 285         Err(err) => bail!("Unable to aquire lock {:?} - {}",
 286                           path, err),
 287     }
 288 }
 289
 290 /// Split a file into equal sized chunks. The last chunk may be
 291 /// smaller. Note: We cannot implement an `Iterator`, because iterators
 292 /// cannot return a borrowed buffer ref (we want zero-copy)
 293 pub fn file_chunker<C, R>(
 294     mut file: R,
 295     chunk_size: usize,
 296     mut chunk_cb: C
 297 ) -> Result<(), Error>
 298     where C: FnMut(usize, &[u8]) -> Result<bool, Error>,
 299           R: Read,
 300 {
 301
 302     const READ_BUFFER_SIZE: usize = 4*1024*1024; // 4M
 303
 304     if chunk_size > READ_BUFFER_SIZE { bail!("chunk size too large!"); }
 305
 306     let mut buf = vec::undefined(READ_BUFFER_SIZE);
 307
 308     let mut pos = 0;
 309     let mut file_pos = 0;
 310     loop {
 311         let mut eof = false;
 312         let mut tmp = &mut buf[..];
 313        // try to read large portions, at least chunk_size
 314         while pos < chunk_size {
 315             match file.read(tmp) {
 316                 Ok(0) => { eof = true; break; },
 317                 Ok(n) => {
 318                     pos += n;
 319                     if pos > chunk_size { break; }
 320                     tmp = &mut tmp[n..];
 321                 }
 322                 Err(ref e) if e.kind() == ErrorKind::Interrupted => { /* try again */ }
 323                 Err(e) => bail!("read chunk failed - {}", e.to_string()),
 324             }
 325         }
 326         let mut start = 0;
 327         while start + chunk_size <= pos {
 328             if !(chunk_cb)(file_pos, &buf[start..start+chunk_size])? { break; }
 329             file_pos += chunk_size;
 330             start += chunk_size;
 331         }
 332         if eof {
 333             if start < pos {
 334                 (chunk_cb)(file_pos, &buf[start..pos])?;
 335                 //file_pos += pos - start;
 336             }
 337             break;
 338         } else {
 339             let rest = pos - start;
 340             if rest > 0 {
 341                 let ptr = buf.as_mut_ptr();
 342                 unsafe { std::ptr::copy_nonoverlapping(ptr.add(start), ptr, rest); }
 343                 pos = rest;
 344             } else {
 345                 pos = 0;
 346             }
 347         }
 348     }
 349
 350     Ok(())
 351 }
 352
 353 /// Returns the Unix uid/gid for the sepcified system user.
 354 pub fn getpwnam_ugid(username: &str) -> Result<(libc::uid_t,libc::gid_t), Error> {
 355     let info = unsafe { libc::getpwnam(std::ffi::CString::new(username).unwrap().as_ptr()) };
 356     if info == std::ptr::null_mut() {
 357         bail!("getwpnam '{}' failed", username);
 358     }
 359
 360     let info = unsafe { *info };
 361
 362     Ok((info.pw_uid, info.pw_gid))
 363 }
 364
 365 /// Creates directory at the provided path with specified ownership
 366 ///
 367 /// Simply returns if the directory already exists.
 368 pub fn create_dir_chown<P: AsRef<Path>>(
 369     path: P,
 370     perm: Option<stat::Mode>,
 371     owner: Option<unistd::Uid>,
 372     group: Option<unistd::Gid>,
 373 ) -> Result<(), nix::Error>
 374 {
 375     let mode : stat::Mode = perm.unwrap_or(stat::Mode::from_bits_truncate(0o770));
 376
 377     let path = path.as_ref();
 378
 379     match nix::unistd::mkdir(path, mode) {
 380         Ok(()) => {},
 381         Err(nix::Error::Sys(nix::errno::Errno::EEXIST)) => {
 382             return Ok(());
 383         },
 384         err => return err,
 385     }
 386
 387     unistd::chown(path, owner, group)?;
 388
 389     Ok(())
 390 }
 391
 392 /// Change ownership of an open file handle
 393 pub fn fchown(
 394     fd: RawFd,
 395     owner: Option<nix::unistd::Uid>,
 396     group: Option<nix::unistd::Gid>
 397 ) -> Result<(), Error> {
 398
 399     // According to the POSIX specification, -1 is used to indicate that owner and group
 400     // are not to be changed.  Since uid_t and gid_t are unsigned types, we have to wrap
 401     // around to get -1 (copied fron nix crate).
 402     let uid = owner.map(Into::into).unwrap_or((0 as libc::uid_t).wrapping_sub(1));
 403     let gid = group.map(Into::into).unwrap_or((0 as libc::gid_t).wrapping_sub(1));
 404
 405     let res = unsafe { libc::fchown(fd, uid, gid) };
 406     nix::errno::Errno::result(res)?;
 407
 408     Ok(())
 409 }
 410
 411 // Returns the hosts node name (UTS node name)
 412 pub fn nodename() -> &'static str {
 413
 414     lazy_static!{
 415         static ref NODENAME: String = {
 416
 417             nix::sys::utsname::uname()
 418                 .nodename()
 419                 .split('.')
 420                 .next()
 421                 .unwrap()
 422                 .to_owned()
 423         };
 424     }
 425
 426     &NODENAME
 427 }
 428
 429 pub fn json_object_to_query(data: Value) -> Result<String, Error> {
 430
 431     let mut query = url::form_urlencoded::Serializer::new(String::new());
 432
 433     let object = data.as_object().ok_or_else(|| {
 434         format_err!("json_object_to_query: got wrong data type (expected object).")
 435     })?;
 436
 437     for (key, value) in object {
 438         match value {
 439             Value::Bool(b) => { query.append_pair(key, &b.to_string()); }
 440             Value::Number(n) => { query.append_pair(key, &n.to_string()); }
 441             Value::String(s) => { query.append_pair(key, &s); }
 442             Value::Array(arr) => {
 443                 for element in arr {
 444                     match element {
 445                         Value::Bool(b) => { query.append_pair(key, &b.to_string()); }
 446                         Value::Number(n) => { query.append_pair(key, &n.to_string()); }
 447                         Value::String(s) => { query.append_pair(key, &s); }
 448                         _ => bail!("json_object_to_query: unable to handle complex array data types."),
 449                     }
 450                 }
 451             }
 452             _ => bail!("json_object_to_query: unable to handle complex data types."),
 453         }
 454     }
 455
 456     Ok(query.finish())
 457 }
 458
 459 pub fn required_string_param<'a>(param: &'a Value, name: &str) -> Result<&'a str, Error> {
 460     match param[name].as_str()   {
 461         Some(s) => Ok(s),
 462         None => bail!("missing parameter '{}'", name),
 463     }
 464 }
 465
 466 pub fn required_integer_param<'a>(param: &'a Value, name: &str) -> Result<i64, Error> {
 467     match param[name].as_i64()   {
 468         Some(s) => Ok(s),
 469         None => bail!("missing parameter '{}'", name),
 470     }
 471 }
 472
 473 pub fn required_array_param<'a>(param: &'a Value, name: &str) -> Result<Vec<Value>, Error> {
 474     match param[name].as_array()   {
 475         Some(s) => Ok(s.to_vec()),
 476         None => bail!("missing parameter '{}'", name),
 477     }
 478 }
 479
 480 pub fn complete_file_name(arg: &str, _param: &HashMap<String, String>) -> Vec<String> {
 481
 482     let mut result = vec![];
 483
 484     use nix::fcntl::OFlag;
 485     use nix::sys::stat::Mode;
 486     use nix::fcntl::AtFlags;
 487
 488     let mut dirname = std::path::PathBuf::from(if arg.len() == 0 { "./" } else { arg });
 489
 490     let is_dir = match nix::sys::stat::fstatat(libc::AT_FDCWD, &dirname, AtFlags::empty()) {
 491         Ok(stat) => (stat.st_mode & libc::S_IFMT) == libc::S_IFDIR,
 492         Err(_) => false,
 493     };
 494
 495     if !is_dir {
 496         if let Some(parent) = dirname.parent() {
 497             dirname = parent.to_owned();
 498         }
 499     }
 500
 501     let mut dir = match nix::dir::Dir::openat(libc::AT_FDCWD, &dirname, OFlag::O_DIRECTORY, Mode::empty()) {
 502         Ok(d) => d,
 503         Err(_) => return result,
 504     };
 505
 506     for item in dir.iter() {
 507         if let Ok(entry) = item {
 508             if let Ok(name) = entry.file_name().to_str() {
 509                 if name == "." || name == ".." { continue; }
 510                 let mut newpath = dirname.clone();
 511                 newpath.push(name);
 512
 513                 if let Ok(stat) = nix::sys::stat::fstatat(libc::AT_FDCWD, &newpath, AtFlags::empty()) {
 514                     if (stat.st_mode & libc::S_IFMT) == libc::S_IFDIR {
 515                         newpath.push("");
 516                         if let Some(newpath) = newpath.to_str() {
 517                             result.push(newpath.to_owned());
 518                         }
 519                         continue;
 520                      }
 521                 }
 522                 if let Some(newpath) = newpath.to_str() {
 523                     result.push(newpath.to_owned());
 524                 }
 525
 526              }
 527         }
 528     }
 529
 530     result
 531 }
 532
 533 /// Scan directory for matching file names.
 534 ///
 535 /// Scan through all directory entries and call `callback()` function
 536 /// if the entry name matches the regular expression. This function
 537 /// used unix `openat()`, so you can pass absolute or relative file
 538 /// names. This function simply skips non-UTF8 encoded names.
 539 pub fn scandir<P, F>(
 540     dirfd: RawFd,
 541     path: &P,
 542     regex: &regex::Regex,
 543     mut callback: F
 544 ) -> Result<(), Error>
 545     where F: FnMut(RawFd, &str, nix::dir::Type) -> Result<(), Error>,
 546           P: ?Sized + nix::NixPath,
 547 {
 548     for entry in self::fs::scan_subdir(dirfd, path, regex)? {
 549         let entry = entry?;
 550         let file_type = match entry.file_type() {
 551             Some(file_type) => file_type,
 552             None => bail!("unable to detect file type"),
 553         };
 554
 555         callback(entry.parent_fd(), unsafe { entry.file_name_utf8_unchecked() }, file_type)?;
 556     }
 557     Ok(())
 558 }
 559
 560 pub fn get_hardware_address() -> Result<String, Error> {
 561
 562     static FILENAME: &str = "/etc/ssh/ssh_host_rsa_key.pub";
 563
 564     let contents = file_get_contents(FILENAME)?;
 565     let digest = md5::compute(contents);
 566
 567     Ok(format!("{:0x}", digest))
 568 }
 569
 570
 571 pub fn assert_if_modified(digest1: &str, digest2: &str) -> Result<(), Error> {
 572     if digest1 != digest2 {
 573         bail!("detected modified configuration - file changed by other user? Try again.");
 574     }
 575     Ok(())
 576 }
 577
 578 /// Extract authentication cookie from cookie header.
 579 /// We assume cookie_name is already url encoded.
 580 pub fn extract_auth_cookie(cookie: &str, cookie_name: &str) -> Option<String> {
 581
 582     for pair in cookie.split(';') {
 583
 584         let (name, value) = match pair.find('=') {
 585             Some(i) => (pair[..i].trim(), pair[(i + 1)..].trim()),
 586             None => return None, // Cookie format error
 587         };
 588
 589         if name == cookie_name {
 590             use url::percent_encoding::percent_decode;
 591             if let Ok(value) = percent_decode(value.as_bytes()).decode_utf8() {
 592                 return Some(value.into());
 593             } else {
 594                 return None; // Cookie format error
 595             }
 596         }
 597     }
 598
 599     None
 600 }
 601
 602 pub fn join(data: &Vec<String>, sep: char) -> String {
 603
 604     let mut list = String::new();
 605
 606     for item in data {
 607         if list.len() != 0 { list.push(sep); }
 608         list.push_str(item);
 609     }
 610
 611     list
 612 }
 613
 614 /// normalize uri path
 615 ///
 616 /// Do not allow ".", "..", or hidden files ".XXXX"
 617 /// Also remove empty path components
 618 pub fn normalize_uri_path(path: &str) -> Result<(String, Vec<&str>), Error> {
 619
 620     let items = path.split('/');
 621
 622     let mut path = String::new();
 623     let mut components = vec![];
 624
 625     for name in items {
 626         if name.is_empty() { continue; }
 627         if name.starts_with(".") {
 628             bail!("Path contains illegal components.");
 629         }
 630         path.push('/');
 631         path.push_str(name);
 632         components.push(name);
 633     }
 634
 635     Ok((path, components))
 636 }
 637
 638 pub fn fd_change_cloexec(fd: RawFd, on: bool) -> Result<(), Error> {
 639     use nix::fcntl::{fcntl, F_GETFD, F_SETFD, FdFlag};
 640     let mut flags = FdFlag::from_bits(fcntl(fd, F_GETFD)?)
 641         .ok_or_else(|| format_err!("unhandled file flags"))?; // nix crate is stupid this way...
 642     flags.set(FdFlag::FD_CLOEXEC, on);
 643     fcntl(fd, F_SETFD(flags))?;
 644     Ok(())
 645 }
 646
 647
 648 static mut SHUTDOWN_REQUESTED: bool = false;
 649
 650 pub fn request_shutdown() {
 651     unsafe { SHUTDOWN_REQUESTED = true; }
 652     crate::server::server_shutdown();
 653 }
 654
 655 #[inline(always)]
 656 pub fn shutdown_requested() -> bool {
 657     unsafe { SHUTDOWN_REQUESTED }
 658 }
 659
 660 pub fn fail_on_shutdown() -> Result<(), Error> {
 661     if shutdown_requested() {
 662         bail!("Server shutdown requested - aborting task");
 663     }
 664     Ok(())
 665 }
 666
 667 /// Guard a raw file descriptor with a drop handler. This is mostly useful when access to an owned
 668 /// `RawFd` is required without the corresponding handler object (such as when only the file
 669 /// descriptor number is required in a closure which may be dropped instead of being executed).
 670 pub struct Fd(pub RawFd);
 671
 672 impl Drop for Fd {
 673     fn drop(&mut self) {
 674         if self.0 != -1 {
 675             unsafe {
 676                 libc::close(self.0);
 677             }
 678         }
 679     }
 680 }
 681
 682 impl AsRawFd for Fd {
 683     fn as_raw_fd(&self) -> RawFd {
 684         self.0
 685     }
 686 }
 687
 688 impl IntoRawFd for Fd {
 689     fn into_raw_fd(mut self) -> RawFd {
 690         let fd = self.0;
 691         self.0 = -1;
 692         fd
 693     }
 694 }
 695
 696 impl FromRawFd for Fd {
 697     unsafe fn from_raw_fd(fd: RawFd) -> Self {
 698         Self(fd)
 699     }
 700 }
 701
 702 // wrap nix::unistd::pipe2 + O_CLOEXEC into something returning guarded file descriptors
 703 pub fn pipe() -> Result<(Fd, Fd), Error> {
 704     let (pin, pout) = nix::unistd::pipe2(nix::fcntl::OFlag::O_CLOEXEC)?;
 705     Ok((Fd(pin), Fd(pout)))
 706 }
 707
 708 /// An easy way to convert types to Any
 709 ///
 710 /// Mostly useful to downcast trait objects (see RpcEnvironment).
 711 pub trait AsAny {
 712     fn as_any(&self) -> &dyn Any;
 713 }
 714
 715 impl<T: Any> AsAny for T {
 716     fn as_any(&self) -> &dyn Any { self }
 717 }
 718
 719
 720 // /usr/include/linux/fs.h: #define BLKGETSIZE64 _IOR(0x12,114,size_t)
 721 // return device size in bytes (u64 *arg)
 722 nix::ioctl_read!(blkgetsize64, 0x12, 114, u64);
 723
 724 /// Return file or block device size
 725 pub fn image_size(path: &Path) -> Result<u64, Error> {
 726
 727     use std::os::unix::fs::FileTypeExt;
 728
 729     let file = std::fs::File::open(path)?;
 730     let metadata = file.metadata()?;
 731     let file_type = metadata.file_type();
 732
 733     if file_type.is_block_device() {
 734         let mut size : u64 = 0;
 735         let res = unsafe { blkgetsize64(file.as_raw_fd(), &mut size) };
 736
 737         if let Err(err) = res {
 738             bail!("blkgetsize64 failed for {:?} - {}", path, err);
 739         }
 740         Ok(size)
 741     } else if file_type.is_file() {
 742         Ok(metadata.len())
 743     } else {
 744         bail!("image size failed - got unexpected file type {:?}", file_type);
 745     }
 746 }