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Implement RFC 1252 expanding the OpenOptions structure #30872

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merged 5 commits into from
Jan 20, 2016
Merged

Implement RFC 1252 expanding the OpenOptions structure #30872

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42f4dd0
Implement RFC 1252 expanding the OpenOptions structure
pitdicker Jan 13, 2016
7a1817c
Move `custom_flags` to `OpenOptionsExt`
pitdicker Jan 13, 2016
1230a08
Fix doctests
pitdicker Jan 14, 2016
9c56918
Addressed comments
pitdicker Jan 15, 2016
ae30294
Remove raw pointer from OpenOptions struct
pitdicker Jan 20, 2016
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203 changes: 156 additions & 47 deletions src/libstd/fs.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -375,7 +375,7 @@ impl<'a> Seek for &'a File {
}

impl OpenOptions {
/// Creates a blank net set of options ready for configuration.
/// Creates a blank new set of options ready for configuration.
///
/// All options are initially set to `false`.
///
Expand All @@ -384,7 +384,8 @@ impl OpenOptions {
/// ```no_run
/// use std::fs::OpenOptions;
///
/// let file = OpenOptions::new().open("foo.txt");
/// let mut options = OpenOptions::new();
/// let file = options.read(true).open("foo.txt");
/// ```
#[stable(feature = "rust1", since = "1.0.0")]
pub fn new() -> OpenOptions {
Expand Down Expand Up @@ -413,6 +414,9 @@ impl OpenOptions {
/// This option, when true, will indicate that the file should be
/// `write`-able if opened.
///
/// If a file already exist, any write calls on the file will overwrite its
/// contents, without truncating it.
///
/// # Examples
///
/// ```no_run
Expand All @@ -429,13 +433,30 @@ impl OpenOptions {
///
/// This option, when true, means that writes will append to a file instead
/// of overwriting previous contents.
/// Note that setting `.write(true).append(true)` has the same effect as
/// setting only `.append(true)`.
///
/// For most filesystems the operating system guarantees all writes are
/// atomic: no writes get mangled because another process writes at the same
/// time.
///
/// One maybe obvious note when using append-mode: make sure that all data
/// that belongs together, is written the the file in one operation. This
/// can be done by concatenating strings before passing them to `write()`,
/// or using a buffered writer (with a more than adequately sized buffer)
/// and calling `flush()` when the message is complete.
///
/// If a file is opened with both read and append access, beware that after
/// opening and after every write the position for reading may be set at the
/// end of the file. So before writing save the current position (using
/// `seek(SeekFrom::Current(0))`, and restore it before the next read.
///
/// # Examples
///
/// ```no_run
/// use std::fs::OpenOptions;
///
/// let file = OpenOptions::new().write(true).append(true).open("foo.txt");
/// let file = OpenOptions::new().append(true).open("foo.txt");
/// ```
#[stable(feature = "rust1", since = "1.0.0")]
pub fn append(&mut self, append: bool) -> &mut OpenOptions {
Expand All @@ -447,6 +468,8 @@ impl OpenOptions {
/// If a file is successfully opened with this option set it will truncate
/// the file to 0 length if it already exists.
///
/// The file must be opened with write access for truncate to work.
///
/// # Examples
///
/// ```no_run
Expand All @@ -464,29 +487,68 @@ impl OpenOptions {
/// This option indicates whether a new file will be created if the file
/// does not yet already exist.
///
/// The file must be opened with write or append access in order to create
/// a new file.
///
/// # Examples
///
/// ```no_run
/// use std::fs::OpenOptions;
///
/// let file = OpenOptions::new().create(true).open("foo.txt");
/// let file = OpenOptions::new().write(true).create(true).open("foo.txt");
/// ```
#[stable(feature = "rust1", since = "1.0.0")]
pub fn create(&mut self, create: bool) -> &mut OpenOptions {
self.0.create(create); self
}

/// Sets the option to always create a new file.
///
/// This option indicates whether a new file will be created.
/// No file is allowed to exist at the target location, also no (dangling)
/// symlink.
///
/// This option is usefull because it as atomic. Otherwise between checking
/// whether a file exists and creating a new one, the file may have been
/// created by another process (a TOCTOU race condition / attack).
///
/// If `.create_new(true)` is set, `.create()` and `.truncate()` are
/// ignored.
///
/// The file must be opened with write or append access in order to create
/// a new file.
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Could this explicitly call out the error mode of failing if the file already exists? (e.g. also calling out that it's atomic)

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O, of course. That is practically its only reason of existence :)

///
/// # Examples
///
/// ```no_run
/// #![feature(expand_open_options)]
/// use std::fs::OpenOptions;
///
/// let file = OpenOptions::new().write(true)
/// .create_new(true)
/// .open("foo.txt");
/// ```
#[unstable(feature = "expand_open_options",
reason = "recently added",
issue = "30014")]
pub fn create_new(&mut self, create_new: bool) -> &mut OpenOptions {
self.0.create_new(create_new); self
}

/// Opens a file at `path` with the options specified by `self`.
///
/// # Errors
///
/// This function will return an error under a number of different
/// circumstances, to include but not limited to:
///
/// * Opening a file that does not exist with read access.
/// * Opening a file that does not exist without setting `create` or
/// `create_new`.
/// * Attempting to open a file with access that the user lacks
/// permissions for
/// * Filesystem-level errors (full disk, etc)
/// * Invalid combinations of open options (truncate without write access,
/// no access mode set, etc)
///
/// # Examples
///
Expand Down Expand Up @@ -2098,61 +2160,108 @@ mod tests {

let mut r = OO::new(); r.read(true);
let mut w = OO::new(); w.write(true);
let mut rw = OO::new(); rw.write(true).read(true);

match r.open(&tmpdir.join("a")) {
Ok(..) => panic!(), Err(..) => {}
}

// Perform each one twice to make sure that it succeeds the second time
// (where the file exists)
check!(c(&w).create(true).open(&tmpdir.join("b")));
assert!(tmpdir.join("b").exists());
check!(c(&w).create(true).open(&tmpdir.join("b")));
check!(w.open(&tmpdir.join("b")));

check!(c(&rw).create(true).open(&tmpdir.join("c")));
assert!(tmpdir.join("c").exists());
let mut rw = OO::new(); rw.read(true).write(true);
let mut a = OO::new(); a.append(true);
let mut ra = OO::new(); ra.read(true).append(true);

let invalid_options = if cfg!(windows) { "The parameter is incorrect" }
else { "Invalid argument" };

// Test various combinations of creation modes and access modes.
//
// Allowed:
// creation mode | read | write | read-write | append | read-append |
// :-----------------------|:-----:|:-----:|:----------:|:------:|:-----------:|
// not set (open existing) | X | X | X | X | X |
// create | | X | X | X | X |
// truncate | | X | X | | |
// create and truncate | | X | X | | |
// create_new | | X | X | X | X |
//
// tested in reverse order, so 'create_new' creates the file, and 'open existing' opens it.

// write-only
check!(c(&w).create_new(true).open(&tmpdir.join("a")));
check!(c(&w).create(true).truncate(true).open(&tmpdir.join("a")));
check!(c(&w).truncate(true).open(&tmpdir.join("a")));
check!(c(&w).create(true).open(&tmpdir.join("a")));
check!(c(&w).open(&tmpdir.join("a")));

// read-only
error!(c(&r).create_new(true).open(&tmpdir.join("b")), invalid_options);
error!(c(&r).create(true).truncate(true).open(&tmpdir.join("b")), invalid_options);
error!(c(&r).truncate(true).open(&tmpdir.join("b")), invalid_options);
error!(c(&r).create(true).open(&tmpdir.join("b")), invalid_options);
check!(c(&r).open(&tmpdir.join("a"))); // try opening the file created with write_only

// read-write
check!(c(&rw).create_new(true).open(&tmpdir.join("c")));
check!(c(&rw).create(true).truncate(true).open(&tmpdir.join("c")));
check!(c(&rw).truncate(true).open(&tmpdir.join("c")));
check!(c(&rw).create(true).open(&tmpdir.join("c")));
check!(rw.open(&tmpdir.join("c")));

check!(c(&w).append(true).create(true).open(&tmpdir.join("d")));
assert!(tmpdir.join("d").exists());
check!(c(&w).append(true).create(true).open(&tmpdir.join("d")));
check!(c(&w).append(true).open(&tmpdir.join("d")));

check!(c(&rw).append(true).create(true).open(&tmpdir.join("e")));
assert!(tmpdir.join("e").exists());
check!(c(&rw).append(true).create(true).open(&tmpdir.join("e")));
check!(c(&rw).append(true).open(&tmpdir.join("e")));

check!(c(&w).truncate(true).create(true).open(&tmpdir.join("f")));
assert!(tmpdir.join("f").exists());
check!(c(&w).truncate(true).create(true).open(&tmpdir.join("f")));
check!(c(&w).truncate(true).open(&tmpdir.join("f")));

check!(c(&rw).truncate(true).create(true).open(&tmpdir.join("g")));
assert!(tmpdir.join("g").exists());
check!(c(&rw).truncate(true).create(true).open(&tmpdir.join("g")));
check!(c(&rw).truncate(true).open(&tmpdir.join("g")));

check!(check!(File::create(&tmpdir.join("h"))).write("foo".as_bytes()));
check!(c(&rw).open(&tmpdir.join("c")));

// append
check!(c(&a).create_new(true).open(&tmpdir.join("d")));
error!(c(&a).create(true).truncate(true).open(&tmpdir.join("d")), invalid_options);
error!(c(&a).truncate(true).open(&tmpdir.join("d")), invalid_options);
check!(c(&a).create(true).open(&tmpdir.join("d")));
check!(c(&a).open(&tmpdir.join("d")));

// read-append
check!(c(&ra).create_new(true).open(&tmpdir.join("e")));
error!(c(&ra).create(true).truncate(true).open(&tmpdir.join("e")), invalid_options);
error!(c(&ra).truncate(true).open(&tmpdir.join("e")), invalid_options);
check!(c(&ra).create(true).open(&tmpdir.join("e")));
check!(c(&ra).open(&tmpdir.join("e")));

// Test opening a file without setting an access mode
let mut blank = OO::new();
error!(blank.create(true).open(&tmpdir.join("f")), invalid_options);

// Test write works
check!(check!(File::create(&tmpdir.join("h"))).write("foobar".as_bytes()));

// Test write fails for read-only
check!(r.open(&tmpdir.join("h")));
{
let mut f = check!(r.open(&tmpdir.join("h")));
assert!(f.write("wut".as_bytes()).is_err());
}

// Test write overwrites
{
let mut f = check!(c(&w).open(&tmpdir.join("h")));
check!(f.write("baz".as_bytes()));
}
{
let mut f = check!(c(&r).open(&tmpdir.join("h")));
let mut b = vec![0; 6];
check!(f.read(&mut b));
assert_eq!(b, "bazbar".as_bytes());
}

// Test truncate works
{
let mut f = check!(c(&w).truncate(true).open(&tmpdir.join("h")));
check!(f.write("foo".as_bytes()));
}
assert_eq!(check!(fs::metadata(&tmpdir.join("h"))).len(), 3);

// Test append works
assert_eq!(check!(fs::metadata(&tmpdir.join("h"))).len(), 3);
{
let mut f = check!(c(&w).append(true).open(&tmpdir.join("h")));
let mut f = check!(c(&a).open(&tmpdir.join("h")));
check!(f.write("bar".as_bytes()));
}
assert_eq!(check!(fs::metadata(&tmpdir.join("h"))).len(), 6);

// Test .append(true) equals .write(true).append(true)
{
let mut f = check!(c(&w).truncate(true).open(&tmpdir.join("h")));
check!(f.write("bar".as_bytes()));
let mut f = check!(c(&w).append(true).open(&tmpdir.join("h")));
check!(f.write("baz".as_bytes()));
}
assert_eq!(check!(fs::metadata(&tmpdir.join("h"))).len(), 3);
assert_eq!(check!(fs::metadata(&tmpdir.join("h"))).len(), 9);
}

#[test]
Expand Down
35 changes: 34 additions & 1 deletion src/libstd/sys/unix/ext/fs.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -99,15 +99,49 @@ pub trait OpenOptionsExt {
///
/// If a new file is created as part of a `File::open_opts` call then this
/// specified `mode` will be used as the permission bits for the new file.
/// If no `mode` is set, the default of `0o666` will be used.
/// The operating system masks out bits with the systems `umask`, to produce
/// the final permissions.
#[stable(feature = "fs_ext", since = "1.1.0")]
fn mode(&mut self, mode: raw::mode_t) -> &mut Self;

/// Pass custom flags to the `flags` agument of `open`.
///
/// The bits that define the access mode are masked out with `O_ACCMODE`, to
/// ensure they do not interfere with the access mode set by Rusts options.
///
/// Custom flags can only set flags, not remove flags set by Rusts options.
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Could this clarify that any previously set custom flags are overwritten?

/// This options overwrites any previously set custom flags.
///
/// # Examples
///
/// ```rust,ignore
/// extern crate libc;
/// use std::fs::OpenOptions;
/// use std::os::unix::fs::OpenOptionsExt;
///
/// let mut options = OpenOptions::new();
/// options.write(true);
/// if cfg!(unix) {
/// options.custom_flags(libc::O_NOFOLLOW);
/// }
/// let file = options.open("foo.txt");
/// ```
#[unstable(feature = "expand_open_options",
reason = "recently added",
issue = "30014")]
fn custom_flags(&mut self, flags: i32) -> &mut Self;
}

#[stable(feature = "fs_ext", since = "1.1.0")]
impl OpenOptionsExt for OpenOptions {
fn mode(&mut self, mode: raw::mode_t) -> &mut OpenOptions {
self.as_inner_mut().mode(mode); self
}

fn custom_flags(&mut self, flags: i32) -> &mut OpenOptions {
self.as_inner_mut().custom_flags(flags); self
}
}

// Hm, why are there casts here to the returned type, shouldn't the types always
Expand Down Expand Up @@ -262,4 +296,3 @@ impl DirBuilderExt for fs::DirBuilder {
self
}
}

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