1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 300 301 302 303 304 305 306 307 308 309 310 311 312 313 314
use std::future::Future;
use crate::fs::File;
use crate::io;
use crate::path::Path;
use crate::task::spawn_blocking;
/// A builder for opening files with configurable options.
///
/// Files can be opened in [`read`] and/or [`write`] mode.
///
/// The [`append`] option opens files in a special writing mode that moves the file cursor to the
/// end of file before every write operation.
///
/// It is also possible to [`truncate`] the file right after opening, to [`create`] a file if it
/// doesn't exist yet, or to always create a new file with [`create_new`].
///
/// This type is an async version of [`std::fs::OpenOptions`].
///
/// [`read`]: #method.read
/// [`write`]: #method.write
/// [`append`]: #method.append
/// [`truncate`]: #method.truncate
/// [`create`]: #method.create
/// [`create_new`]: #method.create_new
/// [`std::fs::OpenOptions`]: https://doc.rust-lang.org/std/fs/struct.OpenOptions.html
///
/// # Examples
///
/// Open a file for reading:
///
/// ```no_run
/// # fn main() -> std::io::Result<()> { async_std::task::block_on(async {
/// #
/// use async_std::fs::OpenOptions;
///
/// let file = OpenOptions::new()
/// .read(true)
/// .open("a.txt")
/// .await?;
/// #
/// # Ok(()) }) }
/// ```
///
/// Open a file for both reading and writing, and create it if it doesn't exist yet:
///
/// ```no_run
/// # fn main() -> std::io::Result<()> { async_std::task::block_on(async {
/// #
/// use async_std::fs::OpenOptions;
///
/// let file = OpenOptions::new()
/// .read(true)
/// .write(true)
/// .create(true)
/// .open("a.txt")
/// .await?;
/// #
/// # Ok(()) }) }
/// ```
#[derive(Clone, Debug)]
pub struct OpenOptions(std::fs::OpenOptions);
impl OpenOptions {
/// Creates a blank set of options.
///
/// All options are initially set to `false`.
///
/// # Examples
///
/// ```no_run
/// # fn main() -> std::io::Result<()> { async_std::task::block_on(async {
/// #
/// use async_std::fs::OpenOptions;
///
/// let file = OpenOptions::new()
/// .read(true)
/// .open("a.txt")
/// .await?;
/// #
/// # Ok(()) }) }
/// ```
pub fn new() -> OpenOptions {
OpenOptions(std::fs::OpenOptions::new())
}
/// Configures the option for read mode.
///
/// When set to `true`, this option means the file will be readable after opening.
///
/// # Examples
///
/// ```no_run
/// # fn main() -> std::io::Result<()> { async_std::task::block_on(async {
/// #
/// use async_std::fs::OpenOptions;
///
/// let file = OpenOptions::new()
/// .read(true)
/// .open("a.txt")
/// .await?;
/// #
/// # Ok(()) }) }
/// ```
pub fn read(&mut self, read: bool) -> &mut OpenOptions {
self.0.read(read);
self
}
/// Configures the option for write mode.
///
/// When set to `true`, this option means the file will be writable after opening.
///
/// If the file already exists, write calls on it will overwrite the previous contents without
/// truncating it.
///
/// # Examples
///
/// ```no_run
/// # fn main() -> std::io::Result<()> { async_std::task::block_on(async {
/// #
/// use async_std::fs::OpenOptions;
///
/// let file = OpenOptions::new()
/// .write(true)
/// .open("a.txt")
/// .await?;
/// #
/// # Ok(()) }) }
/// ```
pub fn write(&mut self, write: bool) -> &mut OpenOptions {
self.0.write(write);
self
}
/// Configures the option for append mode.
///
/// When set to `true`, this option means the file will be writable after opening and the file
/// cursor will be moved to the end of file before every write operaiton.
///
/// # Examples
///
/// ```no_run
/// # fn main() -> std::io::Result<()> { async_std::task::block_on(async {
/// #
/// use async_std::fs::OpenOptions;
///
/// let file = OpenOptions::new()
/// .append(true)
/// .open("a.txt")
/// .await?;
/// #
/// # Ok(()) }) }
/// ```
pub fn append(&mut self, append: bool) -> &mut OpenOptions {
self.0.append(append);
self
}
/// Configures the option for truncating the previous file.
///
/// When set to `true`, the file will be truncated to the length of 0 bytes.
///
/// The file must be opened in [`write`] or [`append`] mode for truncation to work.
///
/// [`write`]: #method.write
/// [`append`]: #method.append
///
/// # Examples
///
/// ```no_run
/// # fn main() -> std::io::Result<()> { async_std::task::block_on(async {
/// #
/// use async_std::fs::OpenOptions;
///
/// let file = OpenOptions::new()
/// .write(true)
/// .truncate(true)
/// .open("a.txt")
/// .await?;
/// #
/// # Ok(()) }) }
/// ```
pub fn truncate(&mut self, truncate: bool) -> &mut OpenOptions {
self.0.truncate(truncate);
self
}
/// Configures the option for creating a new file if it doesn't exist.
///
/// When set to `true`, this option means a new file will be created if it doesn't exist.
///
/// The file must be opened in [`write`] or [`append`] mode for file creation to work.
///
/// [`write`]: #method.write
/// [`append`]: #method.append
///
/// # Examples
///
/// ```no_run
/// # fn main() -> std::io::Result<()> { async_std::task::block_on(async {
/// #
/// use async_std::fs::OpenOptions;
///
/// let file = OpenOptions::new()
/// .write(true)
/// .create(true)
/// .open("a.txt")
/// .await?;
/// #
/// # Ok(()) }) }
/// ```
pub fn create(&mut self, create: bool) -> &mut OpenOptions {
self.0.create(create);
self
}
/// Configures the option for creating a new file or failing if it already exists.
///
/// When set to `true`, this option means a new file will be created, or the open operation
/// will fail if the file already exists.
///
/// The file must be opened in [`write`] or [`append`] mode for file creation to work.
///
/// [`write`]: #method.write
/// [`append`]: #method.append
///
/// # Examples
///
/// ```no_run
/// # fn main() -> std::io::Result<()> { async_std::task::block_on(async {
/// #
/// use async_std::fs::OpenOptions;
///
/// let file = OpenOptions::new()
/// .write(true)
/// .create_new(true)
/// .open("a.txt")
/// .await?;
/// #
/// # Ok(()) }) }
/// ```
pub fn create_new(&mut self, create_new: bool) -> &mut OpenOptions {
self.0.create_new(create_new);
self
}
/// Opens a file with the configured options.
///
/// # Errors
///
/// An error will be returned in the following situations:
///
/// * The file does not exist and neither [`create`] nor [`create_new`] were set.
/// * The file's parent directory does not exist.
/// * The current process lacks permissions to open the file in the configured mode.
/// * The file already exists and [`create_new`] was set.
/// * Invalid combination of options was used, like [`truncate`] was set but [`write`] wasn't,
/// or none of [`read`], [`write`], and [`append`] modes was set.
/// * An OS-level occurred, like too many files are open or the file name is too long.
/// * Some other I/O error occurred.
///
/// [`read`]: #method.read
/// [`write`]: #method.write
/// [`append`]: #method.append
/// [`truncate`]: #method.truncate
/// [`create`]: #method.create
/// [`create_new`]: #method.create_new
///
/// # Examples
///
/// ```no_run
/// # fn main() -> std::io::Result<()> { async_std::task::block_on(async {
/// #
/// use async_std::fs::OpenOptions;
///
/// let file = OpenOptions::new()
/// .read(true)
/// .open("a.txt")
/// .await?;
/// #
/// # Ok(()) }) }
/// ```
pub fn open<P: AsRef<Path>>(&self, path: P) -> impl Future<Output = io::Result<File>> {
let path = path.as_ref().to_owned();
let options = self.0.clone();
async move {
let file = spawn_blocking(move || options.open(path)).await?;
Ok(File::new(file, true))
}
}
}
impl Default for OpenOptions {
fn default() -> Self {
Self::new()
}
}
cfg_unix! {
use crate::os::unix::fs::OpenOptionsExt;
impl OpenOptionsExt for OpenOptions {
fn mode(&mut self, mode: u32) -> &mut Self {
self.0.mode(mode);
self
}
fn custom_flags(&mut self, flags: i32) -> &mut Self {
self.0.custom_flags(flags);
self
}
}
}