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Diffstat (limited to 'vendor/github.com/tetratelabs/wazero/experimental/sys/file.go')
| -rw-r--r-- | vendor/github.com/tetratelabs/wazero/experimental/sys/file.go | 316 |
1 files changed, 316 insertions, 0 deletions
diff --git a/vendor/github.com/tetratelabs/wazero/experimental/sys/file.go b/vendor/github.com/tetratelabs/wazero/experimental/sys/file.go new file mode 100644 index 000000000..b6bfbcfeb --- /dev/null +++ b/vendor/github.com/tetratelabs/wazero/experimental/sys/file.go @@ -0,0 +1,316 @@ +package sys + +import "github.com/tetratelabs/wazero/sys" + +// File is a writeable fs.File bridge backed by syscall functions needed for ABI +// including WASI. +// +// Implementations should embed UnimplementedFile for forward compatibility. Any +// unsupported method or parameter should return ENOSYS. +// +// # Errors +// +// All methods that can return an error return a Errno, which is zero +// on success. +// +// Restricting to Errno matches current WebAssembly host functions, +// which are constrained to well-known error codes. For example, WASI maps syscall +// errors to u32 numeric values. +// +// # Notes +// +// - You must call Close to avoid file resource conflicts. For example, +// Windows cannot delete the underlying directory while a handle to it +// remains open. +// - A writable filesystem abstraction is not yet implemented as of Go 1.20. +// See https://github.com/golang/go/issues/45757 +type File interface { + // Dev returns the device ID (Stat_t.Dev) of this file, zero if unknown or + // an error retrieving it. + // + // # Errors + // + // Possible errors are those from Stat, except ENOSYS should not + // be returned. Zero should be returned if there is no implementation. + // + // # Notes + // + // - Implementations should cache this result. + // - This combined with Ino can implement os.SameFile. + Dev() (uint64, Errno) + + // Ino returns the serial number (Stat_t.Ino) of this file, zero if unknown + // or an error retrieving it. + // + // # Errors + // + // Possible errors are those from Stat, except ENOSYS should not + // be returned. Zero should be returned if there is no implementation. + // + // # Notes + // + // - Implementations should cache this result. + // - This combined with Dev can implement os.SameFile. + Ino() (sys.Inode, Errno) + + // IsDir returns true if this file is a directory or an error there was an + // error retrieving this information. + // + // # Errors + // + // Possible errors are those from Stat, except ENOSYS should not + // be returned. false should be returned if there is no implementation. + // + // # Notes + // + // - Implementations should cache this result. + IsDir() (bool, Errno) + + // IsAppend returns true if the file was opened with O_APPEND, or + // SetAppend was successfully enabled on this file. + // + // # Notes + // + // - This might not match the underlying state of the file descriptor if + // the file was not opened via OpenFile. + IsAppend() bool + + // SetAppend toggles the append mode (O_APPEND) of this file. + // + // # Errors + // + // A zero Errno is success. The below are expected otherwise: + // - ENOSYS: the implementation does not support this function. + // - EBADF: the file or directory was closed. + // + // # Notes + // + // - There is no `O_APPEND` for `fcntl` in POSIX, so implementations may + // have to re-open the underlying file to apply this. See + // https://pubs.opengroup.org/onlinepubs/9699919799/functions/open.html + SetAppend(enable bool) Errno + + // Stat is similar to syscall.Fstat. + // + // # Errors + // + // A zero Errno is success. The below are expected otherwise: + // - ENOSYS: the implementation does not support this function. + // - EBADF: the file or directory was closed. + // + // # Notes + // + // - This is like syscall.Fstat and `fstatat` with `AT_FDCWD` in POSIX. + // See https://pubs.opengroup.org/onlinepubs/9699919799/functions/stat.html + // - A fs.FileInfo backed implementation sets atim, mtim and ctim to the + // same value. + // - Windows allows you to stat a closed directory. + Stat() (sys.Stat_t, Errno) + + // Read attempts to read all bytes in the file into `buf`, and returns the + // count read even on error. + // + // # Errors + // + // A zero Errno is success. The below are expected otherwise: + // - ENOSYS: the implementation does not support this function. + // - EBADF: the file or directory was closed or not readable. + // - EISDIR: the file was a directory. + // + // # Notes + // + // - This is like io.Reader and `read` in POSIX, preferring semantics of + // io.Reader. See https://pubs.opengroup.org/onlinepubs/9699919799/functions/read.html + // - Unlike io.Reader, there is no io.EOF returned on end-of-file. To + // read the file completely, the caller must repeat until `n` is zero. + Read(buf []byte) (n int, errno Errno) + + // Pread attempts to read all bytes in the file into `p`, starting at the + // offset `off`, and returns the count read even on error. + // + // # Errors + // + // A zero Errno is success. The below are expected otherwise: + // - ENOSYS: the implementation does not support this function. + // - EBADF: the file or directory was closed or not readable. + // - EINVAL: the offset was negative. + // - EISDIR: the file was a directory. + // + // # Notes + // + // - This is like io.ReaderAt and `pread` in POSIX, preferring semantics + // of io.ReaderAt. See https://pubs.opengroup.org/onlinepubs/9699919799/functions/pread.html + // - Unlike io.ReaderAt, there is no io.EOF returned on end-of-file. To + // read the file completely, the caller must repeat until `n` is zero. + Pread(buf []byte, off int64) (n int, errno Errno) + + // Seek attempts to set the next offset for Read or Write and returns the + // resulting absolute offset or an error. + // + // # Parameters + // + // The `offset` parameters is interpreted in terms of `whence`: + // - io.SeekStart: relative to the start of the file, e.g. offset=0 sets + // the next Read or Write to the beginning of the file. + // - io.SeekCurrent: relative to the current offset, e.g. offset=16 sets + // the next Read or Write 16 bytes past the prior. + // - io.SeekEnd: relative to the end of the file, e.g. offset=-1 sets the + // next Read or Write to the last byte in the file. + // + // # Behavior when a directory + // + // The only supported use case for a directory is seeking to `offset` zero + // (`whence` = io.SeekStart). This should have the same behavior as + // os.File, which resets any internal state used by Readdir. + // + // # Errors + // + // A zero Errno is success. The below are expected otherwise: + // - ENOSYS: the implementation does not support this function. + // - EBADF: the file or directory was closed or not readable. + // - EINVAL: the offset was negative. + // + // # Notes + // + // - This is like io.Seeker and `fseek` in POSIX, preferring semantics + // of io.Seeker. See https://pubs.opengroup.org/onlinepubs/9699919799/functions/fseek.html + Seek(offset int64, whence int) (newOffset int64, errno Errno) + + // Readdir reads the contents of the directory associated with file and + // returns a slice of up to n Dirent values in an arbitrary order. This is + // a stateful function, so subsequent calls return any next values. + // + // If n > 0, Readdir returns at most n entries or an error. + // If n <= 0, Readdir returns all remaining entries or an error. + // + // # Errors + // + // A zero Errno is success. The below are expected otherwise: + // - ENOSYS: the implementation does not support this function. + // - EBADF: the file was closed or not a directory. + // - ENOENT: the directory could not be read (e.g. deleted). + // + // # Notes + // + // - This is like `Readdir` on os.File, but unlike `readdir` in POSIX. + // See https://pubs.opengroup.org/onlinepubs/9699919799/functions/readdir.html + // - Unlike os.File, there is no io.EOF returned on end-of-directory. To + // read the directory completely, the caller must repeat until the + // count read (`len(dirents)`) is less than `n`. + // - See /RATIONALE.md for design notes. + Readdir(n int) (dirents []Dirent, errno Errno) + + // Write attempts to write all bytes in `p` to the file, and returns the + // count written even on error. + // + // # Errors + // + // A zero Errno is success. The below are expected otherwise: + // - ENOSYS: the implementation does not support this function. + // - EBADF: the file was closed, not writeable, or a directory. + // + // # Notes + // + // - This is like io.Writer and `write` in POSIX, preferring semantics of + // io.Writer. See https://pubs.opengroup.org/onlinepubs/9699919799/functions/write.html + Write(buf []byte) (n int, errno Errno) + + // Pwrite attempts to write all bytes in `p` to the file at the given + // offset `off`, and returns the count written even on error. + // + // # Errors + // + // A zero Errno is success. The below are expected otherwise: + // - ENOSYS: the implementation does not support this function. + // - EBADF: the file or directory was closed or not writeable. + // - EINVAL: the offset was negative. + // - EISDIR: the file was a directory. + // + // # Notes + // + // - This is like io.WriterAt and `pwrite` in POSIX, preferring semantics + // of io.WriterAt. See https://pubs.opengroup.org/onlinepubs/9699919799/functions/pwrite.html + Pwrite(buf []byte, off int64) (n int, errno Errno) + + // Truncate truncates a file to a specified length. + // + // # Errors + // + // A zero Errno is success. The below are expected otherwise: + // - ENOSYS: the implementation does not support this function. + // - EBADF: the file or directory was closed. + // - EINVAL: the `size` is negative. + // - EISDIR: the file was a directory. + // + // # Notes + // + // - This is like syscall.Ftruncate and `ftruncate` in POSIX. See + // https://pubs.opengroup.org/onlinepubs/9699919799/functions/ftruncate.html + // - Windows does not error when calling Truncate on a closed file. + Truncate(size int64) Errno + + // Sync synchronizes changes to the file. + // + // # Errors + // + // A zero Errno is success. The below are expected otherwise: + // - EBADF: the file or directory was closed. + // + // # Notes + // + // - This is like syscall.Fsync and `fsync` in POSIX. See + // https://pubs.opengroup.org/onlinepubs/9699919799/functions/fsync.html + // - This returns with no error instead of ENOSYS when + // unimplemented. This prevents fake filesystems from erring. + // - Windows does not error when calling Sync on a closed file. + Sync() Errno + + // Datasync synchronizes the data of a file. + // + // # Errors + // + // A zero Errno is success. The below are expected otherwise: + // - EBADF: the file or directory was closed. + // + // # Notes + // + // - This is like syscall.Fdatasync and `fdatasync` in POSIX. See + // https://pubs.opengroup.org/onlinepubs/9699919799/functions/fdatasync.html + // - This returns with no error instead of ENOSYS when + // unimplemented. This prevents fake filesystems from erring. + // - As this is commonly missing, some implementations dispatch to Sync. + Datasync() Errno + + // Utimens set file access and modification times of this file, at + // nanosecond precision. + // + // # Parameters + // + // The `atim` and `mtim` parameters refer to access and modification time + // stamps as defined in sys.Stat_t. To retain one or the other, substitute + // it with the pseudo-timestamp UTIME_OMIT. + // + // # Errors + // + // A zero Errno is success. The below are expected otherwise: + // - ENOSYS: the implementation does not support this function. + // - EBADF: the file or directory was closed. + // + // # Notes + // + // - This is like syscall.UtimesNano and `futimens` in POSIX. See + // https://pubs.opengroup.org/onlinepubs/9699919799/functions/futimens.html + // - Windows requires files to be open with O_RDWR, which means you + // cannot use this to update timestamps on a directory (EPERM). + Utimens(atim, mtim int64) Errno + + // Close closes the underlying file. + // + // A zero Errno is returned if unimplemented or success. + // + // # Notes + // + // - This is like syscall.Close and `close` in POSIX. See + // https://pubs.opengroup.org/onlinepubs/9699919799/functions/close.html + Close() Errno +} |