Enum StateError 

pub enum StateError {
    Open(Error),
    Save(Error),
    Decode(Error),
    Encode(Error),
    FileChanged {
        local_file_id: FileId,
        local_file_size: u64,
        remote_file_id: FileId,
        remote_file_size: u64,
    },
    Truncated {
        actual_size: u64,
        recorded_size: u64,
    },
    NotResumable(UrlInfo, Response),
    NoUrl(PathBuf),
    NotAPartFile(PathBuf),
}

Errors that can occur when an explicit resume cannot continue an interrupted download.

These are surfaced through crate::Event::ResumeError so the caller is notified instead of silently falling back to a full re-download.

Variants

Open(Error)

Failed to open or read the .fd state file from disk.

This usually means the file is missing or unreadable (permission error, removed by another process, etc.).

Save(Error)

Failed to persist the .fd state file to disk.

The state was computed but could not be written (disk full, permission error, etc.).

Decode(Error)

Failed to deserialize the .fd state file.

The file was read but is not valid TOML, or its schema no longer matches the current DownloadStateInner definition.

Encode(Error)

Failed to serialize the download state into the .fd state file.

The state could not be encoded as TOML (e.g. a field holds a value that has no valid TOML representation).

FileChanged

The remote file changed (size / etag / last-modified mismatch), so resuming would corrupt the output.

Fields

local_file_id: FileId

local_file_size: u64

remote_file_id: FileId

remote_file_size: u64

Truncated

The .part file is shorter than the progress recorded in the .fd, so the recorded ranges no longer describe bytes that exist on disk.

Continuing would let the sink extend the file with zeros across the missing span and never fetch it, silently corrupting the output.

Fields

actual_size: u64

recorded_size: u64

NotResumable(UrlInfo, Response)

The server does not support resumable (range) downloads.

NoUrl(PathBuf)

No URL is available to resume the download.

resume was called with url = None and the persisted .fd state file carries no resolvable initial URL (it was missing, or written by an older build that did not store one). A URL is required to re-resolve the resource, so the call reports this error instead of silently falling back to a full re-download.

NotAPartFile(PathBuf)

peek_resume 收到的 tmp_path 不是 .part 文件。

peek_resume 需要的是 .part 临时文件路径，其同名 .fd 才是保存的状态； 传入其他扩展名的路径属于参数错误，而非文件读取失败。

Trait Implementations

impl Debug for StateError

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl Display for StateError

fn fmt(&self, __formatter: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl Error for StateError

fn source(&self) -> Option<&(dyn Error + 'static)>

Returns the lower-level source of this error, if any.

fn description(&self) -> &str

👎Deprecated since 1.42.0:

use the Display impl or to_string()

fn cause(&self) -> Option<&dyn Error>

👎Deprecated since 1.33.0:

replaced by Error::source, which can support downcasting

fn provide<'a>(&'a self, request: &mut Request<'a>)

🔬This is a nightly-only experimental API. (error_generic_member_access)

Provides type-based access to context intended for error reports.

impl From<Error> for StateError

fn from(source: Error) -> Self

Converts to this type from the input type.

impl From<Error> for StateError

fn from(source: Error) -> Self

Converts to this type from the input type.