Zig 0.17.0-dev (Split by item)

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fileReadPositional

Dispatch.fileReadPositional

fn fileReadPositional(
    userdata: ?*anyopaque,
    file: File,
    data: []const []u8,
    offset: u64,
) File.ReadPositionalError!usize

File

lib/std/Io/Dispatch.zig:3521

Code

fn fileReadPositional(
    userdata: ?*anyopaque,
    file: File,
    data: []const []u8,
    offset: u64,
) File.ReadPositionalError!usize {
    const ev: *Evented = @ptrCast(@alignCast(userdata));
    _ = ev;
    var iovecs: [max_iovecs_len]iovec = undefined;
    var iovlen: iovlen_t = 0;
    var remaining: Io.Limit = .unlimited;
    for (data) |buf| addBuf(false, &iovecs, &iovlen, &remaining, buf);
    if (iovlen == 0) return 0;
    while (true) {
        const rc = c.preadv(file.handle, &iovecs, iovlen, @bitCast(offset));
        switch (c.errno(rc)) {
            .SUCCESS => return @intCast(rc),
            .INTR => {},
            .NXIO => return error.Unseekable,
            .SPIPE => return error.Unseekable,
            .OVERFLOW => return error.Unseekable,
            .NOBUFS => return error.SystemResources,
            .NOMEM => return error.SystemResources,
            .AGAIN => return error.WouldBlock,
            .IO => return error.InputOutput,
            .ISDIR => return error.IsDir,
            .NOTCONN => |err| return errnoBug(err), // not a socket
            .CONNRESET => |err| return errnoBug(err), // not a socket
            .INVAL => |err| return errnoBug(err),
            .FAULT => |err| return errnoBug(err),
            .BADF => return error.NotOpenForReading,
            else => |err| return unexpectedErrno(err),
        }
    }
}