Function ReadFile [src]

If buffer's length exceeds what a Windows DWORD integer can hold, it will be broken into multiple non-atomic reads.

Prototype

pub fn ReadFile(in_hFile: HANDLE, buffer: []u8, offset: ?u64) ReadFileError!usize

Parameters

in_hFile: HANDLEbuffer: []u8offset: ?u64

Possible Errors

BrokenPipe

ConnectionResetByPeer

The specified network name is no longer available.

LockViolation

Unable to read file due to lock.

OperationAborted

Unexpected

Source

  pub fn ReadFile(in_hFile: HANDLE, buffer: []u8, offset: ?u64) ReadFileError!usize {
    while (true) {
        const want_read_count: DWORD = @min(@as(DWORD, maxInt(DWORD)), buffer.len);
        var amt_read: DWORD = undefined;
        var overlapped_data: OVERLAPPED = undefined;
        const overlapped: ?*OVERLAPPED = if (offset) |off| blk: {
            overlapped_data = .{
                .Internal = 0,
                .InternalHigh = 0,
                .DUMMYUNIONNAME = .{
                    .DUMMYSTRUCTNAME = .{
                        .Offset = @as(u32, @truncate(off)),
                        .OffsetHigh = @as(u32, @truncate(off >> 32)),
                    },
                },
                .hEvent = null,
            };
            break :blk &overlapped_data;
        } else null;
        if (kernel32.ReadFile(in_hFile, buffer.ptr, want_read_count, &amt_read, overlapped) == 0) {
            switch (GetLastError()) {
                .IO_PENDING => unreachable,
                .OPERATION_ABORTED => continue,
                .BROKEN_PIPE => return 0,
                .HANDLE_EOF => return 0,
                .NETNAME_DELETED => return error.ConnectionResetByPeer,
                .LOCK_VIOLATION => return error.LockViolation,
                else => |err| return unexpectedError(err),
            }
        }
        return amt_read;
    }
}  