barecat.io.copyfile

Fast file copy utilities with kernel-space zero-copy when available.

Methods tried in order of preference: 1. splice (Linux, kernel-space, zero-copy, requires one pipe end) 2. copy_file_range (Linux 4.5+, kernel-space, zero-copy, file-to-file) 3. sendfile (kernel-space, file-to-file or file-to-socket) 4. Buffered user-space copy

For CRC32c variants, must use buffered copy since data needs to pass through user space.

Classes

_FdType	Generic enumeration.
_CopyContext	Encapsulates copy setup: file descriptors, offsets, overlap detection.

Functions

copy(src, dst[, size, src_offset, dst_offset, bufsize])	Copy bytes between file objects using the fastest available method.
copy_crc32c(src, dst[, size, src_offset, dst_offset, ...])	Copy bytes and compute CRC32c in a single pass (when possible).
accumulate_crc32c(fileobj[, size, offset, bufsize, ...])	Compute CRC32c of file contents (read-only scan).
write_zeroes(file, n[, bufsize])	Write n zero bytes. Tries fallocate first, falls back to buffered.
_get_fd_type(fd)	Determine file descriptor type with single fstat call.
_is_seekable(f)	Safely check if file object is seekable (handles broken seekable() methods).
_copy_buffered(ctx[, compute_crc, initial_crc])	Buffered copy with optional CRC. Handles same-file backward overlap.
_copy_buffered_eof(ctx[, compute_crc, initial_crc])	Buffered copy until EOF.
_copy_same_file_overlap(ctx)	Copy within same file with overlap (memmove-style).
_copy_file_range_loop(ctx)	Copy using copy_file_range (kernel-space, zero-copy).
_copy_sendfile(ctx)	Copy using sendfile (kernel-space, dst must be socket).
_copy_splice(ctx)	Copy using splice (kernel-space, requires one pipe end).
_sync_position(f)	Sync fd position to match Python's logical position.