Verify that decompress_cluster returns EIO when given invalid
compressed data that the decoder cannot process.
Signed-off-by: Anatol Belski <anbelski@linux.microsoft.com>
Compress a known 64K buffer with raw deflate, pass it through
decompress_cluster with ZlibDecoder, and verify the output matches
the original data.
Signed-off-by: Anatol Belski <anbelski@linux.microsoft.com>
Verify that pread_alloc returns the correct data for a full read
from the start and a partial read at an arbitrary offset. Also
confirm that reading past the end of file produces an error.
Signed-off-by: Anatol Belski <anbelski@linux.microsoft.com>
Add a test utility that converts standard uncompressed clusters in
a QCOW2 image into compressed clusters in place. It walks the L1/L2
tables, compresses each allocated cluster with raw deflate, appends
the compressed payload at the end of the file, and rewrites the L2
entry with the compressed layout.
This enables end to end testing of the compressed read path without
external tools like qemu-img.
Signed-off-by: Anatol Belski <anbelski@linux.microsoft.com>
Add two reusable helpers for the compressed cluster read path:
- pread_alloc(fd, offset, len) allocates a buffer and fills it with
pread_exact, returning the owned Vec.
- decompress_cluster(compressed, cluster_size, decoder) allocates the
output buffer, decodes via the Decoder trait, and validates that the
decoder produced exactly cluster_size bytes.
These will be used by QcowSync, QcowAsync, Qcow2Backing, and the
legacy QcowFile.
Signed-off-by: Anatol Belski <anbelski@linux.microsoft.com>
When the data file is opened with O_DIRECT, buffer address, length,
and file offset must satisfy the device alignment.
Add AlignedBuf RAII wrapper and aligned_pread/aligned_pwrite helpers
in qcow_common that use bounce buffers when alignment constraints
are not met. For writes with misaligned offset, a read modify write
is performed on the aligned region.
gather_from_iovecs_into gathers iovec data directly into a caller
provided buffer, avoiding an intermediate Vec allocation.
Fixes: #8007
Signed-off-by: CMGS <ilskdw@gmail.com>
Co-authored-by: Anatol Belski <anbelski@linux.microsoft.com>
Signed-off-by: Anatol Belski <anbelski@linux.microsoft.com>
Move scatter_to_iovecs, zero_fill_iovecs and gather_from_iovecs into
qcow_common so they can be shared with the upcoming qcow_async backend.
These helpers treat an iovec array as a flat byte stream and are used by
both read_vectored and write_vectored code paths.
Signed-off-by: Anatol Belski <anbelski@linux.microsoft.com>
These position independent I/O helpers use pread64/pwrite64 to avoid
races on the shared file position when multiple queues operate on
duplicated file descriptors. Extracting them prepares for reuse by
the upcoming qcow_async backend.
Signed-off-by: Anatol Belski <anbelski@linux.microsoft.com>
