On 5/20/21 11:14 AM, Pavel Hrdina wrote:
From QEMU docs/interop/qcow2.txt :
Byte 20 - 23: cluster_bits Number of bits that are used for addressing an offset within a cluster (1 << cluster_bits is the cluster size).
With this patch libvirt will be able to report the current cluster_size for all existing storage volumes managed by storage driver.
Signed-off-by: Pavel Hrdina <phrdina@redhat.com> ---
Changes in v2: - Reworkded to use callback.
src/storage/storage_util.c | 3 ++ src/storage_file/storage_file_probe.c | 70 ++++++++++++++++++++------- 2 files changed, 56 insertions(+), 17 deletions(-)
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+static unsigned long long +qcow2GetClusterSize(const char *buf, + size_t buf_size, + int endian) +{ + int clusterBits = 0; + + if ((QCOWX_HDR_CLUSTER_BITS_OFFSET + 4) > buf_size) + return 0; + + if (endian == LV_LITTLE_ENDIAN) + clusterBits = virReadBufInt32LE(buf + QCOWX_HDR_CLUSTER_BITS_OFFSET); + else + clusterBits = virReadBufInt32BE(buf + QCOWX_HDR_CLUSTER_BITS_OFFSET); + + if (clusterBits > 0) + return 1 << clusterBits; +
Coverity showed me a new error today: OVERFLOW_BEFORE_WIDEN 1) Event overflow_before_widen: Potentially overflowing expression "1 << clusterBits" with type "int" (32 bits, signed) is evaluated using 32-bit arithmetic, and then used in a context that expects an expression of type "unsigned long long" (64 bits, unsigned). (2) Event remediation: To avoid overflow, cast "1" to type "unsigned long long". John
+ return 0; +} + +
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