Current qemu_put_compression_data can only work with no writable QEMUFile, and can't work with the writable QEMUFile. But it does not provide any measure to prevent users from using it with a writable QEMUFile.
We should fix this flaw to make it works with writable QEMUFile. Suggested-by: Juan Quintela <quint...@redhat.com> Signed-off-by: Liang Li <liang.z...@intel.com> --- migration/qemu-file.c | 23 +++++++++++++++++++++-- migration/ram.c | 6 +++++- 2 files changed, 26 insertions(+), 3 deletions(-) diff --git a/migration/qemu-file.c b/migration/qemu-file.c index 6f4a129..b0ef1f3 100644 --- a/migration/qemu-file.c +++ b/migration/qemu-file.c @@ -607,8 +607,14 @@ uint64_t qemu_get_be64(QEMUFile *f) return v; } -/* compress size bytes of data start at p with specific compression +/* Compress size bytes of data start at p with specific compression * level and store the compressed data to the buffer of f. + * + * When f is not writable, return -1 if f has no space to save the + * compressed data. + * When f is wirtable and it has no space to save the compressed data, + * do fflush first, if f still has no space to save the compressed + * data, return -1. */ ssize_t qemu_put_compression_data(QEMUFile *f, const uint8_t *p, size_t size, @@ -617,7 +623,14 @@ ssize_t qemu_put_compression_data(QEMUFile *f, const uint8_t *p, size_t size, ssize_t blen = IO_BUF_SIZE - f->buf_index - sizeof(int32_t); if (blen < compressBound(size)) { - return 0; + if (!qemu_file_is_writable(f)) { + return -1; + } + qemu_fflush(f); + blen = IO_BUF_SIZE - sizeof(int32_t); + if (blen < compressBound(size)) { + return -1; + } } if (compress2(f->buf + f->buf_index + sizeof(int32_t), (uLongf *)&blen, (Bytef *)p, size, level) != Z_OK) { @@ -625,7 +638,13 @@ ssize_t qemu_put_compression_data(QEMUFile *f, const uint8_t *p, size_t size, return 0; } qemu_put_be32(f, blen); + if (f->ops->writev_buffer) { + add_to_iovec(f, f->buf + f->buf_index, blen); + } f->buf_index += blen; + if (f->buf_index == IO_BUF_SIZE) { + qemu_fflush(f); + } return blen + sizeof(int32_t); } diff --git a/migration/ram.c b/migration/ram.c index 704f6a9..4de13c2 100644 --- a/migration/ram.c +++ b/migration/ram.c @@ -817,7 +817,11 @@ static int do_compress_ram_page(CompressParam *param) RAM_SAVE_FLAG_COMPRESS_PAGE); blen = qemu_put_compression_data(param->file, p, TARGET_PAGE_SIZE, migrate_compress_level()); - bytes_sent += blen; + if (blen < 0) { + error_report("Insufficient buffer for compressed data!"); + } else { + bytes_sent += blen; + } return bytes_sent; } -- 1.7.1