diff options
| -rw-r--r-- | include/migration/qemu-file.h | 2 | ||||
| -rw-r--r-- | migration/qemu-file.c | 37 |
2 files changed, 39 insertions, 0 deletions
diff --git a/include/migration/qemu-file.h b/include/migration/qemu-file.h index 29a338d..86bb972 100644 --- a/include/migration/qemu-file.h +++ b/include/migration/qemu-file.h @@ -163,9 +163,11 @@ void qemu_put_be32(QEMUFile *f, unsigned int v); void qemu_put_be64(QEMUFile *f, uint64_t v); size_t qemu_peek_buffer(QEMUFile *f, uint8_t **buf, size_t size, size_t offset); size_t qemu_get_buffer(QEMUFile *f, uint8_t *buf, size_t size); +size_t qemu_get_buffer_in_place(QEMUFile *f, uint8_t **buf, size_t size); ssize_t qemu_put_compression_data(QEMUFile *f, const uint8_t *p, size_t size, int level); int qemu_put_qemu_file(QEMUFile *f_des, QEMUFile *f_src); + /* * Note that you can only peek continuous bytes from where the current pointer * is; you aren't guaranteed to be able to peak to +n bytes unless you've diff --git a/migration/qemu-file.c b/migration/qemu-file.c index df49023..e41a677 100644 --- a/migration/qemu-file.c +++ b/migration/qemu-file.c @@ -434,6 +434,43 @@ size_t qemu_get_buffer(QEMUFile *f, uint8_t *buf, size_t size) } /* + * Read 'size' bytes of data from the file. + * 'size' can be larger than the internal buffer. + * + * The data: + * may be held on an internal buffer (in which case *buf is updated + * to point to it) that is valid until the next qemu_file operation. + * OR + * will be copied to the *buf that was passed in. + * + * The code tries to avoid the copy if possible. + * + * It will return size bytes unless there was an error, in which case it will + * return as many as it managed to read (assuming blocking fd's which + * all current QEMUFile are) + * + * Note: Since **buf may get changed, the caller should take care to + * keep a pointer to the original buffer if it needs to deallocate it. + */ +size_t qemu_get_buffer_in_place(QEMUFile *f, uint8_t **buf, size_t size) +{ + if (size < IO_BUF_SIZE) { + size_t res; + uint8_t *src; + + res = qemu_peek_buffer(f, &src, size, 0); + + if (res == size) { + qemu_file_skip(f, res); + *buf = src; + return res; + } + } + + return qemu_get_buffer(f, *buf, size); +} + +/* * Peeks a single byte from the buffer; this isn't guaranteed to work if * offset leaves a gap after the previous read/peeked data. */ |