diff options
| -rw-r--r-- | include/qemu/iov.h | 13 | ||||
| -rw-r--r-- | iov.c | 51 |
2 files changed, 64 insertions, 0 deletions
diff --git a/include/qemu/iov.h b/include/qemu/iov.h index d06f8b9ce3..68d25f29b7 100644 --- a/include/qemu/iov.h +++ b/include/qemu/iov.h @@ -99,4 +99,17 @@ unsigned iov_copy(struct iovec *dst_iov, unsigned int dst_iov_cnt, const struct iovec *iov, unsigned int iov_cnt, size_t offset, size_t bytes); +/* + * Remove a given number of bytes from the front or back of a vector. + * This may update iov and/or iov_cnt to exclude iovec elements that are + * no longer required. + * + * The number of bytes actually discarded is returned. This number may be + * smaller than requested if the vector is too small. + */ +size_t iov_discard_front(struct iovec **iov, unsigned int *iov_cnt, + size_t bytes); +size_t iov_discard_back(struct iovec *iov, unsigned int *iov_cnt, + size_t bytes); + #endif @@ -354,3 +354,54 @@ size_t qemu_iovec_memset(QEMUIOVector *qiov, size_t offset, { return iov_memset(qiov->iov, qiov->niov, offset, fillc, bytes); } + +size_t iov_discard_front(struct iovec **iov, unsigned int *iov_cnt, + size_t bytes) +{ + size_t total = 0; + struct iovec *cur; + + for (cur = *iov; *iov_cnt > 0; cur++) { + if (cur->iov_len > bytes) { + cur->iov_base += bytes; + cur->iov_len -= bytes; + total += bytes; + break; + } + + bytes -= cur->iov_len; + total += cur->iov_len; + *iov_cnt -= 1; + } + + *iov = cur; + return total; +} + +size_t iov_discard_back(struct iovec *iov, unsigned int *iov_cnt, + size_t bytes) +{ + size_t total = 0; + struct iovec *cur; + + if (*iov_cnt == 0) { + return 0; + } + + cur = iov + (*iov_cnt - 1); + + while (*iov_cnt > 0) { + if (cur->iov_len > bytes) { + cur->iov_len -= bytes; + total += bytes; + break; + } + + bytes -= cur->iov_len; + total += cur->iov_len; + cur--; + *iov_cnt -= 1; + } + + return total; +} |