On Fri, Apr 03, 2026 at 06:42:40PM +0200, Laurent Vivier wrote:
Add iov_push_header_() and its typed wrapper IOV_PUSH_HEADER() to write a header into an iov_tail at the current offset and advance past it.
This is the write counterpart to IOV_PEEK_HEADER() / IOV_REMOVE_HEADER(), using iov_from_buf() to copy the header data across iovec boundaries.
Signed-off-by: Laurent Vivier
Reviewed-by: David Gibson
--- iov.c | 23 +++++++++++++++++++++++ iov.h | 11 +++++++++++ 2 files changed, 34 insertions(+)
diff --git a/iov.c b/iov.c index 28c6d40d2986..b1bcdc4649df 100644 --- a/iov.c +++ b/iov.c @@ -360,6 +360,29 @@ void *iov_peek_header_(struct iov_tail *tail, void *v, size_t len, size_t align) return v; }
+/** + * iov_push_header_() - Write a new header to an IOV tail + * @tail: IOV tail to write header to + * @v: Pointer to header data to write + * @len: Length of header to write, in bytes + * + * Return: number of bytes written + */ +/* cppcheck-suppress unusedFunction */ +size_t iov_push_header_(struct iov_tail *tail, const void *v, size_t len) +{ + size_t l; + + if (!iov_tail_prune(tail)) + return 0; /* No space */ + + l = iov_from_buf(tail->iov, tail->cnt, tail->off, v, len); + + tail->off = tail->off + l; + + return l; +} + /** * iov_remove_header_() - Remove a header from an IOV tail * @tail: IOV tail to remove header from (modified) diff --git a/iov.h b/iov.h index 3c63308e554f..4fdf14a85b19 100644 --- a/iov.h +++ b/iov.h @@ -93,6 +93,7 @@ bool iov_tail_prune(struct iov_tail *tail); size_t iov_tail_size(struct iov_tail *tail); bool iov_drop_header(struct iov_tail *tail, size_t len); void *iov_peek_header_(struct iov_tail *tail, void *v, size_t len, size_t align); +size_t iov_push_header_(struct iov_tail *tail, const void *v, size_t len); void *iov_remove_header_(struct iov_tail *tail, void *v, size_t len, size_t align); ssize_t iov_tail_clone(struct iovec *dst_iov, size_t dst_iov_cnt, struct iov_tail *tail); @@ -115,6 +116,16 @@ ssize_t iov_tail_clone(struct iovec *dst_iov, size_t dst_iov_cnt, sizeof(var_), \ __alignof__(var_))))
+/** + * IOV_PUSH_HEADER() - Write a new header to an IOV tail + * @tail_: IOV tail to write header to + * @var_: A variable containing the header data to write + * + * Return: number of bytes written + */ +#define IOV_PUSH_HEADER(tail_, var_) \ + (iov_push_header_((tail_), &(var_), sizeof(var_))) + /** * IOV_REMOVE_HEADER() - Remove and return typed header from an IOV tail * @tail_: IOV tail to remove header from (modified) -- 2.53.0
-- David Gibson (he or they) | I'll have my music baroque, and my code david AT gibson.dropbear.id.au | minimalist, thank you, not the other way | around. http://www.ozlabs.org/~dgibson