I happened to touch these functions for a change that turned out to be
unnecessary, but coding style and documentation could still benefit
from some rephrasing and fixes.
Signed-off-by: Stefano Brivio
---
iov.c | 68 +++++++++++++++++++++++++----------------------------------
1 file changed, 29 insertions(+), 39 deletions(-)
diff --git a/iov.c b/iov.c
index 8c74a59..d31464d 100644
--- a/iov.c
+++ b/iov.c
@@ -20,24 +20,21 @@
* Contributions after 2012-01-13 are licensed under the terms of the
* GNU GPL, version 2 or (at your option) any later version.
*/
+
#include
#include "util.h"
#include "iov.h"
-
/**
- * iov_skip_bytes() - Skip leading bytes of an IO vector
- * @iov: IO vector
+ * iov_skip_bytes() - Find index and offset in iovec array given byte offset
+ * @iov: iovec array
* @n: Number of entries in @iov
- * @skip: Number of leading bytes of @iov to skip
- * @offset: Offset of first unskipped byte in its @iov entry
+ * @skip: Byte offset: leading bytes of @iov to skip
+ * @offset: Offset within matching @iov entry, set on return, can be NULL
*
- * Return: index I of individual struct iovec which contains the byte at @skip
- * bytes into the vector (as though all its buffers were contiguous).
- * If @offset is non-NULL, update it to the offset of that byte within
- * @iov[I] (guaranteed to be less than @iov[I].iov_len) If the whole
- * vector has <= @skip bytes, return @n.
+ * Return: index of iovec array containing the @skip byte counted as if buffers
+ * were contiguous. If iovec has less than @skip bytes, return @n.
*/
size_t iov_skip_bytes(const struct iovec *iov, size_t n,
size_t skip, size_t *offset)
@@ -57,17 +54,14 @@ size_t iov_skip_bytes(const struct iovec *iov, size_t n,
}
/**
- * iov_from_buf() - Copy data from a buffer to an I/O vector (struct iovec)
- * efficiently.
- *
- * @iov: Pointer to the array of struct iovec describing the
- * scatter/gather I/O vector.
- * @iov_cnt: Number of elements in the iov array.
- * @offset: Byte offset in the iov array where copying should start.
- * @buf: Pointer to the source buffer containing the data to copy.
- * @bytes: Total number of bytes to copy from buf to iov.
+ * iov_from_buf() - Copy from flat buffer to iovec array
+ * @iov: Destination iovec array
+ * @iov_cnt: Number of elements in the iovec array
+ * @offset: Destination offset in iovec array
+ * @buf: Source buffer
+ * @bytes: Bytes to copy
*
- * Return: the number of bytes successfully copied.
+ * Return: number of bytes copied
*/
size_t iov_from_buf(const struct iovec *iov, size_t iov_cnt,
size_t offset, const void *buf, size_t bytes)
@@ -78,12 +72,12 @@ size_t iov_from_buf(const struct iovec *iov, size_t iov_cnt,
if (__builtin_constant_p(bytes) && iov_cnt &&
offset <= iov[0].iov_len && bytes <= iov[0].iov_len - offset) {
memcpy((char *)iov[0].iov_base + offset, buf, bytes);
+
return bytes;
}
i = iov_skip_bytes(iov, iov_cnt, offset, &offset);
- /* copying data */
for (copied = 0; copied < bytes && i < iov_cnt; i++) {
size_t len = MIN(iov[i].iov_len - offset, bytes - copied);
@@ -97,17 +91,14 @@ size_t iov_from_buf(const struct iovec *iov, size_t iov_cnt,
}
/**
- * iov_to_buf() - Copy data from a scatter/gather I/O vector (struct iovec) to
- * a buffer efficiently.
- *
- * @iov: Pointer to the array of struct iovec describing the scatter/gather
- * I/O vector.
- * @iov_cnt: Number of elements in the iov array.
- * @offset: Offset within the first element of iov from where copying should start.
- * @buf: Pointer to the destination buffer where data will be copied.
- * @bytes: Total number of bytes to copy from iov to buf.
+ * iov_to_buf() - Copy from iovec to flat buffer
+ * @iov: Source iovec array
+ * @iov_cnt: Number of elements in iovec array
+ * @offset: Source offset in @iov, counted as if buffers were contiguous
+ * @buf: Destination buffer
+ * @bytes: Bytes to copy
*
- * Return: the number of bytes successfully copied.
+ * Return: number of bytes copied
*/
size_t iov_to_buf(const struct iovec *iov, size_t iov_cnt,
size_t offset, void *buf, size_t bytes)
@@ -118,15 +109,17 @@ size_t iov_to_buf(const struct iovec *iov, size_t iov_cnt,
if (__builtin_constant_p(bytes) && iov_cnt &&
offset <= iov[0].iov_len && bytes <= iov[0].iov_len - offset) {
memcpy(buf, (char *)iov[0].iov_base + offset, bytes);
+
return bytes;
}
i = iov_skip_bytes(iov, iov_cnt, offset, &offset);
- /* copying data */
for (copied = 0; copied < bytes && i < iov_cnt; i++) {
size_t len = MIN(iov[i].iov_len - offset, bytes - copied);
+
ASSERT(iov[i].iov_base);
+
memcpy((char *)buf + copied, (char *)iov[i].iov_base + offset,
len);
copied += len;
@@ -137,14 +130,11 @@ size_t iov_to_buf(const struct iovec *iov, size_t iov_cnt,
}
/**
- * iov_size() - Calculate the total size of a scatter/gather I/O vector
- * (struct iovec).
+ * iov_size() - Calculate total data size of iovec
+ * @iov: Source iovec array
+ * @iov_cnt: Number of elements in iovec array
*
- * @iov: Pointer to the array of struct iovec describing the
- * scatter/gather I/O vector.
- * @iov_cnt: Number of elements in the iov array.
- *
- * Return: the total size in bytes.
+ * Return: total size in bytes
*/
size_t iov_size(const struct iovec *iov, size_t iov_cnt)
{
--
2.43.0