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IOOperation::Finish():

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* Fixed the read with bounce buffer case. When skipping a partial bounce
  buffer before the part we're interested in, we forgot to update "offset".
* Added some more comments for readability.


git-svn-id: file:///srv/svn/repos/haiku/haiku/trunk@29999 a95241bf-73f2-0310-859d-f6bbb57e9c96
This commit is contained in:
Ingo Weinhold 2009-04-07 16:06:30 +00:00
parent 53cce89bf5
commit 0228ef3608
1 changed files with 12 additions and 2 deletions
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14
src/system/kernel/device_manager/IORequest.cpp
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@ -246,9 +246,12 @@ IOOperation::Finish()
status_t error = B_OK;
// We iterate through the vecs we have read, moving offset (the device
// offset) as we go. If [offset, offset + vec.iov_len) intersects with
// [startOffset, endOffset) we copy to the final location.
off_t offset = fOffset;
off_t startOffset = fOriginalOffset;
off_t endOffset = fOriginalOffset + fOriginalLength;
const off_t startOffset = fOriginalOffset;
const off_t endOffset = fOriginalOffset + fOriginalLength;
for (uint32 i = 0; error == B_OK && i < vecCount; i++) {
const iovec& vec = vecs[i];
@ -256,21 +259,28 @@ IOOperation::Finish()
size_t length = vec.iov_len;
if (offset < startOffset) {
// If the complete vector is before the start offset, skip it.
if (offset + length <= startOffset) {
offset += length;
continue;
}
// The vector starts before the start offset, but intersects
// with it. Skip the part we aren't interested in.
size_t diff = startOffset - offset;
offset += diff;
base += diff;
length -= diff;
}
if (offset + length > endOffset) {
// If we're already beyond the end offset, we're done.
if (offset >= endOffset)
break;
// The vector extends beyond the end offset -- cut it.
length = endOffset - offset;
length -= offset + length - endOffset;
}
if (base >= bounceBufferStart && base < bounceBufferEnd) {