On Sun, Dec 4, 2016 at 9:05 PM, Rick Payne <ri...@rossfell.co.uk> wrote:
>
> What about something like the following. Not sure if you favour a
> different approach rather than checking the extents in the sendfile code,
> but this certainly gets me moving forward again.
>
Your patch looks good - my only question was whether we should be using
fstat() here or, because we already have the file structure in_fp, we could
also use in_fp->stat() (I think) directly. But maybe you're right and it's
better to just use the general system calls like you did - we are already
using lseek() and mmap() in the same code, and not some internal functions,
so why not use fstat() as well?
>
> I can work on some tst-sendfile code too if you want - but don’t want to
> duplicate effort if you’re already looking into it… Will send proper patch
> after discussion.
>
That would be great. I only open the bug tracker issue (please write "Fixes
#..." on the commit message so it will be closed), but wasn't working on
any code or test.
Thanks!
Nadav.
>
> Cheers,
> Rick
>
> diff --git a/fs/vfs/main.cc b/fs/vfs/main.cc
> index 8fecc08..b611ff2 100644
> --- a/fs/vfs/main.cc
> +++ b/fs/vfs/main.cc
> @@ -2039,6 +2039,21 @@ int sendfile(int out_fd, int in_fd, off_t *_offset,
> size_t count)
> offset = lseek(in_fd, 0, SEEK_CUR);
> }
>
> + // Constrain count to the extent of the file...
> + struct stat st;
> + if (fstat(in_fd, &st) < 0) {
> + return -1;
> + } else {
> + if (offset >= st.st_size) {
> + return 0;
> + } else if ((offset + count) >= st.st_size) {
> + count = st.st_size - offset;
> + if (count == 0) {
> + return 0;
> + }
> + }
> + }
> +
> size_t bytes_to_mmap = count + (offset % mmu::page_size);
> off_t offset_for_mmap = align_down(offset, (off_t)mmu::page_size);
>
>
>
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