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Re: [PATCH 01/18] block: Make blk_{pread,pwrite}() return 0 on success
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From: |
Eric Blake |
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Subject: |
Re: [PATCH 01/18] block: Make blk_{pread,pwrite}() return 0 on success |
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Date: |
Wed, 18 May 2022 07:57:29 -0500 |
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User-agent: |
NeoMutt/20220429-71-6f7d3e |
On Tue, May 17, 2022 at 12:35:07PM +0100, Alberto Faria wrote:
> They currently return the value of their 'bytes' parameter on success.
>
> Make them return 0 instead, for consistency with other I/O functions and
> in preparation to implement them using generated_co_wrapper. This also
> makes it clear that short reads/writes are not possible.
>
> Signed-off-by: Alberto Faria <afaria@redhat.com>
> ---
> +++ b/qemu-img.c
> @@ -5120,30 +5120,27 @@ static int img_dd(int argc, char **argv)
> in.buf = g_new(uint8_t, in.bsz);
>
> for (out_pos = 0; in_pos < size; block_count++) {
in_pos, out_pos, and size are int64_t...
> - int in_ret, out_ret;
> + int bytes, in_ret, out_ret;
>
> - if (in_pos + in.bsz > size) {
> - in_ret = blk_pread(blk1, in_pos, in.buf, size - in_pos);
> - } else {
> - in_ret = blk_pread(blk1, in_pos, in.buf, in.bsz);
> - }
> + bytes = (in_pos + in.bsz > size) ? size - in_pos : in.bsz;
...but in.bsz is int, so declaring 'int bytes' appears safe.
Reviewed-by: Eric Blake <eblake@redhat.com>
--
Eric Blake, Principal Software Engineer
Red Hat, Inc. +1-919-301-3266
Virtualization: qemu.org | libvirt.org