On 11/11/17 7:57 AM, Zorro Lang wrote:
> The 'Coverity Scan' found a problem in new write_once() function:
>
> 272 size_t bytes;
> 273 bytes = do_pwrite(file->fd, offset, count, count, pwritev2_flags);
>>>> CID 1420710: Control flow issues (NO_EFFECT)
>>>> This less-than-zero comparison of an unsigned value is never true. "bytes < 0UL".
> 274 if (bytes < 0)
> 275 return -1;
>
> That's unreasonable. do_pwrite return 'ssize_t' type value, which can
> be less than zero, but we use a 'size_t' to get the return value. So
> change the size_t to ssize_t for it can store the return value
> correctly.
>
> By the chance, correct all 'ssize_t' type problems in pwrite related
> functions.
>
> Signed-off-by: Zorro Lang <zlang@xxxxxxxxxx>
> ---
>
> V2 changed more than V1, as below:
> 1) The return value type of do_pwritev and do_pwrite, from 'int' to 'ssize_t'
> 2) The arguments type of do_pwritev and do_pwrite, from 'ssize_t' to 'size_t'
>
> Thanks,
> Zorro
>
> io/pwrite.c | 14 +++++++-------
> 1 file changed, 7 insertions(+), 7 deletions(-)
>
> diff --git a/io/pwrite.c b/io/pwrite.c
> index 26f79579..3df976a8 100644
> --- a/io/pwrite.c
> +++ b/io/pwrite.c
> @@ -61,12 +61,12 @@ pwrite_help(void)
> }
>
> #ifdef HAVE_PWRITEV
> -static int
> +static ssize_t
> do_pwritev(
> int fd,
> off64_t offset,
> - ssize_t count,
> - ssize_t buffer_size,
> + size_t count,
> + size_t buffer_size,
I had not noticed this before, but this is odd; buffer_size is not used
in this function. Instead, we test the global "buffersize"
I'm not sure what's going on there, need to read the code bit more.
That's probably a separate fix though.
I think the rest looks ok,
Reviewed-by: Eric Sandeen <sandeen@xxxxxxxxxxx>
> int pwritev2_flags)
> {
> int vecs = 0;
> @@ -105,12 +105,12 @@ do_pwritev(
> #define do_pwritev(fd, offset, count, buffer_size) (0)
> #endif
>
> -static int
> +static ssize_t
> do_pwrite(
> int fd,
> off64_t offset,
> - ssize_t count,
> - ssize_t buffer_size,
> + size_t count,
> + size_t buffer_size,
> int pwritev2_flags)
> {
> if (!vectors)
> @@ -269,7 +269,7 @@ write_once(
> long long *total,
> int pwritev2_flags)
> {
> - size_t bytes;
> + ssize_t bytes;
> bytes = do_pwrite(file->fd, offset, count, count, pwritev2_flags);
> if (bytes < 0)
> return -1;
>
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