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Re: [Qemu-devel] [PATCH v4 1/5] Use qemu_strtoul instead of strtol

From: Eric Blake
Subject: Re: [Qemu-devel] [PATCH v4 1/5] Use qemu_strtoul instead of strtol
Date: Fri, 8 Jan 2016 10:35:36 -0700
User-agent: Mozilla/5.0 (X11; Linux x86_64; rv:38.0) Gecko/20100101 Thunderbird/38.4.0

On 01/08/2016 01:37 AM, Cao jin wrote:
> strtol() don`t guarantee errno to be ERANGE on overflow.

I stand slightly corrected: C99 requires ERANGE on overflow, but not
EINVAL; it is POSIX that adds EINVAL, but does not properly require it.
 At any rate, my main point was that errno is not always properly set by
all strtol implementations, and furthermore that you can't rely on it
being set to a sane value if you didn't pre-set it to 0.

> This wrapper returns either -EINVAL or the errno set by strtol()
> function (e.g -ERANGE).

The subject line doesn't start with a topic.  Maybe a better commit
message would be:

xen: Use qemu_strtoul instead of strtol

No need to roll our own (with slightly incorrect handling of errno),
when we can use the common version.

> Signed-off-by: Cao jin <address@hidden>
> ---
>  hw/xen/xen-host-pci-device.c | 11 +++--------
>  1 file changed, 3 insertions(+), 8 deletions(-)

>      buf[rc] = 0;
> -    value = strtol(buf, &endptr, base);
> -    if (endptr == buf || *endptr != '\n') {
> -        rc = -1;
> -    } else if ((value == LONG_MIN || value == LONG_MAX) && errno == ERANGE) {
> -        rc = -errno;
> -    } else {
> -        rc = 0;
> +    rc = qemu_strtoul(buf, &endptr, base, &value);

Why did you switch from strtol() to qemu_strtoul()?  Was signed parsing
incorrect, and unsigned parsing a bug fix?  If so, please mention it in
the commit message as intentional.  Otherwise, use qemu_strtol() (and
adjust the commit message accordingly).

Eric Blake   eblake redhat com    +1-919-301-3266
Libvirt virtualization library http://libvirt.org

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