Re: [Xen-devel] [[PATCH v2 2/2] libxl: replace deprecated readdir_r() with readdir()

[Chris Patterson <cjp256@xxxxxxxxx>]

On Thu, Jun 2, 2016 at 6:11 AM, Ian Jackson <Ian.Jackson@xxxxxxxxxxxxx> wrote:
> Chris Patterson writes ("[[PATCH v2 2/2] libxl: replace deprecated 
> readdir_r() with readdir()"):
>> -    for (;;) {
>> +    while ((de = readdir(dir)) != NULL) {
> ...
>> -        int r = readdir_r(dir, de_buf, &de);
>> -        if (r) {
>> -            LOGE(ERROR, "failed to readdir %s", SYSFS_USB_DEV);
>> -            break;
>
> Sadly this is not right because it mishandles errors when reading the
> directory, treating them all as EOF.  See the error handling info
> in the specification for readdir:
>   http://pubs.opengroup.org/onlinepubs/9699919799/functions/readdir.html
>

You're right, it should check for the error afterwards.

How about something along the lines of:

int saved_errno = errno;
errno = 0;
while ((de = readdir(dir)) != NULL) {
    ...
}

if (errno) {
   LOGE(ERROR, "readdir failed: %s", strerror(errno));
   rc = ERROR_FAIL;
}
errno = saved_errno;
...

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