On 10/26/2017 10:54 PM, Collin L. Walling wrote:
> On 10/26/2017 04:48 PM, Alexander Graf wrote:
>>
>> On 26.10.17 22:37, Collin L. Walling wrote:
>>> On 10/26/2017 04:25 PM, Alexander Graf wrote:
>>>> On 26.10.17 20:52, Collin L. Walling wrote:
>>>>> The sclp console in the s390 bios writes raw data,
>>>>> leading console emulators (such as virsh console) to
>>>>> treat a new line ('\n') as just a new line instead
>>>>> of as a Unix line feed. Because of this, output
>>>>> appears in a "stair case" pattern.
>>>>>
>>>>> Let's print \r\n on every occurrence of a new line
>>>>> in the string passed to write to amend this issue.
>>>>>
>>>>> This is in sync with the guest Linux code in
>>>>> drivers/s390/char/sclp_vt220.c which also does a line feed
>>>>> conversion in the console part of the driver.
>>>>>
>>>>> This fixes the s390-ccw and s390-netboot output like
>>>>> $ virsh start test --console
>>>>> Domain test started
>>>>> Connected to domain test
>>>>> Escape character is ^]
>>>>> Network boot starting...
>>>>> Using MAC address: 02:01:02:03:04:05
>>>>>
>>>>> Requesting information via DHCP: 010
>>>>>
>>>>> Signed-off-by: Collin L. Walling <wall...@linux.vnet.ibm.com>
>>>>> Signed-off-by: Christian Borntraeger <borntrae...@de.ibm.com>
>>>>> ---
>>>>> pc-bios/s390-ccw/sclp.c | 16 +++++++++++++---
>>>>> 1 file changed, 13 insertions(+), 3 deletions(-)
>>>>>
>>>>> diff --git a/pc-bios/s390-ccw/sclp.c b/pc-bios/s390-ccw/sclp.c
>>>>> index 486fce1..f8ad5ae 100644
>>>>> --- a/pc-bios/s390-ccw/sclp.c
>>>>> +++ b/pc-bios/s390-ccw/sclp.c
>>>>> @@ -68,17 +68,27 @@ void sclp_setup(void)
>>>>> long write(int fd, const void *str, size_t len)
>>>>> {
>>>>> WriteEventData *sccb = (void *)_sccb;
>>>>> + const char *p = str;
>>>>> + size_t data_len = 0;
>>>>> + size_t i;
>>>>> if (fd != 1 && fd != 2) {
>>>>> return -EIO;
>>>>> }
>>>>> - sccb->h.length = sizeof(WriteEventData) + len;
>>>>> + for (i = len; i > 0; i--) {
>>>> Where did the bounds check go? If you write(max) before, you were
>>>> writing max bytes. If you do it now, you end up writing max + n bytes
>>>> and potentially overflow the array, no?
>>>>
>>>>
>>>> Alex
>>> I wasn't a fan of the code aesthetics and being that the SCCB write buffer
>>> allows about 4k bytes of data to be written to it, I felt it was safe to
>>> remove it. It's unlikely we'd be writing that much data in the bios, plus
>>> that check did not exist prior to this fixup.
>>>
>>> Though, reading that out loud, it probably isn't the best idea to sacrifice
>>> code robustness for code aesthetics.
>>>
>>> for (i = len; i > 0; i--) {
>>> if (data_len > SCCB_DATA_LEN - 1) {
>>> return -SOME_ERROR
>>> }
>>> if (*p == '\n') {
>>> sccb->data[data_len++] = '\r';
>>> }
>>> sccb->data[data_len++] = *p;
>>> p++;
>>> }
>>>
>>> What do you think?
>> Normally write() would just write less bytes than it was requested to
>> write and tell you that in the return value. So how about
>>
>> for (i = 0; i < len; i++) {
>> if ((data_len + 1) >= SCCB_DATA_LEN) {
>> /* We would overflow the sccb buffer, abort early */
>> len = i;
>> break;
>> }
>>
>> if (*p == '\n') {
>> /* Terminal emulators might need \r\n, so generate it */
>> sccb->data[data_len++] = '\r';
>> }
>>
>> sccb->data[data_len++] = *p;
>> p++;
>> }
>>
>>
>> Alex
>>
> Makes sense to me. I'll let this patch sit on the list for a little
> while longer before fixing up for v3 in case Imight have missed
> something else :)
Alex version looks sane. Can you post the patch today? soft freeze is
approaching soon.
