Re: [Qemu-devel] [PATCH] s390-ccw: print carriage return with new lines

[Christian Borntraeger]

On 10/20/2017 12:41 PM, Christian Borntraeger wrote:
[...]
>>> @@ -76,17 +76,28 @@ static int _strlen(const char *str)
>>>  long write(int fd, const void *str, size_t len)
>>>  {
>>>      WriteEventData *sccb = (void *)_sccb;
>>> +    const char *p;
>>> +    size_t data_len = 0;
>>>  
>>>      if (fd != 1 && fd != 2) {
>>>          return -EIO;
>>>      }
>>>  
>>> -    sccb->h.length = sizeof(WriteEventData) + len;
>>> +    for (p = str; *p; ++p) {
>>> +        if (data_len > SCCB_DATA_LEN - 1) {
>>> +            return -EFBIG;
>>> +        }
>>> +        if (*p == '\n') {
>>> +            sccb->data[data_len++] = '\r';
>>> +        }
>>> +        sccb->data[data_len++] = *p;
>>> +    }
>>> +
>>> +    sccb->h.length = sizeof(WriteEventData) + data_len;
>>
>> This subtly changes the semantics of the write() function from an
>> explicitly passed in "len" argument to NULL termination determined
>> sizing, no?
>>
>> In that case, wouldn't it make sense to either remove the len argument
>> altogether or keep respecting it?
> 
> Yes, well spotted.
> The write function is used in other code (SLOF related network boot),
> so we should change it to respect the length, I think.

Something like this on top?

--- a/pc-bios/s390-ccw/sclp.c
+++ b/pc-bios/s390-ccw/sclp.c
@@ -83,7 +83,7 @@ long write(int fd, const void *str, size_t len)
         return -EIO;
     }
 
-    for (p = str; *p; ++p) {
+    for (p = str; len ; ++p, len--) {
         if (data_len > SCCB_DATA_LEN - 1) {
             return -EFBIG;
         }