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

[Alexander Graf]

On 20.10.17 12:25, Christian Borntraeger wrote:
> From: "Collin L. Walling" <address@hidden>
> 
> 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 <address@hidden>
> Signed-off-by: Christian Borntraeger <address@hidden>
> ---
>  pc-bios/s390-ccw/s390-ccw.h |  3 +++
>  pc-bios/s390-ccw/sclp.c     | 17 ++++++++++++++---
>  2 files changed, 17 insertions(+), 3 deletions(-)
> 
> diff --git a/pc-bios/s390-ccw/s390-ccw.h b/pc-bios/s390-ccw/s390-ccw.h
> index 25d4d21..a8bd204 100644
> --- a/pc-bios/s390-ccw/s390-ccw.h
> +++ b/pc-bios/s390-ccw/s390-ccw.h
> @@ -33,6 +33,9 @@ typedef unsigned long long __u64;
>  #ifndef EBUSY
>  #define EBUSY   2
>  #endif
> +#ifndef EFBIG
> +#define EFBIG   3
> +#endif
>  #ifndef NULL
>  #define NULL    0
>  #endif
> diff --git a/pc-bios/s390-ccw/sclp.c b/pc-bios/s390-ccw/sclp.c
> index b1fc8ff..4795259 100644
> --- a/pc-bios/s390-ccw/sclp.c
> +++ b/pc-bios/s390-ccw/sclp.c
> @@ -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?


Alex

>      sccb->h.function_code = SCLP_FC_NORMAL_WRITE;
> -    sccb->ebh.length = sizeof(EventBufferHeader) + len;
> +    sccb->ebh.length = sizeof(EventBufferHeader) + data_len;
>      sccb->ebh.type = SCLP_EVENT_ASCII_CONSOLE_DATA;
>      sccb->ebh.flags = 0;
> -    memcpy(sccb->data, str, len);
>  
>      sclp_service_call(SCLP_CMD_WRITE_EVENT_DATA, sccb);
>  
>