[Info-vax] CRTL and RMS vs SSIO

[Arne Vajhøj]

On 10/7/2021 12:01 PM, Craig A. Berry wrote:
> On 10/7/21 9:42 AM, Arne Vajhøj wrote:
>> On 10/7/2021 9:34 AM, Arne Vajhøj wrote:
>>>          fseek(fp, ix, SEEK_SET);
>>
>>> var.txt size = 14 bytes
>>> var.txt sequential read (text): 1=41 2=0A 3=42 4=42 5=0A 6=43 7=43 
>>> 8=43 9=0A
>>> var.txt sequential read (binary): 1=41 2=42 3=42 4=43 5=43 6=43
>>> var.txt direct read (text): 1=41 2=-1 3=02 4=-1 5=42 6=-1 7=-1 8=-1 
>>> 9=43 10=-1 11=-1 12=-1 13=FF 14=-1
>>> var.txt direct read (binary): 1=41 2=-1 3=02 4=-1 5=42 6=-1 7=-1 8=-1 
>>> 9=43 10=-1 11=-1 12=-1 13=FF 14=-1
>>> $ mcr sys$disk:[]process stmlf.txt
>>> stmlf.txt size = 9 bytes
>>> stmlf.txt sequential read (text): 1=41 2=0A 3=42 4=42 5=0A 6=43 7=43 
>>> 8=43 9=0A
>>> stmlf.txt sequential read (binary): 1=41 2=0A 3=42 4=42 5=0A 6=43 
>>> 7=43 8=43 9=0A
>>> stmlf.txt direct read (text): 1=41 2=0A 3=42 4=42 5=0A 6=43 7=43 8=43 
>>> 9=0A
>>> stmlf.txt direct read (binary): 1=41 2=0A 3=42 4=42 5=0A 6=43 7=43 
>>> 8=43 9=0A
>>
>> In all fairness then I believe there are some documentation
>> somewhere that states that fseek is only supported to
>> beginning of a record. I cannot find it right now,
>> but I believe I once saw it somewhere.
> 
> Is this what you're looking for?
> 
> $ help crtl fseek description
> 
> CRTL
> 
>    fseek
> 
>      Description
> 
>           The fseek function can position a fixed-length record-access
>           file with no carriage control or a stream-access file on any
>           byte offset, but can position all other files only on record
>           boundaries.
> 
>           The available Standard I/O functions position a variable-length
>           or VFC record file at its first byte, at the end-of-file, or on
>           a record boundary. Therefore, the arguments given to fseek must
>           specify any of the following:
> 
>           o  The beginning or end of the file
> 
>           o  A 0 offset from the current position (an arbitrary record
>              boundary)
> 
>           o  The position returned by a previous, valid ftell call

YES.

And shame on me, because I only checked help crtl fseek arguments.

Arne