Re: Problems with read() on /proc/devices with x86_64 system

[Jan Engelhardt <jengelh@linux01.gwdg.de>]

>> If your code ever worked, it's probably because of some
>> fortuitous buffering in the 'C' runtime library.
>
>Not my code .. I just did a minimal hack to get it to build with klibc
>(klibc do not support fscanf(), so used fread() and sscanf() ..).
>
Ah, you can't do fread(ptr, 4096, 1, fp), because it would probably never 
return 1 if the file was smaller than 4096. Bad luck with stdio, I'd say. 
Back to read(2).

>>  Most
>> of the 'read' code in drivers that have a /proc interface
>> is not designed for 1-character-at-a-time I/O. It's expected
>> that it will be accessed like `cat` or `more` or other
>> such tools access it, -- one read with 4096-byte buffer --
>> 
>> read(3, "MemTotal:       773860 kB\nMemFre"..., 4096) = 670
>> write(1, "MemTotal:       773860 kB\nMemFre"..., 670) = 670

Jan Engelhardt
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