RE: [Cocci] [PATCH] usb: atm: don't use snprintf() for sysfs attrs

[David Laight <David.Laight@ACULAB.COM>]

From: Kees Cook
> Sent: 27 August 2020 23:21
...
> 
> Agreed. This just makes me cringe. If the API design declares that when
> a show() callback starts, buf has been allocated with PAGE_SIZE bytes,
> then that's how the logic should proceed, and it should be using
> scnprintf...
> 
> show(...) {
> 	size_t remaining = PAGE_SIZE;
> 
> 	...
> 	remaining -= scnprintf(buf, remaining, "fmt", var args ...);
> 	remaining -= scnprintf(buf, remaining, "fmt", var args ...);
> 	remaining -= scnprintf(buf, remaining, "fmt", var args ...);

Not quite what you had in mind, maybe:
	char *end = buf + PAGE_SIZE;

	buf += scnprintf(buf, end - buf, ...);

	return PAGE_SIZE - (end - buf);

	David

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