Re: [PATCH] strtok -> strsep (The Easy Cases)

[Rusty Russell]

In message <01050120580701.01713@golmepha> you write:
> Hello,
> 
> the patch at the bottom does the bulk job of strtok replacement. It's a
> very boring patch, containing easy cases, only. It became a bit big, too,
> but I trust you can digest it nevertheless. It's made against kernel
> version 2.4.4.

There are two cases where the substitution is problematic:

Array:
	char tmparray[500];
	strcpy(tmparray, str);

	/* for (p = strtok(tmparray, "n"); p; p = strtok(NULL, "n")) { */
	while ((p = strsep(&tmparray, ","))) {

This is clearly wrong, and invokes a compiler warning.  &tmparray ==
tmparray (a cute C oddity I've never really liked).  You are blowing
away the first few characters in tmparray, and your parser won't work
properly.

Dynamic:

	char *tmp = strdup(str);

	/* for (p = strtok(tmp, "n"); p; p = strtok(NULL, "n")) { */
	while ((p = strsep(&tmp, ","))) {
	...
	}

	kfree(tmp);

Here, tmp has changed in the strsep implementation, and kfree will do
bad things.

There is a real reason to avoid strtok, and that is SMP and multple
threads calling it at once (that said, I don't know of a problem yet).
But this patch is a step backwards.

Rusty.
--
Premature optmztion is rt of all evl. --DK