Uwe Kleine-Konig(ARM系開発者)がstrcmpのインプリが間違っているとパッチを提出

strcmp("\x01", "\xef") returns 18 but it should return something < 0.

The reason is that the variable holding the result of the subtraction is

too small and overflows.



As strcmp is e.g. used to access data in squashfs this might result in

not finding files.



The same problem is fixed in strncmp.

Linuxが間違っとるわ。POSIX標準も知らんのか。と噛み付き、おれの実装が最高だもんねと別パッチをポスト

No. The reason is that whoever wrote that function is a moron and doesn't 

know the standard. And your fix is not correct _either_



The comparison should be done as *unsigned char*. As specified by POSIX



  "The sign of a non-zero return value shall be determined by the sign of 

   the difference between the values of the first pair of bytes (both 

   interpreted as type unsigned char) that differ in the strings being 

   compared."



and both the original code and your change gets it wrong in different 

ways.

Uweは大人なので素直にAck

OK, right.



Acked-by: Uwe Kleine-König 



(BTW, this was already broken in 2.4.0, so I was unable to find out who

is the moron :-) 

・・・とみせかけて、最後に壊れたは2.4.0以前なんだけど、池沼なのは誰なんだろうね。と最後っ屁

In fact, it goes back to at least 1.2.13.



And the copyright dates do imply that they could go back way further. 



At least the comment says it all:



	"These are buggy as well.."



so I can at least claim that back in the _original_ 0.01 release, it was 

correct:



	extern inline int strcmp(const char * cs,const char * ct)

	{

	register int __res __asm__("ax");

	__asm__("cld\n"

	        "1:\tlodsb\n\t"

	        "scasb\n\t"

	        "jne 2f\n\t"

	        "testb %%al,%%al\n\t"

	        "jne 1b\n\t"

	        "xorl %%eax,%%eax\n\t"

	        "jmp 3f\n"

	        "2:\tmovl $1,%%eax\n\t"

	        "jl 3f\n\t"

	        "negl %%eax\n"

	        "3:"

	        :"=a" (__res):"D" (cs),"S" (ct):"si","di");

	return __res;

	}



and as far as I can tell, the above is actually correct, even if you have 

to be a bit crazy to write 'strcmp' as gcc inline asm (hey, I wrote _all_ 

the string routines that way, and I made gcc do some of them built-in. 

Because I was a MAN, dammit!).



So the bug was apparently introduced when we went portable. 

Linusがどう考えても自分が犯人だと認めつつv0.0.1の時はあってたんだ、v1.1でコードをポータブルにするときにミスったに違いない。僕だって人間なんだ。と言い訳


Joe Perches がなぜか、そのときのパッチを探し出してくる。オマイすごすぎ

It's been like that for awhile.



http://www.linuxhq.com/kernel/v1.1/75/lib/string.c 

こうして、Linux界の２ｃｈことLKMLの一日は流れていくのであった