# SEGV on "abcd\\xf0".force\_encoding("utf-8").reverse

**URL:** <https://www.ruby-forum.com/t/segv-on-abcd-xf0-force-encoding-utf-8-reverse/122054>\
**Category:** Development\
**Created:** [December 4, 2007, 7:31am UTC](https://www.ruby-forum.com/t/segv-on-abcd-xf0-force-encoding-utf-8-reverse/122054 "2007-12-04T07:31:39Z")\
**Posts on this page:** 4\
**Page:** 1

<div class="post-metadata">

**Author:** ![Tanaka\_A](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/t/c67d28/32.png) [@Tanaka\_A](https://www.ruby-forum.com/u/Tanaka_A)\
**Post date:** [December 4, 2007, 7:31am UTC](https://www.ruby-forum.com/t/segv-on-abcd-xf0-force-encoding-utf-8-reverse/122054/1 "2007-12-04T07:31:39Z")

</div>

e$B0J2\<$N$h$&$K$9$k$He(B SEGV e$B$7$^$9!#e(B

## % ./ruby -ve ‘p “abcd\xf0”.force\_encoding(“utf-8”).reverse’ ruby 1.9.0 (2007-12-04 patchlevel 0) [i686-linux] -e:1: – control frame ---------- c:0004 p:---- s:0009 b:0009 l:000008 d:000008 CFUNC 😛 c:0003 p:0023 s:0005 b:0005 l:000004 d:000004 TOP -e:1 c:0002 p:---- s:0003 b:0003 l:000002 d:000002 FINISH :inherited c:0001 p:---- s:0001 b:-001 l:000000 d:000000 ------

DBG\> : “-e:1:in `’”  
– backtrace of native function call (Use addr2line) –  
0x8102232  
0x812141c  
0x81214bb  
0x80ca351  
0xb7f23440  
0x8058f8d  
0x805c6e5  
0x805c92b  
0x805cb9d  
0x807e8cb  
0x806fb90  
0x806fbec  
0x80f8361  
0x80ffc66  
0x80ff7da  
0x80fc1a1  
0x80ffe3f  
0x8100484  
0x805aadd  
0x805ab8c  
0x8057d74  
0xb7d84ea8  
0x8057c91

---

<div class="post-metadata">

**Author:** ![Tanaka\_A](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/t/c67d28/32.png) [@Tanaka\_A](https://www.ruby-forum.com/u/Tanaka_A)\
**Post date:** [December 4, 2007, 8:04am UTC](https://www.ruby-forum.com/t/segv-on-abcd-xf0-force-encoding-utf-8-reverse/122054/2 "2007-12-04T08:04:58Z")

</div>

e$B$J$+$@$G$9!#e(B

At Tue, 4 Dec 2007 15:29:09 +0900,  
Tanaka A. wrote in [ruby-dev:32448]:

> e$B0J2\<$N$h$&$K$9$k$He(B SEGV e$B$7$^$9!#e(B
> 
> % ./ruby -ve ‘p “abcd\xf0”.force\_encoding(“utf-8”).reverse’  
> ruby 1.9.0 (2007-12-04 patchlevel 0) [i686-linux]  
> [BUG] Segmentation fault  
> ruby 1.9.0 (2007-12-04) [i686-linux]

e$B$I$&$J$k$N$,$$$$$s$G$7$g$&$M!#Nc30e(B?

# Index: string.c

— string.c (revision 14096)  
+++ string.c (working copy)  
@@ -2709,4 +2709,5 @@ rb\_str\_reverse(VALUE str)  
VALUE obj;  
char \*s, \*e, \*p;

- int cr;

- cr = ENC\_CODERANGE(str);  
if (RSTRING\_LEN(str) \> 1) {

- if (rb\_enc\_mbmaxlen(enc) == 1) {

- if (rb\_enc\_mbmaxlen(enc) == 1 || cr == ENC\_CODERANGE\_7BIT) {  
while (s \< e) {  
\*–p = \*s++;  
@@ -2726,6 +2728,16 @@ rb\_str\_reverse(VALUE str)  
int clen = rb\_enc\_mbclen(s, e, enc);

- if (clen == 0) {

- switch (clen) {
- 

```
 default:

```

- 

```
   if (s + clen <= e) break;

```

+#if !RAISE\_ON\_REVERSING\_BROKEN\_CHAR

- 

```
   clen = e - s;

```

- 

```
   break;

```

+#endif

- 

```
 case 0:
   rb_raise(rb_eArgError, "invalid mbstring sequence");

```

- 

```
 case 1:

```

- 

```
   *--p = *s++;

```

- 

```
   continue;

```

}  
p -= clen;  
@@ -2738,4 +2750,5 @@ rb\_str\_reverse(VALUE str)  
OBJ\_INFECT(obj, str);  
rb\_enc\_associate(obj, enc);

- ENC\_CODERANGE\_SET(obj, cr);

---

<div class="post-metadata">

**Author:** ![Tanaka\_A](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/t/c67d28/32.png) [@Tanaka\_A](https://www.ruby-forum.com/u/Tanaka_A)\
**Post date:** [December 4, 2007, 1:14pm UTC](https://www.ruby-forum.com/t/segv-on-abcd-xf0-force-encoding-utf-8-reverse/122054/3 "2007-12-04T13:14:00Z")

</div>

In article [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid),  
Nobuyoshi N. [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid) writes:

> e$B$I$&$J$k$N$,$$$$$s$G$7$g$&$M!#Nc30e(B?

e$B;W$C$?$s$G$9$,!"e(Brb\_enc\_mbclen e$B$,J8;zNs=\*C\<$r1[$($k$h$&$JCM$Oe(B  
e$BJV$5$J$$$h$&$K$9$k$N$O$I$&$G$9$+$M!#e(B

rb\_enc\_mbclen e$B$O%(%s%3!\<%G%#%s%0$NLdBj$r$A$c$s$H8!=P$9$k$o$1e(B  
e$B$G$O$J$$$N$G!"$I$&$;$J$i%(%i!\<$K$O7h$7$F$J$i$J$$$b$N$H$7$FDje(B  
e$B5A$7$J$\*$9$H$$$&$+!#e(B

---

<div class="post-metadata">

**Author:** ![Tanaka\_A](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/t/c67d28/32.png) [@Tanaka\_A](https://www.ruby-forum.com/u/Tanaka_A)\
**Post date:** [December 5, 2007, 12:41pm UTC](https://www.ruby-forum.com/t/segv-on-abcd-xf0-force-encoding-utf-8-reverse/122054/4 "2007-12-05T12:41:57Z")

</div>

At 21:10 07/12/04, Tanaka A. wrote:

> e$B5A$7$J$_$9$H$$$&$+!#e(B  
> e$B$=$&$G$9$M!#e(BRuby  
> e$B%W%m%0%i%^$+$i8+$k$H!“!V$3$N4X?t$O%(%s%3!\<%G%#%s%0e(B  
> e$B$r%A%'%C%/e(B (validate)  
> e$B$7$F$$$k!W!”!V$3$N4X?t$O%A%'%/$7$F$J$$!We(B  
> e$B$HJ,$+$k$H$"$j$,$?$$5$$,$7$^$9!#%(%s%3!\<%G%#%s%0$K$h$C$F!"e(B  
> e$B6qBNE_$JCM$d\>l=j$K$h$C$F?6$kIq$$$,0c$&$H$J$+$J$+BP1~$,Fq$7$$$H;W$$$^$9!#e(B

e$B59$7$/!"e(B Martin.

#-#-# Martin J. Du"rst, Assoc. Professor, Aoyama Gakuin University  
#-#-# [http://www.sw.it.aoyama.ac.jp](http://www.sw.it.aoyama.ac.jp)[mailto:removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid)