On Sat, 2008-08-09 at 20:05 +0000, Derick Eddington wrote:
> $ ikarus -- λ
> Ikarus Scheme version 0.0.3+ (revision 1579, build 2008-08-09)
> Copyright (c) 2006-2008 Abdulaziz Ghuloum
> 
> > (command-line)    ;; goes berserk
> Unhandled exception:
>  Condition components:
>    1. &interrupted
>    2. &message: "received an interrupt signal"
> $
> 
> Note the REPL did not reset, the ikarus process terminated.
> 
> I don't yet know why it's going berserk.

It's going berserk because integer_to_char(s[i]) returns a word with the
high bits set because s[i] is a char and integer_to_char casts it to
int, so for λ it's doing:

  ce => ffffce0f
  bb => ffffbb0f

When I make this change, it does not go berserk (but still transcodes as
Latin-1):

=== modified file 'src/ikarus-main.c'
--- src/ikarus-main.c	2008-08-09 12:47:44 +0000
+++ src/ikarus-main.c	2008-08-10 01:46:33 +0000
@@ -76,7 +76,7 @@
       {
         int i;
         for(i=0; i<n; i++){
-          string_set(str, i, integer_to_char(s[i]));
+          string_set(str, i, integer_to_char((unsigned char)s[i]));
         }
       }
       ikptr p = ik_unsafe_alloc(pcb, pair_size);


$ ./command-line λ
("./command-line" "Î\xBB;")


I didn't try to figure out if those high bits are revealing another bug
somewhere in Ikarus's character / string processing or if they are just
breaking an invariant.  

Here's the strace of the berserking allocating a ton of memory:

execve("/home/d/bin/ikarus", ["ikarus", "--r6rs-script", "command-line.sps", "\316\273"], [/* 
[... start-up stuff ...]
open("command-line.sps", O_RDONLY)      = 3
read(3, "(import (rnrs))\n(write (command-"..., 16384) = 49
read(3, "", 16384)                      = 0
close(3)                                = 0
mmap2(NULL, 4096, PROT_READ|PROT_WRITE|PROT_EXEC, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0xb75c2000
mmap2(NULL, 4194304, PROT_READ|PROT_WRITE|PROT_EXEC, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0xb71c2000
mmap2(NULL, 4194304, PROT_READ|PROT_WRITE|PROT_EXEC, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0xb6916000
mmap2(NULL, 24576, PROT_READ|PROT_WRITE|PROT_EXEC, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0xb71bc000
munmap(0xb6ff8000, 20480)               = 0
mmap2(NULL, 24576, PROT_READ|PROT_WRITE|PROT_EXEC, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0xb71b6000
munmap(0xb70c7000, 20480)               = 0
[... much more ...]
mmap2(NULL, 843776, PROT_READ|PROT_WRITE|PROT_EXEC, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x84afa000
munmap(0x84fc8000, 835584)              = 0
mmap2(NULL, 843776, PROT_READ|PROT_WRITE|PROT_EXEC, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0xb70f4000
munmap(0x8e787000, 835584)              = 0
mmap2(NULL, 4194304, PROT_READ|PROT_WRITE|PROT_EXEC, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x846fa000


Also, this wasn't necessary to fix the berserking, and I don't
completely understand C casting, and I didn't look for other similar
casting spots, but it seems like these types should be something more
like this:

=== modified file 'src/ikarus-data.h'
--- src/ikarus-data.h	2008-07-20 07:14:09 +0000
+++ src/ikarus-data.h	2008-08-10 01:34:13 +0000
@@ -91,7 +91,7 @@
 
 typedef unsigned long int ikptr;
 
-typedef int ikchar;
+typedef ikptr ikchar;
 
 void ik_error(ikptr args);
 
@@ -272,9 +272,9 @@
 #define off_string_data (disp_string_data - string_tag)
 
 #define string_set(x,i,c) \
-  (((ikchar*)(((long)(x)) + off_string_data))[i] = ((ikchar)(c)))
+  (((ikchar*)(((ikptr)(x)) + off_string_data))[i] = ((ikchar)(c)))
 #define integer_to_char(x) \
-  ((ikchar)((((int)(x)) << char_shift) + char_tag))
+  ((ikchar)((((unsigned long)(x)) << char_shift) + char_tag))
 #define string_char_size 4
 
 #define vector_tag 5