[uClibc]ftruncate64 on arm

[Miles Bader]

libc/sysdeps/linux/arm/ftruncate64.c, says:

   /* Unlike some architectures, arm can pass an off64_t directly 
    * into a syscall so we don't need to do anything special */
   extern _syscall2 (int, _ftruncate64, int, fd, __off64_t, length);

Are you sure about this?

This is the arm code for _syscall2 (from asm/unistd.h):

   #define _syscall2(type,name,type1,arg1,type2,arg2)			\
   type name(type1 arg1,type2 arg2) {					\
     long __res;							\
     __asm__ __volatile__ (						\
     "mov\tr0,%1\n\t"							\
     "mov\tr1,%2\n\t"							\
     __syscall(name)							\
     "mov\t%0,r0"							\
           : "=r" (__res)						\
           : "r" ((long)(arg1)),"r" ((long)(arg2))			\
           : "r0","r1","lr");						\
     __syscall_return(type,__res);					\
   }

Notice the casts to (long) -- it seems as if it will truncate all
arguments to long, i.e., 32 bits, so even though you don't get a compile
error, the code generated for ftruncate64 will be wrong.

[Perhaps there's magic of which I'm not aware though.]

-Miles
-- 
Come now, if we were really planning to harm you, would we be waiting here, 
 beside the path, in the very darkest part of the forest?