Re: [PATCH] register_printf_speficier.3, register_printf_modifier.3, register_printf_type.3: Add new manual page and links

[Alex Colomar <alx.manpages@gmail.com>]

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On 9/19/22 00:16, Alex Colomar wrote:
> And it seems I also need some help with my own example, since I
> discovered there's some sort of undefined behavior in it (just run
> it several times and see; some work, but some do show weird stuff
> for the cases where with modifiers that make the number wider than
> unsigned int).  If you find the undefined behavior, please show
> me.  I'll continue debugging, anyway.
> 


This is the UB I'm experiencing:

alx@dell7760:~/tmp$ ./a.out | head
....----....----....----....----
0000000000000000000000000000000000000000000000011111111111110100000000000000000000000001011110;
0000000000000000000000000000000000000000000000011111111111110100000000000000000000000001011110;
00000001011110;
00000001011110;
00000001011110;
0000000000000000000000000000000000000000000000011111111111110100000000000000000000000001011110;
0000000000000000000000000000000000000000000000011111111111110100000000000000000000000001011110;
....----....----....----....----
0b00000001011110;
alx@dell7760:~/tmp$ ./a.out | head
....----....----....----....----
00000001011110;
00000001011110;
00000001011110;
00000001011110;
00000001011110;
00000001011110;
00000001011110;
....----....----....----....----
0b00000001011110;


The first run is wrong, and the second one is correct.  The relevant 
printf(3) lines are:


            printf("....----....----....----....----\n");
            printf("%llb;\n", 0x5Ellu);
            printf("%lB;\n", 0x5Elu);
            printf("%b;\n", 0x5Eu);
            printf("%hB;\n", 0x5Eu);
            printf("%hhb;\n", 0x5Eu);
            printf("%jb;\n", (uintmax_t)0x5E);
            printf("%zb;\n", (size_t)0x5E);
            printf("....----....----....----....----\n");
            printf("%#b;\n", 0x5Eu);


Cheers,

Alex


-- 
<http://www.alejandro-colomar.es/>


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