Date: Sun, 6 Apr 2003 06:24:50 +0300 From: Giorgos Keramidas <keramida@ceid.upatras.gr> To: Alex Semenyaka <alexs@ratmir.ru> Cc: freebsd-hackers@freebsd.org Subject: Re: /bin/sh and BIG NUMBERS Message-ID: <20030406032450.GC4130@gothmog.gr> In-Reply-To: <20030405030629.GA2669@snark.ratmir.ru> References: <20030405030629.GA2669@snark.ratmir.ru>
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On 2003-04-05 07:06, Alex Semenyaka <alexs@ratmir.ru> wrote:
> I found that /bin/sh cannot handle numbers those do not fit to integer
> type. That is not too bad. Too bad that it just silently warps them
> in arithmetical operations:
>
> alexs@snark> /bin/sh -c 'echo $((10000000000-1))'
> 2147483646
>
> That was not a problem 5 years ago... But now we have a lot of 64-bits
> values. So those old scripts which perfectly worked for a long time
> now can give wrong results, and you will not be able even to notice
> it, there is no any diagnostics or such. The simplest way to fix it is
> to switch internal /bin/sh arithmetics from 32 to 64-bits (you know,
> approach "640K ought to be enough for anybody"). I've did the patch
> for this (below), please, look at it. Any comments or suggestions?
>
> diff -u -U1 -r ../sh.old/arith.h ./arith.h
> --- ../sh.old/arith.h Fri Jul 19 08:38:51 2002
> +++ ./arith.h Sat Apr 5 06:26:48 2003
> @@ -36,3 +36,3 @@
>
> -int arith(char *);
> +long long arith(char *);
> int expcmd(int , char **);
>
> [snip rest of long-long using patch]
Nice idea, but we should probably ask the -standards people if we
can/should make this use uint64_t and %jd instead of `long long'
(using %qd is deprecated and %lld is advised in printf(3) anyway).
: giorgos@gothmog[06:19]/tmp/lala$ cat lala.c
: #include <limits.h>
: #include <stdint.h>
: #include <stdio.h>
:
: int
: main(void)
: {
: uint64_t foo;
:
: foo = UINT_MAX;
: printf("%jd\n", foo);
: return (0);
: }
: giorgos@gothmog[06:19]/tmp/lala$ make WARNS=5
: Warning: Object directory not changed from original /tmp/lala
: cc -O -pipe -Wsystem-headers -Werror -Wall -Wno-format-y2k \
: -W -Wstrict-prototypes -Wmissing-prototypes -Wpointer-arith \
: -Wreturn-type -Wcast-qual -Wwrite-strings -Wswitch -Wshadow \
: -Wcast-align -Wuninitialized -Wformat=2 -Wno-format-extra-args \
: -Werror -c lala.c
: cc -O -pipe -Wsystem-headers -Werror -Wall -Wno-format-y2k \
: -W -Wstrict-prototypes -Wmissing-prototypes -Wpointer-arith \
: -Wreturn-type -Wcast-qual -Wwrite-strings -Wswitch -Wshadow \
: -Wcast-align -Wuninitialized -Wformat=2 -Wno-format-extra-args \
: -Werror -o lala lala.o
: giorgos@gothmog[06:19]/tmp/lala$ ./lala
: 4294967295
: giorgos@gothmog[06:19]/tmp/lala$
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