Bug involving GMP and mpz_urandomb

[leif]

Perry Lee wrote:
> Hello,
>
> I believe that I've found a bug involving the GMP library (though I suspect it could just be the compiler?).
> I'm running Windows XP with MinGW GCC 4.7.2,  and I compiled using the MSYS shell.
> My CPU is an Intel Atom N270.
> The version of I'm using is GMP 5.1.0 (the unmodified source from the release version), configured with
>
> ./configure --enable-cxx --enable-fat --disable-shared --enable-static --with-gnu-ld
>
> 'make check' passed all of the tests.
>
>
> When I run this code:
>
> #include <gmp.h>
> int main(void)
> {
>    gmp_randstate_t rs;
>    mpz_t randNum;
>    gmp_randinit_default(rs);
>    int i;
>    for (i = 0; i < 1; ++i) /* the "1" can be any number, really */
>      mpz_urandomb(randNum, rs, 32);
>    gmp_randclear(rs);
>    return 0;
> }


How about initializing randNum, i.e., adding

     mpz_init(randNum);

? ;-)



-leif

>
> (compiled with gcc -g test.c -lgmp -o test.exe, where "test.c" is the name of the file containing this code)
> I get a crash on the line "mpz_urandomb(randNum, rs, 32);", as shown by this GDB backtrace:
> Program received signal SIGSEGV, Segmentation fault.
> 0x00402dd0 in __gmp_randget_mt ()
> (gdb) bt full
> #0  0x00402dd0 in __gmp_randget_mt ()
> No symbol table info available.
> #1  0x0040144c in __gmpz_urandomb ()
> No symbol table info available.
> #2  0x004013f0 in main () at test.c:9
>          rs = {{_mp_seed = {{_mp_alloc = 625, _mp_size = 4358142,
>                  _mp_d = 0x3e42d0}}, _mp_alg = (unknown: 1), _mp_algdata = {
>                _mp_lc = 0x42a064}}}
>          randNum = {{_mp_alloc = 2009288233, _mp_size = 2009288258,
>              _mp_d = 0x427fa0 <__do_global_dtors>}}
>          i = 0
>
> The interesting part is that if I remove the loop (the line "for (i = 0; i < 1; ++i)" ), then the program runs normally, without crashing, which leads me to suspect that this could be a compiler problem (the loop only runs once in the test code, so the effect should be the exact same, right?).
> Unfortunately, due to the rather large amount of time it takes for me to compile GMP on my computer, I haven't had the opportunity to test this with an earlier version of MinGW GCC, an earlier version of GMP, or GMP with any of the debug options. (if you'd like, I can recompile with one of those to see if it still crashes)
>
> Here's some info about my system:
>
> The output of 'gcc -v':
> Using built-in specs.
> COLLECT_GCC=gcc
> COLLECT_LTO_WRAPPER=c:/mingw/bin/../libexec/gcc/mingw32/4.7.2/lto-wrapper.exe
> Target: mingw32
> Configured with: ../gcc-4.7.2/configure --enable-languages=c,c++,ada,fortran,obj
> c,obj-c++ --disable-sjlj-exceptions --with-dwarf2 --enable-shared --enable-libgo
> mp --disable-win32-registry --enable-libstdcxx-debug --disable-build-poststage1-
> with-cxx --enable-version-specific-runtime-libs --build=mingw32 --prefix=/mingw
> Thread model: win32
> gcc version 4.7.2 (GCC)
>
> The output of 'uname -a':
> MINGW32_NT-5.1 EMACHINE-97610C 1.0.18(0.48/3/2) 2012-11-21 22:34 i686 Msys
>
> The output of './config.guess':
> atom-pc-mingw32
>
> The output of './configfsf.guess':
> i686-pc-mingw32
>
> If you need any other information, feel free to ask.
>
> Thanks!
> _______________________________________________
> gmp-bugs mailing list
> gmp-bugs at gmplib.org
> https://gmplib.org/mailman/listinfo/gmp-bugs
>


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