* extract_integer_content(): integer_content() can also return a rational number, e.g if the expression is a polynomial over rationals (in this case expr/content is polynomial over integers with integer content being 1). Therefore check if integer_content() is really an integer (and if it's not just return 1, GCD for polynomials over a field is defined up to arbitrary element of the field). This fixes possible segfault when computing GCD of polynomials over rationals (this is not theoretical, see the added test case). --- check/bugme_chinrem_gcd.cpp | 18 ++++++++++++++++-- ginac/polynomial/mgcd.cpp | 10 ++++++++++ 2 files changed, 26 insertions(+), 2 deletions(-) diff --git a/check/bugme_chinrem_gcd.cpp b/check/bugme_chinrem_gcd.cpp index d3c0330..87c718c 100644 --- a/check/bugme_chinrem_gcd.cpp +++ b/check/bugme_chinrem_gcd.cpp @@ -38,13 +38,27 @@ static const std::string p1_srep("\ static const std::string p2_srep("\ 1882371920+29943249139*x^9-21558061051*x^35+24497174109*x^69+3363043648*x^25+5186524611*x^98-17753230977*x^56+16461882236*x^72+11039962159*x^11-85814533599*x^43-12986831645*x^85+4813620791*x^29-2133682609*x^2+9141433582*x^88-14841292646*x^13+19494168654*x^51-426278523*x^15-18246235652*x^59-12424469513*x^16-14414308862*x^38-16262001424*x^75+1584505491*x^3+6616907060*x^46+9411879011*x^91+7056872613*x^20+29675566382*x^78-48441925739*x^54+12038293769*x^33-22463329638*x^65+21957440404*x^41+26252749471*x^81-28689993421*x^24+1190623161*x^94-3323333429*x^62+778770195*x^68-23673866858*x^49+10263027507*x^97+29115114125*x^28-34230002076*x^36-217623403*x^71-6344703601*x^84+2789684836*x^100-44973929094*x^57-6061422988*x^44+18964048763*x^87+3160532878*x^8-8039690791*x^19-5750277357*x^74+5544486596*x^23+1800283356*x^90-8174921854*x^52+2577247520*x^64-1088265300*x^10+18566882873*x^39+12678193001*x^77-7204610489*x^27+9980611956*x^60+12672890141*x^80+4463462090*x^12-30937311949*x^47-3883570155*x^93+7561875663*x^14-3850452489*x^55+20714527103*x^31-9973372012*x^34+440594870*x^67+10385086102*x^96-20693764726*x^63+11049483001*x^18-11578701274*x^70-5548876327*x^42+20393397488*x^83+20531692560*x^50+1309311388*x^99-7521320830*x-2750892631*x^37-6001481047*x^73+7149046134*x^22+10287410396*x^86+7332053562*x^58-1135211878*x^4-7420079075*x^45+9742202475*x^89-214559874*x^26+29530802947*x^30-2280622009*x^32-4237029618*x^5+13760397067*x^76+18073788685*x^53+2485463829*x^40+1889202286*x^79+8841198971*x^6+13562767020*x^92+110919258*x^7+6961020716*x^61+11700952246*x^17-13528331424*x^66-19801882818*x^21+25061328813*x^82+1553111326*x^48+4638169279*x^95"); -int main(int argc, char** argv) +static void check_poly_cra() { - cout << "checking for bugs in poly_cra() " << flush; parser the_parser; ex p1 = the_parser(p1_srep); ex p2 = the_parser(p2_srep); ex g = chinrem_gcd(p1, p2); +} + +static void check_extract_integer_content() +{ + parser readme; + ex A = readme("1/282901891126422365*(x + y)"); + ex B = readme("165888/282901891126422365*(x - y)"); + ex g = chinrem_gcd(A, B); +} + +int main(int argc, char** argv) +{ + cout << "checking for bugs in poly_cra() and friends " << flush; + check_poly_cra(); + check_extract_integer_content(); cout << "not found."; return 0; } diff --git a/ginac/polynomial/mgcd.cpp b/ginac/polynomial/mgcd.cpp index 24da934..5b9da12 100644 --- a/ginac/polynomial/mgcd.cpp +++ b/ginac/polynomial/mgcd.cpp @@ -30,6 +30,9 @@ #include <numeric> // std::accumulate #include <cln/integer.h> +#include <cln/integer_ring.h> +#include <cln/rational.h> +#include <cln/rational_ring.h> namespace GiNaC { @@ -37,6 +40,13 @@ static cln::cl_I extract_integer_content(ex& Apr, const ex& A) { static const cln::cl_I n1(1); const numeric icont_ = A.integer_content(); + if (cln::instanceof(icont_.to_cl_N(), cln::cl_RA_ring)) { + Apr = (A/icont_).expand(); + // A is a polynomail over rationals, so GCD is defined + // up to arbitrary rational number. + return n1; + } + GINAC_ASSERT(cln::instanceof(icont_.to_cl_N(), cln::cl_I_ring)); const cln::cl_I icont = cln::the<cln::cl_I>(icont_.to_cl_N()); if (icont != 1) { Apr = (A/icont_).expand(); -- 1.7.2.3