[PATCH] Fix a segfault in soapy_source_c

When the get_gain_names(chan) returns an empty vector calls set_gain(gain, chan) instead of set_gain(gain, names.front(), chan); (gdb) bt #0 std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >::basic_string (__str=..., this=0x7fffffffdb10) at /usr/include/c++/7/bits/basic_string.h:424 #1 soapy_source_c::set_if_gain (this=0x555556b85250, gain=32, chan=0) at ./lib/soapy/soapy_source_c.cc:257 #2 0x00007fffdf0b82a4 in source_impl::set_if_gain (this=0x555555bb6f30, gain=32, chan=<optimized out>) at ./lib/source_impl.cc:708 #3 0x00007fffdf3a860d in _wrap_source_sptr_set_if_gain (args=<optimized out>, kwargs=<optimized out>) at ./obj-x86_64-linux-gnu/swig/osmosdr_swigPYTHON_wrap.cxx:23069 #4 0x000055555564f3ca in call_function (oparg=<optimized out>, pp_stack=0x7fffffffdd10) at ../Python/ceval.c:4352 --- lib/soapy/soapy_source_c.cc | 20 ++++++++++++++------ 1 file changed, 14 insertions(+), 6 deletions(-) diff --git a/lib/soapy/soapy_source_c.cc b/lib/soapy/soapy_source_c.cc index a645361..e9e7377 100644 --- a/lib/soapy/soapy_source_c.cc +++ b/lib/soapy/soapy_source_c.cc @@ -253,16 +253,24 @@ double soapy_source_c::get_gain( const std::string & name, size_t chan ) double soapy_source_c::set_if_gain( double gain, size_t chan ) { - //docs specify RF gain is the first element - const std::string name = this->get_gain_names(chan).front(); - return this->set_gain(gain, name, chan); + std::vector<std::string> names = this->get_gain_names(chan); + if (names.length()) { + //docs specify RF gain is the first element + return this->set_gain(gain, names.front(), chan); + } else { + return this->set_gain(gain, chan); + } } double soapy_source_c::set_bb_gain( double gain, size_t chan ) { - //docs specify baseband gain is the last element - const std::string name = this->get_gain_names(chan).back(); - return this->set_gain(gain, name, chan); + std::vector<std::string> names =this->get_gain_names(chan); + if (names.length()) { + //docs specify baseband gain is the last element + return this->set_gain(gain, names.back(), chan); + } else { + return this->set_gain(gain, chan); + } } std::vector< std::string > soapy_source_c::get_antennas( size_t chan ) -- 2.13.6