"Research on the principle of Coredump" Linux x86 version 7.8 vector-related iterator objects

In front of a vectorcoredump example, contact with the vector iterator, can know that the vector iterator only one member _m_current point to a vector element.

First look at the example:

1 #include <vector>  2   3 void init (std::vector<int>& vec)  4 {  5 for     (int i = 0; I &l T 0x10 i++)  6     {  7         vec.push_back (i);  8     }  9}  getsum int (std::vector<int>& VEC) {     std::vector<int>::iterator Iter     int result = 0;     (iter = Vec.begin (); ITER! = Vec.end (); iter++) (     +)         + result + = *iter;  (     ) +     return result; () the (). (  ). {     std::vector<int> Vec;     VEC);     getsum return (VEC); 30}

Because it is only to examine iterator, only to see the Getsum assembly:

(GDB) disassemble getsumdump of assembler code for function _Z6GETSUMRST6VECTORIISAIIEE:0X080486CD <+0>:p ush%e bp 0x080486ce <+1>:mov%esp,%ebp 0x080486d0 <+3>:sub $0x38,%esp 0x080486d3 <+6>:lea-0x18 (%EBP),%eax 0x080486d6 <+9>:mov%eax, (%ESP) 0x080486d9 <+12>:call 0x8048840 <_zn9__gnu_cxx17__norm Al_iteratoripist6vectoriisaiieeec2ev> 0x080486de <+17>:movl $0x0,-0xc (%EBP) 0x080486e5 <+24>:lea-  0x1c (%EBP),%eax 0x080486e8 <+27>:mov 0x8 (%EBP),%edx 0x080486eb <+30>:mov%edx,0x4 (%ESP) 0x080486ef <+34>:mov%eax, (%ESP) 0x080486f2 <+37>:call 0x804884e <_ZNSt6vectorIiSaIiEE5beginEv> 0x080486f 7 <+42>:sub $0x4,%esp 0x080486fa <+45>:mov-0x1c (%EBP),%eax 0x080486fd <+48>:mov%eax,-0x18 (%EBP) 0x08048700 <+51>:jmp 0x804872f <_Z6getSumRSt6vectorIiSaIiEE+98> 0x08048702 <+53>:lea-0 X18 (%EBP),%eax 0x08048705 <+56>:mov%eax, (%ESP) 0x08048708 <+59>:call 0x80488f8 <_znk9__gnu_cxx17__normal_iteratoripist6ve Ctoriisaiieeedeev> 0x0804870d <+64>:mov (%eax),%eax 0x0804870f <+66>:add%eax,-0xc (%EBP) 0x0804 8712 <+69>:lea-0x10 (%EBP),%eax 0x08048715 <+72>:movl $0x0,0x8 (%esp) 0x0804871d <+80>:lea-0 X18 (%EBP),%edx 0x08048720 <+83>:mov%edx,0x4 (%esp) 0x08048724 <+87>:mov%eax, (%ESP) 0x08048727 &lt ; +90>:call 0x80488c4 <_ZN9__gnu_cxx17__normal_iteratorIPiSt6vectorIiSaIiEEEppEi> 0x0804872c <+95>: Sub $0x4,%esp 0x0804872f <+98>:lea-0x14 (%EBP),%eax 0x08048732 <+101>:mov 0x8 (%EBP),%edx 0x0804 8735 <+104>:mov%edx,0x4 (%esp) 0x08048739 <+108>:mov%eax, (%ESP) 0x0804873c <+111>:call 0x80 48872 <_ZNSt6vectorIiSaIiEE3endEv> 0x08048741 <+116>:sub $0x4,%esp 0x08048744 <+119>:lea-0x14 (%EBP),%eax 0x08048747 <+122>:mov%eax,0x4 (%ESP) 0x0804874b <+126>:lea-0x18 (%EBP),%eax 0x0804874e <+129>:mov%eax, (%e SP) 0x08048751 <+132>:call 0x8048898 <_zn9__gnu_cxxneipist6vectoriisaiieeeebrkns_17__normal_iteratorit_t0 _eesa_> 0x08048756 <+137>:test%al,%al 0x08048758 <+139>:jne 0x8048702 <_Z6getSumRSt6vectorIiSa Iiee+53> 0x0804875a <+141>:mov-0xc (%EBP),%eax 0x0804875d <+144>:leave 0x0804875e <+145>:r Et End of assembler dump.

At the 0x0804874b break point. By the above assembly, ITER's this pointer is ebp-0x18, and the VEC's this pointer is placed in ebp+0x8.

Run to the breakpoint and look at the contents of the VEC:

(GDB) x $ebp +80xbffff5a0:0xbffff5b4 (gdb) x/4x 0xbffff5b40xbffff5b4:0x0804b0680x0804b0a80x0804b0a80x080491f0 (GDB) x/ 16x 0x0804b0680x804b068:0x000000000x000000010x000000020x000000030x804b078:0 x000000040x000000050x000000060x000000070x804b088:0x000000080x000000090x0000000a0x0000000b0x804b098:0 x0000000c0x0000000d0x0000000e0x0000000f

Take a look at how the contents of ITER change, after running a few C commands (note that the breakpoint address is after running iter++):

It is true that the iterator of a vector does have only one member _ptr, and its value range is

Vec. _m_start? <= _m_current < VEC. _m_finish

"Research on the principle of Coredump" Linux x86 version 7.8 vector-related iterator objects