Obtaining libc function name (e.g., scanf) with Intel PIN Instrumentation - c++

Question

I'm trying to obtain a routine name for libc functions (e.g., scanf in this case) with the Intel PIN instrumentation. After trying a lot of ways, I am under the belief that this is difficult, but I figured to ask first.
For the sake of brevity, below is a minimal example of an input binary source code and Intel PIN instrumentation code of what I have tried, I feel that the result is close, yet missing the final detail.
Example source code (test.c):
#include <stdio.h>
#include <stdlib.h>
void foo(char *buffer) {
scanf("%s", buffer);
printf("Unsafe gets: %s\n", buffer);
}
int main() {
char *buf = malloc(sizeof(char)*50);
foo(buf);
return 0;
}
Intel PIN instrumentation source code (test_pin.so):
VOID do_call(ADDRINT addr)
{
printf("%p - %s\n", (void*)addr, RTN_FindNameByAddress(addr).c_str());
//fprintf(trace, "\n[%s]\n", RTN_FindNameByAddress(addr).c_str()));
//fflush(trace);
}
VOID Instruction(INS ins, VOID *v)
{
if (INS_IsCall(ins))
{
if (INS_IsDirectBranchOrCall(ins))
{
const ADDRINT addr = INS_DirectBranchOrCallTargetAddress(ins);
INS_InsertPredicatedCall(ins, IPOINT_BEFORE, AFUNPTR(do_call),
IARG_PTR, addr, IARG_FUNCARG_CALLSITE_VALUE, 0, IARG_END);
}
}
}
int main(int argc, char **argv)
{
/* initialize symbol processing */
PIN_InitSymbols();
/* initialize Pin; optimized branch */
if (unlikely(PIN_Init(argc, argv)))
/* Pin initialization failed */
goto err;
INS_AddInstrumentFunction(Instruction, 0);
/* start Pin */
PIN_StartProgram();
/* typically not reached; make the compiler happy */
return EXIT_SUCCESS;
}
So the reason why I'm saying that I feel somewhat close is that running the above Intel PIN Instrumentation using the command pin -t test_pin.so -- ./test will result in the following output:
...
0x7f27aac14280 - brk
0x7f27aac142e0 - sbrk
0x7f27aab97a70 - pthread_attr_setschedparam
0x55a6dcbb8189 - foo
0x55a6dcbb8090 - .plt.sec
0x7f27aab63a00 - psiginfo
0x7f27aab91c30 - __uflow
0x7f27aab91e80 - _IO_doallocbuf
...
where we can observe that two addresses start with 0x5 (to indicate that this is from the main application rather than calling from a shared library such as 0x7):
0x55a6dcbb8189 - foo
0x55a6dcbb8090 - .plt.sec
Doing additional investigation using objdump or gdb of the above source code example, it can be found that the entry address of foo function and the mystery target of .plt.sec from the Intel PIN is (after removing the relocation base address):
0000000000001189 <foo>:
...
11ac: e8 df fe ff ff call 1090 <__isoc99_scanf#plt>
So instead of getting the output of .plt.sec, is it possible to somehow resolve this mysterious .plt.sec name into __isoc99_scanf? I would appreciate any suggestions.