trace_function_calls.cpp

#include <elfutils/libdwfl.h>
#include <elfutils/libdw.h>
#include <sys/ptrace.h>
#include <unistd.h>
#include <cstdio>
#include <cstdlib>
#include <sys/wait.h>
#include <sys/ptrace.h>
#include <sys/types.h>
#include <sys/wait.h>
#include <sys/user.h>
#include <syscall.h>
#include <cstring>

static char *debuginfo_path = NULL;
static const Dwfl_Callbacks proc_callbacks =
  {
    .find_elf = dwfl_linux_proc_find_elf,
    .find_debuginfo = dwfl_standard_find_debuginfo,
    .debuginfo_path = &debuginfo_path,
  };
  
int main(int argc, char **argv) {  
    if (argc < 2) {
        printf("Usage: %s pid\n", argv[0]);
        return 1;
    }
    pid_t pid = atoi(argv[1]);

    Dwfl *dwfl = dwfl_begin(&proc_callbacks);
    if (!dwfl) {
        printf("dwfl_begin failed\n");
        return 1;
    }

    if (ptrace(PTRACE_ATTACH, pid, NULL, NULL) < 0) {
        printf("ptrace attach failed\n");
        return 1;
    }

    waitpid(pid, NULL, 0);

    dwfl_linux_proc_report(dwfl, pid);
    if (dwfl_linux_proc_attach(dwfl, pid, true) != 0) {
        printf("dwfl_linux_proc_attach failed\n");
        return 1;
    }

    Dwarf_Addr pc;
    Dwarf_Addr bias;
    Dwarf_Addr prev_pc = 0;
    Dwarf_Addr prev_bias = 0;
    const char *prev_name = NULL;
    struct user_regs_struct regs;
    while (true) {
        ptrace(PTRACE_SINGLESTEP, pid, NULL, NULL);
        waitpid(pid, NULL, 0);

        if (ptrace(PTRACE_GETREGS, pid, NULL, &regs) < 0) {
            printf("ptrace getregs failed\n");
            continue;
        }

        pc = regs.rip;
        Dwfl_Module *mod = dwfl_addrmodule(dwfl, pc);
        if (!mod) {
            printf("dwfl_addrmodule failed\n");
            continue;
        }
        GElf_Sym sym;
        const char *name = dwfl_module_addrsym(mod, pc, &sym, NULL);
        if (name && (pc != prev_pc) && (!prev_name || strcmp(prev_name, name) != 0 )) {
            printf("Symbol: ");
            printf("%s\n", name);
            prev_pc = pc;
            prev_name = name;
        }

    }
    dwfl_end(dwfl);
    return 0;
}