Trace function calls using -finstrument-functions

instr_trace.c

#define _GNU_SOURCE

#include <stdio.h>
#include <limits.h>
#include <string.h>
#include <errno.h>

/* ========================================================================= */
static int indent_level = 0;

__attribute__ ((no_instrument_function)) static void
indent()
{
	int i;

	/* green TRACE word */
	printf("\x1B[32m" "TRACE:" "\x1B[0m");

	for (i=0; i<indent_level; i++) {
		putc(' ', stdout);
	}
}

__attribute__ ((no_instrument_function)) void
__cyg_profile_func_enter(void *this_fn, void *call_site)
{
	char cmd[PATH_MAX];
	FILE *p;

	(void)call_site;

	indent();

	sprintf(cmd, "addr2line -pif -e %s %p", program_invocation_name,
		this_fn);
	p = popen(cmd, "r");
	if (p) {
		char res[PATH_MAX];
		size_t len;

		fgets(res, sizeof(res), p);
		len = strlen(res);
		if (len > 1) {
			res[len - 1] = '\0';
		}
		pclose(p);
		printf("function %s {\n", res);
	} else {
		printf("function UNKNOWN (addr %p) {\n", this_fn);
	}
	indent_level++;
}

__attribute__ ((no_instrument_function)) void
__cyg_profile_func_exit(void *this_fn, void *call_site)
{
	(void)this_fn;
	(void)call_site;

	indent_level--;
	indent();

	printf("}\n");
}

/* ========================================================================= */

static void
world()
{
	printf("Hello world!\n");
}

static void
hello()
{
	world();
}

int
main()
{
	hello();
	return 0;
}