stacktrace with libunwind and elfutils

stack_trace.c

// stack_trace.c
//
// gcc stack_trace.c -ldw -lunwind -g -o stack_trace

#define UNW_LOCAL_ONLY

#include <elfutils/libdwfl.h>
#include <libunwind.h>

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <stdarg.h>
#include <unistd.h>
#include <errno.h>
#include <assert.h>

static void debugInfo(FILE* out,const void* ip)
{

	char *debuginfo_path=NULL;

	Dwfl_Callbacks callbacks={
		.find_elf=dwfl_linux_proc_find_elf,
		.find_debuginfo=dwfl_standard_find_debuginfo,
		.debuginfo_path=&debuginfo_path,
	};

	Dwfl* dwfl=dwfl_begin(&callbacks);
	assert(dwfl!=NULL);

	assert(dwfl_linux_proc_report (dwfl, getpid())==0);
	assert(dwfl_report_end (dwfl, NULL, NULL)==0);

	Dwarf_Addr addr = (uintptr_t)ip;

	Dwfl_Module* module=dwfl_addrmodule (dwfl, addr);

	const char* function_name = dwfl_module_addrname(module, addr);

	fprintf(out,"%s(",function_name);

	Dwfl_Line *line=dwfl_getsrc (dwfl, addr);
	if(line!=NULL)
	{
		int nline;
		Dwarf_Addr addr;
		const char* filename=dwfl_lineinfo (line, &addr,&nline,NULL,NULL,NULL);
		fprintf(out,"%s:%d",strrchr(filename,'/')+1,nline);
	}
	else
	{
		fprintf(out,"%p",ip);
	}
}

static void __attribute__((noinline)) printStackTrace(FILE* out, int skip)
{

	unw_context_t uc;
	unw_getcontext(&uc);

	unw_cursor_t cursor;
	unw_init_local(&cursor, &uc);

	while(unw_step(&cursor)>0)
	{

		unw_word_t ip;
		unw_get_reg(&cursor, UNW_REG_IP, &ip);

		unw_word_t offset;
		char name[32];
		assert(unw_get_proc_name(&cursor, name,sizeof(name), &offset)==0);

		if(skip<=0)
		{
			fprintf(out,"\tat ");
			debugInfo(out,(void*)(ip-4));
			fprintf(out,")\n");
		}

		if(strcmp(name,"main")==0)
			break;
		
		skip--;

	}

}

void c(void)
{
	printStackTrace(stdout,0);
}

void b(void)
{
	c();
}

void a(void)
{
	b();
}

int main(int argc, char*argv[])
{
	a();
}

Works nicely, thank you for sharing.

To compile it as C++ and demangle C++ symbols do

--- stack_trace.c   2014-10-12 13:53:06.906109053 +0100
+++ stack_trace.c   2014-10-12 13:56:55.499288962 +0100
@@ -15,16 +15,17 @@
 #include <errno.h>
 #include <assert.h>

+#include <boost/core/demangle.hpp>
+
 static void debugInfo(FILE* out,const void* ip)
 {

    char *debuginfo_path=NULL;

-   Dwfl_Callbacks callbacks={
-       .find_elf=dwfl_linux_proc_find_elf,
-       .find_debuginfo=dwfl_standard_find_debuginfo,
-       .debuginfo_path=&debuginfo_path,
-   };
+   Dwfl_Callbacks callbacks = {};
+   callbacks.find_elf=dwfl_linux_proc_find_elf;
+   callbacks.find_debuginfo=dwfl_standard_find_debuginfo;
+   callbacks.debuginfo_path=&debuginfo_path;

    Dwfl* dwfl=dwfl_begin(&callbacks);
    assert(dwfl!=NULL);
@@ -38,7 +39,7 @@

    const char* function_name = dwfl_module_addrname(module, addr);

-   fprintf(out,"%s(",function_name);
+   fprintf(out,"%s(",boost::core::demangle(function_name).c_str());

    Dwfl_Line *line=dwfl_getsrc (dwfl, addr);
    if(line!=NULL)

Yes thank you very much for this snippet.

Here's how to get the .so name when the file name is not available:

--- stacktrace.c    2015-07-31 00:08:16.844089668 -0700
+++ stacktrace.c    2015-07-31 00:08:11.280271152 -0700
@@ -50,7 +50,9 @@
    }
    else
    {
-       fprintf(out,"%p",ip);
+        const char *module_name = dwfl_module_info(module,
+                NULL, NULL, NULL, NULL, NULL, NULL, NULL);
+        fprintf(out, "in %s", module_name);
    }
 }