stacktrace.hpp

#ifndef _STACKTRACE_HPP_
#define _STACKTRACE_HPP_

#include <execinfo.h>

#ifdef __GLIBCXX__
    #include <cxxabi.h>
#endif

#include <cstdio>
#include <cstdlib>

#include <string>

/** Print a demangled stack backtrace of the caller function to FILE* out. */
template< size_t max_frames = 63 >
inline void print_stacktrace( FILE *out = stderr )
{
    fprintf( out, "stack trace:\n" );

    // storage array for stack trace address data
    void* addrlist[ max_frames + 1 ];

    // retrieve current stack addresses
    int addrlen = backtrace( addrlist, sizeof( addrlist ) / sizeof( void* ) );

    if ( addrlen == 0 ) 
    {
        fprintf( out, "  <empty, possibly corrupt>\n" );
        return;
    }

    // resolve addresses into strings containing "filename(function+address)",
    // this array must be free()-ed
    char** symbollist = backtrace_symbols( addrlist, addrlen );

    // allocate string which will be filled with the demangled function name
    size_t funcnamesize = 256;
    char* funcname = (char*) malloc( funcnamesize );

    // iterate over the returned symbol lines. skip the first, it is the
    // address of this function.
    for ( int i = 1; i < addrlen; i++ )
    {
        char *begin_name = 0, *begin_offset = 0, *end_offset = 0;

        // find parentheses and +address offset surrounding the mangled name:
        // ./module(function+0x15c) [0x8048a6d]
        for ( char *p = symbollist[ i ]; *p; ++p )
        {
            if ( *p == '(' )
                begin_name = p;
            else if ( *p == '+' )
                begin_offset = p;
            else if ( *p == ')' && begin_offset )
            {
                end_offset = p;
                break;
            }
        }

        if ( begin_name && begin_offset && end_offset && begin_name < begin_offset )
        {
            *begin_name++   = '\0';
            *begin_offset++ = '\0';
            *end_offset     = '\0';

            // mangled name is now in [begin_name, begin_offset) and caller
            // offset in [begin_offset, end_offset). now apply
            // __cxa_demangle():

            int   status = 0;
            char* ret    = nullptr;

            #ifdef __GLIBCXX__
                ret = abi::__cxa_demangle( begin_name, funcname, &funcnamesize, &status );
            #endif

            if ( status == 0 ) 
            {
                funcname = ret; // use possibly realloc()-ed string
                fprintf( out, "  %s : %s+%s\n", symbollist[ i ], funcname, begin_offset );
            }
            else 
            {
                // demangling failed. Output function name as a C function with
                // no arguments.
                
                ret = nullptr; // avoiding unused warning... 
                fprintf( out, "  %s : %s()+%s\n", symbollist[ i ], begin_name, begin_offset );
            }
        }
        else
        {
            // couldn't parse the line? print the whole line.
            fprintf( out, "  %s\n", symbollist[ i ] );
        }
    }

    free( funcname );
    free( symbollist );
}

template< size_t max_frames = 63 >
std::string get_function_name( size_t i=0 )
{
    i += 1; // we don't want the name of this here...

    // storage array for stack trace address data
    void* addrlist[ max_frames + 1 ];

    // retrieve current stack addresses
    int addrlen = backtrace( addrlist, sizeof( addrlist ) / sizeof( void* ) );

    if ( addrlen == 0 ) 
    {
        return "";
    }

    // resolve addresses into strings containing "filename(function+address)",
    // this array must be free()-ed
    char** symbollist = backtrace_symbols( addrlist, addrlen );

    // allocate string which will be filled with the demangled function name
    size_t funcnamesize = 256;
    char* funcname = (char*) malloc( funcnamesize );

    // iterate over the returned symbol lines. skip the first, it is the
    // address of this function.
    
    char *begin_name = 0, *begin_offset = 0, *end_offset = 0;

    // find parentheses and +address offset surrounding the mangled name:
    // ./module(function+0x15c) [0x8048a6d]
    for ( char *p = symbollist[ i ]; *p; ++p )
    {
        if ( *p == '(' )
            begin_name = p;
        else if ( *p == '+' )
            begin_offset = p;
        else if ( *p == ')' && begin_offset )
        {
            end_offset = p;
            break;
        }
    }
        
    std::string name;

    if ( begin_name && begin_offset && end_offset && begin_name < begin_offset )
    {
        *begin_name++   = '\0';
        *begin_offset++ = '\0';
        *end_offset     = '\0';

        // mangled name is now in [begin_name, begin_offset) and caller
        // offset in [begin_offset, end_offset). now apply
        // __cxa_demangle():

        int   status = 0;
        char* ret    = nullptr;

        #ifdef __GLIBCXX__
            ret = abi::__cxa_demangle( begin_name, funcname, &funcnamesize, &status );
        #endif

        if ( status == 0 ) 
        {
            #ifdef __GLIBCXX__
                funcname = ret; // use possibly realloc()-ed string
            #endif
            
            name = funcname;
        }
        else // demangle failed 
        {
            name = begin_name;
        }
    }
    else
    {
        // couldn't parse the line? print the whole line.
       
        name = symbollist[ i ];
    }
    
    free( funcname );
    free( symbollist );
    
    return name;
}

#endif // _STACKTRACE_HPP_