include/barrett/detail/stacktrace.h

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#ifndef BARRETT_DETAIL_STACKTRACE_H_
#define BARRETT_DETAIL_STACKTRACE_H_


#include <stdio.h>
#include <syslog.h>
#include <stdlib.h>
#include <execinfo.h>
#include <cxxabi.h>


namespace barrett {
namespace detail {


/* Print a demangled stack backtrace of the caller function to FILE* out. */
static inline void print_stacktrace(FILE *out = stderr,
                unsigned int max_frames = 63)
{
    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(addrlist[0]));

    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 = reinterpret_cast<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;
            char* ret = abi::__cxa_demangle(begin_name,
                                            funcname, &funcnamesize, &status);
            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.
                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);
}

/* Print a demangled stack backtrace of the caller function to syslog. */
static inline void syslog_stacktrace(int pri = LOG_ERR,
                unsigned int max_frames = 63)
{
    syslog(pri, "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(addrlist[0]));

    if (addrlen == 0) {
    syslog(pri, "  <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 = reinterpret_cast<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;
            char* ret = abi::__cxa_demangle(begin_name,
                                            funcname, &funcnamesize, &status);
            if (status == 0) {
                funcname = ret; // use possibly realloc()-ed string
                syslog(pri, "  %s : %s+%s\n",
                        symbollist[i], funcname, begin_offset);
            } else {
                // demangling failed. Output function name as a C function with
                // no arguments.
                syslog(pri, "  %s : %s()+%s\n",
                        symbollist[i], begin_name, begin_offset);
            }
        } else {
            // couldn't parse the line? print the whole line.
            syslog(pri, "  %s\n", symbollist[i]);
        }
    }

    free(funcname);
    free(symbollist);
}


}
}


#endif /* BARRETT_DETAIL_STACKTRACE_H_ */