prints stack trace to stderr and file `backtrace-MILLISECONDS.trace`

c_log_backtrace.c

#ifndef EXT_BACKTRACE_H
#define EXT_BACKTRACE_H 1

#if defined(_WIN32) || defined(__WIN32__) || defined(WIN32)

static void ext_log_backtrace()
{
    // TODO: backtrace not implemented
}

#else

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <errno.h>
#include <execinfo.h>
#include <unistd.h>
#include <sys/time.h>


static int _ext__get_backtrace(char*** strings, int* count)
{
    const int backtrace_max_size = 128;

    void* buf[backtrace_max_size];
    int nptrs = backtrace(buf, backtrace_max_size);
    if(!nptrs)
    {
        fprintf(stderr, "ext_get_backtrace: backtrace failed: '%s'", strerror(errno));
        return 0;
    }

    char** lines = backtrace_symbols(buf, nptrs);
    if(!lines)
    {
        fprintf(stderr, "ext_get_backtrace: backtrace_symbols failed: '%s'", strerror(errno));
        return 0;
    }

    *strings = lines;
    *count = nptrs;

    return 1;
}

static long _ext__get_milliseconds()
{
    timeval t;
    if(gettimeofday(&t, NULL) == -1)
    {
        fprintf(stderr, "ext_get_milliseconds: gettimeofday failed: '%s'", strerror(errno));
        return 0;
    }

    return (t.tv_sec * 1000) + (t.tv_usec / 1000);
}

// filename: backtrace-MILLISECONDS.trace
static char* _ext__make_log_filename()
{
    const int max_filename_chars = 64;
    char* filename = (char*)malloc(max_filename_chars);
    if(filename)
    {
        snprintf(filename, max_filename_chars, "backtrace-%ld.trace", ext_get_milliseconds());
    }

    return filename;
}

static void _ext__log_backtrace_file(char** strings, int count)
{
    char* filename = _ext__make_log_filename();
    if(!filename)
        return;

    FILE* fp = fopen(filename, "w");
    if(!fp)
    {
        fprintf(stderr, "ext_log_backtrace_file: fopen for '%s' failed: '%s'", filename, strerror(errno));
        free(filename);
        return;
    }

    for (int i = 0; i != count; ++i)
    {
       fprintf(fp, "%s\n", strings[i]);
    }

    free(filename);
    fclose(fp);
}

static void _ext__log_backtrace_stderr(char** strings, int count)
{
    for (int i = 0; i != count; ++i)
    {
        fprintf(stderr, "%s\n", strings[i]);
    }
}

// Logs backtrace to stderr and file in the current directory
static void ext_log_backtrace()
{
    char** strings;
    int count;
    if(_ext__get_backtrace(&strings, &count))
    {
        _ext__log_backtrace_file(strings, count);
        _ext__log_backtrace_stderr(strings, count);

        free(strings);
    }
}

#endif

#endif // #ifndef EXT_BACKTRACE_H