src/lib/backtrace-string.c

/* Copyright (c) 2006-2018 Dovecot authors, see the included COPYING file */

#include "lib.h"
#include "str.h"
#include "backtrace-string.h"

#define MAX_STACK_SIZE 30
#define STACK_SKIP_COUNT 2

#if defined(HAVE_BACKTRACE_SYMBOLS) && defined(HAVE_EXECINFO_H)
/* Linux */
#include <execinfo.h>

int backtrace_append(string_t *str)
{
    void *stack[MAX_STACK_SIZE];
    char **strings;
    int ret, i;

    ret = backtrace(stack, N_ELEMENTS(stack));
    if (ret <= STACK_SKIP_COUNT)
        return -1;

    strings = backtrace_symbols(stack, ret);
    for (i = STACK_SKIP_COUNT; i < ret; i++) {
        if (i > STACK_SKIP_COUNT)
            str_append(str, " -> ");

        if (strings != NULL)
            str_append(str, strings[i]);
        else {
            /* out of memory case */
            str_printfa(str, "0x%p", stack[i]);
        }
    }
    free(strings);
    return 0;
}
#elif defined(HAVE_WALKCONTEXT) && defined(HAVE_UCONTEXT_H)
/* Solaris */
#include <ucontext.h>

struct walk_context {
    string_t *str;
    unsigned int pos;
};

static int walk_callback(uintptr_t ptr, int signo ATTR_UNUSED,
             void *context)
{
    struct walk_context *ctx = context;

    if (ctx->pos >= STACK_SKIP_COUNT) {
        if (ctx->pos > STACK_SKIP_COUNT)
            str_append(ctx->str, " -> ");
        str_printfa(ctx->str, "0x%p", (void *)ptr);
    }
    ctx->pos++;
    return 0;
}

int backtrace_append(string_t *str)
{
    ucontext_t uc;
    struct walk_context ctx;

    if (getcontext(&uc) < 0)
        return -1;

    ctx.str = str;
    ctx.pos = 0;
    walkcontext(&uc, walk_callback, &ctx);
    return 0;
}
#else
int backtrace_append(string_t *str ATTR_UNUSED)
{
    return -1;
}
#endif

int backtrace_get(const char **backtrace_r)
{
    string_t *str;

    str = t_str_new(512);
    if (backtrace_append(str) < 0)
        return -1;

    *backtrace_r = str_c(str);
    return 0;
}