dbug.c

/* dbug - resolve symbols and print stack traces
 * Copyright (c) 2004 Michael B. Allen <mba2000 ioplex.com>
 *
 * The MIT License
 *
 * Permission is hereby granted, free of charge, to any person obtaining a
 * copy of this software and associated documentation files (the "Software"),
 * to deal in the Software without restriction, including without limitation
 * the rights to use, copy, modify, merge, publish, distribute, sublicense,
 * and/or sell copies of the Software, and to permit persons to whom the
 * Software is furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included
 * in all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
 * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR
 * OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
 * ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
 * OTHER DEALINGS IN THE SOFTWARE.
 */

#include <stdlib.h>
#include <stdio.h>

#if defined(_GNU_SOURCE) && defined(__i386__)

#include <execinfo.h>
#include <dlfcn.h>

#include "mba/path.h"
#include "mba/text.h"

int
dbug_stacktrace(void **buf, int off, int n)
{
  int i;
  void *_buf[16];

  if (n < 1 || n > 15) {
    n = 15;
  }
  off++;

  n = backtrace(_buf, n + off);

  for (i = off; i < n; i++) {
    buf[i - off] = _buf[i];
  }

  return i - off;
}
/* Put 'fname\0sname\0' into buf and return pointer to sname
 * Put '\0hexval\0' into buf and return pointer to hexval if
 * sym cannot be resolved
 */
unsigned char *
dbug_resolve_symbol(void *sym,
    unsigned char *buf,
    unsigned char *blim)
{
  Dl_info info;
  const char *name;

  if (dladdr(sym, &info) == 0) {
    *buf++ = '\0'; /* no filename */
    dsnprintf(buf, blim - buf, "%p", sym);
    return buf;
  }

  name = info.dli_fname;
  name = path_name((unsigned char *)name, (unsigned char *)name + 255, '/');
  buf += str_copy(name, name + 255, buf, blim, -1) + 1;
  name = info.dli_sname;
  str_copy(name, name + 255, buf, blim, -1);

  return buf;
}
int
dbug_sprint_stacktrace(unsigned char *str,
      unsigned char *slim,
      void **syms,
      int sn,
      const unsigned char *msg)
{
  unsigned char *start = str;
  const unsigned char *pad = ":  \n", *in = pad + 1, *nl = pad + 3;
  int si = 0;

  while (si < sn) {
    unsigned char buf[1024], *blim = buf + 1024, *sname;

    sname = dbug_resolve_symbol(syms[si++], buf, blim);
    *(sname - 1) = ':';
    str += str_copy(buf, blim, str, slim, -1);
    if (si == 1 && msg) {
      str += str_copy(pad, pad + 3, str, slim, 2);
      str += str_copy(msg, msg + 1024, str, slim, -1);
    }
    str += str_copy(nl, nl + 2, str, slim, 1);
    if (si == sn) {
      break;
    }
    str += str_copy(in, in + 3, str, slim, 2);
  }

  return str - start;
}
int
dbug_fprint_stacktrace(FILE *stream, int off, int n, const char *msg)
{
  void *syms[16];
  unsigned char str[1024];

  n = dbug_stacktrace(syms, off, n + 1);
  if (n && (n = dbug_sprint_stacktrace(str, str + 1024, syms + 1, n - 1, msg)) == -1) {
    return -1;
  }
  fwrite(str, 1, n, stream);
  fflush(stream);

  return 0;
}

#else /* backtraces not supported - emit stub implementation */

int
dbug_stacktrace(void **buf, int off, int n)
{
  (void)buf;
  (void)off;
  (void)n;
  return 0;
}
unsigned char *
dbug_resolve_symbol(void *sym, unsigned char *buf, unsigned char *blim)
{
  (void)sym;
  (void)buf;
  (void)blim;
  return NULL;
}
int
dbug_sprint_stacktrace(unsigned char *str,
      unsigned char *slim,
      void **syms,
      int sn,
      const unsigned char *msg)
{
  (void)str;
  (void)slim;
  (void)syms;
  (void)sn;
  (void)msg;
  return 0;
}
int
dbug_fprint_stacktrace(FILE *stream, int off, int n, const char *msg)
{
  (void)stream;
  (void)off;
  (void)n;
  (void)msg;
  return 0;
}

#endif