/*-*- Mode: C; c-basic-offset: 8 -*-*/
/***
This file is part of memstomp.
Copyright 2009 Lennart Poettering
Copyright 2011 Red Hat
memstomp is free software: you can redistribute it and/or modify it
under the terms of the GNU Lesser General Public License as
published by the Free Software Foundation, either version 3 of the
License, or (at your option) any later version.
memstomp is distributed in the hope that it will be useful, but
WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public
License along with memstomp. If not, see .
***/
#include "config.h"
#include
#include
#include
#include
#include
#include
#include
#include
#include
#include
#include
#include
#include
#include
#include
#include
#if !defined (__linux__) || !defined(__GLIBC__)
#error "This stuff only works on Linux!"
#endif
#include
#define ABRT_TRAP raise(SIGSEGV)
static bool abrt_trap = false;
#ifndef SCHED_RESET_ON_FORK
/* "Your libc lacks the definition of SCHED_RESET_ON_FORK. We'll now
* define it ourselves, however make sure your kernel is new
* enough! */
#define SCHED_RESET_ON_FORK 0x40000000
#endif
#if defined(__i386__) || defined(__x86_64__)
#define DEBUG_TRAP __asm__("int $3")
#else
#include
#define DEBUG_TRAP raise(SIGTRAP)
#endif
#define LIKELY(x) (__builtin_expect(!!(x),1))
#define UNLIKELY(x) (__builtin_expect(!!(x),0))
static unsigned frames_max = 16;
static volatile unsigned n_broken = 0;
static volatile unsigned n_collisions = 0;
static volatile unsigned n_self_contended = 0;
static void (*real_exit)(int status) __attribute__((noreturn)) = NULL;
static void (*real__exit)(int status) __attribute__((noreturn)) = NULL;
static void (*real__Exit)(int status) __attribute__((noreturn)) = NULL;
static int (*real_backtrace)(void **array, int size) = NULL;
static char **(*real_backtrace_symbols)(void *const *array, int size) = NULL;
static void (*real_backtrace_symbols_fd)(void *const *array, int size, int fd) = NULL;
static __thread bool recursive = false;
static volatile bool initialized = false;
static volatile bool threads_existing = false;
static void setup(void) __attribute ((constructor));
static void shutdown(void) __attribute ((destructor));
static pid_t _gettid(void) {
return (pid_t) syscall(SYS_gettid);
}
static const char *get_prname(void) {
static char prname[17];
int r;
r = prctl(PR_GET_NAME, prname);
assert(r == 0);
prname[16] = 0;
return prname;
}
#if 0
static int parse_env(const char *n, unsigned *t) {
const char *e;
char *x = NULL;
unsigned long ul;
if (!(e = getenv(n)))
return 0;
errno = 0;
ul = strtoul(e, &x, 0);
if (!x || *x || errno != 0)
return -1;
*t = (unsigned) ul;
if ((unsigned long) *t != ul)
return -1;
return 0;
}
#endif
#define LOAD_FUNC(name) \
do { \
*(void**) (&real_##name) = dlsym(RTLD_NEXT, #name); \
assert(real_##name); \
} while (false)
#define LOAD_FUNC_VERSIONED(name, version) \
do { \
*(void**) (&real_##name) = dlvsym(RTLD_NEXT, #name, version); \
assert(real_##name); \
} while (false)
static void load_functions(void) {
static volatile bool loaded = false;
if (LIKELY(loaded))
return;
recursive = true;
LOAD_FUNC(exit);
LOAD_FUNC(_exit);
LOAD_FUNC(_Exit);
LOAD_FUNC(backtrace);
LOAD_FUNC(backtrace_symbols);
LOAD_FUNC(backtrace_symbols_fd);
loaded = true;
recursive = false;
}
static void setup(void) {
load_functions();
if (LIKELY(initialized))
return;
if (!dlsym(NULL, "main"))
fprintf(stderr,
"memstomp: Application appears to be compiled without -rdynamic. It might be a\n"
"memstomp: good idea to recompile with -rdynamic enabled since this produces more\n"
"memstomp: useful stack traces.\n\n");
if (getenv("MEMSTOMP_KILL"))
abrt_trap = true;
initialized = true;
fprintf(stderr, "memstomp: "PACKAGE_VERSION" sucessfully initialized for process %s (pid %lu).\n",
get_prname(), (unsigned long) getpid());
}
static void show_summary(void) { }
static void shutdown(void) {
show_summary();
}
void exit(int status) {
show_summary();
real_exit(status);
}
void _exit(int status) {
show_summary();
real_exit(status);
}
void _Exit(int status) {
show_summary();
real__Exit(status);
}
static bool verify_frame(const char *s) {
/* Generated by glibc's native backtrace_symbols() on Fedora */
if (strstr(s, "/" SONAME "("))
return false;
/* Generated by glibc's native backtrace_symbols() on Debian */
if (strstr(s, "/" SONAME " ["))
return false;
/* Generated by backtrace-symbols.c */
if (strstr(s, __FILE__":"))
return false;
return true;
}
static char* generate_stacktrace(void) {
void **buffer;
char **strings, *ret, *p;
int n, i;
size_t k;
bool b;
buffer = malloc(sizeof(void*) * frames_max);
assert(buffer);
n = real_backtrace(buffer, frames_max);
assert(n >= 0);
strings = real_backtrace_symbols(buffer, n);
assert(strings);
free(buffer);
k = 0;
for (i = 0; i < n; i++)
k += strlen(strings[i]) + 2;
ret = malloc(k + 1);
assert(ret);
b = false;
for (i = 0, p = ret; i < n; i++) {
if (!b && !verify_frame(strings[i]))
continue;
if (!b && i > 0) {
/* Skip all but the first stack frame of ours */
*(p++) = '\t';
strcpy(p, strings[i-1]);
p += strlen(strings[i-1]);
*(p++) = '\n';
}
b = true;
*(p++) = '\t';
strcpy(p, strings[i]);
p += strlen(strings[i]);
*(p++) = '\n';
}
*p = 0;
free(strings);
return ret;
}
int backtrace(void **array, int size) {
int r;
load_functions();
/* backtrace() internally uses a mutex. To avoid an endless
* loop we need to disable ourselves so that we don't try to
* call backtrace() ourselves when looking at that lock. */
recursive = true;
r = real_backtrace(array, size);
recursive = false;
return r;
}
char **backtrace_symbols(void *const *array, int size) {
char **r;
load_functions();
recursive = true;
r = real_backtrace_symbols(array, size);
recursive = false;
return r;
}
void backtrace_symbols_fd(void *const *array, int size, int fd) {
load_functions();
recursive = true;
real_backtrace_symbols_fd(array, size, fd);
recursive = false;
}
static void warn_memcpy(void * dest, const void * src, size_t count)
{
fprintf(stderr, "memcpy(0x%p, 0x%p, %ld) overlap for %s(%d)\n",
dest, src, count, get_prname(), getpid());
/* generate stack backtrace */
fprintf(stderr, "%s", generate_stacktrace());
}
void * memcpy(void * dest, const void * src, size_t count)
{
size_t distance = (dest > src) ? ((char *)dest - (char *)src)
: ((char *) src - (char *) dest);
/* Check for overlap. */
if (distance < count) {
if (abrt_trap) ABRT_TRAP;
/* report the overlap */
warn_memcpy(dest, src, count);
}
/* be safe use memmove */
return memmove(dest, src, count);
}