/*
* Example program for unwinding core dumps.
*
* Compile a-la:
* gcc -Os -Wall \
* -Wl,--start-group \
* -lunwind -lunwind-x86 -lunwind-coredump \
* example-core-unwind.c \
* -Wl,--end-group \
* -oexample-core-unwind
*
* Run:
* eu-unstrip -n --core COREDUMP
* figure out which virtual addresses in COREDUMP correspond to which mapped executable files
* (binary and libraries), then supply them like this:
* ./example-core-unwind COREDUMP 0x400000:/bin/crashed_program 0x3458600000:/lib/libc.so.6 [...]
*
* Note: Program eu-unstrip is part of elfutils, virtual addresses of shared
* libraries can be determined by ldd (at least on linux).
*/
#include "compiler.h"
#undef _GNU_SOURCE
#define _GNU_SOURCE 1
#undef __USE_GNU
#define __USE_GNU 1
#include <assert.h>
#include <ctype.h>
#include <dirent.h>
#include <errno.h>
#include <fcntl.h>
#include <inttypes.h>
#include <setjmp.h>
#include <signal.h>
#include <stdio.h>
#include <stdlib.h>
#include <stdarg.h>
#include <stddef.h>
#include <string.h>
#include <syslog.h>
#include <sys/poll.h>
#include <sys/mman.h>
#include <sys/socket.h>
#include <sys/stat.h>
#include <sys/time.h>
#include <sys/types.h>
#include <sys/wait.h>
#include <sys/param.h>
#include <termios.h>
#include <time.h>
#include <unistd.h>
#include <stdbool.h>
#include <limits.h>
#include <pwd.h>
#include <grp.h>
/* For SIGSEGV handler code */
#include <execinfo.h>
#include <sys/ucontext.h>
#include <libunwind-coredump.h>
/* Utility logging functions */
enum {
LOGMODE_NONE = 0,
LOGMODE_STDIO = (1 << 0),
LOGMODE_SYSLOG = (1 << 1),
LOGMODE_BOTH = LOGMODE_SYSLOG + LOGMODE_STDIO,
};
const char *msg_prefix = "";
const char *msg_eol = "\n";
int logmode = LOGMODE_STDIO;
int xfunc_error_retval = EXIT_FAILURE;
void xfunc_die(void)
{
exit(xfunc_error_retval);
}
static void verror_msg_helper(const char *s,
va_list p,
const char* strerr,
int flags)
{
char *msg;
int prefix_len, strerr_len, msgeol_len, used;
if (!logmode)
return;
used = vasprintf(&msg, s, p);
if (used < 0)
return;
/* This is ugly and costs +60 bytes compared to multiple
* fprintf's, but is guaranteed to do a single write.
* This is needed for e.g. when multiple children
* can produce log messages simultaneously. */
prefix_len = msg_prefix[0] ? strlen(msg_prefix) + 2 : 0;
strerr_len = strerr ? strlen(strerr) : 0;
msgeol_len = strlen(msg_eol);
/* +3 is for ": " before strerr and for terminating NUL */
char *msg1 = (char*) realloc(msg, prefix_len + used + strerr_len + msgeol_len + 3);
if (!msg1)
{
free(msg);
return;
}
msg = msg1;
/* TODO: maybe use writev instead of memmoving? Need full_writev? */
if (prefix_len)
{
char *p;
memmove(msg + prefix_len, msg, used);
used += prefix_len;
p = stpcpy(msg, msg_prefix);
p[0] = ':';
p[1] = ' ';
}
if (strerr)
{
if (s[0])
{
msg[used++] = ':';
msg[used++] = ' ';
}
strcpy(&msg[used], strerr);
used += strerr_len;
}
strcpy(&msg[used], msg_eol);
if (flags & LOGMODE_STDIO)
{
fflush(stdout);
used += write(STDERR_FILENO, msg, used + msgeol_len);
}
msg[used] = '\0'; /* remove msg_eol (usually "\n") */
if (flags & LOGMODE_SYSLOG)
{
syslog(LOG_ERR, "%s", msg + prefix_len);
}
free(msg);
}
void log_msg(const char *s, ...)
{
va_list p;
va_start(p, s);
verror_msg_helper(s, p, NULL, logmode);
va_end(p);
}
/* It's a macro, not function, since it collides with log() from math.h */
#undef log
#define log(...) log_msg(__VA_ARGS__)
void error_msg(const char *s, ...)
{
va_list p;
va_start(p, s);
verror_msg_helper(s, p, NULL, logmode);
va_end(p);
}
void error_msg_and_die(const char *s, ...)
{
va_list p;
va_start(p, s);
verror_msg_helper(s, p, NULL, logmode);
va_end(p);
xfunc_die();
}
void perror_msg(const char *s, ...)
{
va_list p;
va_start(p, s);
/* Guard against "<error message>: Success" */
verror_msg_helper(s, p, errno ? strerror(errno) : NULL, logmode);
va_end(p);
}
void perror_msg_and_die(const char *s, ...)
{
va_list p;
va_start(p, s);
/* Guard against "<error message>: Success" */
verror_msg_helper(s, p, errno ? strerror(errno) : NULL, logmode);
va_end(p);
xfunc_die();
}
void die_out_of_memory(void)
{
error_msg_and_die("Out of memory, exiting");
}
/* End of utility logging functions */
static
void handle_sigsegv(int sig, siginfo_t *info, void *ucontext)
{
long ip = 0;
ucontext_t *uc UNUSED;
uc = ucontext;
#if defined(__linux__)
#ifdef UNW_TARGET_X86
ip = uc->uc_mcontext.gregs[REG_EIP];
#elif defined(UNW_TARGET_X86_64)
ip = uc->uc_mcontext.gregs[REG_RIP];
#elif defined(UNW_TARGET_ARM)
ip = uc->uc_mcontext.arm_pc;
#endif
#elif defined(__FreeBSD__)
#ifdef __i386__
ip = uc->uc_mcontext.mc_eip;
#elif defined(__amd64__)
ip = uc->uc_mcontext.mc_rip;
#else
#error Port me
#endif
#else
#error Port me
#endif
dprintf(2, "signal:%d address:0x%lx ip:0x%lx\n",
sig,
/* this is void*, but using %p would print "(null)"
* even for ptrs which are not exactly 0, but, say, 0x123:
*/
(long)info->si_addr,
ip);
{
/* glibc extension */
void *array[50];
int size;
size = backtrace(array, 50);
#ifdef __linux__
backtrace_symbols_fd(array, size, 2);
#endif
}
_exit(1);
}
static void install_sigsegv_handler(void)
{
struct sigaction sa;
memset(&sa, 0, sizeof(sa));
sa.sa_sigaction = handle_sigsegv;
sa.sa_flags = SA_SIGINFO;
sigaction(SIGSEGV, &sa, NULL);
sigaction(SIGILL, &sa, NULL);
sigaction(SIGFPE, &sa, NULL);
sigaction(SIGBUS, &sa, NULL);
}
int
main(int argc UNUSED, char **argv)
{
unw_addr_space_t as;
struct UCD_info *ui;
unw_cursor_t c;
int ret;
#define TEST_FRAMES 4
#define TEST_NAME_LEN 32
int testcase = 0;
int test_cur = 0;
long test_start_ips[TEST_FRAMES];
char test_names[TEST_FRAMES][TEST_NAME_LEN];
install_sigsegv_handler();
const char *progname = strrchr(argv[0], '/');
if (progname)
progname++;
else
progname = argv[0];
if (!argv[1])
error_msg_and_die("Usage: %s COREDUMP [VADDR:BINARY_FILE]...", progname);
msg_prefix = progname;
as = unw_create_addr_space(&_UCD_accessors, 0);
if (!as)
error_msg_and_die("unw_create_addr_space() failed");
ui = _UCD_create(argv[1]);
if (!ui)
error_msg_and_die("_UCD_create('%s') failed", argv[1]);
ret = unw_init_remote(&c, as, ui);
if (ret < 0)
error_msg_and_die("unw_init_remote() failed: ret=%d\n", ret);
argv += 2;
/* Enable checks for the crasher test program? */
if (*argv && !strcmp(*argv, "-testcase"))
{
testcase = 1;
logmode = LOGMODE_NONE;
argv++;
}
while (*argv)
{
char *colon;
long vaddr = strtol(*argv, &colon, 16);
if (*colon != ':')
error_msg_and_die("Bad format: '%s'", *argv);
if (_UCD_add_backing_file_at_vaddr(ui, vaddr, colon + 1) < 0)
error_msg_and_die("Can't add backing file '%s'", colon + 1);
argv++;
}
for (;;)
{
unw_word_t ip;
ret = unw_get_reg(&c, UNW_REG_IP, &ip);
if (ret < 0)
error_msg_and_die("unw_get_reg(UNW_REG_IP) failed: ret=%d\n", ret);
unw_proc_info_t pi;
ret = unw_get_proc_info(&c, &pi);
if (ret < 0)
error_msg_and_die("unw_get_proc_info(ip=0x%lx) failed: ret=%d\n", (long) ip, ret);
if (!testcase)
printf("\tip=0x%08lx proc=%08lx-%08lx handler=0x%08lx lsda=0x%08lx\n",
(long) ip,
(long) pi.start_ip, (long) pi.end_ip,
(long) pi.handler, (long) pi.lsda);
if (testcase && test_cur < TEST_FRAMES)
{
unw_word_t off;
test_start_ips[test_cur] = (long) pi.start_ip;
if (unw_get_proc_name(&c, test_names[test_cur], sizeof(test_names[0]), &off) != 0)
{
test_names[test_cur][0] = '\0';
}
test_cur++;
}
log("step");
ret = unw_step(&c);
log("step done:%d", ret);
if (ret < 0)
error_msg_and_die("FAILURE: unw_step() returned %d", ret);
if (ret == 0)
break;
}
log("stepping ended");
/* Check that the second and third frames are equal, but distinct of the
* others */
if (testcase &&
(test_cur != 4
|| test_start_ips[1] != test_start_ips[2]
|| test_start_ips[0] == test_start_ips[1]
|| test_start_ips[2] == test_start_ips[3]
)
)
{
fprintf(stderr, "FAILURE: start IPs incorrect\n");
return -1;
}
if (testcase &&
( strcmp(test_names[0], "a")
|| strcmp(test_names[1], "b")
|| strcmp(test_names[2], "b")
|| strcmp(test_names[3], "main")
)
)
{
fprintf(stderr, "FAILURE: procedure names are missing/incorrect\n");
return -1;
}
_UCD_destroy(ui);
unw_destroy_addr_space(as);
return 0;
}