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/* 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 BACKTRACE_SKIP_PREFIX "backtrace_"
#if defined(HAVE_LIBUNWIND)
#include <libunwind.h>
static int backtrace_append_unwind(string_t *str)
{
size_t str_orig_size = str_len(str);
char proc_name[256];
int ret;
unsigned int fp = 0;
unw_cursor_t c;
unw_context_t ctx;
unw_proc_info_t pip;
bool success = FALSE;
if ((ret = unw_getcontext(&ctx)) != 0) {
str_printfa(str, "unw_getcontext() failed: %d", ret);
return -1;
}
if ((ret = unw_init_local(&c, &ctx)) != 0) {
str_printfa(str, "unw_init_local() failed: %d", ret);
return -1;
}
do {
str_printfa(str, "#%d ", fp);
if ((ret = unw_get_proc_info(&c, &pip)) != 0) {
str_printfa(str, "[unw_get_proc_info_failed(): %d]", ret);
} else if (pip.start_ip == 0 || pip.end_ip == 0) {
str_append(str, "[no start/end information]");
} else if ((ret = unw_get_proc_name(&c, proc_name, sizeof(proc_name), 0)) != 0 &&
ret != UNW_ENOMEM) {
str_printfa(str, "[unw_get_proc_name() failed: %d]", ret);
} else if (!success && str_begins(proc_name, BACKTRACE_SKIP_PREFIX)) {
str_truncate(str, str_orig_size);
continue;
} else {
str_append_max(str, proc_name, sizeof(proc_name));
str_printfa(str, "[0x%08zx]", pip.start_ip);
success = TRUE;
}
str_append(str, " -> ");
fp++;
} while ((ret = unw_step(&c)) > 0);
/* remove ' -> ' */
if (str->used > 4)
str_truncate(str, str->used - 4);
return ret == 0 && success ? 0 : -1;
}
#endif
#if defined(HAVE_BACKTRACE_SYMBOLS) && defined(HAVE_EXECINFO_H)
/* Linux */
#include <execinfo.h>
static int backtrace_append_libc(string_t *str)
{
size_t str_orig_size = str_len(str);
void *stack[MAX_STACK_SIZE];
char **strings;
int ret, i;
ret = backtrace(stack, N_ELEMENTS(stack));
if (ret <= 0)
return -1;
strings = backtrace_symbols(stack, ret);
for (i = 0; i < ret; i++) {
if (str_len(str) > str_orig_size)
str_append(str, " -> ");
if (strings == NULL) {
/* out of memory case */
str_printfa(str, "0x%p", stack[i]);
} else if (str_len(str) != str_orig_size ||
!str_begins(strings[i], BACKTRACE_SKIP_PREFIX))
str_append(str, strings[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 > 0)
str_append(ctx->str, " -> ");
str_printfa(ctx->str, "0x%p", (void *)ptr);
ctx->pos++;
return 0;
}
static int backtrace_append_libc(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
static int backtrace_append_libc(string_t *str ATTR_UNUSED)
{
return -1;
}
#endif
int backtrace_append(string_t *str)
{
#if defined(HAVE_LIBUNWIND)
size_t orig_len = str_len(str);
if (backtrace_append_unwind(str) == 0)
return 0;
/* failed to get useful backtrace. libc's own method is likely
better. */
str_truncate(str, orig_len);
#endif
return backtrace_append_libc(str);
}
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;
}
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