lib: backtrace_append() - If libunwind returns failure, fallback to libc's method

diff --git a/src/lib/backtrace-string.c b/src/lib/backtrace-string.c
index eb87fc38167bab2ad0bb45e566f21e5fea86d7c5..4c76a73db24c318ecbeb2f1f0a96e15fb370aca2 100644 (file)
--- a/src/lib/backtrace-string.c
+++ b/src/lib/backtrace-string.c
@@ -11,7 +11,7 @@
 
 #include <libunwind.h>
 
-int backtrace_append(string_t *str)
+static int backtrace_append_unwind(string_t *str)
 {
        size_t str_orig_size = str_len(str);
        char proc_name[256];
@@ -57,12 +57,13 @@ int backtrace_append(string_t *str)
                str_truncate(str, str->used - 4);
        return ret == 0 && success ? 0 : -1;
 }
+#endif
 
-#elif defined(HAVE_BACKTRACE_SYMBOLS) && defined(HAVE_EXECINFO_H)
+#if defined(HAVE_BACKTRACE_SYMBOLS) && defined(HAVE_EXECINFO_H)
 /* Linux */
 #include <execinfo.h>
 
-int backtrace_append(string_t *str)
+static int backtrace_append_libc(string_t *str)
 {
        size_t str_orig_size = str_len(str);
        void *stack[MAX_STACK_SIZE];
@@ -109,7 +110,7 @@ static int walk_callback(uintptr_t ptr, int signo ATTR_UNUSED,
        return 0;
 }
 
-int backtrace_append(string_t *str)
+static int backtrace_append_libc(string_t *str)
 {
        ucontext_t uc;
        struct walk_context ctx;
@@ -123,12 +124,25 @@ int backtrace_append(string_t *str)
        return 0;
 }
 #else
-int backtrace_append(string_t *str ATTR_UNUSED)
+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;