backtrace: Allow to build without libbacktrace.

For apitrace integrated into Regal they want to opt-out of backtrace
support, for now.  One reason is that it's fairly platform-specific.
Another concern is potential build issue across various Linux flavors.

Based on Nigel Stewart patch on issue #168.

3 files changed, 27 insertions, 48 deletions

diff --git a/CMakeLists.txt b/CMakeLists.txt
index 4566db59..81e5cdcd 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -269,6 +269,7 @@ if (CMAKE_EXECUTABLE_FORMAT STREQUAL "ELF")
     add_subdirectory (thirdparty/libbacktrace)
     include_directories (${CMAKE_CURRENT_SOURCE_DIR}/thirdparty/libbacktrace)
     set (LIBBACKTRACE_LIBRARIES dl backtrace)
+    add_definitions (-DHAVE_BACKTRACE=1)
 endif ()
 
 # Always use bundled QJSon.
diff --git a/common/os_backtrace.cpp b/common/os_backtrace.cpp
index 1a555900..c95692bd 100644
--- a/common/os_backtrace.cpp
+++ b/common/os_backtrace.cpp
@@ -30,14 +30,25 @@
  */
 
 
-
 #include "os_backtrace.hpp"
 
-#if defined(ANDROID) || defined(__ELF__)
-
 #include <set>
+#include <vector>
 #include "os.hpp"
 
+#if defined(ANDROID)
+#  include <dlfcn.h>
+#elif HAVE_BACKTRACE
+#  include <stdint.h>
+#  include <dlfcn.h>
+#  include <unistd.h>
+#  include <map>
+#  include <vector>
+#  include <cxxabi.h>
+#  include <backtrace.h>
+#endif
+
+
 using trace::Id;
 
 namespace os {
@@ -111,16 +122,8 @@ bool backtrace_is_needed(const char* fname) {
     return backtraceFunctionNamePrefixes.contain(fname);
 }
 
-} /* namespace os */
-
 #if defined(ANDROID)
 
-#include <dlfcn.h>
-#include "os.hpp"
-#include <vector>
-
-namespace os {
-
 /* The following two declarations are copied from Android sources */
 
 enum DebugTargetKind {
@@ -274,21 +277,9 @@ void dump_backtrace() {
     /* TODO */
 }
 
-} /* namespace os */
 
-/* end ANDROID */
-#elif defined(__ELF__)
+#elif HAVE_BACKTRACE
 
-#include <stdint.h>
-#include <dlfcn.h>
-#include <unistd.h>
-#include <map>
-#include <vector>
-#include <cxxabi.h>
-
-#include <backtrace.h>
-
-namespace os {
 
 static char* format(uintptr_t num, int base, char *buf, int maxlen)
 {
@@ -480,8 +471,16 @@ void dump_backtrace() {
 }
 
 
-} /* namespace os */
+#else /* !HAVE_BACKTRACE */
 
-#endif /* __ELF__ */
+std::vector<RawStackFrame> get_backtrace() {
+    return std::vector<RawStackFrame>();
+}
 
-#endif /* ANDROID or LINUX */
+void dump_backtrace() {
+}
+
+#endif
+
+
+} /* namespace os */
diff --git a/common/os_backtrace.hpp b/common/os_backtrace.hpp
index ae1c831a..27dcc90f 100644
--- a/common/os_backtrace.hpp
+++ b/common/os_backtrace.hpp
@@ -36,32 +36,11 @@ namespace os {
 using trace::RawStackFrame;
 
 
-#if defined(ANDROID) || defined(__ELF__)
-
 std::vector<RawStackFrame> get_backtrace();
 bool backtrace_is_needed(const char* fname);
 
-#else
-
-static inline std::vector<RawStackFrame> get_backtrace() {
-    return std::vector<RawStackFrame>();
-}
-
-static inline bool backtrace_is_needed(const char*) {
-    return false;
-}
-
-#endif
-
-#if defined(__ELF__)
-
 void dump_backtrace();
 
-#else
-
-static inline void dump_backtrace() {}
-
-#endif
 
 } /* namespace os */