Don't fail if execinfo is not available

Previously, cmake aborted when execinfo was not found. With this commit the
backtrace code is just disabled when execinfo is not available.

Signed-off-by: Uli Schlachter <psychon@znc.in>

awesomeConfig.cmake

@@ -167,14 +167,23 @@ endmacro()
 a_find_library(LIB_EV ev)
 # GNU libc has <execinfo.h> and backtrace() stuff. If this is not available, we
 # need libexecinfo.
+message(STATUS "checking for execinfo")
 try_compile(HAS_EXECINFO
     ${CMAKE_BINARY_DIR}
     ${CMAKE_SOURCE_DIR}/build-tests/execinfo.c)
 if(NOT HAS_EXECINFO)
-    a_find_library(LIB_EXECINFO execinfo)
-    set(AWESOME_REQUIRED_LIBRARIES
-        ${AWESOME_REQUIRED_LIBRARIES}
-        ${LIB_EXECINFO})
+    find_library(LIB_EXECINFO execinfo)
+    if(LIB_EXECINFO)
+        set(HAS_EXECINFO 1)
+        set(AWESOME_REQUIRED_LIBRARIES
+            ${AWESOME_REQUIRED_LIBRARIES}
+            ${LIB_EXECINFO})
+    endif()
+endif()
+if(HAS_EXECINFO)
+    message(STATUS "checking for execinfo -- found")
+else()
+    message(STATUS "checking for execinfo -- not found")
 endif()
 
 # Error check

common/backtrace.c

@@ -19,9 +19,13 @@
  *
  */
 
-#include <execinfo.h>
+#include "config.h"
 #include "common/backtrace.h"
 
+#ifdef HAS_EXECINFO
+#include <execinfo.h>
+#endif
+
 #define MAX_STACK_SIZE 32
 
 /** Get a backtrace.
@@ -30,6 +34,9 @@
 void
 backtrace_get(buffer_t *buf)
 {
+    buffer_init(buf);
+
+#ifdef HAS_EXECINFO
     void *stack[MAX_STACK_SIZE];
     char **bt;
     int stack_size;
@@ -37,7 +44,6 @@ backtrace_get(buffer_t *buf)
     stack_size = backtrace(stack, countof(stack));
     bt = backtrace_symbols(stack, stack_size);
 
-    buffer_init(buf);
     if(bt)
     {
         for(int i = 0; i < stack_size; i++)
@@ -49,6 +55,7 @@ backtrace_get(buffer_t *buf)
         p_delete(&bt);
     }
     else
+#endif
         buffer_addsl(buf, "Cannot get backtrace symbols.");
 }
 

config.h.in

@@ -6,5 +6,6 @@
 #define AWESOME_IS_BIG_ENDIAN @AWESOME_IS_BIG_ENDIAN@
 
 #cmakedefine WITH_DBUS
+#cmakedefine HAS_EXECINFO
 
 #endif //_CONFIG_H_