awesomeConfig: test for execinfo.h/backtrace()

add a test for execinfo.h and backtrace() function which are defined by
GNU libc. If it fails, require libexecinfo.

Signed-off-by: Julien Danjou <julien@danjou.info>

awesomeConfig.cmake

@@ -165,6 +165,17 @@ endmacro()
 
 # Check for libev
 a_find_library(LIB_EV ev)
+# GNU libc has <execinfo.h> and backtrace() stuff. If this is not available, we
+# need libexecinfo.
+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})
+endif()
 
 # Error check
 if(NOT LUA51_FOUND AND NOT LUA50_FOUND) # This is a workaround to a cmake bug

build-tests/execinfo.c

@@ -0,0 +1,42 @@
+/*
+ * build-tests/execinfo.c
+ * stolen from http://www.gnu.org/s/libc/manual/html_node/Backtraces.html
+ */
+#include <execinfo.h>
+#include <stdio.h>
+#include <stdlib.h>
+
+/* Obtain a backtrace and print it to stdout. */
+void
+print_trace (void)
+{
+  void *array[10];
+  size_t size;
+  char **strings;
+  size_t i;
+
+  size = backtrace (array, 10);
+  strings = backtrace_symbols (array, size);
+
+  printf ("Obtained %zd stack frames.\n", size);
+
+  for (i = 0; i < size; i++)
+     printf ("%s\n", strings[i]);
+
+  free (strings);
+}
+
+/* A dummy function to make the backtrace more interesting. */
+void
+dummy_function (void)
+{
+  print_trace ();
+}
+
+int
+main (void)
+{
+  dummy_function ();
+  return 0;
+}
+