Use getauxval for obtaining the executable path.

It appears that reading /proc/self/exe actually can return the path
of the shared library from which the reading is made.

query_classifier/qc_pp/qc_pp.c

@@ -22,6 +22,8 @@
  *
  */
 
+#include <sys/auxv.h>
+#include <elf.h>
 #include <log_manager.h>
 #include <modules.h>
 #include <query_classifier.h>
@@ -86,37 +88,32 @@ static void end_and_unload_classifier(QUERY_CLASSIFIER* classifier, const char*
 static bool resolve_pp_path(char* path, int size)
 {
     bool success = false;
-    ssize_t sz = readlink("/proc/self/exe", path, size);
+    const char* exe_path = (const char*) getauxval(AT_EXECFN);
+    size_t len = strlen(exe_path);
 
-    if (sz >= 0)
+    if (len < size)
     {
-        if (sz == size)
+        strcpy(path, exe_path);
-        {
+        char* s = path + len;
-            MXS_ERROR("The full path of the current executable does not fit in a "
-                      "buffer of %d bytes.", size);
-        }
-        else
-        {
-            char* s = path + sz;
 
         // Find the last '/'.
         while ((*s != '/') && (s != path))
         {
             --s;
-                --sz;
+            --len;
         }
 
         if (*s == '/')
         {
             ++s;
-                ++sz;
+            ++len;
         }
 
         *s = 0;
 
-            int required_size = sz + sizeof(MAXPP) + 1;
+        int required_size = len + sizeof(MAXPP) + 1;
 
-            if (required_size + 1 <= size)
+        if (required_size <= size)
         {
             strcat(path, MAXPP);
 
@@ -129,10 +126,10 @@ static bool resolve_pp_path(char* path, int size)
                       "not fit into a buffer of %d bytes. ", size);
         }
     }
-    }
     else
     {
-        MXS_ERROR("Could not establish location of current process.");
+        MXS_ERROR("The full path of the current executable does not fit in a "
+                  "buffer of %d bytes.", size);
     }
 
     return success;