Use __builtin_strrchr to get file base name

Prior to this change, pinelog used __FILE__ in the backtrace call.
However, this has a limitation that if used in a build system with
sources in subdirectories and/or a separate build directory, the
relative path to the file is used, giving us a backtrace like this.

    ../../daemon/x52d_main.c:51

This change checks if the compiler supports the __builtin_strrchr to
compute the file basename at compile time. If the compiler does not
support it, it falls back to using __FILE__ directly. This should not be
an issue on a modern compiler like gcc or clang.

pinelog.h

@@ -134,34 +134,44 @@ void pinelog_log_message(int level, const char *file, int line, const char *fmt,
 #define pinelog_exit exit
 #endif
 
+// Base filename
+#if defined __has_builtin
+#   if __has_builtin(__builtin_strrchr)
+#       define PINELOG_FILE __builtin_strrchr(__FILE__, '/') ? __builtin_strrchr(__FILE__, '/') + 1 : __FILE__
+#   endif
+#endif
+#ifndef PINELOG_FILE
+#   define PINELOG_FILE __FILE__
+#endif
+
 #define PINELOG_FATAL(fmt, ...) do { \
     if (PINELOG_LVL_FATAL <= pinelog_get_level()) { \
-        pinelog_log_message(PINELOG_LVL_FATAL, __FILE__, __LINE__, fmt, ##__VA_ARGS__); \
+        pinelog_log_message(PINELOG_LVL_FATAL, PINELOG_FILE, __LINE__, fmt, ##__VA_ARGS__); \
     } \
     pinelog_exit(1); \
 } while (0)
 
 #define PINELOG_ERROR(fmt, ...) do { \
     if (PINELOG_LVL_ERROR <= pinelog_get_level()) { \
-        pinelog_log_message(PINELOG_LVL_ERROR, __FILE__, __LINE__, fmt, ##__VA_ARGS__); \
+        pinelog_log_message(PINELOG_LVL_ERROR, PINELOG_FILE, __LINE__, fmt, ##__VA_ARGS__); \
     } \
 } while (0)
 
 #define PINELOG_WARN(fmt, ...) do { \
     if (PINELOG_LVL_WARNING <= pinelog_get_level()) { \
-        pinelog_log_message(PINELOG_LVL_WARNING, __FILE__, __LINE__, fmt, ##__VA_ARGS__); \
+        pinelog_log_message(PINELOG_LVL_WARNING, PINELOG_FILE, __LINE__, fmt, ##__VA_ARGS__); \
     } \
 } while(0)
 
 #define PINELOG_INFO(fmt, ...) do { \
     if (PINELOG_LVL_INFO <= pinelog_get_level()) { \
-        pinelog_log_message(PINELOG_LVL_INFO, __FILE__, __LINE__, fmt, ##__VA_ARGS__); \
+        pinelog_log_message(PINELOG_LVL_INFO, PINELOG_FILE, __LINE__, fmt, ##__VA_ARGS__); \
     } \
 } while(0)
 
 #define PINELOG_DEBUG(fmt, ...) do { \
     if (PINELOG_LVL_DEBUG <= pinelog_get_level()) { \
-        pinelog_log_message(PINELOG_LVL_DEBUG, __FILE__, __LINE__, fmt, ##__VA_ARGS__); \
+        pinelog_log_message(PINELOG_LVL_DEBUG, PINELOG_FILE, __LINE__, fmt, ##__VA_ARGS__); \
     } \
 } while(0)
 
@@ -169,7 +179,7 @@ void pinelog_log_message(int level, const char *file, int line, const char *fmt,
 #ifndef PINELOG_DISABLE_TRACE
 #define PINELOG_TRACE(fmt, ...) do { \
     if (PINELOG_LVL_TRACE <= pinelog_get_level()) { \
-        pinelog_log_message(PINELOG_LVL_TRACE, __FILE__, __LINE__, fmt, ##__VA_ARGS__); \
+        pinelog_log_message(PINELOG_LVL_TRACE, PINELOG_FILE, __LINE__, fmt, ##__VA_ARGS__); \
     } \
 } while(0)
 #else

test_pinelog.c

@@ -98,9 +98,16 @@ static int test_setup(int level, int filter, const char *file, int line)
         }
 
         if (PINELOG_SHOW_BACKTRACE) {
+            char * basename = strrchr(file, '/');
+            if (basename != NULL) {
+                basename++;
+            } else {
+                // Override the const
+                basename = (char *)file;
+            }
             expected_len += snprintf(&expected_output[expected_len],
                                      sizeof(expected_output) - expected_len,
-                                     "%s:%d ", file, line);
+                                     "%s:%d ", basename, line);
         }
 
         return 1;