Mark hooked functions as visibility(("protected")).

[coloredstderr/coloredstderr.git] / src / compiler.h

diff --git a/src/compiler.h b/src/compiler.h
index 5ede8b21802e3610eb4385640948feb5102896c9..d1c12dc05719262b64443366e0fb817138d7da42 100644 (file)
--- a/src/compiler.h
+++ b/src/compiler.h
@@ -20,15 +20,25 @@
 #ifndef COMPILER_H
 #define COMPILER_H 1
 
-/* Prevent/force inlining. Used to improve performance. */
 #ifdef HAVE___ATTRIBUTE__
+/* Prevent/force inlining. Used to improve performance. */
 # define noinline      __attribute__((noinline))
 # define always_inline __attribute__((always_inline))
+/* Unused parameter. */
 # define unused        __attribute__((unused))
+/* Mark the function protected, which means it can't be overwritten by other
+ * modules (libraries), e.g. with LD_PRELOAD); otherwise same as the default
+ * visibility. This causes the compiler not use the PLT (and no relocations)
+ * for local calls from inside this module; but the symbols are still
+ * exported. This is faster and in this case prevents useless lookups as we
+ * hook those functions and nobody else should modify them. Not strictly
+ * necessary, but nice to have. */
+# define visibility_protected __attribute__((visibility("protected")))
 #else
 # define noinline
 # define always_inline
 # define unused
+# define visibility_protected
 #endif
 
 /* Branch prediction information for the compiler. */