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-rw-r--r--NEWS6
-rw-r--r--include/features.h5
-rw-r--r--manual/creature.texi3
-rw-r--r--misc/sys/cdefs.h9
4 files changed, 22 insertions, 1 deletions
diff --git a/NEWS b/NEWS
index 86e05fb..8e02dbd 100644
--- a/NEWS
+++ b/NEWS
@@ -28,6 +28,12 @@ Major new features:
The 32-bit RISC-V port requires at least Linux 5.4, GCC 7.1 and binutils
2.28.
+* A new fortification level _FORTIFY_SOURCE=3 is available. At this level,
+ glibc may use additional checks that may have an additional performance
+ overhead. At present these checks are available only on LLVM 9 and later.
+ The latest GCC available at this time (10.2) does not support this level of
+ fortification.
+
Deprecated and removed features, and other changes affecting compatibility:
* The mallinfo function is marked deprecated. Callers should call
diff --git a/include/features.h b/include/features.h
index 540230b..066eb0e 100644
--- a/include/features.h
+++ b/include/features.h
@@ -397,6 +397,11 @@
# warning _FORTIFY_SOURCE requires compiling with optimization (-O)
# elif !__GNUC_PREREQ (4, 1)
# warning _FORTIFY_SOURCE requires GCC 4.1 or later
+# elif _FORTIFY_SOURCE > 2 && __glibc_clang_prereq (9, 0)
+# if _FORTIFY_SOURCE > 3
+# warning _FORTIFY_SOURCE > 3 is treated like 3 on this platform
+# endif
+# define __USE_FORTIFY_LEVEL 3
# elif _FORTIFY_SOURCE > 1
# if _FORTIFY_SOURCE > 2
# warning _FORTIFY_SOURCE > 2 is treated like 2 on this platform
diff --git a/manual/creature.texi b/manual/creature.texi
index be50504..31208cc 100644
--- a/manual/creature.texi
+++ b/manual/creature.texi
@@ -254,7 +254,8 @@ included.
@standards{GNU, (none)}
If this macro is defined to @math{1}, security hardening is added to
various library functions. If defined to @math{2}, even stricter
-checks are applied.
+checks are applied. If defined to @math{3}, @theglibc{} may also use
+checks that may have an additional performance overhead.
@end defvr
@defvr Macro _REENTRANT
diff --git a/misc/sys/cdefs.h b/misc/sys/cdefs.h
index a06f1cf..5fb6e30 100644
--- a/misc/sys/cdefs.h
+++ b/misc/sys/cdefs.h
@@ -127,6 +127,15 @@
#define __bos(ptr) __builtin_object_size (ptr, __USE_FORTIFY_LEVEL > 1)
#define __bos0(ptr) __builtin_object_size (ptr, 0)
+/* Use __builtin_dynamic_object_size at _FORTIFY_SOURCE=3 when available. */
+#if __USE_FORTIFY_LEVEL == 3 && __glibc_clang_prereq (9, 0)
+# define __glibc_objsize0(__o) __builtin_dynamic_object_size (__o, 0)
+# define __glibc_objsize(__o) __builtin_dynamic_object_size (__o, 1)
+#else
+# define __glibc_objsize0(__o) __bos0 (__o)
+# define __glibc_objsize(__o) __bos (__o)
+#endif
+
#if __GNUC_PREREQ (4,3)
# define __warnattr(msg) __attribute__((__warning__ (msg)))
# define __errordecl(name, msg) \