Fix <features.h> (_BSD_SOURCE and _GNU_SOURCE).

<features.h> is supposed to take user-settable stuff like _GNU_SOURCE
and _BSD_SOURCE and turn them into __USE_GNU and __USE_BSD for use in
the C library headers. Instead, bionic used to unconditionally define
_BSD_SOURCE and _GNU_SOURCE, and then test _GNU_SOURCE in the header
files (which makes no sense whatsoever).

Bug: 14659579
Change-Id: Ice4cf21a364ea2e559071dc8329e995277d5b987

libc/bionic/clone.cpp

@@ -26,7 +26,7 @@
  * SUCH DAMAGE.
  */
 
-#define __GNU_SOURCE 1
+#define _GNU_SOURCE 1
 #include <sched.h>
 #include <stdlib.h>
 #include <stdarg.h>

libc/include/features.h

@@ -25,18 +25,17 @@
  * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  * SUCH DAMAGE.
  */
+
 #ifndef _FEATURES_H_
 #define _FEATURES_H_
 
-/* certain Linux-specific programs expect a <features.h> header file
- * that defines various features macros
- */
+#if defined(_BSD_SOURCE)
+# define __USE_BSD 1
+#endif
 
-/* we do include a number of BSD extensions */
-#define  _BSD_SOURCE  1
-
-/* we do include a number of GNU extensions */
-#define  _GNU_SOURCE  1
+#if defined(_GNU_SOURCE)
+# define __USE_GNU 1
+#endif
 
 /* C95 support */
 #undef __USE_ISOC95

libc/include/sched.h

@@ -28,6 +28,7 @@
 #ifndef _SCHED_H_
 #define _SCHED_H_
 
+#include <features.h>
 #include <sys/cdefs.h>
 #include <sys/time.h>
 
@@ -52,7 +53,7 @@ extern int sched_setparam(pid_t, const struct sched_param*);
 extern int sched_getparam(pid_t, struct sched_param*);
 extern int sched_rr_get_interval(pid_t, struct timespec*);
 
-#ifdef _GNU_SOURCE
+#if defined(__USE_GNU)
 
 extern int clone(int (*)(void*), void*, int, void*, ...);
 extern int unshare(int);
@@ -146,7 +147,7 @@ extern void       __sched_cpufree(cpu_set_t* set);
 
 extern int __sched_cpucount(size_t setsize, cpu_set_t* set);
 
-#endif /* _GNU_SOURCE */
+#endif /* __USE_GNU */
 
 __END_DECLS
 

libc/include/unistd.h

@@ -28,6 +28,7 @@
 #ifndef _UNISTD_H_
 #define _UNISTD_H_
 
+#include <features.h>
 #include <stddef.h>
 #include <sys/cdefs.h>
 #include <sys/types.h>
@@ -112,7 +113,7 @@ extern int chdir(const char *);
 extern int fchdir(int);
 extern int rmdir(const char *);
 extern int pipe(int *);
-#ifdef _GNU_SOURCE
+#if defined(__USE_GNU)
 extern int pipe2(int *, int);
 #endif
 extern int chroot(const char *);
@@ -143,7 +144,7 @@ extern ssize_t pwrite64(int, const void *, size_t, off64_t);
 
 extern int dup(int);
 extern int dup2(int, int);
-#ifdef _GNU_SOURCE
+#if defined(__USE_GNU)
 extern int dup3(int, int, int);
 #endif
 extern int fcntl(int, int, ...);

libm/include/math.h

@@ -17,6 +17,7 @@
 #ifndef _MATH_H_
 #define	_MATH_H_
 
+#include <features.h>
 #include <sys/cdefs.h>
 #include <limits.h>
 
@@ -462,11 +463,11 @@ long double	truncl(long double);
 
 #endif /* __ISO_C_VISIBLE >= 1999 */
 
-#if defined(_GNU_SOURCE)
+#if defined(__USE_GNU)
 void sincos(double, double*, double*);
 void sincosf(float, float*, float*);
 void sincosl(long double, long double*, long double*);
-#endif /* _GNU_SOURCE */
+#endif /* __USE_GNU */
 
 #pragma GCC visibility pop
 __END_DECLS

libm/sincos.c

@@ -22,8 +22,8 @@
  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  * SUCH DAMAGE.
- *
  */
+
 #define _GNU_SOURCE 1
 #include <math.h>
 

tests/math_sincos_test.cpp

@@ -14,6 +14,8 @@
  * limitations under the License.
  */
 
+#define _GNU_SOURCE 1
+
 #include <math.h>
 
 #include <gtest/gtest.h>