Fix GNU/POSIX basename headers.

Including glibc's <libgen.h> will result in the user getting the POSIX
version of basename always, regardless of when it is included relative
to <string.h>. Prior to this patch, our implementation would result in
the one that's included first winning.

Bug: http://b/25459151
Change-Id: Id4aaf1670dad317d6bbc05763a84ee87596e8e59

2 files changed, 11 insertions, 10 deletions

diff --git a/libc/include/libgen.h b/libc/include/libgen.h
index e89328e..4d22d15 100644
--- a/libc/include/libgen.h
+++ b/libc/include/libgen.h
@@ -32,18 +32,19 @@
 #include <sys/cdefs.h>
 #include <sys/types.h>
 
+
 __BEGIN_DECLS
 
-#if !defined(__bionic_using_gnu_basename)
 /*
- * <string.h> gets you the GNU basename.
- * <libgen.h> the POSIX one.
- * Note that our "POSIX" one has the wrong argument cv-qualifiers, but doesn't
- * modify its input and uses thread-local storage for the result if necessary.
+ * Including <string.h> will get you the GNU basename, unless <libgen.h> is
+ * included, either before or after including <string.h>.
+ *
+ * Note that this has the wrong argument cv-qualifiers, but doesn't modify its
+ * input and uses thread-local storage for the result if necessary.
  */
-extern char* basename(const char*);
-#define __bionic_using_posix_basename
-#endif
+extern char* __posix_basename(const char*) __RENAME(basename);
+
+#define basename __posix_basename
 
 /* This has the wrong argument cv-qualifiers, but doesn't modify its input and uses thread-local storage for the result if necessary. */
 extern char* dirname(const char*);
diff --git a/libc/include/string.h b/libc/include/string.h
index d32c164..8ceccd5 100644
--- a/libc/include/string.h
+++ b/libc/include/string.h
@@ -107,18 +107,18 @@ extern size_t strxfrm(char* __restrict, const char* __restrict, size_t);
 extern int    strcoll_l(const char *, const char *, locale_t) __purefunc;
 extern size_t strxfrm_l(char* __restrict, const char* __restrict, size_t, locale_t);
 
-#if defined(__USE_GNU) && !defined(__bionic_using_posix_basename)
+#if defined(__USE_GNU) && !defined(basename)
 /*
  * glibc has a basename in <string.h> that's different to the POSIX one in <libgen.h>.
  * It doesn't modify its argument, and in C++ it's const-correct.
  */
+
 #if defined(__cplusplus)
 extern "C++" char* basename(char*) __RENAME(__gnu_basename) __nonnull((1));
 extern "C++" const char* basename(const char*) __RENAME(__gnu_basename) __nonnull((1));
 #else
 extern char* basename(const char*) __RENAME(__gnu_basename) __nonnull((1));
 #endif
-#define __bionic_using_gnu_basename
 #endif
 
 extern void* __memchr_chk(const void*, int, size_t, size_t);