Implement the GNU basename(3) in addition to the POSIX one.

Code like perf(1) needs this.

Bug: 11860789
Change-Id: I907eb448052a7b165e4012d74303330d32328cb2

libc/Android.mk

@@ -122,6 +122,7 @@ libc_bionic_src_files := \
     bionic/getpgrp.cpp \
     bionic/getpid.cpp \
     bionic/gettid.cpp \
+    bionic/__gnu_basename.cpp \
     bionic/inotify_init.cpp \
     bionic/lchown.cpp \
     bionic/lfs64_support.cpp \

libc/bionic/__gnu_basename.cpp

@@ -0,0 +1,35 @@
+/*
+ * Copyright (C) 2014 The Android Open Source Project
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *  * Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ *  * Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in
+ *    the documentation and/or other materials provided with the
+ *    distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+ * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+ * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
+ * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
+ * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 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 <string.h>
+
+extern "C" const char* __gnu_basename(const char* path) {
+  const char* last_slash = strrchr(path, '/');
+  return (last_slash != NULL) ? last_slash + 1 : path;
+}

libc/include/libgen.h

@@ -25,6 +25,7 @@
  * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  * SUCH DAMAGE.
  */
+
 #ifndef _LIBGEN_H
 #define _LIBGEN_H
 
@@ -33,9 +34,18 @@
 
 __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.
+ */
+extern char* basename(const char*);
+#define __bionic_using_posix_basename
+#endif
+
 /* our version of dirname/basename don't modify the input path */
 extern char*  dirname (const char*  path);
-extern char*  basename(const char*  path);
 
 /* special thread-safe Bionic versions
  *

libc/include/string.h

@@ -25,8 +25,9 @@
  * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  * SUCH DAMAGE.
  */
-#ifndef _STRING_H_
-#define _STRING_H_
+
+#ifndef _STRING_H
+#define _STRING_H
 
 #include <sys/cdefs.h>
 #include <stddef.h>
@@ -92,6 +93,20 @@ 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)
+/*
+ * 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
+
 #if defined(__BIONIC_FORTIFY)
 
 __BIONIC_FORTIFY_INLINE
@@ -289,4 +304,4 @@ char* strrchr(const char *s, int c) {
 
 __END_DECLS
 
-#endif /* _STRING_H_ */
+#endif /* _STRING_H */

tests/libgen_test.cpp

@@ -14,11 +14,10 @@
  * limitations under the License.
  */
 
-#include <gtest/gtest.h>
-
 #include <libgen.h>
 
 #include <errno.h>
+#include <gtest/gtest.h>
 
 static void TestBasename(const char* in, const char* expected_out) {
   char* writable_in = (in != NULL) ? strdup(in) : NULL;
@@ -40,7 +39,7 @@ static void TestDirname(const char* in, const char* expected_out) {
 
 // Do not use basename as the test name, it's defined to another value in glibc
 // so leads to a differently named test on host versus target architectures.
-TEST(libgen, basename_smoke) {
+TEST(libgen, posix_basename) {
   TestBasename(NULL, ".");
   TestBasename("", ".");
   TestBasename("/usr/lib", "lib");

tests/string_test.cpp

@@ -14,12 +14,12 @@
  * limitations under the License.
  */
 
-#include <gtest/gtest.h>
+#include <string.h>
 
 #include <errno.h>
+#include <gtest/gtest.h>
 #include <malloc.h>
 #include <math.h>
-#include <string.h>
 
 #include "buffer_tests.h"
 
@@ -1287,3 +1287,22 @@ TEST(string, strchr_align) {
 TEST(string, strchr_overread) {
   RunSingleBufferOverreadTest(DoStrchrTest);
 }
+
+static void TestBasename(const char* in, const char* expected_out) {
+  errno = 0;
+  const char* out = basename(in);
+  ASSERT_STREQ(expected_out, out) << in;
+  ASSERT_EQ(0, errno) << in;
+}
+
+TEST(string, __gnu_basename) {
+  TestBasename("", "");
+  TestBasename("/usr/lib", "lib");
+  TestBasename("/usr/", "");
+  TestBasename("usr", "usr");
+  TestBasename("/", "");
+  TestBasename(".", ".");
+  TestBasename("..", "..");
+  TestBasename("///", "");
+  TestBasename("//usr//lib//", "");
+}