Support statvfs on API levels before 19.

Split statfs and statvfs. The former has been available forever, and the
latter is implemented in terms of the former. The implementation has
been moved into headers so that it can be used at low API levels.

There's no reason for any Android or Linux code to use statvfs rather
than statfs, but code that needs to build on Darwin too will want to use
statvfs because Darwin's statfs is very spartan.

Bug: android/ndk#609
Test: treehugger
Change-Id: Icf3d5723a260099fddb2d9f902e3047b0f041647

libc/Android.bp

@@ -1133,6 +1133,7 @@ cc_library_static {
         "bionic/sigprocmask.cpp",
         "bionic/spawn.cpp",
         "bionic/stat.cpp",
+        "bionic/statfs.cpp",
         "bionic/statvfs.cpp",
         "bionic/stdlib_l.cpp",
         "bionic/strchrnul.cpp",

libc/bionic/statfs.cpp

@@ -0,0 +1,55 @@
+/*
+ * Copyright (C) 2013 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include <sys/statfs.h>
+
+// Paper over the fact that 32-bit kernels use fstatfs64/statfs64 with
+// an extra argument, but 64-bit kernels don't have the "64" bit suffix or
+// the extra size_t argument.
+#if defined(__LP64__)
+extern "C" int __fstatfs(int, struct statfs*);
+extern "C" int __statfs(const char*, struct statfs*);
+#  define __fstatfs64(fd,size,buf) __fstatfs(fd,buf)
+#  define __statfs64(path,size,buf) __statfs(path,buf)
+#else
+extern "C" int __fstatfs64(int, size_t, struct statfs*);
+extern "C" int __statfs64(const char*, size_t, struct statfs*);
+#endif
+
+// The kernel sets a private ST_VALID flag to signal to the C library
+// whether the f_flags field is valid. This flag should not be exposed to
+// users of the C library.
+#define ST_VALID 0x0020
+
+int fstatfs(int fd, struct statfs* result) {
+  int rc = __fstatfs64(fd, sizeof(*result), result);
+  if (rc != 0) {
+    return rc;
+  }
+  result->f_flags &= ~ST_VALID;
+  return 0;
+}
+__strong_alias(fstatfs64, fstatfs);
+
+int statfs(const char* path, struct statfs* result) {
+  int rc = __statfs64(path, sizeof(*result), result);
+  if (rc != 0) {
+    return rc;
+  }
+  result->f_flags &= ~ST_VALID;
+  return 0;
+}
+__strong_alias(statfs64, statfs);

libc/bionic/statvfs.cpp

@@ -16,76 +16,19 @@
 
 #include <sys/statvfs.h>
 
-#include <sys/statfs.h>
+// libc++ uses statvfs (for Darwin compatibility), but on Linux statvfs is
+// just another name for statfs, so it didn't arrive until API level 19. We
+// make the implementation available as inlines to support std::filesystem
+// for NDK users (see https://github.com/android-ndk/ndk/issues/609).
 
-// Paper over the fact that 32-bit kernels use fstatfs64/statfs64 with an extra argument,
-// but 64-bit kernels don't have the "64" bit suffix or the extra size_t argument.
-#if defined(__LP64__)
-extern "C" int __fstatfs(int, struct statfs*);
-extern "C" int __statfs(const char*, struct statfs*);
-#  define __fstatfs64(fd,size,buf) __fstatfs(fd,buf)
-#  define __statfs64(path,size,buf) __statfs(path,buf)
-#else
-extern "C" int __fstatfs64(int, size_t, struct statfs*);
-extern "C" int __statfs64(const char*, size_t, struct statfs*);
-#endif
+#define __BIONIC_SYS_STATVFS_INLINE /* Out of line. */
+#include <bits/sys_statvfs_inlines.h>
 
-// The kernel sets a private ST_VALID flag to signal to the C library whether the
-// f_flags field is valid. This flag should not be exposed to users of the C library.
-#define ST_VALID 0x0020
+// Historically we provided actual symbols for statvfs64 and fstatvfs64.
+// They're not particularly useful, but we can't take them away.
 
-static void __statfs_to_statvfs(const struct statfs& in, struct statvfs* out) {
-  out->f_bsize = in.f_bsize;
-  out->f_frsize = in.f_frsize;
-  out->f_blocks = in.f_blocks;
-  out->f_bfree = in.f_bfree;
-  out->f_bavail = in.f_bavail;
-  out->f_files = in.f_files;
-  out->f_ffree = in.f_ffree;
-  out->f_favail = in.f_ffree;
-  out->f_fsid = in.f_fsid.__val[0] | (static_cast<uint64_t>(in.f_fsid.__val[1]) << 32);
-  out->f_flag = in.f_flags;
-  out->f_namemax = in.f_namelen;
-}
-
-int fstatfs(int fd, struct statfs* result) {
-  int rc = __fstatfs64(fd, sizeof(*result), result);
-  if (rc != 0) {
-    return rc;
-  }
-  result->f_flags &= ~ST_VALID;
-  return 0;
-}
-__strong_alias(fstatfs64, fstatfs);
-
-int statfs(const char* path, struct statfs* result) {
-  int rc = __statfs64(path, sizeof(*result), result);
-  if (rc != 0) {
-    return rc;
-  }
-  result->f_flags &= ~ST_VALID;
-  return 0;
-}
-__strong_alias(statfs64, statfs);
-
-int statvfs(const char* path, struct statvfs* result) {
-  struct statfs tmp;
-  int rc = statfs(path, &tmp);
-  if (rc != 0) {
-    return rc;
-  }
-  __statfs_to_statvfs(tmp, result);
-  return 0;
-}
+#undef statvfs64
 __strong_alias(statvfs64, statvfs);
 
-int fstatvfs(int fd, struct statvfs* result) {
-  struct statfs tmp;
-  int rc = fstatfs(fd, &tmp);
-  if (rc != 0) {
-    return rc;
-  }
-  __statfs_to_statvfs(tmp, result);
-  return 0;
-}
+#undef fstatvfs64
 __strong_alias(fstatvfs64, fstatvfs);

libc/include/android/legacy_sys_statvfs_inlines.h

@@ -0,0 +1,43 @@
+/*
+ * Copyright (C) 2019 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.
+ */
+
+#pragma once
+
+/**
+ * @file legacy_sys_statvfs_inlines.h
+ * @brief Inline definitions of statvfs/fstatvfs for old API levels.
+ */
+
+#include <sys/cdefs.h>
+
+#if __ANDROID_API__ < 19
+
+#define __BIONIC_SYS_STATVFS_INLINE static __inline
+#include <bits/sys_statvfs_inlines.h>
+
+#endif

libc/include/bits/sys_statvfs_inlines.h

@@ -0,0 +1,75 @@
+/*
+ * Copyright (C) 2019 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.
+ */
+
+#pragma once
+
+#include <sys/cdefs.h>
+#include <sys/statfs.h>
+#include <sys/statvfs.h>
+
+#if defined(__BIONIC_SYS_STATVFS_INLINE)
+
+__BEGIN_DECLS
+
+static __inline void __bionic_statfs_to_statvfs(const struct statfs* __in,
+                                                struct statvfs* __out) {
+  __out->f_bsize = __in->f_bsize;
+  __out->f_frsize = __in->f_frsize;
+  __out->f_blocks = __in->f_blocks;
+  __out->f_bfree = __in->f_bfree;
+  __out->f_bavail = __in->f_bavail;
+  __out->f_files = __in->f_files;
+  __out->f_ffree = __in->f_ffree;
+  __out->f_favail = __in->f_ffree;
+  __out->f_fsid = __in->f_fsid.__val[0] |
+      __BIONIC_CAST(static_cast, uint64_t, __in->f_fsid.__val[1]) << 32;
+  __out->f_flag = __in->f_flags;
+  __out->f_namemax = __in->f_namelen;
+}
+
+__BIONIC_SYS_STATVFS_INLINE int statvfs(const char* path,
+                                        struct statvfs* result) {
+  struct statfs __tmp;
+  int __rc = statfs(path, &__tmp);
+  if (__rc != 0) return __rc;
+  __bionic_statfs_to_statvfs(&__tmp, result);
+  return 0;
+}
+
+__BIONIC_SYS_STATVFS_INLINE int fstatvfs(int fd,
+                                         struct statvfs* result) {
+  struct statfs __tmp;
+  int __rc = fstatfs(fd, &__tmp);
+  if (__rc != 0) return __rc;
+  __bionic_statfs_to_statvfs(&__tmp, result);
+  return 0;
+}
+
+__END_DECLS
+
+#endif

libc/include/sys/statvfs.h

@@ -14,56 +14,99 @@
  * limitations under the License.
  */
 
-#ifndef _SYS_STATVFS_H_
-#define _SYS_STATVFS_H_
+#pragma once
+
+/**
+ * @file sys/statvfs.h
+ * @brief Filesystem statistics.
+ */
 
 #include <stdint.h>
 #include <sys/cdefs.h>
 #include <sys/types.h>
 
 __BEGIN_DECLS
 
-#ifdef __LP64__
-#define __STATVFS64_RESERVED uint32_t __f_reserved[6];
-#else
-#define __STATVFS64_RESERVED
-#endif
+struct statvfs {
+  /** Block size. */
+  unsigned long f_bsize;
+  /** Fragment size. */
+  unsigned long f_frsize;
+  /** Total size of filesystem in `f_frsize` blocks. */
+  fsblkcnt_t f_blocks;
+  /** Number of free blocks. */
+  fsblkcnt_t f_bfree;
+  /** Number of free blocks for non-root. */
+  fsblkcnt_t f_bavail;
+  /** Number of inodes. */
+  fsfilcnt_t f_files;
+  /** Number of free inodes. */
+  fsfilcnt_t f_ffree;
+  /** Number of free inodes for non-root. */
+  fsfilcnt_t f_favail;
+  /** Filesystem id. */
+  unsigned long f_fsid;
+  /** Mount flags. (See `ST_` constants.) */
+  unsigned long f_flag;
+  /** Maximum filename length. */
+  unsigned long f_namemax;
 
-#define __STATVFS64_BODY \
-  unsigned long f_bsize; \
-  unsigned long f_frsize; \
-  fsblkcnt_t    f_blocks; \
-  fsblkcnt_t    f_bfree; \
-  fsblkcnt_t    f_bavail; \
-  fsfilcnt_t    f_files; \
-  fsfilcnt_t    f_ffree; \
-  fsfilcnt_t    f_favail; \
-  unsigned long f_fsid; \
-  unsigned long f_flag; \
-  unsigned long f_namemax; \
-  __STATVFS64_RESERVED
-
-struct statvfs { __STATVFS64_BODY };
-struct statvfs64 { __STATVFS64_BODY };
-
-#undef __STATVFS64_BODY
-#undef __STATVFS64_RESERVED
+#if defined(__LP64__)
+  uint32_t __f_reserved[6];
+#endif
+};
 
+/** Flag for `f_flag` in `struct statvfs`: mounted read-only. */
 #define ST_RDONLY      0x0001
+
+/** Flag for `f_flag` in `struct statvfs`: setuid/setgid ignored. */
 #define ST_NOSUID      0x0002
+
+/** Flag for `f_flag` in `struct statvfs`: access to device files disallowed. */
 #define ST_NODEV       0x0004
+
+/** Flag for `f_flag` in `struct statvfs`: execution disallowed. */
 #define ST_NOEXEC      0x0008
+
+/** Flag for `f_flag` in `struct statvfs`: writes synced immediately. */
 #define ST_SYNCHRONOUS 0x0010
+
+/** Flag for `f_flag` in `struct statvfs`: mandatory locking permitted. */
 #define ST_MANDLOCK    0x0040
+
+/** Flag for `f_flag` in `struct statvfs`: access times not updated. */
 #define ST_NOATIME     0x0400
+
+/** Flag for `f_flag` in `struct statvfs`: directory access times not updated. */
 #define ST_NODIRATIME  0x0800
+
+/** Flag for `f_flag` in `struct statvfs`: see `MS_RELATIME`. */
 #define ST_RELATIME    0x1000
 
+#if __ANDROID_API__ >= 19
+// This file is implemented as static inlines before API level 19.
+
+/**
+ * [statvfs(3)](http://man7.org/linux/man-pages/man3/statvfs.3.html)
+ * queries filesystem statistics for the given path.
+ *
+ * Returns 0 on success, and returns -1 and sets `errno` on failure.
+ */
 int statvfs(const char* __path, struct statvfs* __buf) __INTRODUCED_IN(19);
-int statvfs64(const char* __path, struct statvfs64* __buf) __INTRODUCED_IN(21);
+
+/**
+ * [fstatvfs(3)](http://man7.org/linux/man-pages/man3/fstatvfs.3.html)
+ * queries filesystem statistics for the given file descriptor.
+ *
+ * Returns 0 on success, and returns -1 and sets `errno` on failure.
+ */
 int fstatvfs(int __fd, struct statvfs* __buf) __INTRODUCED_IN(19);
-int fstatvfs64(int __fd, struct statvfs64* __buf) __INTRODUCED_IN(21);
+
+#endif
+
+#define statvfs64 statvfs
+#define fstatvfs64 fstatvfs
 
 __END_DECLS
 
-#endif
+#include <android/legacy_sys_statvfs_inlines.h>