Hide statfs/fstatfs' ST_VALID flag from userspace.
Spotted while debugging the strace 4.10 upgrade.
Change-Id: I1af1be9c9440151f55f74a835e1df71529b0e4fe
diff --git a/libc/bionic/legacy_32_bit_support.cpp b/libc/bionic/legacy_32_bit_support.cpp
index 73f77be..50e4643 100644
--- a/libc/bionic/legacy_32_bit_support.cpp
+++ b/libc/bionic/legacy_32_bit_support.cpp
@@ -40,9 +40,7 @@
// System calls we need.
extern "C" int __fcntl64(int, int, void*);
-extern "C" int __fstatfs64(int, size_t, struct statfs*);
extern "C" int __llseek(int, unsigned long, unsigned long, off64_t*, int);
-extern "C" int __statfs64(const char*, size_t, struct statfs*);
// For fcntl we use the fcntl64 system call to signal that we're using struct flock64.
int fcntl(int fd, int cmd, ...) {
@@ -55,18 +53,6 @@
return __fcntl64(fd, cmd, arg);
}
-// For fstatfs we need to add the extra argument giving the kernel the size of the buffer.
-int fstatfs(int fd, struct statfs* stat) {
- return __fstatfs64(fd, sizeof(*stat), stat);
-}
-__strong_alias(fstatfs64, fstatfs);
-
-// For statfs we need to add the extra argument giving the kernel the size of the buffer.
-int statfs(const char* path, struct statfs* stat) {
- return __statfs64(path, sizeof(*stat), stat);
-}
-__strong_alias(statfs64, statfs);
-
// For lseek64 we need to use the llseek system call which splits the off64_t in two and
// returns the off64_t result via a pointer because 32-bit kernels can't return 64-bit results.
off64_t lseek64(int fd, off64_t off, int whence) {
diff --git a/libc/bionic/statvfs.cpp b/libc/bionic/statvfs.cpp
index f1e2833..39ffb64 100644
--- a/libc/bionic/statvfs.cpp
+++ b/libc/bionic/statvfs.cpp
@@ -21,13 +21,17 @@
// 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 __LP64__
-# define __fstatfs64(fd,size,buf) fstatfs(fd,buf)
-# define __statfs64(path,size,buf) statfs(path,buf)
+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
static void __statfs_to_statvfs(const struct statfs& in, struct statvfs* out) {
@@ -40,13 +44,33 @@
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 & ~ST_VALID;
+ 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 = __statfs64(path, sizeof(tmp), &tmp);
+ int rc = statfs(path, &tmp);
if (rc != 0) {
return rc;
}
@@ -57,7 +81,7 @@
int fstatvfs(int fd, struct statvfs* result) {
struct statfs tmp;
- int rc = __fstatfs64(fd, sizeof(tmp), &tmp);
+ int rc = fstatfs(fd, &tmp);
if (rc != 0) {
return rc;
}