bsd-user: Implement statfs related syscalls

Implement the following syscalls:
statfs(2)
fstatfs(2)
getfsstat(2)

Signed-off-by: Stacey Son <sson@FreeBSD.org>
Signed-off-by: Karim Taha <kariem.taha2.7@gmail.com>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Signed-off-by: Warner Losh <imp@bsdimp.com>

bsd-user/freebsd/os-stat.h

@@ -210,4 +210,73 @@ static inline abi_long do_freebsd_fhstatfs(abi_ulong target_fhp_addr,
     return h2t_freebsd_statfs(target_stfs_addr, &host_stfs);
 }
 
+/* statfs(2) */
+static inline abi_long do_freebsd_statfs(abi_long arg1, abi_long arg2)
+{
+    abi_long ret;
+    void *p;
+    struct statfs host_stfs;
+
+    LOCK_PATH(p, arg1);
+    ret = get_errno(statfs(path(p), &host_stfs));
+    UNLOCK_PATH(p, arg1);
+    if (is_error(ret)) {
+        return ret;
+    }
+
+    return h2t_freebsd_statfs(arg2, &host_stfs);
+}
+
+/* fstatfs(2) */
+static inline abi_long do_freebsd_fstatfs(abi_long fd, abi_ulong target_addr)
+{
+    abi_long ret;
+    struct statfs host_stfs;
+
+    ret = get_errno(fstatfs(fd, &host_stfs));
+    if (is_error(ret)) {
+        return ret;
+    }
+
+    return h2t_freebsd_statfs(target_addr, &host_stfs);
+}
+
+/* getfsstat(2) */
+static inline abi_long do_freebsd_getfsstat(abi_ulong target_addr,
+        abi_long bufsize, abi_long flags)
+{
+    abi_long ret;
+    struct statfs *host_stfs;
+    int count;
+    long host_bufsize;
+
+    count = bufsize / sizeof(struct target_statfs);
+
+    /* if user buffer is NULL then return number of mounted FS's */
+    if (target_addr == 0 || count == 0) {
+        return get_errno(freebsd11_getfsstat(NULL, 0, flags));
+    }
+
+    /* XXX check count to be reasonable */
+    host_bufsize = sizeof(struct statfs) * count;
+    host_stfs = alloca(host_bufsize);
+    if (!host_stfs) {
+        return -TARGET_EINVAL;
+    }
+
+    ret = count = get_errno(getfsstat(host_stfs, host_bufsize, flags));
+    if (is_error(ret)) {
+        return ret;
+    }
+
+    while (count--) {
+        if (h2t_freebsd_statfs((target_addr +
+                        (count * sizeof(struct target_statfs))),
+                    &host_stfs[count])) {
+            return -TARGET_EFAULT;
+        }
+    }
+    return ret;
+}
+
 #endif /* BSD_USER_FREEBSD_OS_STAT_H */