sandbox: add lseek helper

Follow up patches want to be able to seek fd's.

Acked-by: Simon Glass <sjg@chromium.org>
Signed-off-by: Mike Frysinger <vapier@gentoo.org>

arch/sandbox/cpu/os.c

@@ -45,6 +45,19 @@ ssize_t os_write(int fd, const void *buf, size_t count)
 	return write(fd, buf, count);
 }
 
+off_t os_lseek(int fd, off_t offset, int whence)
+{
+	if (whence == OS_SEEK_SET)
+		whence = SEEK_SET;
+	else if (whence == OS_SEEK_CUR)
+		whence = SEEK_CUR;
+	else if (whence == OS_SEEK_END)
+		whence = SEEK_END;
+	else
+		os_exit(1);
+	return lseek(fd, offset, whence);
+}
+
 int os_open(const char *pathname, int flags)
 {
 	return open(pathname, flags);

include/os.h

@@ -48,6 +48,21 @@ ssize_t os_read(int fd, void *buf, size_t count);
  */
 ssize_t os_write(int fd, const void *buf, size_t count);
 
+/**
+ * Access to the OS lseek() system call
+ *
+ * \param fd	File descriptor as returned by os_open()
+ * \param offset	File offset (based on whence)
+ * \param whence	Position offset is relative to (see below)
+ * \return new file offset
+ */
+off_t os_lseek(int fd, off_t offset, int whence);
+
+/* Defines for "whence" in os_lseek() */
+#define OS_SEEK_SET	0
+#define OS_SEEK_CUR	1
+#define OS_SEEK_END	2
+
 /**
  * Access to the OS open() system call
  *