initial check-in of file positioning stdio functions

git-svn-id: svn://svn.cc65.org/cc65/trunk@275 b7a2c559-68d2-44c3-8de9-860c34a00d81

libsrc/common/ftell.c

@@ -0,0 +1,27 @@
+/*
+ * ftell.c
+ *
+ * Christian Groessler, 07-Aug-2000
+ */
+
+
+#include <stdio.h>
+#include <errno.h>
+#include <fcntl.h>
+#include "_file.h"
+
+
+long ftell(FILE* f)
+{
+    long pos;
+
+    /* Is the file open? */
+    if ((f->f_flags & _FOPEN) == 0) {
+        _errno = EINVAL;                /* File not open */
+        return -1L;
+    }
+
+    pos = lseek(f->f_fd, 0L, SEEK_CUR);
+    return pos;    /* -1 for error, comes from lseek() */
+}
+