Implemented rewinddir/seekdir.

git-svn-id: svn://svn.cc65.org/cc65/trunk@5676 b7a2c559-68d2-44c3-8de9-860c34a00d81

libsrc/cbm/seekdir.c

@@ -0,0 +1,55 @@
+/*
+ * Ullrich von Bassewitz, 2012-06-03. Based on code by Groepaz.
+ */
+
+#include <fcntl.h>
+#include <unistd.h>
+#include <errno.h>
+#include "dir.h"
+
+
+
+void __fastcall__ seekdir (register DIR* dir, long offs)
+{
+    unsigned      o;
+    unsigned char count;
+    unsigned char buf[128];
+
+    /* Make sure we have a reasonable value for offs */
+    if (offs > 0x1000) {
+        errno = EINVAL;
+        return;
+    }
+
+    /* Close the directory file descriptor */
+    close (dir->fd);
+
+    /* Reopen it using the old name */
+    dir->fd = open (dir->name, O_RDONLY);
+    if (dir->fd < 0) {
+        /* Oops! */
+        return;
+    }
+
+    /* Skip until we've reached the target offset in the directory */
+    o = dir->off = offs;
+    while (o) {
+
+        /* Determine size of next chunk to read */
+        if (o > sizeof (buf)) {  
+            count = sizeof (buf);
+            o -= sizeof (buf);
+        } else {
+            count = offs;
+            o = 0;
+        }
+
+        /* Skip */
+        if (!_dirread (dir, buf, count)) {
+            return;
+        }
+    }
+}
+
+
+