1 files changed, 145 insertions, 0 deletions
diff --git a/newlib/libc/stdio/ungetc.c b/newlib/libc/stdio/ungetc.c
new file mode 100644
index 0000000..418717e
--- /dev/null
+++ b/newlib/libc/stdio/ungetc.c
@@ -0,0 +1,145 @@
+/*
+ * Copyright (c) 1990 The Regents of the University of California.
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms are permitted
+ * provided that the above copyright notice and this paragraph are
+ * duplicated in all such forms and that any documentation,
+ * advertising materials, and other materials related to such
+ * distribution and use acknowledge that the software was developed
+ * by the University of California, Berkeley.  The name of the
+ * University may not be used to endorse or promote products derived
+ * from this software without specific prior written permission.
+ * THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR
+ * IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED
+ * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
+ */
+
+#if defined(LIBC_SCCS) && !defined(lint)
+static char sccsid[] = "%W% (Berkeley) %G%";
+#endif /* LIBC_SCCS and not lint */
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include "local.h"
+
+/*
+ * Expand the ungetc buffer `in place'.  That is, adjust fp->_p when
+ * the buffer moves, so that it points the same distance from the end,
+ * and move the bytes in the buffer around as necessary so that they
+ * are all at the end (stack-style).
+ */
+
+/*static*/
+int
+__submore (fp)
+     register FILE *fp;
+{
+  register int i;
+  register unsigned char *p;
+
+  if (fp->_ub._base == fp->_ubuf)
+    {
+      /*
+       * Get a new buffer (rather than expanding the old one).
+       */
+      if ((p = (unsigned char *) _malloc_r (fp->_data, (size_t) BUFSIZ)) == NULL)
+	return EOF;
+      fp->_ub._base = p;
+      fp->_ub._size = BUFSIZ;
+      p += BUFSIZ - sizeof (fp->_ubuf);
+      for (i = sizeof (fp->_ubuf); --i >= 0;)
+	p[i] = fp->_ubuf[i];
+      fp->_p = p;
+      return 0;
+    }
+  i = fp->_ub._size;
+  p = (unsigned char *) _realloc_r (fp->_data, (_PTR) (fp->_ub._base), i << 1);
+  if (p == NULL)
+    return EOF;
+  (void) memcpy ((void *) (p + i), (void *) p, (size_t) i);
+  fp->_p = p + i;
+  fp->_ub._base = p;
+  fp->_ub._size = i << 1;
+  return 0;
+}
+
+int
+ungetc (c, fp)
+     int c;
+     register FILE *fp;
+{
+  if (c == EOF)
+    return (EOF);
+
+  /* Ensure stdio has been initialized.
+     ??? Might be able to remove this as some other stdio routine should
+     have already been called to get the char we are un-getting.  */
+
+  CHECK_INIT (fp);
+
+  /* After ungetc, we won't be at eof anymore */
+  fp->_flags &= ~__SEOF;
+
+  if ((fp->_flags & __SRD) == 0)
+    {
+      /*
+       * Not already reading: no good unless reading-and-writing.
+       * Otherwise, flush any current write stuff.
+       */
+      if ((fp->_flags & __SRW) == 0)
+	return EOF;
+      if (fp->_flags & __SWR)
+	{
+	  if (fflush (fp))
+	    return EOF;
+	  fp->_flags &= ~__SWR;
+	  fp->_w = 0;
+	  fp->_lbfsize = 0;
+	}
+      fp->_flags |= __SRD;
+    }
+  c = (unsigned char) c;
+
+  /*
+   * If we are in the middle of ungetc'ing, just continue.
+   * This may require expanding the current ungetc buffer.
+   */
+
+  if (HASUB (fp))
+    {
+      if (fp->_r >= fp->_ub._size && __submore (fp))
+	return EOF;
+      *--fp->_p = c;
+      fp->_r++;
+      return c;
+    }
+
+  /*
+   * If we can handle this by simply backing up, do so,
+   * but never replace the original character.
+   * (This makes sscanf() work when scanning `const' data.)
+   */
+
+  if (fp->_bf._base != NULL && fp->_p > fp->_bf._base && fp->_p[-1] == c)
+    {
+      fp->_p--;
+      fp->_r++;
+      return c;
+    }
+
+  /*
+   * Create an ungetc buffer.
+   * Initially, we will use the `reserve' buffer.
+   */
+
+  fp->_ur = fp->_r;
+  fp->_up = fp->_p;
+  fp->_ub._base = fp->_ubuf;
+  fp->_ub._size = sizeof (fp->_ubuf);
+  fp->_ubuf[sizeof (fp->_ubuf) - 1] = c;
+  fp->_p = &fp->_ubuf[sizeof (fp->_ubuf) - 1];
+  fp->_r = 1;
+  return c;
+}