import newlib-2000-02-17 snapshot

newlib/libc/stdio/makebuf.c

@@ -0,0 +1,96 @@
+/* No user fns here.  Pesch 15apr92. */
+
+/*
+ * 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.
+ */
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <sys/stat.h>
+#include <sys/types.h>
+#include <sys/unistd.h>
+
+#include "local.h"
+
+/*
+ * Allocate a file buffer, or switch to unbuffered I/O.
+ * Per the ANSI C standard, ALL tty devices default to line buffered.
+ *
+ * As a side effect, we set __SOPT or __SNPT (en/dis-able fseek
+ * optimization) right after the _fstat() that finds the buffer size.
+ */
+
+void
+__smakebuf (fp)
+     register FILE *fp;
+{
+  register size_t size, couldbetty;
+  register _PTR p;
+  struct stat st;
+
+  if (fp->_flags & __SNBF)
+    {
+      fp->_bf._base = fp->_p = fp->_nbuf;
+      fp->_bf._size = 1;
+      return;
+    }
+  if (fp->_file < 0 || _fstat_r (fp->_data, fp->_file, &st) < 0)
+    {
+      couldbetty = 0;
+      size = BUFSIZ;
+      /* do not try to optimise fseek() */
+      fp->_flags |= __SNPT;
+    }
+  else
+    {
+      couldbetty = (st.st_mode & S_IFMT) == S_IFCHR;
+#ifdef HAVE_BLKSIZE
+      size = st.st_blksize <= 0 ? BUFSIZ : st.st_blksize;
+#else
+      size = BUFSIZ;
+#endif
+      /*
+       * Optimize fseek() only if it is a regular file.
+       * (The test for __sseek is mainly paranoia.)
+       */
+      if ((st.st_mode & S_IFMT) == S_IFREG && fp->_seek == __sseek)
+	{
+	  fp->_flags |= __SOPT;
+#ifdef HAVE_BLKSIZE
+	  fp->_blksize = st.st_blksize;
+#else
+	  fp->_blksize = 1024;
+#endif
+	}
+      else
+	fp->_flags |= __SNPT;
+    }
+  if ((p = _malloc_r (fp->_data, size)) == NULL)
+    {
+      fp->_flags |= __SNBF;
+      fp->_bf._base = fp->_p = fp->_nbuf;
+      fp->_bf._size = 1;
+    }
+  else
+    {
+      fp->_data->__cleanup = _cleanup_r;
+      fp->_flags |= __SMBF;
+      fp->_bf._base = fp->_p = (unsigned char *) p;
+      fp->_bf._size = size;
+      if (couldbetty && isatty (fp->_file))
+	fp->_flags |= __SLBF;
+    }
+}