[project @ 1998-02-02 17:27:26 by simonm]

[ghc-hetmet.git] / ghc / lib / std / cbits / getBufferMode.lc

diff --git a/ghc/lib/std/cbits/getBufferMode.lc b/ghc/lib/std/cbits/getBufferMode.lc
new file mode 100644 (file)
index 0000000..cb0b984
--- /dev/null
+++ b/ghc/lib/std/cbits/getBufferMode.lc
@@ -0,0 +1,52 @@
+%
+% (c) The GRASP/AQUA Project, Glasgow University, 1994
+%
+\subsection[getBufferMode.lc]{hIs...Buffered Runtime Support}
+
+\begin{code}
+
+#include "rtsdefs.h"
+#include "stgio.h"
+
+#ifdef HAVE_SYS_TYPES_H
+#include <sys/types.h>
+#endif
+
+#ifdef HAVE_SYS_STAT_H
+#include <sys/stat.h>
+#endif
+
+/*
+ * We try to guess what the default buffer mode is going to be based 
+ * on the type of file we're attached to.
+ */
+
+#define GBM_NB (0)
+#define GBM_LB (-1)
+#define GBM_BB (-2)
+#define GBM_ERR (-3)
+
+StgInt
+getBufferMode(fp)
+StgForeignObj fp;
+{
+    struct stat sb;
+
+    /* Try to find out the file type */
+    while (fstat(fileno((FILE *) fp), &sb) < 0) {
+       /* highly unlikely */
+       if (errno != EINTR) {
+           cvtErrno();
+           stdErrno();
+           return GBM_ERR;
+       }
+    }
+    /* Terminals are line-buffered by default */
+    if (S_ISCHR(sb.st_mode) && isatty(fileno((FILE *) fp)) == 1)
+       return GBM_LB;
+    /* Default size block buffering for the others */
+    else
+       return GBM_BB;
+}
+
+\end{code}