1 files changed, 77 insertions, 0 deletions
diff --git a/lib/safe-read.c b/lib/safe-read.c
new file mode 100644
index 0000000..3dde5b5
--- /dev/null
+++ b/lib/safe-read.c
@@ -0,0 +1,77 @@
+/* An interface to read and write that retries after interrupts.
+
+   Copyright (C) 1993-1994, 1998, 2002-2006, 2009-2016 Free Software
+   Foundation, Inc.
+
+   This program is free software: you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation; either version 3 of the License, or
+   (at your option) any later version.
+
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
+
+#include <config.h>
+
+/* Specification.  */
+#ifdef SAFE_WRITE
+# include "safe-write.h"
+#else
+# include "safe-read.h"
+#endif
+
+/* Get ssize_t.  */
+#include <sys/types.h>
+#include <unistd.h>
+
+#include <errno.h>
+
+#ifdef EINTR
+# define IS_EINTR(x) ((x) == EINTR)
+#else
+# define IS_EINTR(x) 0
+#endif
+
+#include <limits.h>
+
+#ifdef SAFE_WRITE
+# define safe_rw safe_write
+# define rw write
+#else
+# define safe_rw safe_read
+# define rw read
+# undef const
+# define const /* empty */
+#endif
+
+/* Read(write) up to COUNT bytes at BUF from(to) descriptor FD, retrying if
+   interrupted.  Return the actual number of bytes read(written), zero for EOF,
+   or SAFE_READ_ERROR(SAFE_WRITE_ERROR) upon error.  */
+size_t
+safe_rw (int fd, void const *buf, size_t count)
+{
+  /* Work around a bug in Tru64 5.1.  Attempting to read more than
+     INT_MAX bytes fails with errno == EINVAL.  See
+     <http://lists.gnu.org/archive/html/bug-gnu-utils/2002-04/msg00010.html>.
+     When decreasing COUNT, keep it block-aligned.  */
+  enum { BUGGY_READ_MAXIMUM = INT_MAX & ~8191 };
+
+  for (;;)
+    {
+      ssize_t result = rw (fd, buf, count);
+
+      if (0 <= result)
+        return result;
+      else if (IS_EINTR (errno))
+        continue;
+      else if (errno == EINVAL && BUGGY_READ_MAXIMUM < count)
+        count = BUGGY_READ_MAXIMUM;
+      else
+        return result;
+    }
+}