1 files changed, 71 insertions, 0 deletions
diff --git a/lib/safe-read.c b/lib/safe-read.c
new file mode 100644
index 0000000..04ffa7b
--- /dev/null
+++ b/lib/safe-read.c
@@ -0,0 +1,71 @@
+/* An interface to read and write that retries after interrupts.
+
+   Copyright (C) 1993-1994, 1998, 2002-2006, 2009-2022 Free Software
+   Foundation, Inc.
+
+   This file is free software: you can redistribute it and/or modify
+   it under the terms of the GNU Lesser General Public License as
+   published by the Free Software Foundation; either version 2.1 of the
+   License, or (at your option) any later version.
+
+   This file 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 Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public License
+   along with this program.  If not, see <https://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 "sys-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)
+{
+  for (;;)
+    {
+      ssize_t result = rw (fd, buf, count);
+
+      if (0 <= result)
+        return result;
+      else if (IS_EINTR (errno))
+        continue;
+      else if (errno == EINVAL && SYS_BUFSIZE_MAX < count)
+        count = SYS_BUFSIZE_MAX;
+      else
+        return result;
+    }
+}