From 30bc0e2791d1593043531988fe1c88500f3d77c3 Mon Sep 17 00:00:00 2001
From: Josh Durgin <josh.durgin@inktank.com>
Date: Sun, 20 Oct 2013 10:46:49 -0700
Subject: [PATCH] safe_io: add functions for handling splice

Like the other functions, these don't handle non-blocking I/O.

Signed-off-by: Josh Durgin <josh.durgin@inktank.com>
---
 configure.ac         |  6 ++++++
 src/common/safe_io.c | 34 ++++++++++++++++++++++++++++++++++
 src/common/safe_io.h | 13 +++++++++++++
 3 files changed, 53 insertions(+)

diff --git a/configure.ac b/configure.ac
index 58c5e1b94a634..91c623abdaf16 100644
--- a/configure.ac
+++ b/configure.ac
@@ -536,6 +536,12 @@ AC_CHECK_FUNC([fallocate],
 	[])
 
 
+# splice/tee
+AC_CHECK_FUNC([splice],
+	[AC_DEFINE([CEPH_HAVE_SPLICE], [], [splice(2) is supported])],
+	[])
+
+AC_CHECK_HEADERS([arpa/nameser_compat.h])
 AC_CHECK_HEADERS([sys/prctl.h])
 AC_CHECK_FUNCS([prctl])
 
diff --git a/src/common/safe_io.c b/src/common/safe_io.c
index afee82edf0778..16cc7293d9cd3 100644
--- a/src/common/safe_io.c
+++ b/src/common/safe_io.c
@@ -117,6 +117,40 @@ ssize_t safe_pwrite(int fd, const void *buf, size_t count, off_t offset)
 	return 0;
 }
 
+#ifdef CEPH_HAVE_SPLICE
+ssize_t safe_splice(int fd_in, loff_t *off_in, int fd_out, loff_t *off_out,
+		    size_t len, unsigned int flags)
+{
+  size_t cnt = 0;
+
+  while (cnt < len) {
+    ssize_t r = splice(fd_in, off_in, fd_out, off_out, len - cnt, flags);
+    if (r <= 0) {
+      if (r == 0) {
+	// EOF
+	return cnt;
+      }
+      if (errno == EINTR)
+	continue;
+      return -errno;
+    }
+    cnt += r;
+  }
+  return cnt;
+}
+
+ssize_t safe_splice_exact(int fd_in, loff_t *off_in, int fd_out,
+			  loff_t *off_out, size_t len, unsigned int flags)
+{
+  ssize_t ret = safe_splice(fd_in, off_in, fd_out, off_out, len, flags);
+  if (ret < 0)
+    return ret;
+  if ((size_t)ret != len)
+    return -EDOM;
+  return 0;
+}
+#endif
+
 int safe_write_file(const char *base, const char *file,
 		    const char *val, size_t vallen)
 {
diff --git a/src/common/safe_io.h b/src/common/safe_io.h
index a4c9bc7a72f91..c45589eee7e05 100644
--- a/src/common/safe_io.h
+++ b/src/common/safe_io.h
@@ -15,6 +15,7 @@
 #ifndef CEPH_SAFE_IO
 #define CEPH_SAFE_IO
 
+#include "acconfig.h"
 #include "common/compiler_extensions.h"
 #include <sys/types.h>
 
@@ -35,6 +36,18 @@ extern "C" {
       WARN_UNUSED_RESULT;
   ssize_t safe_pwrite(int fd, const void *buf, size_t count, off_t offset)
       WARN_UNUSED_RESULT;
+#ifdef CEPH_HAVE_SPLICE
+  /*
+   * Similar to the above (non-exact version) and below (exact version).
+   * See splice(2) for parameter descriptions.
+   */
+  ssize_t safe_splice(int fd_in, loff_t *off_in, int fd_out, loff_t *off_out,
+		      size_t len, unsigned int flags)
+    WARN_UNUSED_RESULT;
+  ssize_t safe_splice_exact(int fd_in, loff_t *off_in, int fd_out,
+			    loff_t *off_out, size_t len, unsigned int flags)
+    WARN_UNUSED_RESULT;
+#endif
 
   /*
    * Same as the above functions, but return -EDOM unless exactly the requested
-- 
2.39.5