Add trivial functions to loop over read()'ing and write()'ing with a

file descriptor (i.e., read and write complete messages, transparently
handling partial reads/writes, EAGAIN, and EINTR).

This code effectively already exists in a few places in the code base;
this is mainly a consolidation.

This commit was SVN r23450.

opal/util/Makefile.am

@@ -9,7 +9,7 @@
 #                         University of Stuttgart.  All rights reserved.
 # Copyright (c) 2004-2005 The Regents of the University of California.
 #                         All rights reserved.
-# Copyright (c) 2007-2009 Cisco Systems, Inc.  All rights reserved.
+# Copyright (c) 2007-2010 Cisco Systems, Inc.  All rights reserved.
 # $COPYRIGHT$
 #
 # Additional copyrights may follow
@@ -39,6 +39,8 @@ headers = \
         daemon_init.h \
         error.h \
         few.h \
+        fd.h \
+        fd.c \
         if.h \
         keyval_parse.h \
         malloc.h \

opal/util/fd.c

@@ -0,0 +1,67 @@
+/*
+ * Copyright (c) 2008-2009 Cisco Systems, Inc.  All rights reserved.
+ * Copyright (c) 2009 Sandia National Laboratories. All rights reserved.
+ *
+ * $COPYRIGHT$
+ * 
+ * Additional copyrights may follow
+ * 
+ * $HEADER$
+ */
+
+#include "opal_config.h"
+
+#include <unistd.h>
+#include <errno.h>
+
+#include "opal/util/fd.h"
+#include "opal/constants.h"
+
+
+/*
+ * Simple loop over reading from a fd
+ */
+int opal_fd_read(int fd, int len, void *buffer)
+{
+    int rc;
+    char *b = buffer;
+
+    while (len > 0) {
+        rc = read(fd, b, len);
+        if (rc < 0 && (EAGAIN == errno || EINTR == errno)) {
+            continue;
+        } else if (rc > 0) {
+            len -= rc;
+            b += rc;
+        } else {
+            return OPAL_ERR_IN_ERRNO;
+        }
+    }
+    return OPAL_SUCCESS;
+}
+
+
+/*
+ * Simple loop over writing to an fd
+ */
+int opal_fd_write(int fd, int len, void *buffer)
+{
+    int rc;
+    char *b = buffer;
+
+    while (len > 0) {
+        rc = write(fd, b, len);
+        if (rc < 0 && (EAGAIN == errno || EINTR == errno)) {
+            continue;
+        } else if (rc > 0) {
+            len -= rc;
+            b += rc;
+        } else {
+            return OPAL_ERR_IN_ERRNO;
+        }
+    }
+
+    return OPAL_SUCCESS;
+}
+
+

opal/util/fd.h

@@ -0,0 +1,49 @@
+/*
+ * Copyright (c) 2008-2009 Cisco Systems, Inc.  All rights reserved.
+ * Copyright (c) 2009 Sandia National Laboratories. All rights reserved.
+ *
+ * $COPYRIGHT$
+ * 
+ * Additional copyrights may follow
+ * 
+ * $HEADER$
+ */
+
+/* @file */
+
+#ifndef OPAL_UTIL_FD_H_
+#define OPAL_UTIL_FD_H_
+
+#include "opal_config.h"
+
+/**
+ * Read a complete buffer from a file descriptor.
+ *
+ * @param fd File descriptor
+ * @param len Number of bytes to read
+ * @param buffer Pre-allocated buffer (large enough to hold len bytes)
+ *
+ * @returns OPAL_SUCCESS upon success.
+ * @returns OPAL_ERR_IN_ERRNO otherwise.
+ *
+ * Loop over reading from the fd until len bytes are read or an error
+ * occurs.  EAGAIN and EINTR are transparently handled.
+ */
+OPAL_DECLSPEC int opal_fd_read(int fd, int len, void *buffer);
+
+/**
+ * Write a complete buffer to a file descriptor.
+ *
+ * @param fd File descriptor
+ * @param len Number of bytes to write
+ * @param buffer Buffer to write from
+ *
+ * @returns OPAL_SUCCESS upon success.
+ * @returns OPAL_ERR_IN_ERRNO otherwise.
+ *
+ * Loop over writing to the fd until len bytes are written or an error
+ * occurs.  EAGAIN and EINTR are transparently handled.
+ */
+OPAL_DECLSPEC int opal_fd_write(int fd, int len, void *buffer);
+
+#endif