1 files changed, 145 insertions, 18 deletions

diff --git a/lib/network.c b/lib/network.c
index 3373983b..61d98717 100644
--- a/lib/network.c
+++ b/lib/network.c
@@ -17,14 +17,23 @@
  * You should have received a copy of the GNU General Public License
  * along with GNU Zebra; see the file COPYING.  If not, write to the Free
  * Software Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA
- * 02111-1307, USA.  
+ * 02111-1307, USA.
  */
 
 #include <zebra.h>
 #include "log.h"
 #include "network.h"
 
-/* Read nbytes from fd and store into ptr. */
+/*------------------------------------------------------------------------------
+ * Read nbytes from fd and store into ptr -- BLOCKING
+ *
+ * Loops internally if gets EINTR.
+ *
+ * Returns: >= 0 -- number of bytes read
+ *           < 0 => error
+ *
+ * NB: if applied to a NON-BLOCKING fd, may return EAGAIN or EWOULDBLOCK
+ */
 int
 readn (int fd, u_char *ptr, int nbytes)
 {
@@ -33,24 +42,86 @@ readn (int fd, u_char *ptr, int nbytes)
 
   nleft = nbytes;
 
-  while (nleft > 0) 
+  while (nleft > 0)
     {
       nread = read (fd, ptr, nleft);
 
-      if (nread < 0) 
-	return (nread);
+      if (nread > 0)
+        {
+          nleft -= nread;
+          ptr   += nread;
+        }
+      else if (nread == 0)
+	break;
       else
-	if (nread == 0) 
-	  break;
-
-      nleft -= nread;
-      ptr += nread;
+        {
+          if (errno != EINTR)
+            return (nread);
+        }
     }
 
   return nbytes - nleft;
-}  
+}
+
+/*------------------------------------------------------------------------------
+ * Read up to nbyte bytes into buf -- assuming NON-BLOCKING.
+ *
+ * Loops internally if gets EINTR -- so if does not read everything asked for,
+ * that must be because the read would otherwise block.
+ *
+ * Returns: 0..n -- number of bytes read
+ *         -1 => failed -- see errno
+ *         -2 => EOF met immediately
+ *
+ * NB: if asked to write zero bytes, does nothing and will return 0.
+ *
+ *     Reading zero bytes is defined for all types of files, and may be used
+ *     to probe for error state.
+ */
+int
+read_nb(int fd, void* buf, size_t nbyte)
+{
+  size_t nleft = nbyte ;
+
+  do
+    {
+      int ret = read(fd, buf, nleft);
+
+      if (ret > 0)
+        {
+          buf    = (char*)buf + ret ;
+          nleft -= ret ;
+        }
+      else if (ret == 0)
+        {
+          if (nleft < nbyte)
+            break ;             /* if read something before EOF */
+
+          return -2 ;           /* hit EOF immediately          */
+        }
+      else
+        {
+          int err = errno ;
+          if ((err == EAGAIN) || (err == EWOULDBLOCK))
+            break ;
+          if (err != EINTR)
+            return -1 ;         /* failed                       */
+        } ;
+    } while (nleft > 0) ;
+
+  return (nbyte - nleft) ;
+} ;
 
-/* Write nbytes from ptr to fd. */
+/*------------------------------------------------------------------------------
+ * Write nbytes to fd from ptr -- BLOCKING
+ *
+ * Loops internally if gets EINTR.
+ *
+ * Returns: >= 0 -- number of bytes written
+ *           < 0 => error
+ *
+ * NB: if applied to a NON-BLOCKING fd, may return EAGAIN or EWOULDBLOCK
+ */
 int
 writen(int fd, const u_char *ptr, int nbytes)
 {
@@ -59,19 +130,75 @@ writen(int fd, const u_char *ptr, int nbytes)
 
   nleft = nbytes;
 
-  while (nleft > 0) 
+  while (nleft > 0)
     {
       nwritten = write(fd, ptr, nleft);
-      
-      if (nwritten <= 0) 
-	return (nwritten);
 
-      nleft -= nwritten;
-      ptr += nwritten;
+      if (nwritten > 0)
+        {
+          nleft -= nwritten;
+          ptr   += nwritten;
+        }
+      else if (nwritten == 0)
+        break ;
+      else
+        {
+          if (errno != EINTR)
+            return (nwritten);
+        }
     }
   return nbytes - nleft;
 }
 
+/*------------------------------------------------------------------------------
+ * Write up to nbyte bytes from buf -- assuming NON-BLOCKING.
+ *
+ * Loops internally if gets EINTR.
+ *
+ * Returns: 0..n -- number of bytes written
+ *         -1 => failed -- see errno
+ *
+ * NB: if asked to write zero bytes, does nothing and will return 0.
+ *
+ *     Writing zero bytes is defined for "regular files", but not for anything
+ *     else.
+ */
+int
+write_nb(int fd, void* buf, size_t nbyte)
+{
+  size_t nleft = nbyte ;
+
+  while (nleft > 0)
+    {
+      int ret = write(fd, buf, nleft);
+
+      if (ret > 0)
+        {
+          buf    = (char*)buf + ret ;
+          nleft -= ret ;
+        }
+      else if (ret == 0)
+        break ;                 /* not sure can happen... but
+                                   cannot assume will go away   */
+      else
+        {
+          int err = errno ;
+          if ((err == EAGAIN) || (err == EWOULDBLOCK))
+            break ;
+          if (err != EINTR)
+            return -1 ;         /* failed                       */
+        } ;
+    } ;
+
+  return (nbyte - nleft) ;
+} ;
+
+/*------------------------------------------------------------------------------
+ * Set fd to non-blocking
+ *
+ * Returns:  0 => OK
+ *          -1 => failed
+ */
 int
 set_nonblocking(int fd)
 {