[PATCH] Properly check for short writes when sending the response in nscd

[Andreas Schwab <schwab at suse dot de>]

This fixes spurious short write messages in nscd.  The response record
is only a part of the dataset structure, but total contains the size of
the complete structure, so it will never equal what is written as
response.

Andreas.

	* nscd/grpcache.c (cache_addgr): Properly check for short write.
	* nscd/initgrcache.c (addinitgroupsX): Likewise.
	* nscd/pwdcache.c (cache_addpw): Likewise.
	* nscd/servicescache.c (cache_addserv): Likewise.  Don't write
	more than recsize.

diff --git a/nscd/grpcache.c b/nscd/grpcache.c
index d25d8e9..eccb7b1 100644
--- a/nscd/grpcache.c
+++ b/nscd/grpcache.c
@@ -75,6 +75,7 @@ cache_addgr (struct database_dyn *db, int fd, request_header *req,
 	     const void *key, struct group *grp, uid_t owner,
 	     struct hashentry *const he, struct datahead *dh, int errval)
 {
+  bool all_written = true;
   ssize_t total;
   ssize_t written;
   time_t t = time (NULL);
@@ -114,8 +115,12 @@ cache_addgr (struct database_dyn *db, int fd, request_header *req,
 	  total = sizeof (notfound);
 
 	  if (fd != -1)
-	    written = TEMP_FAILURE_RETRY (send (fd, &notfound, total,
-						MSG_NOSIGNAL));
+	    {
+	      written = TEMP_FAILURE_RETRY (send (fd, &notfound, total,
+						  MSG_NOSIGNAL));
+	      if (written != total)
+		all_written = false;
+	    }
 	  else
 	    written = total;
 
@@ -342,6 +347,9 @@ cache_addgr (struct database_dyn *db, int fd, request_header *req,
 # endif
 #endif
 	    written = writeall (fd, &dataset->resp, dataset->head.recsize);
+
+	  if (written != dataset->head.recsize)
+	    all_written = false;
 	}
 
       /* Add the record to the database.  But only if it has not been
@@ -401,7 +409,7 @@ cache_addgr (struct database_dyn *db, int fd, request_header *req,
 	}
     }
 
-  if (__builtin_expect (written != total, 0) && debug_level > 0)
+  if (__builtin_expect (!all_written, 0) && debug_level > 0)
     {
       char buf[256];
       dbg_log (_("short write in %s: %s"),  __FUNCTION__,
diff --git a/nscd/initgrcache.c b/nscd/initgrcache.c
index 196407c8..6b0b26b 100644
--- a/nscd/initgrcache.c
+++ b/nscd/initgrcache.c
@@ -171,10 +171,12 @@ addinitgroupsX (struct database_dyn *db, int fd, request_header *req,
 	nip = nip->next;
     }
 
+  bool all_written;
   ssize_t total;
   ssize_t written;
   time_t timeout;
  out:
+  all_written = true;
   timeout = MAX_TIMEOUT_VALUE;
   if (!any_success)
     {
@@ -198,8 +200,12 @@ addinitgroupsX (struct database_dyn *db, int fd, request_header *req,
 	  /* We have no data.  This means we send the standard reply for this
 	     case.  */
 	  if (fd != -1)
-	    written = TEMP_FAILURE_RETRY (send (fd, &notfound, total,
-						MSG_NOSIGNAL));
+	    {
+	      written = TEMP_FAILURE_RETRY (send (fd, &notfound, total,
+						  MSG_NOSIGNAL));
+	      if (written != total)
+		all_written = false;
+	    }
 
 	  /* If we have a transient error or cannot permanently store
 	     the result, so be it.  */
@@ -379,6 +385,9 @@ addinitgroupsX (struct database_dyn *db, int fd, request_header *req,
 # endif
 #endif
 	    written = writeall (fd, &dataset->resp, dataset->head.recsize);
+
+	  if (written != dataset->head.recsize)
+	    all_written = false;
 	}
 
 
@@ -405,7 +414,7 @@ addinitgroupsX (struct database_dyn *db, int fd, request_header *req,
 
   free (groups);
 
-  if (__builtin_expect (written != total, 0) && debug_level > 0)
+  if (__builtin_expect (!all_written, 0) && debug_level > 0)
     {
       char buf[256];
       dbg_log (_("short write in %s: %s"), __FUNCTION__,
diff --git a/nscd/pwdcache.c b/nscd/pwdcache.c
index ef492b5..aa82ead 100644
--- a/nscd/pwdcache.c
+++ b/nscd/pwdcache.c
@@ -81,6 +81,7 @@ cache_addpw (struct database_dyn *db, int fd, request_header *req,
 	     const void *key, struct passwd *pwd, uid_t owner,
 	     struct hashentry *const he, struct datahead *dh, int errval)
 {
+  bool all_written = true;
   ssize_t total;
   ssize_t written;
   time_t t = time (NULL);
@@ -120,8 +121,12 @@ cache_addpw (struct database_dyn *db, int fd, request_header *req,
 	  written = total = sizeof (notfound);
 
 	  if (fd != -1)
-	    written = TEMP_FAILURE_RETRY (send (fd, &notfound, total,
-						MSG_NOSIGNAL));
+	    {
+	      written = TEMP_FAILURE_RETRY (send (fd, &notfound, total,
+						  MSG_NOSIGNAL));
+	      if (written != total)
+		all_written = false;
+	    }
 
 	  /* If we have a transient error or cannot permanently store
 	     the result, so be it.  */
@@ -306,7 +311,7 @@ cache_addpw (struct database_dyn *db, int fd, request_header *req,
 			  + db->head->data_size));
 	      written = sendfileall (fd, db->wr_fd,
 				     (char *) &dataset->resp
-				     - (char *) db->head, dataset->head.recsize );
+				     - (char *) db->head, dataset->head.recsize);
 # ifndef __ASSUME_SENDFILE
 	      if (written == -1 && errno == ENOSYS)
 		goto use_write;
@@ -318,6 +323,9 @@ cache_addpw (struct database_dyn *db, int fd, request_header *req,
 # endif
 #endif
 	    written = writeall (fd, &dataset->resp, dataset->head.recsize);
+
+	  if (written != dataset->head.recsize)
+	    all_written = false;
 	}
 
 
@@ -377,7 +385,7 @@ cache_addpw (struct database_dyn *db, int fd, request_header *req,
 	}
     }
 
-  if (__builtin_expect (written != total, 0) && debug_level > 0)
+  if (__builtin_expect (!all_written, 0) && debug_level > 0)
     {
       char buf[256];
       dbg_log (_("short write in %s: %s"),  __FUNCTION__,
diff --git a/nscd/servicescache.c b/nscd/servicescache.c
index d29cde7..bdbc495 100644
--- a/nscd/servicescache.c
+++ b/nscd/servicescache.c
@@ -65,6 +65,7 @@ cache_addserv (struct database_dyn *db, int fd, request_header *req,
 	       const void *key, struct servent *serv, uid_t owner,
 	       struct hashentry *const he, struct datahead *dh, int errval)
 {
+  bool all_written = true;
   ssize_t total;
   ssize_t written;
   time_t t = time (NULL);
@@ -104,8 +105,12 @@ cache_addserv (struct database_dyn *db, int fd, request_header *req,
 	  written = total = sizeof (notfound);
 
 	  if (fd != -1)
-	    written = TEMP_FAILURE_RETRY (send (fd, &notfound, total,
-						MSG_NOSIGNAL));
+	    {
+	      written = TEMP_FAILURE_RETRY (send (fd, &notfound, total,
+						  MSG_NOSIGNAL));
+	      if (written != total)
+		all_written = false;
+	    }
 
 	  /* If we have a transient error or cannot permanently store
 	     the result, so be it.  */
@@ -290,14 +295,14 @@ cache_addserv (struct database_dyn *db, int fd, request_header *req,
 	    {
 	      assert (db->wr_fd != -1);
 	      assert ((char *) &dataset->resp > (char *) db->data);
-	      assert ((char *) &dataset->resp - (char *) db->head
+	      assert ((char *) dataset - (char *) db->head
 		      + total
 		      <= (sizeof (struct database_pers_head)
 			  + db->head->module * sizeof (ref_t)
 			  + db->head->data_size));
 	      written = sendfileall (fd, db->wr_fd,
 				     (char *) &dataset->resp
-				     - (char *) db->head, total);
+				     - (char *) db->head, dataset->head.recsize);
 # ifndef __ASSUME_SENDFILE
 	      if (written == -1 && errno == ENOSYS)
 		goto use_write;
@@ -308,7 +313,10 @@ cache_addserv (struct database_dyn *db, int fd, request_header *req,
 	  use_write:
 # endif
 #endif
-	    written = writeall (fd, &dataset->resp, total);
+	    written = writeall (fd, &dataset->resp, dataset->head.recsize);
+
+	  if (written != dataset->head.recsize)
+	    all_written = false;
 	}
 
       /* Add the record to the database.  But only if it has not been
@@ -332,7 +340,7 @@ cache_addserv (struct database_dyn *db, int fd, request_header *req,
 	}
     }
 
-  if (__builtin_expect (written != total, 0) && debug_level > 0)
+  if (__builtin_expect (!all_written, 0) && debug_level > 0)
     {
       char buf[256];
       dbg_log (_("short write in %s: %s"),  __FUNCTION__,
-- 
1.8.2.1

-- 
Andreas Schwab, SUSE Labs, schwab@suse.de
GPG Key fingerprint = 0196 BAD8 1CE9 1970 F4BE  1748 E4D4 88E3 0EEA B9D7
"And now for something completely different."