[svn-r14984] Purpose: Fix bug in H5G_get_name_by_addr where buffer size is less than size of name

Description:
Backport of the bug found earlier today in HDF5 1.9.  The H5G_get_name_by_addr function makes a call to strncat writes an extra null byte when the buffer is smaller than the dataset name.  Also, comment out 2 lines that are no longer necessary because of the fix.

Tested:
kagiso

1 files changed, 6 insertions, 4 deletions

diff --git a/src/H5Gname.c b/src/H5Gname.c
index 78c1ea0..9a00fae 100644
--- a/src/H5Gname.c
+++ b/src/H5Gname.c
@@ -1242,10 +1242,12 @@ H5G_get_name_by_addr(hid_t file, hid_t dxpl_id, const H5G_entry_t *loc,
             HDstrcpy(name, "/");
 
             /* Append the rest of the path */
-            /* (less one character, for the initial path separator) */
-            HDstrncat(name, udata.path, (size - 1));
-            if((size_t)ret_value >= size)
-                name[size - 1] = '\0';
+            /* (less two characters, for the initial path separator, */
+	    /*  and because strncat appends a null byte) */
+            HDstrncat(name, udata.path, (size - 2));
+	    // Unnecessary, because strncat will always set the last byte null.
+            // if((size_t)ret_value >= size)
+            //     name[size - 1] = '\0';
         } /* end if */
     } /* end if */
     else