Add additional error message for prng

Prior to this update any error produced by the nwipe_random_verify() or
nwipe_random_pass functions would be displayed in the GUI with a generic
message "IOERROR", while the details of the error would be displayed in
log file.

With this patch the GUI now displayes "I/O ERROR" for any read/write
errors, "PRNG ERROR" for all errors returned by the prng generators and
"FAILURE" for any signal errors.

The nwipe_random_verify() and nwipe_random_pass() functions previously
only returned a -1 to indicate some failure. They now return -1 for
read/write I/O errors and -2 for prng errors.

Identifing a prng error will be particulary important for an upcoming
commit related to the aes-ctr prng which calls external libraries.

src/gui.c

@@ -6598,9 +6598,27 @@ void* nwipe_gui_status( void* ptr )
                         }
                         else
                         {
-                            wattron( main_window, COLOR_PAIR( 9 ) );
-                            mvwprintw( main_window, yy++, 4, "(>>> IOERROR! <<<, code %i) ", c[i]->result );
-                            wattroff( main_window, COLOR_PAIR( 9 ) );
+                            switch( c[i]->result )
+                            {
+                                case -1:
+                                    wattron( main_window, COLOR_PAIR( 9 ) );
+                                    mvwprintw( main_window, yy++, 4, "(>>> I/O ERROR! <<<, code %i) ", c[i]->result );
+                                    wattroff( main_window, COLOR_PAIR( 9 ) );
+                                    break;
+
+                                case -2:
+                                    wattron( main_window, COLOR_PAIR( 9 ) );
+                                    mvwprintw( main_window, yy++, 4, "(>>> PRNG ERROR! <<<, code %i) ", c[i]->result );
+                                    wattroff( main_window, COLOR_PAIR( 9 ) );
+                                    break;
+
+                                default:
+                                    wattron( main_window, COLOR_PAIR( 9 ) );
+                                    mvwprintw(
+                                        main_window, yy++, 4, "(>>> SANITY ERROR! <<<, code %i) ", c[i]->result );
+                                    wattroff( main_window, COLOR_PAIR( 9 ) );
+                                    break;
+                            }
                         }
 
                     } /* child returned */

src/pass.c

@@ -37,6 +37,10 @@ int nwipe_random_verify( nwipe_context_t* c )
     /**
      * Verifies that a random pass was correctly written to the device.
      *
+     * returns:
+     *          0   = Success
+     *          -1  = I/O error
+     *          -2  = PRNG error
      */
 
     /* The result holder. */
@@ -59,14 +63,14 @@ int nwipe_random_verify( nwipe_context_t* c )
 
     if( c->prng_seed.s == NULL )
     {
-        nwipe_log( NWIPE_LOG_SANITY, "Null seed pointer." );
-        return -1;
+        nwipe_log( NWIPE_LOG_SANITY, "Null seed pointer on verification." );
+        return -2;
     }
 
     if( c->prng_seed.length <= 0 )
     {
-        nwipe_log( NWIPE_LOG_SANITY, "The entropy length member is %i.", c->prng_seed.length );
-        return -1;
+        nwipe_log( NWIPE_LOG_SANITY, "On verification the entropy length member is %i.", c->prng_seed.length );
+        return -2;
     }
 
     /* Create the input buffer. */
@@ -133,7 +137,11 @@ int nwipe_random_verify( nwipe_context_t* c )
     }
 
     /* Reseed the PRNG. */
-    c->prng->init( &c->prng_state, &c->prng_seed );
+    if( c->prng->init( &c->prng_state, &c->prng_seed ) )
+    {
+        nwipe_log( NWIPE_LOG_ERROR, "Initialising PRNG failed on verification" );
+        return -2;
+    }
 
     while( z > 0 )
     {
@@ -154,7 +162,11 @@ int nwipe_random_verify( nwipe_context_t* c )
         }
 
         /* Fill the output buffer with the random pattern. */
-        c->prng->read( &c->prng_state, d, blocksize );
+        if( c->prng->read( &c->prng_state, d, blocksize ) )
+        {
+            nwipe_log( NWIPE_LOG_ERROR, "Reading PRNG failed on verification" );
+            return -2;
+        }
 
         /* Read the buffer in from the device. */
         r = read( c->device_fd, b, blocksize );
@@ -253,14 +265,14 @@ int nwipe_random_pass( NWIPE_METHOD_SIGNATURE )
 
     if( c->prng_seed.s == NULL )
     {
-        nwipe_log( NWIPE_LOG_SANITY, "__FUNCTION__: Null seed pointer." );
-        return -1;
+        nwipe_log( NWIPE_LOG_SANITY, "__FUNCTION__: Null seed pointer on erasure" );
+        return -2;
     }
 
     if( c->prng_seed.length <= 0 )
     {
-        nwipe_log( NWIPE_LOG_SANITY, "__FUNCTION__: The entropy length member is %i.", c->prng_seed.length );
-        return -1;
+        nwipe_log( NWIPE_LOG_SANITY, "__FUNCTION__: On erasure the entropy length member is %i.", c->prng_seed.length );
+        return -2;
     }
 
     /* Create the initialised output buffer. Initialised because we don't want memory leaks
@@ -276,7 +288,11 @@ int nwipe_random_pass( NWIPE_METHOD_SIGNATURE )
     }
 
     /* Seed the PRNG. */
-    c->prng->init( &c->prng_state, &c->prng_seed );
+    if( c->prng->init( &c->prng_state, &c->prng_seed ) )
+    {
+        nwipe_log( NWIPE_LOG_ERROR, "Initialising PRNG failed on erasure" );
+        return -2;
+    }
 
     /* Reset the file pointer. */
     offset = lseek( c->device_fd, 0, SEEK_SET );
@@ -319,7 +335,11 @@ int nwipe_random_pass( NWIPE_METHOD_SIGNATURE )
         }
 
         /* Fill the output buffer with the random pattern. */
-        c->prng->read( &c->prng_state, b, blocksize );
+        if( c->prng->read( &c->prng_state, b, blocksize ) )
+        {
+            nwipe_log( NWIPE_LOG_ERROR, "Reading PRNG failed during erasure" );
+            return -2;
+        }
 
         /* For the first block only, check the prng actually wrote something to the buffer */
         if( z == c->device_size )