Treat read error (fread() returns 0) the same as EOF.

src/sbbs3/zmodem.c

@@ -1379,7 +1379,7 @@ int zmodem_send_from(zmodem_t* zm, FILE* fp, ulong pos, ulong fsize, ulong* sent
 		/*
 		 * at end of file wait for an ACK - can't use feof() here!
 		 */
-		if((ulong)ftell(fp) >= fsize)
+		if((ulong)ftell(fp) >= fsize || n==0)
 			type = ZCRCW;
 
 		zmodem_send_data(zm, type, zm->tx_data_subpacket, n);
@@ -1407,6 +1407,11 @@ int zmodem_send_from(zmodem_t* zm, FILE* fp, ulong pos, ulong fsize, ulong* sent
 				lprintf(zm,LOG_DEBUG,"zmodem_send_from: end of file (%ld)", fsize );
 				return ZACK;
 			}
+			if(n==0) {
+				lprintf(zm,LOG_DEBUG,"zmodem_send_from: read error at offset %lu", ftell(fp) );
+				return ZACK;
+			}
+
 		}
 
 		/*