Implement NTAG writing for YHY

1 files changed, 43 insertions, 0 deletions

diff --git a/reader.c b/reader.c
index 7bc20e3..2c3a06b 100644
--- a/reader.c
+++ b/reader.c
@@ -12,10 +12,21 @@
 
 #define MAX_PLUGIN_PATH NAME_MAX
 #define DEFAULT_POLL_TIMEOUT 1000
+
+/*
+ * Pointers into the tags array are used as stable identifiers
+ * across the different NFCommander modules, so this array should
+ * never be reallocated dynamically.
+ *
+ * As most readers have a limited number of tags they can power in
+ * the field, this should not pose a practical limitation.
+ */
 #define MAX_TAGS 5
 
 #define FLAG_PRESENT 16
 #define FLAG_ACTIVE 32
+#define FLAG_WRITE_FULL 64
+#define FLAG_WRITE_DYNAMIC 128
 
 static void* reader_module = NULL;
 static reader_plugin_handle reader_backend_handle = NULL;
@@ -195,6 +206,15 @@ int reader_tag_present(uint8_t flags, nfc_tag_info_t* tag){
 				//if data has not yet been fully read, request a full read
 				return TAG_READ_REQUESTED;
 			}
+
+			if(tags[n].flags & (FLAG_WRITE_FULL | FLAG_WRITE_DYNAMIC)){
+				flags = tags[n].flags;
+				tags[n].flags &= ~(FLAG_WRITE_FULL | FLAG_WRITE_DYNAMIC);
+				//this is kinda dangerous as we hand the reader backend our pointers
+				memcpy(tag, &(tags[n].info), sizeof(nfc_tag_info_t));
+
+				return (flags & FLAG_WRITE_FULL) ? TAG_WRITE_FULL : TAG_WRITE_DYNAMIC;
+			}
 			return 0;
 		}
 	}
@@ -214,6 +234,23 @@ int reader_tag_present(uint8_t flags, nfc_tag_info_t* tag){
 	return 0;
 }
 
+int reader_write(nfc_tag_info_t* tag, uint8_t flags){
+	size_t n = 0;
+
+	for(n = 0; n < MAX_TAGS; n++){
+		if(tag == &(tags[n].info)){
+			if(flags & TAG_WRITE_FULL){
+				tags[n].flags |= FLAG_WRITE_FULL;
+			}
+
+			if(flags & TAG_WRITE_DYNAMIC){
+				tags[n].flags |= FLAG_WRITE_DYNAMIC;
+			}
+		}
+	}
+	return 0;
+}
+
 int reader_handle(int fd){
 	uint8_t buffer[1024];
 
@@ -240,6 +277,8 @@ int reader_handle(int fd){
 }
 
 void reader_free(){
+	size_t n = 0;
+
 	if(reader_module){
 		dlclose(reader_module);
 		reader_backend_handle = NULL;
@@ -247,6 +286,10 @@ void reader_free(){
 		reader_module = NULL;
 	}
 
+	for(n = 0; n < MAX_TAGS; n++){
+		tag_info_free(&(tags[n].info));
+	}
+
 	core_manage_fd(timer_fd, 0, system_reader);
 	close(timer_fd);
 	timer_fd = -1;