fixup! Update sys/net/application_layer/gcoap/fileserver.c

sys/net/application_layer/gcoap/fileserver.c

@@ -121,16 +121,10 @@ static size_t gcoap_fileserver_errno_handler(coap_pkt_t *pdu, uint8_t *buf, size
     return gcoap_response(pdu, buf, len, code);
 }
 
-static void _calc_szx2(coap_pkt_t *pdu, uint8_t *buf, size_t len, struct requestdata *request)
+static void _calc_szx2(coap_pkt_t *pdu, size_t reserve, struct requestdata *request)
 {
-    /* To best see how this works set CONFIG_GCAOP_PDU_BUF_SIZE to 532 or 533.
-     * If we did a sharper estimation (factoring in the block2 size option with
-     * the current blockum), we'd even pack 512 bytes into 530 until block
-     * numbers get large enough to eat another byte, which is when the block
-     * size would decrease in-flight. */
-    size_t remaining_length = len - (pdu->payload - buf);
-    remaining_length -= 5; /* maximum block2 option usable in nanocoap */
-    remaining_length -= 1; /* payload marker */
+    assert(pdu->payload_len > reserve);
+    size_t remaining_length = pdu->payload_len - reserve;
     /* > 0: To not wrap around; if that still won't fit that's later caught in
      * an assertion */
     while ((coap_szx2size(request->szx2) > remaining_length) && (request->szx2 > 0)) {
@@ -162,7 +156,9 @@ static ssize_t gcoap_fileserver_file_handler(coap_pkt_t *pdu, uint8_t *buf, size
     gcoap_resp_init(pdu, buf, len, COAP_CODE_CONTENT);
     coap_opt_add_opaque(pdu, COAP_OPT_ETAG, &etag, sizeof(etag));
     coap_block_slicer_t slicer;
-    _calc_szx2(pdu, buf, len, request);
+    _calc_szx2(pdu,
+               5 + 1 + 1 /* reserve BLOCK2 size + payload marker + more */,
+               request);
     coap_block_slicer_init(&slicer, request->blocknum2, coap_szx2size(request->szx2));
     coap_opt_add_block2(pdu, &slicer, true);
     size_t resp_len = coap_opt_finish(pdu, COAP_OPT_FINISH_PAYLOAD);
@@ -179,16 +175,13 @@ static ssize_t gcoap_fileserver_file_handler(coap_pkt_t *pdu, uint8_t *buf, size
      * space by CONFIG_GCOAP_RESP_OPTIONS_BUF
      * */
     assert(pdu->payload + slicer.end - slicer.start <= buf + len);
-    int read = vfs_read(fd, pdu->payload, slicer.end - slicer.start);
+    bool more = 1;
+    int read = vfs_read(fd, pdu->payload, slicer.end - slicer.start + more);
     if (read < 0) {
         goto late_err;
     }
-
-    uint8_t morebuf;
-    int more = vfs_read(fd, &morebuf, 1);
-    if (more < 0) {
-        goto late_err;
-    }
+    more = (unsigned)read > slicer.end - slicer.start;
+    read -= more;
 
     vfs_close(fd);
 
@@ -221,11 +214,11 @@ static ssize_t gcoap_fileserver_directory_handler(coap_pkt_t *pdu, uint8_t *buf,
     }
     DEBUG("gcoap_fileserver: Serving directory listing\n");
 
-    coap_block2_init(pdu, &slicer);
-
     gcoap_resp_init(pdu, buf, len, COAP_CODE_CONTENT);
     coap_opt_add_format(pdu, COAP_FORMAT_LINK);
-    _calc_szx2(pdu, buf, len, request);
+    _calc_szx2(pdu,
+               5 + 1 /* reserve BLOCK2 size + payload marker */,
+               request);
     coap_block_slicer_init(&slicer, request->blocknum2, coap_szx2size(request->szx2));
     coap_opt_add_block2(pdu, &slicer, true);
     buf += coap_opt_finish(pdu, COAP_OPT_FINISH_PAYLOAD);