Add the most important part of README

Uninitialized variables, reading past array end, etc.

src/kernel/fat16.c

@@ -357,7 +357,7 @@ fs_node_t *fat16_open_at(const fs_node_t *directory, uint16_t index, uint64_t fl
     ei++;
   }
 
-  fs_node_t *result = ei < entries_count ? open_entry(dir_cluster, entries, ei) : NUL;
+  fs_node_t *result = open_entry(dir_cluster, entries, ei);
 
   memory_free(entries);
 

src/kernel/xhci.c

@@ -538,7 +538,7 @@ uint64_t xhci_control_transfer(xhci_slot_t slot, uint64_t setup, void *data, uin
 }
 
 xhci_endpoint_t xhci_open_endpoint(xhci_slot_t slot, uint8_t address, uint8_t type, uint16_t max_packet_size, uint8_t interval) {
-  LOG_LN_STEP("Opening endpoint slot %d address %hhx...", slot, address);
+  LOG_LN_INFO("Opening endpoint slot %d address %hhx...", slot, address);
 
   ASSERT(slot < MAX_SLOTS, "xhci_control_transfer: Slot does not exist.");
   ASSERT(tsf_r_attached_slot == slot, "xhci_open_endpoint: Slot is not attached.");
@@ -549,11 +549,11 @@ xhci_endpoint_t xhci_open_endpoint(xhci_slot_t slot, uint8_t address, uint8_t ty
   uint8_t ep_dir = (address >> 7) & 1;
   uint8_t dci = ep_num * 2 + ep_dir;
 
-  LOG_LN_STEP("Setting up endpoint ring...");
+  LOG_LN_INFO("Setting up endpoint ring...");
   RING_WRAP(ep);
   XHCI_TRB_CYCLE_W(&ep_r[RING_LENGTH], ep_r_cycle);
 
-  LOG_LN_STEP("Configuring endpoint...");
+  LOG_LN_INFO("Configuring endpoint...");
   memory_set(0, sizeof(xhci_input_ctx_t), &input_ctx);
   input_ctx.slot = device_ctx.slot;
   input_ctx.control.add_flags = (1 << 0) | (1 << dci);
@@ -597,10 +597,9 @@ uint16_t xhci_read_endpoint(xhci_slot_t slot, xhci_endpoint_t endpoint, uint16_t
       XHCI_TRB_TRB_TYPE_W(ere, XHCI_TRB_TYPE_TRANSFER_NORMAL);
       XHCI_TRB_IOC_W(ere, 1);
       XHCI_TRB_CYCLE_W(ere, ep_r_cycle);
+      RING_ADVANCE(ep);
     }
 
-    ep_r_cycle ^= 1;
-
     db_regs[tsf_r_attached_slot] = ep_r_attached_endpoint;
 
     return 0;
@@ -608,14 +607,6 @@ uint16_t xhci_read_endpoint(xhci_slot_t slot, xhci_endpoint_t endpoint, uint16_t
 
   uint16_t transferred = 0;
   while (XHCI_TRB_CYCLE_R(&evt_r[evt_r_i]) == evt_r_cycle && !transferred) {
-    if (ep_processed_events == 0) {
-      // A bit of a hack: flip link TRB cycle only after the first event is processed. There is some delay between controller
-      // posting the last success event of the batch, and consuming the link TRB. Flipping the link cycle together with the batch
-      // might happen before the controller got a chance to check the link cycle, and stall the consumption. If we received the
-      // first event of the next batch, we're certain the link TRB has just been processed, and there's plenty of time before the next loop.
-      XHCI_TRB_CYCLE_W(&ep_r[RING_LENGTH], !ep_r_cycle);
-    }
-
     xhci_trb_t *cmp = &evt_r[evt_r_i];
 
     if (XHCI_TRB_TRB_TYPE_R(cmp) != XHCI_TRB_TYPE_EVENT_TRANSFER_COMPLETION) {
@@ -657,7 +648,7 @@ uint16_t xhci_read_endpoint(xhci_slot_t slot, xhci_endpoint_t endpoint, uint16_t
 }
 
 void xhci_close_endpoint(xhci_slot_t slot, xhci_endpoint_t endpoint) {
-  LOG_LN_STEP("Closing endpoind %hhx...", endpoint);
+  LOG_LN_INFO("Closing endpoind %hhx...", endpoint);
 
   ASSERT(slot < MAX_SLOTS, "xhci_control_transfer: Slot does not exist.");
   ASSERT(tsf_r_attached_slot == slot, "xhci_close_endpoint: Slot is not attached.");

src/user/app/cat/cat.c

@@ -5,7 +5,7 @@
 #define BLOCK_SIZE 65536
 
 exit_code_t pass(uint64_t fd) {
-  static char buffer[BLOCK_SIZE];
+  char buffer[BLOCK_SIZE];
   uint64_t bytes;
   while ((bytes = read(fd, BLOCK_SIZE, buffer))) {
     if (bytes == (uint64_t)-1) {

src/user/app/wc/wc.c

@@ -6,7 +6,7 @@
 #define BLOCK_SIZE 65536
 
 exit_code_t pass(uint64_t fd) {
-  static char buffer[BLOCK_SIZE];
+  char buffer[BLOCK_SIZE];
   uint64_t bytes;
   uint64_t total = 0;
   while ((bytes = read(fd, BLOCK_SIZE, buffer))) {