tty: add nonblocking stdin (fd 0) via ring buffer

diff --git a/include/keyboard.h b/include/keyboard.h
index 9d0f3f5c3fef03b66a625af339646794ab141ac8..ec990059f333bebc49261f2ae8817a84afef8883 100644 (file)
--- a/include/keyboard.h
+++ b/include/keyboard.h
@@ -18,4 +18,6 @@ typedef void (*keyboard_callback_t)(char);
 void keyboard_init(void);
 void keyboard_set_callback(keyboard_callback_t callback);
 
+int keyboard_read_nonblock(char* out, uint32_t max_len);
+
 #endif

diff --git a/src/drivers/keyboard.c b/src/drivers/keyboard.c
index da6fed9b5fc8a083cce2f9b6b67930d4f3a96398..47f3ce4e943eb476722281e0248866af63e6c042 100644 (file)
--- a/src/drivers/keyboard.c
+++ b/src/drivers/keyboard.c
@@ -15,7 +15,22 @@
 
 static keyboard_callback_t active_callback = NULL;
 
+#define KBD_BUF_SIZE 256
+static volatile uint32_t kbd_head = 0;
+static volatile uint32_t kbd_tail = 0;
+static char kbd_buf[KBD_BUF_SIZE];
+
+static void kbd_push_char(char c) {
+    uint32_t next = (kbd_head + 1U) % KBD_BUF_SIZE;
+    if (next == kbd_tail) {
+        kbd_tail = (kbd_tail + 1U) % KBD_BUF_SIZE;
+    }
+    kbd_buf[kbd_head] = c;
+    kbd_head = next;
+}
+
 static void hal_kbd_bridge(char c) {
+    kbd_push_char(c);
     if (active_callback) {
         active_callback(c);
     }
@@ -23,9 +38,23 @@ static void hal_kbd_bridge(char c) {
 
 void keyboard_init(void) {
     uart_print("[KBD] Initializing Keyboard Driver...\n");
+    kbd_head = 0;
+    kbd_tail = 0;
     hal_keyboard_init(hal_kbd_bridge);
 }
 
 void keyboard_set_callback(keyboard_callback_t callback) {
     active_callback = callback;
 }
+
+int keyboard_read_nonblock(char* out, uint32_t max_len) {
+    if (!out || max_len == 0) return 0;
+
+    uint32_t count = 0;
+    while (count < max_len) {
+        if (kbd_tail == kbd_head) break;
+        out[count++] = kbd_buf[kbd_tail];
+        kbd_tail = (kbd_tail + 1U) % KBD_BUF_SIZE;
+    }
+    return (int)count;
+}

diff --git a/src/kernel/syscall.c b/src/kernel/syscall.c
index b4270d08c4a5e54f40b5675d63559583021e3dcf..b9deb644a39cac0e928570fc1689656d5046c95d 100644 (file)
--- a/src/kernel/syscall.c
+++ b/src/kernel/syscall.c
@@ -11,6 +11,8 @@
 #include "idt.h"
 #include "fs.h"
 #include "heap.h"
+#include "keyboard.h"
+#include "keyboard.h"
 #include "process.h"
 #include "uart_console.h"
 #include "uaccess.h"
@@ -90,6 +92,18 @@ static int syscall_read_impl(int fd, void* user_buf, uint32_t len) {
     if (len > 1024 * 1024) return -1;
     if (user_range_ok(user_buf, (size_t)len) == 0) return -1;
 
+    if (fd == 0) {
+        char kbuf[256];
+        uint32_t chunk = len;
+        if (chunk > sizeof(kbuf)) chunk = (uint32_t)sizeof(kbuf);
+        int rd = keyboard_read_nonblock(kbuf, chunk);
+        if (rd <= 0) return 0;
+        if (copy_to_user(user_buf, kbuf, (size_t)rd) < 0) return -1;
+        return rd;
+    }
+
+    if (fd == 1 || fd == 2) return -1;
+
     struct file* f = fd_get(fd);
     if (!f || !f->node) return -1;