From 3e101d71ff9bd3e53c54b9f1c50bcfaa3671dfc8 Mon Sep 17 00:00:00 2001
From: fslongjin <fslongjin@vip.qq.com>
Date: Thu, 28 Apr 2022 23:24:53 +0800
Subject: [PATCH] sys_write

---
 kernel/syscall/syscall.c     | 37 ++++++++++++++++++++++++++++++++++++
 kernel/syscall/syscall_num.h |  1 +
 2 files changed, 38 insertions(+)

diff --git a/kernel/syscall/syscall.c b/kernel/syscall/syscall.c
index 4ea2cb5a..94db5375 100644
--- a/kernel/syscall/syscall.c
+++ b/kernel/syscall/syscall.c
@@ -268,6 +268,43 @@ uint64_t sys_read(struct pt_regs *regs)
     return ret;
 }
 
+
+/**
+ * @brief 向文件写入数据
+ *
+ * @param fd_num regs->r8 文件描述符号
+ * @param buf regs->r9 输入缓冲区
+ * @param count regs->r10 要写入的字节数
+ *
+ * @return uint64_t
+ */
+uint64_t sys_write(struct pt_regs *regs)
+{
+    int fd_num = (int)regs->r8;
+    void *buf = (void *)regs->r9;
+    int64_t count = (int64_t)regs->r10;
+
+    // kdebug("sys read: fd=%d", fd_num);
+
+    // 校验文件描述符范围
+    if (fd_num < 0 || fd_num > PROC_MAX_FD_NUM)
+        return -EBADF;
+
+    // 文件描述符不存在
+    if (current_pcb->fds[fd_num] == NULL)
+        return -EBADF;
+
+    if (count < 0)
+        return -EINVAL;
+
+    struct vfs_file_t *file_ptr = current_pcb->fds[fd_num];
+    uint64_t ret;
+    if (file_ptr->file_ops && file_ptr->file_ops->write)
+        ret = file_ptr->file_ops->write(file_ptr, (char *)buf, count, &(file_ptr->position));
+
+    return ret;
+}
+
 ul sys_ahci_end_req(struct pt_regs *regs)
 {
     ahci_end_request();
diff --git a/kernel/syscall/syscall_num.h b/kernel/syscall/syscall_num.h
index cb79334d..f93ed8f5 100644
--- a/kernel/syscall/syscall_num.h
+++ b/kernel/syscall/syscall_num.h
@@ -14,5 +14,6 @@
 #define SYS_OPEN 2
 #define SYS_CLOSE 3
 #define SYS_READ 4
+#define SYS_WRITE 5
 
 #define SYS_AHCI_END_REQ 255    // AHCI DMA请求结束end_request的系统调用
\ No newline at end of file