实现函数sys_getcwd,借鉴https://www.cnblogs.com/alan-forever/p/3721908.html

stat.c

@@ -0,0 +1,66 @@
+/*
+ *  linux/fs/stat.c
+ *
+ *  (C) 1991  Linus Torvalds
+ */
+
+#include <errno.h>
+#include <sys/stat.h>
+
+#include <linux/fs.h>
+#include <linux/sched.h>
+#include <linux/kernel.h>
+#include <asm/segment.h>
+
+static void cp_stat(struct m_inode * inode, struct stat * statbuf)
+{
+	struct stat tmp;
+	int i;
+
+	verify_area(statbuf,sizeof (* statbuf));
+	tmp.st_dev = inode->i_dev;
+	tmp.st_ino = inode->i_num;
+	tmp.st_mode = inode->i_mode;
+	tmp.st_nlink = inode->i_nlinks;
+	tmp.st_uid = inode->i_uid;
+	tmp.st_gid = inode->i_gid;
+	tmp.st_rdev = inode->i_zone[0];
+	tmp.st_size = inode->i_size;
+	tmp.st_atime = inode->i_atime;
+	tmp.st_mtime = inode->i_mtime;
+	tmp.st_ctime = inode->i_ctime;
+	for (i=0 ; i<sizeof (tmp) ; i++)
+		put_fs_byte(((char *) &tmp)[i],&((char *) statbuf)[i]);
+}
+
+int sys_stat(char * filename, struct stat * statbuf)
+{
+	struct m_inode * inode;
+
+	if (!(inode=namei(filename)))
+		return -ENOENT;
+	cp_stat(inode,statbuf);
+	iput(inode);
+	return 0;
+}
+
+int sys_lstat(char * filename, struct stat * statbuf)
+{
+	return sys_stat(filename, statbuf);
+}
+
+int sys_fstat(unsigned int fd, struct stat * statbuf)
+{
+	struct file * f;
+	struct m_inode * inode;
+
+	if (fd >= NR_OPEN || !(f=current->filp[fd]) || !(inode=f->f_inode))
+		return -EBADF;
+	cp_stat(inode,statbuf);
+	return 0;
+}
+
+int sys_readlink()
+{
+	return -ENOSYS;
+}