add lab answers

labcodes_answer/lab8_result/user/libs/dir.c

@@ -0,0 +1,46 @@
+#include <defs.h>
+#include <string.h>
+#include <syscall.h>
+#include <stat.h>
+#include <dirent.h>
+#include <file.h>
+#include <dir.h>
+#include <error.h>
+#include <unistd.h>
+
+DIR dir, *dirp=&dir;
+DIR *
+opendir(const char *path) {
+
+    if ((dirp->fd = open(path, O_RDONLY)) < 0) {
+        goto failed;
+    }
+    struct stat __stat, *stat = &__stat;
+    if (fstat(dirp->fd, stat) != 0 || !S_ISDIR(stat->st_mode)) {
+        goto failed;
+    }
+    dirp->dirent.offset = 0;
+    return dirp;
+
+failed:
+    return NULL;
+}
+
+struct dirent *
+readdir(DIR *dirp) {
+    if (sys_getdirentry(dirp->fd, &(dirp->dirent)) == 0) {
+        return &(dirp->dirent);
+    }
+    return NULL;
+}
+
+void
+closedir(DIR *dirp) {
+    close(dirp->fd);
+}
+
+int
+getcwd(char *buffer, size_t len) {
+    return sys_getcwd(buffer, len);
+}
+