From 89e1c349efb603ac8cf950315a913284fdd930e1 Mon Sep 17 00:00:00 2001
From: Saturneric <eric.bktu@gmail.com>
Date: Tue, 8 Dec 2020 11:33:48 +0800
Subject: [PATCH] Finish 4.

---
 .gitignore                      |   2 ++
 4/fileDirectory/.dirent.c.swp   | Bin 12288 -> 0 bytes
 4/fileDirectory/.filetime.c.swp | Bin 12288 -> 0 bytes
 4/fileDirectory/.mkdir.c.swp    | Bin 12288 -> 0 bytes
 4/fileDirectory/chdir.c         |  11 ++++++++++-
 4/fileDirectory/dev.c           |  26 ++++++++++++++++++++++++++
 README.md                       |   2 +-
 7 files changed, 39 insertions(+), 2 deletions(-)
 delete mode 100644 4/fileDirectory/.dirent.c.swp
 delete mode 100644 4/fileDirectory/.filetime.c.swp
 delete mode 100644 4/fileDirectory/.mkdir.c.swp
 create mode 100644 4/fileDirectory/dev.c

diff --git a/.gitignore b/.gitignore
index c6127b3..95f24b0 100644
--- a/.gitignore
+++ b/.gitignore
@@ -50,3 +50,5 @@ modules.order
 Module.symvers
 Mkfile.old
 dkms.conf
+*.swp
+*.swo
diff --git a/4/fileDirectory/.dirent.c.swp b/4/fileDirectory/.dirent.c.swp
deleted file mode 100644
index 65e0b12835e446ec13bd6a98560402306b156854..0000000000000000000000000000000000000000
GIT binary patch
literal 0
HcmV?d00001

literal 12288
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diff --git a/4/fileDirectory/.filetime.c.swp b/4/fileDirectory/.filetime.c.swp
deleted file mode 100644
index d1733e34430a66fcd886d92d362088b6b9d4e6b1..0000000000000000000000000000000000000000
GIT binary patch
literal 0
HcmV?d00001

literal 12288
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diff --git a/4/fileDirectory/.mkdir.c.swp b/4/fileDirectory/.mkdir.c.swp
deleted file mode 100644
index 37480d0a233f9da32d727ed0f94892c23eee770d..0000000000000000000000000000000000000000
GIT binary patch
literal 0
HcmV?d00001

literal 12288
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diff --git a/4/fileDirectory/chdir.c b/4/fileDirectory/chdir.c
index 0eeaf73..3e13ea7 100644
--- a/4/fileDirectory/chdir.c
+++ b/4/fileDirectory/chdir.c
@@ -1,6 +1,15 @@
 #include <unistd.h>
+#include <stdio.h>
 
 int main(void) {
-  // TODO
+  if(chdir("/home/eric") < 0) {
+    printf("chdir error\n");
+    return -1;
+  }
+
+  char buf[1024];
+
+  char *pbuf = getcwd(buf, 1024);
+  printf("CWD: %s\n", pbuf);
   return 0;
 }
diff --git a/4/fileDirectory/dev.c b/4/fileDirectory/dev.c
new file mode 100644
index 0000000..214558f
--- /dev/null
+++ b/4/fileDirectory/dev.c
@@ -0,0 +1,26 @@
+#include <sys/stat.h>
+#include <stdio.h>
+#include <sys/types.h>
+
+int main(void) {
+  struct stat buf;
+
+  if(stat("/dev/sda", &buf) < 0){
+    printf("stat error for /dev/sda\n");
+    return -1;
+  }
+
+  printf("dev = %ld\nrdev = %ld\n", buf.st_dev, buf.st_rdev);
+
+  if(S_ISCHR(buf.st_mode)){
+    printf("character device\n");
+  }
+  else if (S_ISBLK(buf.st_mode)){
+    printf("block device\n");
+  }
+  else {
+    printf("unkonwn device\n");
+  }
+  
+  return 0;
+}
diff --git a/README.md b/README.md
index fc153e5..f002ccb 100644
--- a/README.md
+++ b/README.md
@@ -24,7 +24,7 @@
 ```
 2. 已加载的内核模块
 ```
-    Module                  Size  Used by
+  Module                  Size  Used by
   ipt_MASQUERADE         16384  1
   nf_conntrack_netlink    49152  0
   xfrm_user              40960  1