From d379f6d7f04f56c2f7fa475e9aba0939b73742eb Mon Sep 17 00:00:00 2001
From: Victor <victor.yingyi@gmail.com>
Date: Mon, 6 Nov 2023 00:24:57 -0800
Subject: [PATCH] add destructor to close fd to open device one time, and make
 dir be const char* type

---
 include/rawdisk.h | 43 +++++++++++--------------------------------
 test/layer0.cpp   |  7 +------
 2 files changed, 12 insertions(+), 38 deletions(-)

diff --git a/include/rawdisk.h b/include/rawdisk.h
index 62074df..ffc7f1c 100644
--- a/include/rawdisk.h
+++ b/include/rawdisk.h
@@ -8,21 +8,20 @@
 
 class RawDisk{
 
-    char* dir;
+    int fd;
+    const char* dir;
     off_t numSectors;
     off_t diskSize;
 
 public:
-    RawDisk(char *directory){
+    RawDisk(const char *directory){
         dir = directory;
         /*dir = strdup("/dev/vdc");
         numSectors = 62914560;
         diskSize = 32212254720;*/
         
-        int fd;
-
         // Open the block device (replace /dev/sdX with the actual device)
-        fd = open(dir, O_RDONLY);
+        fd = open(dir, O_RDWR); // Allow read and write
         if (fd == -1) {
             perror("Error opening device");
             exit(1);
@@ -41,58 +40,41 @@ public:
         printf("====Initializing RawDisk====\n");
         printf("Number of sectors: %llu\n", numSectors);
         printf("Disk size (in bytes): %llu\n", diskSize);
+    }
 
-        close(fd);
+    ~RawDisk() {
+        if (fd != -1) {
+            close(fd);
+        }
     }
 
     int rawdisk_read(off_t blockNumber, char *buffer){
-        int fd;
-
-        fd = open(dir, O_RDONLY);
-        if (fd == -1) {
-            perror("Error opening device");
-            return -1;
-        }
-
         // Calculate the offset in bytes
         off_t offset = blockNumber * 512;
 
         // Move the file pointer to the desired block
         if (lseek(fd, offset, SEEK_SET) == -1) {
             perror("Error seeking to block");
-            close(fd);
             return -1;
         }
 
-        // Read a block of data
+        // Read a 512 byte-size block of data
         ssize_t bytesRead = read(fd, buffer, 512);
         if (bytesRead == -1) {
             perror("Error reading from device");
-            close(fd);
             return -1;
         }
 
-        // Process the data (e.g., data recovery or analysis)
-        close(fd);
-        
+        return 0;
     }
 
     int rawdisk_write(off_t blockNumber, char *buffer){
-        int fd;
-
-        fd = open(dir, O_WRONLY);
-        if (fd == -1) {
-            perror("Error opening device");
-            return -1;
-        }
-
         // Calculate the offset in bytes
         off_t offset = blockNumber * 512;
 
         // Move the file pointer to the desired block
         if (lseek(fd, offset, SEEK_SET) == -1) {
             perror("Error seeking to block");
-            close(fd);
             return -1;
         }
 
@@ -100,12 +82,9 @@ public:
         ssize_t bytesWrite = write(fd, buffer, 512);
         if (bytesWrite == -1) {
             perror("Error writing from device");
-            close(fd);
             return -1;
         }
 
-        // Process the data (e.g., data recovery or analysis)
-        close(fd);
         return 0;
     }
 
diff --git a/test/layer0.cpp b/test/layer0.cpp
index 1b8faeb..3a73b0b 100644
--- a/test/layer0.cpp
+++ b/test/layer0.cpp
@@ -4,12 +4,7 @@
 #include "rawdisk.h"
 
 int main(int argc, char *argv[]) {
-    char *d = NULL;
-    if(argc < 2){
-        d = strdup("/dev/vdc");
-    }else{
-        d = argv[1];
-    }
+    const char* d = (argc < 2) ? "/dev/vdc" : argv[1];
     
     RawDisk *H = new RawDisk(d);