From b25f0f167da0f74db53d259cd5517d4cb7cb0ab1 Mon Sep 17 00:00:00 2001
From: Victor <victor.yingyi@gmail.com>
Date: Mon, 6 Nov 2023 14:00:14 -0800
Subject: [PATCH] revise rawdisk R/W API to set with offset and length

---
 include/rawdisk.h | 33 ++++++++++++---------------------
 test/layer0.cpp   |  4 ++--
 2 files changed, 14 insertions(+), 23 deletions(-)

diff --git a/include/rawdisk.h b/include/rawdisk.h
index ffc7f1c..efd45ed 100644
--- a/include/rawdisk.h
+++ b/include/rawdisk.h
@@ -14,7 +14,7 @@ class RawDisk{
     off_t diskSize;
 
 public:
-    RawDisk(const char *directory){
+    RawDisk(const char *directory) : fd(-1), dir(nullptr), numSectors(0), diskSize(0) {
         dir = directory;
         /*dir = strdup("/dev/vdc");
         numSectors = 62914560;
@@ -48,18 +48,13 @@ public:
         }
     }
 
-    int rawdisk_read(off_t blockNumber, char *buffer){
-        // 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");
+    int rawdisk_read(off_t offset, char *buffer, size_t length) {
+        if (lseek(fd, offset, SEEK_SET) == (off_t)-1) {
+            perror("Error seeking to offset");
             return -1;
         }
 
-        // Read a 512 byte-size block of data
-        ssize_t bytesRead = read(fd, buffer, 512);
+        ssize_t bytesRead = read(fd, buffer, length);
         if (bytesRead == -1) {
             perror("Error reading from device");
             return -1;
@@ -68,20 +63,16 @@ public:
         return 0;
     }
 
-    int rawdisk_write(off_t blockNumber, char *buffer){
-        // 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");
+    // Write a specified number of bytes at a given byte offset
+    int rawdisk_write(off_t offset, char *buffer, size_t length) {
+        if (lseek(fd, offset, SEEK_SET) == (off_t)-1) {
+            perror("Error seeking to offset");
             return -1;
         }
 
-        // Write a block of data
-        ssize_t bytesWrite = write(fd, buffer, 512);
-        if (bytesWrite == -1) {
-            perror("Error writing from device");
+        ssize_t bytesWritten = write(fd, buffer, length);
+        if (bytesWritten == -1) {
+            perror("Error writing to device");
             return -1;
         }
 
diff --git a/test/layer0.cpp b/test/layer0.cpp
index 3a73b0b..5e61c72 100644
--- a/test/layer0.cpp
+++ b/test/layer0.cpp
@@ -15,11 +15,11 @@ int main(int argc, char *argv[]) {
 
     //use number to substitute H->getnumSector(), getnumSectors() are not yest implemented
     for(off_t i = 0; i < 10; i++) {
-        H->rawdisk_write(i, buf);
+        H->rawdisk_write(i*512, buf, sizeof(buf));//Change write_API
     }
     //use number to substitute H->getnumSector(), getnumSectors() are not yest implemented
     for(off_t i = 0; i < 10; i++) {
-        H->rawdisk_read(i, readBuffer);
+        H->rawdisk_read(i*512, readBuffer, sizeof(readBuffer));//Change read_API
         assert(strncmp(readBuffer, buf, strlen(buf)) == 0);
     }