Application skills of system calls and file system operations of Golang functions

With the continuous development of computer technology, various languages ​​​​have also emerged. Among them, Golang (also known as GO language) has become more and more popular among developers in recent years because of its efficiency, simplicity, and ease of learning. In Golang, function system calls and file system operations are common application techniques. This article will introduce the application methods of these techniques in detail to help everyone better master Golang development skills.

1. Function system call

1. What is the system call?

System call is a service interface provided by the operating system kernel and an interactive interface between user space and kernel space. By calling system calls, user space programs can send requests to the kernel space, obtain access and usage rights to system resources, and process underlying hardware resources.

2.What are the system call functions in Golang?

The system call functions of different operating systems in Golang are different. The following are several common system call functions:

• Unix/Linux system: syscall.Syscall in the syscall package Function
• Windows system: syscall.Syscall and syscall.Syscall6 functions in the syscall package

Common system calls include file reading and writing, network communication, sub-process operation, and system parameter acquisition wait.

3. How to use system call function?

The following is the basic method of using system call functions in Golang:

• Unix/Linux system:

Use syscall.Syscall to call system calls , and return the call result. For example, the following code demonstrates how to use system calls to read and write files:

data := []byte("hello, world!") 
file, err := syscall.Open("./test.txt", syscall.O_CREAT|syscall.O_TRUNC|syscall.O_RDWR, 0666) 
if err != nil {
    panic(err)
}
defer syscall.Close(file) 

_, _, err = syscall.Syscall(syscall.SYS_WRITE, uintptr(file), uintptr(unsafe.Pointer(&data[0])), uintptr(len(data))) 
if err != 0 {
    panic(err)
}

Among them, the function syscall.Open is used to open files, and syscall.Syscall is used to make system calls. Finally use syscall.Close to close the file.

• Windows system:

Use syscall.Syscall and syscall.Syscall6 to call system calls. For example, the following code demonstrates how to use system calls to open a file:

h, _, _ := syscall.Syscall(
    procCreateFileW.Addr(),
    6,
    uintptr(unsafe.Pointer(syscall.StringToUTF16Ptr(path))),
    uintptr(desiredAccess),
    uintptr(shareMode),
    uintptr(unsafe.Pointer(lpSecurityAttributes)),
    uintptr(creationDisposition),
    uintptr(flagsAndAttributes),
)

if h == uintptr(syscall.InvalidHandle) {
    return nil, os.NewSyscallError(fmt.Sprintf("invalid handle: %X", h), err)
}
defer syscall.CloseHandle(syscall.Handle(h))

Among them, syscall.Syscall6 is used to open the file, and syscall.CloseHandle is used to close the file handle.

2. File system operations

1. What are file system operations?

File system operations are technologies that perform operations such as reading, writing, creating, and deleting files and directories. In Golang, the file system of the operating system can be easily implemented using the file system operation functions provided by the os package.

2.What are the file system operation functions in Golang?

The following are common file system operation functions in Golang:

• os.Open: open a file
• os.Create: create a file
• os.Remove: Delete the file
• os.Rename: Rename the file
• os.Mkdir: Create the directory
• os.Chdir: Change the current working directory
• os.Stat: Get file information
• os.ReadFile: Read file content
• os.WriteFile: Write file content

3. How to use File system operation function?

The following is the basic method of using file system operation functions in Golang:

Read file content:

data, err := ioutil.ReadFile("./test.txt")
if err != nil {
    panic(err)
}

fmt.Print(string(data))

Write file content:

data := []byte("hello, world!")
err := ioutil.WriteFile("./test.txt", data, 0666)
if err != nil {
    panic(err)
}

Create Directory:

err := os.Mkdir("./test", 0755)
if err != nil {
    panic(err)
}

Delete file:

err := os.Remove("./test.txt")
if err != nil {
    panic(err)
}

Rename file:

err := os.Rename("./test.txt", "./test_new.txt")
if err != nil {
    panic(err)
}

Get file information:

info, err := os.Stat("./test_new.txt")
if err != nil {
    panic(err)
}

fmt.Println(info.Name(), info.Size())

3. Summary

In this article, we introduce the application skills of function system calls and file system operations in Golang, including the basic understanding of system calls, different system call functions of the operating system, and the use of system call functions to implement file read and write operations. At the same time, we also introduced the basic understanding of file system operations, common file system operation functions, and methods of using these functions to perform file reading, writing, creation, deletion and other operations. I hope this article can help everyone better master Golang development skills.

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