How to Determine the Number of Hard Links to a File in Go?

Determining the Number of Hard Links to a File in Go

In Go, the FileInfo interface provides access to information obtained from the stat() system call. While this interface encompasses details such as file name, size, modification time, and file permissions, it lacks direct access to the number of hard links pointing to a given file.

Accessing Link Count via Underlying Data Source

To retrieve the link count, you can leverage the Sys() method of the FileInfo interface. This method provides access to the underlying system-specific data structure, which may include additional information beyond what is directly exposed by FileInfo.

In specific, for Unix-based systems, the Sys() method returns a pointer to *syscall.Stat_t type, which contains a field named Nlink. This field represents the number of hard links to the file.

Example Implementation

Here's an example implementation in Go that demonstrates how to obtain the hard link count of a file:

<code class="go">package main

import (
    "fmt"
    "os"
    "syscall"
)

func main() {
    fi, err := os.Stat("filename")
    if err != nil {
        fmt.Println(err)
        return
    }

    // Retrieve the underlying system data structure
    nlink := uint64(0)
    if sys := fi.Sys(); sys != nil {
        if stat, ok := sys.(*syscall.Stat_t); ok {
            // Extract the link count from the underlying data
            nlink = uint64(stat.Nlink)
        }
    }

    // Print the link count
    fmt.Println(nlink)
}</code>

In this example, the os.Stat() function is used to obtain an os.FileInfo object for the file specified by "filename." The FileInfo object's Sys() method is invoked to access the underlying *syscall.Stat_t structure. The Nlink field of this structure contains the link count for the file.

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