From 15b347db92f11d4aa0841d601e3f612c74df23b6 Mon Sep 17 00:00:00 2001
From: Muhammed Efe Cetin <efectn@protonmail.com>
Date: Sat, 5 Aug 2023 22:31:39 +0300
Subject: [PATCH] filesystem: refactor: use `errors.Is` instead of
 `os.IsNotExist`

---
 internal/gopsutil/net/net_linux.go         |  3 ++-
 internal/gopsutil/process/process_posix.go |  4 +++-
 middleware/filesystem/filesystem.go        | 15 ++++++++-------
 3 files changed, 13 insertions(+), 9 deletions(-)

diff --git a/internal/gopsutil/net/net_linux.go b/internal/gopsutil/net/net_linux.go
index de8a3a7e80..964b053c73 100644
--- a/internal/gopsutil/net/net_linux.go
+++ b/internal/gopsutil/net/net_linux.go
@@ -10,6 +10,7 @@ import (
 	"errors"
 	"fmt"
 	"io"
+	"io/fs"
 	"net"
 	"os"
 	"strconv"
@@ -673,7 +674,7 @@ func getProcInodesAll(root string, max int) (map[string][]inodeMap, error) {
 		t, err := getProcInodes(root, pid, max)
 		if err != nil {
 			// skip if permission error or no longer exists
-			if os.IsPermission(err) || os.IsNotExist(err) || err == io.EOF {
+			if os.IsPermission(err) || errors.Is(err, fs.ErrNotExist) || err == io.EOF {
 				continue
 			}
 			return ret, err
diff --git a/internal/gopsutil/process/process_posix.go b/internal/gopsutil/process/process_posix.go
index 1b6c6fc2d7..ee09574c74 100644
--- a/internal/gopsutil/process/process_posix.go
+++ b/internal/gopsutil/process/process_posix.go
@@ -5,7 +5,9 @@ package process
 
 import (
 	"context"
+	"errors"
 	"fmt"
+	"io/fs"
 	"os"
 	"os/user"
 	"path/filepath"
@@ -86,7 +88,7 @@ func PidExistsWithContext(ctx context.Context, pid int32) (bool, error) {
 		// This covers the case when running inside container with a different process namespace (by default)
 
 		_, err := os.Stat(common.HostProc(strconv.Itoa(int(pid))))
-		if os.IsNotExist(err) {
+		if errors.Is(err, fs.ErrNotExist) {
 			return false, nil
 		}
 		return err == nil, err
diff --git a/middleware/filesystem/filesystem.go b/middleware/filesystem/filesystem.go
index 4b5b6c2928..42276a9b5b 100644
--- a/middleware/filesystem/filesystem.go
+++ b/middleware/filesystem/filesystem.go
@@ -1,9 +1,10 @@
 package filesystem
 
 import (
+	"errors"
 	"fmt"
+	"io/fs"
 	"net/http"
-	"os"
 	"strconv"
 	"strings"
 	"sync"
@@ -143,11 +144,11 @@ func New(config ...Config) fiber.Handler {
 			path = utils.TrimRight(path, '/')
 		}
 		file, err := cfg.Root.Open(path)
-		if err != nil && os.IsNotExist(err) && cfg.NotFoundFile != "" {
+		if err != nil && errors.Is(err, fs.ErrNotExist) && cfg.NotFoundFile != "" {
 			file, err = cfg.Root.Open(cfg.NotFoundFile)
 		}
 		if err != nil {
-			if os.IsNotExist(err) {
+			if errors.Is(err, fs.ErrNotExist) {
 				return c.Status(fiber.StatusNotFound).Next()
 			}
 			return fmt.Errorf("failed to open: %w", err)
@@ -217,10 +218,10 @@ func New(config ...Config) fiber.Handler {
 }
 
 // SendFile ...
-func SendFile(c *fiber.Ctx, fs http.FileSystem, path string) error {
-	file, err := fs.Open(path)
+func SendFile(c *fiber.Ctx, filesystem http.FileSystem, path string) error {
+	file, err := filesystem.Open(path)
 	if err != nil {
-		if os.IsNotExist(err) {
+		if errors.Is(err, fs.ErrNotExist) {
 			return fiber.ErrNotFound
 		}
 		return fmt.Errorf("failed to open: %w", err)
@@ -234,7 +235,7 @@ func SendFile(c *fiber.Ctx, fs http.FileSystem, path string) error {
 	// Serve index if path is directory
 	if stat.IsDir() {
 		indexPath := utils.TrimRight(path, '/') + ConfigDefault.Index
-		index, err := fs.Open(indexPath)
+		index, err := filesystem.Open(indexPath)
 		if err == nil {
 			indexStat, err := index.Stat()
 			if err == nil {