Merge pull request containerd#4240 from apostasie/2025-05-fs

internal/filesystem: finish moving os.WriteFile and os.ReadFile (and blacklist future use)

Author: AkihiroSuda

.golangci.yml

@@ -48,6 +48,9 @@ linters:
         - pattern: ^os\.WriteFile.*$
           pkg: github.com/containerd/nerdctl/v2/pkg
           msg: os.WriteFile is neither atomic nor durable - use nerdctl filesystem.WriteFile instead
+        - pattern: ^os\.ReadFile.*$
+          pkg: github.com/containerd/nerdctl/v2/pkg
+          msg: use filesystem.ReadFile instead of os.ReadFile
     staticcheck:
       checks:
         # Below is the default set

pkg/apparmorutil/apparmorutil_linux.go

@@ -26,6 +26,8 @@ import (
 	"github.com/moby/sys/userns"
 
 	"github.com/containerd/log"
+
+	"github.com/containerd/nerdctl/v2/pkg/internal/filesystem"
 )
 
 var (
@@ -55,7 +57,7 @@ func hostSupports() bool {
 			return
 		}
 		var buf []byte
-		buf, err = os.ReadFile("/sys/module/apparmor/parameters/enabled")
+		buf, err = filesystem.ReadFile("/sys/module/apparmor/parameters/enabled")
 		appArmorSupported = err == nil && len(buf) == 2 && string(buf) == "Y\n"
 	})
 	return appArmorSupported
@@ -88,7 +90,7 @@ var (
 // Related: https://gitlab.com/apparmor/apparmor/-/blob/v3.0.3/libraries/libapparmor/src/kernel.c#L311
 func CanApplyExistingProfile() bool {
 	paramEnabledOnce.Do(func() {
-		buf, err := os.ReadFile("/sys/module/apparmor/parameters/enabled")
+		buf, err := filesystem.ReadFile("/sys/module/apparmor/parameters/enabled")
 		paramEnabled = err == nil && len(buf) == 2 && string(buf) == "Y\n"
 	})
 	return paramEnabled
@@ -132,7 +134,7 @@ func Profiles() ([]Profile, error) {
 	res := make([]Profile, len(ents))
 	for i, ent := range ents {
 		namePath := filepath.Join(profilesPath, ent.Name(), "name")
-		b, err := os.ReadFile(namePath)
+		b, err := filesystem.ReadFile(namePath)
 		if err != nil {
 			log.L.WithError(err).Warnf("failed to read %q", namePath)
 			continue

pkg/buildkitutil/buildkitutil.go

@@ -39,6 +39,7 @@ import (
 
 	"github.com/containerd/log"
 
+	"github.com/containerd/nerdctl/v2/pkg/internal/filesystem"
 	"github.com/containerd/nerdctl/v2/pkg/rootlessutil"
 )
 
@@ -196,11 +197,11 @@ func BuildKitFile(dir, inputfile string) (absDir string, file string, err error)
 		_, cErr := os.Lstat(filepath.Join(absDir, ContainerfileName))
 		if dErr == nil && cErr == nil {
 			// both files exist, prefer Dockerfile.
-			dockerfile, err := os.ReadFile(filepath.Join(absDir, DefaultDockerfileName))
+			dockerfile, err := filesystem.ReadFile(filepath.Join(absDir, DefaultDockerfileName))
 			if err != nil {
 				return "", "", err
 			}
-			containerfile, err := os.ReadFile(filepath.Join(absDir, ContainerfileName))
+			containerfile, err := filesystem.ReadFile(filepath.Join(absDir, ContainerfileName))
 			if err != nil {
 				return "", "", err
 			}

pkg/cmd/builder/build.go

@@ -467,7 +467,7 @@ func generateBuildctlArgs(ctx context.Context, client *containerd.Client, option
 }
 
 func getDigestFromMetaFile(path string) (string, error) {
-	data, err := os.ReadFile(path)
+	data, err := filesystem.ReadFile(path)
 	if err != nil {
 		return "", err
 	}

pkg/composer/create.go

@@ -29,6 +29,7 @@ import (
 	"github.com/containerd/log"
 
 	"github.com/containerd/nerdctl/v2/pkg/composer/serviceparser"
+	"github.com/containerd/nerdctl/v2/pkg/internal/filesystem"
 	"github.com/containerd/nerdctl/v2/pkg/labels"
 )
 
@@ -208,7 +209,7 @@ func (c *Composer) createServiceContainer(ctx context.Context, service *servicep
 		return "", fmt.Errorf("error while creating container %s: %w", container.Name, err)
 	}
 
-	cid, err := os.ReadFile(cidFilename)
+	cid, err := filesystem.ReadFile(cidFilename)
 	if err != nil {
 		return "", fmt.Errorf("error while creating container %s: %w", container.Name, err)
 	}

pkg/composer/up_service.go

@@ -31,6 +31,7 @@ import (
 	"github.com/containerd/log"
 
 	"github.com/containerd/nerdctl/v2/pkg/composer/serviceparser"
+	"github.com/containerd/nerdctl/v2/pkg/internal/filesystem"
 	"github.com/containerd/nerdctl/v2/pkg/labels"
 )
 
@@ -198,7 +199,7 @@ func (c *Composer) upServiceContainer(ctx context.Context, service *serviceparse
 		return "", fmt.Errorf("error while creating container %s: %w", container.Name, err)
 	}
 
-	cid, err := os.ReadFile(cidFilename)
+	cid, err := filesystem.ReadFile(cidFilename)
 	if err != nil {
 		return "", fmt.Errorf("error while creating container %s: %w", container.Name, err)
 	}

pkg/containerutil/container_network_manager.go

@@ -686,7 +686,7 @@ func (m *hostNetworkManager) ContainerNetworkingOpts(_ context.Context, containe
 		return nil, nil, err
 	}
 
-	content, err := os.ReadFile("/etc/hosts")
+	content, err := filesystem.ReadFile("/etc/hosts")
 	if err != nil {
 		return nil, nil, err
 	}

pkg/dnsutil/hostsstore/hostsstore.go

@@ -352,14 +352,7 @@ func (x *hostsStore) updateAllHosts() (err error) {
 			return err
 		}
 
-		// Because the file is mounted, we cannot do atomic writes here as that would change inode.
-		// The practical implications of this are that a partial / interrupted write would leave the hosts file with
-		// an invalid entry and/or missing entries. At worse, this would lead to a container losing localhost network
-		// capabilities.
-		// Proper consistency requires that we would have a rollback mechanism in case of recoverable failure,
-		// and a disaster management / cleanup mechanism, presumably at the top-level of the operation.
-		// nolint:forbidigo
-		err = os.WriteFile(loc, buf.Bytes(), 0o644)
+		err = filesystem.WriteFile(loc, buf.Bytes(), 0o644)
 		if err != nil {
 			log.L.WithError(err).Errorf("failed to write hosts file for %q", entry)
 		}

pkg/logging/logging.go

@@ -142,7 +142,7 @@ func LoadLogConfig(dataStore, ns, id string) (LogConfig, error) {
 	logConfig := LogConfig{}
 
 	logConfigFilePath := LogConfigFilePath(dataStore, ns, id)
-	logConfigData, err := os.ReadFile(logConfigFilePath)
+	logConfigData, err := filesystem.ReadFile(logConfigFilePath)
 	if err != nil {
 		return logConfig, fmt.Errorf("failed to read log config file %q: %w", logConfigFilePath, err)
 	}

pkg/netutil/netutil.go

@@ -37,6 +37,7 @@ import (
 	"github.com/containerd/log"
 
 	"github.com/containerd/nerdctl/v2/pkg/api/types"
+	"github.com/containerd/nerdctl/v2/pkg/internal/filesystem"
 	"github.com/containerd/nerdctl/v2/pkg/labels"
 	"github.com/containerd/nerdctl/v2/pkg/netutil/nettype"
 	subnetutil "github.com/containerd/nerdctl/v2/pkg/netutil/subnet"
@@ -481,7 +482,7 @@ func cniLoad(fileNames []string) (configList []*NetworkConfig, err error) {
 
 	for _, fileName = range fileNames {
 		var bytes []byte
-		bytes, err = os.ReadFile(fileName)
+		bytes, err = filesystem.ReadFile(fileName)
 		if err != nil {
 			return nil, fmt.Errorf("error reading %s: %w", fileName, err)
 		}