Read ldcache at construction instead of on each locate call

This change udpates the ldcache locator to read the ldcache at construction
and use these contents to perform future lookups against. Each of the cache
entries are resolved and lookups return the resolved target.

Assuming a symlink chain: libcuda.so -> libcuda.so.1 -> libcuda.so.VERSION, this
means that libcuda.so.VERION will be returned for any of the following inputs:
libcuda.so, libcuda.so.1, libcudal.so.*.

Signed-off-by: Evan Lezar <elezar@nvidia.com>

internal/ldcache/ldcache.go

@@ -22,15 +22,12 @@ import (
 	"bytes"
 	"encoding/binary"
 	"errors"
-	"fmt"
 	"os"
 	"path/filepath"
-	"strings"
 	"syscall"
 	"unsafe"
 
 	"github.com/NVIDIA/nvidia-container-toolkit/internal/logger"
-	"github.com/NVIDIA/nvidia-container-toolkit/internal/lookup/symlinks"
 )
 
 const ldcachePath = "/etc/ld.so.cache"
@@ -82,10 +79,9 @@ type entry2 struct {
 
 // LDCache represents the interface for performing lookups into the LDCache
 //
-//go:generate moq -out ldcache_mock.go . LDCache
+//go:generate moq -rm -out ldcache_mock.go . LDCache
 type LDCache interface {
 	List() ([]string, []string)
-	Lookup(...string) ([]string, []string)
 }
 
 type ldcache struct {
@@ -105,14 +101,7 @@ func New(logger logger.Interface, root string) (LDCache, error) {
 
 	logger.Debugf("Opening ld.conf at %v", path)
 	f, err := os.Open(path)
-	if os.IsNotExist(err) {
-		logger.Warningf("Could not find ld.so.cache at %v; creating empty cache", path)
-		e := &empty{
-			logger: logger,
-			path:   path,
-		}
-		return e, nil
-	} else if err != nil {
+	if err != nil {
 		return nil, err
 	}
 	defer f.Close()
@@ -196,7 +185,7 @@ type entry struct {
 }
 
 // getEntries returns the entires of the ldcache in a go-friendly struct.
-func (c *ldcache) getEntries(selected func(string) bool) []entry {
+func (c *ldcache) getEntries() []entry {
 	var entries []entry
 	for _, e := range c.entries {
 		bits := 0
@@ -223,9 +212,6 @@ func (c *ldcache) getEntries(selected func(string) bool) []entry {
 			c.logger.Debugf("Skipping invalid lib")
 			continue
 		}
-		if !selected(lib) {
-			continue
-		}
 		value := bytesToString(c.libs[e.Value:])
 		if value == "" {
 			c.logger.Debugf("Skipping invalid value for lib %v", lib)
@@ -236,51 +222,19 @@ func (c *ldcache) getEntries(selected func(string) bool) []entry {
 			bits:    bits,
 			value:   value,
 		}
-
 		entries = append(entries, e)
 	}
-
 	return entries
 }
 
 // List creates a list of libraries in the ldcache.
 // The 32-bit and 64-bit libraries are returned separately.
 func (c *ldcache) List() ([]string, []string) {
-	all := func(s string) bool { return true }
-
-	return c.resolveSelected(all)
-}
-
-// Lookup searches the ldcache for the specified prefixes.
-// The 32-bit and 64-bit libraries matching the prefixes are returned.
-func (c *ldcache) Lookup(libPrefixes ...string) ([]string, []string) {
-	c.logger.Debugf("Looking up %v in cache", libPrefixes)
-
-	// We define a functor to check whether a given library name matches any of the prefixes
-	matchesAnyPrefix := func(s string) bool {
-		for _, p := range libPrefixes {
-			if strings.HasPrefix(s, p) {
-				return true
-			}
-		}
-		return false
-	}
-
-	return c.resolveSelected(matchesAnyPrefix)
-}
-
-// resolveSelected process the entries in the LDCach based on the supplied filter and returns the resolved paths.
-// The paths are separated by bittage.
-func (c *ldcache) resolveSelected(selected func(string) bool) ([]string, []string) {
 	paths := make(map[int][]string)
 	processed := make(map[string]bool)
 
-	for _, e := range c.getEntries(selected) {
-		path, err := c.resolve(e.value)
-		if err != nil {
-			c.logger.Debugf("Could not resolve entry: %v", err)
-			continue
-		}
+	for _, e := range c.getEntries() {
+		path := filepath.Join(c.root, e.value)
 		if processed[path] {
 			continue
 		}
@@ -291,29 +245,6 @@ func (c *ldcache) resolveSelected(selected func(string) bool) ([]string, []strin
 	return paths[32], paths[64]
 }
 
-// resolve resolves the specified ldcache entry based on the value being processed.
-// The input is the name of the entry in the cache.
-func (c *ldcache) resolve(target string) (string, error) {
-	name := filepath.Join(c.root, target)
-
-	c.logger.Debugf("checking %v", name)
-
-	link, err := symlinks.Resolve(name)
-	if err != nil {
-		return "", fmt.Errorf("failed to resolve symlink: %v", err)
-	}
-	if link == name {
-		return name, nil
-	}
-
-	// We return absolute paths for all targets
-	if !filepath.IsAbs(link) || strings.HasPrefix(link, ".") {
-		link = filepath.Join(filepath.Dir(target), link)
-	}
-
-	return c.resolve(link)
-}
-
 // bytesToString converts a byte slice to a string.
 // This assumes that the byte slice is null-terminated
 func bytesToString(value []byte) string {

internal/ldcache/ldcache_mock.go

@@ -20,9 +20,6 @@ var _ LDCache = &LDCacheMock{}
 //			ListFunc: func() ([]string, []string) {
 //				panic("mock out the List method")
 //			},
-//			LookupFunc: func(strings ...string) ([]string, []string) {
-//				panic("mock out the Lookup method")
-//			},
 //		}
 //
 //		// use mockedLDCache in code that requires LDCache
@@ -33,22 +30,13 @@ type LDCacheMock struct {
 	// ListFunc mocks the List method.
 	ListFunc func() ([]string, []string)
 
-	// LookupFunc mocks the Lookup method.
-	LookupFunc func(strings ...string) ([]string, []string)
-
 	// calls tracks calls to the methods.
 	calls struct {
 		// List holds details about calls to the List method.
 		List []struct {
 		}
-		// Lookup holds details about calls to the Lookup method.
-		Lookup []struct {
-			// Strings is the strings argument value.
-			Strings []string
-		}
 	}
 	lockList sync.RWMutex
-	lockLookup sync.RWMutex
 }
 
 // List calls ListFunc.
@@ -77,35 +65,3 @@ func (mock *LDCacheMock) ListCalls() []struct {
 	mock.lockList.RUnlock()
 	return calls
 }
-
-// Lookup calls LookupFunc.
-func (mock *LDCacheMock) Lookup(strings ...string) ([]string, []string) {
-	if mock.LookupFunc == nil {
-		panic("LDCacheMock.LookupFunc: method is nil but LDCache.Lookup was just called")
-	}
-	callInfo := struct {
-		Strings []string
-	}{
-		Strings: strings,
-	}
-	mock.lockLookup.Lock()
-	mock.calls.Lookup = append(mock.calls.Lookup, callInfo)
-	mock.lockLookup.Unlock()
-	return mock.LookupFunc(strings...)
-}
-
-// LookupCalls gets all the calls that were made to Lookup.
-// Check the length with:
-//
-//	len(mockedLDCache.LookupCalls())
-func (mock *LDCacheMock) LookupCalls() []struct {
-	Strings []string
-} {
-	var calls []struct {
-		Strings []string
-	}
-	mock.lockLookup.RLock()
-	calls = mock.calls.Lookup
-	mock.lockLookup.RUnlock()
-	return calls
-}

internal/lookup/ldcache.go

@@ -0,0 +1,118 @@
+/**
+# Copyright 2024 NVIDIA CORPORATION
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+**/
+
+package lookup
+
+import (
+	"fmt"
+	"path/filepath"
+	"slices"
+
+	"github.com/NVIDIA/nvidia-container-toolkit/internal/ldcache"
+)
+
+type ldcacheLocator struct {
+	*builder
+	resolvesTo map[string]string
+}
+
+var _ Locator = (*ldcacheLocator)(nil)
+
+func NewLdcacheLocator(opts ...Option) Locator {
+	b := newBuilder(opts...)
+
+	cache, err := ldcache.New(b.logger, b.root)
+	if err != nil {
+		b.logger.Warningf("Failed to load ldcache: %v", err)
+		if b.isOptional {
+			return &null{}
+		}
+		return &notFound{}
+	}
+
+	chain := NewSymlinkChainLocator(WithOptional(true))
+
+	resolvesTo := make(map[string]string)
+	_, libs64 := cache.List()
+	for _, library := range libs64 {
+		if _, processed := resolvesTo[library]; processed {
+			continue
+		}
+		candidates, err := chain.Locate(library)
+		if err != nil {
+			b.logger.Errorf("error processing library %s from ldcache: %v", library, err)
+			continue
+		}
+
+		if len(candidates) == 0 {
+			resolvesTo[library] = library
+			continue
+		}
+
+		// candidates represents a symlink chain.
+		// The first element represents the start of the chain and the last
+		// element the final target.
+		target := candidates[len(candidates)-1]
+		for _, candidate := range candidates {
+			resolvesTo[candidate] = target
+		}
+	}
+
+	return &ldcacheLocator{
+		builder:    b,
+		resolvesTo: resolvesTo,
+	}
+}
+
+// Locate finds the specified libraryname.
+// If the input is a library name, the ldcache is searched otherwise the
+// provided path is resolved as a symlink.
+func (l ldcacheLocator) Locate(libname string) ([]string, error) {
+	var matcher func(string, string) bool
+
+	if filepath.IsAbs(libname) {
+		matcher = func(p string, c string) bool {
+			m, _ := filepath.Match(filepath.Join(l.root, p), c)
+			return m
+		}
+	} else {
+		matcher = func(p string, c string) bool {
+			m, _ := filepath.Match(p, filepath.Base(c))
+			return m
+		}
+	}
+
+	var matches []string
+	seen := make(map[string]bool)
+	for name, target := range l.resolvesTo {
+		if !matcher(libname, name) {
+			continue
+		}
+		if seen[target] {
+			continue
+		}
+		seen[target] = true
+		matches = append(matches, target)
+	}
+
+	slices.Sort(matches)
+
+	if len(matches) == 0 && !l.isOptional {
+		return nil, fmt.Errorf("%s: %w", libname, ErrNotFound)
+	}
+
+	return matches, nil
+}

internal/lookup/ldcache_test.go

@@ -29,21 +29,39 @@ func TestLDCacheLookup(t *testing.T) {
 		},
 		{
 			rootFs: "rootfs-1",
-			inputs:   []string{"libcuda.so.1", "libcuda.so.*", "libcuda.so.*.*", "libcuda.so.999.88.77"},
+			inputs: []string{
+				"libcuda.so.1",
+				"libcuda.so.*",
+				"libcuda.so.*.*",
+				"libcuda.so.999.88.77",
+				"/lib/x86_64-linux-gnu/libcuda.so.1",
+				"/lib/x86_64-linux-gnu/libcuda.so.*",
+				"/lib/x86_64-linux-gnu/libcuda.so.*.*",
+				"/lib/x86_64-linux-gnu/libcuda.so.999.88.77",
+			},
 			expected: "/lib/x86_64-linux-gnu/libcuda.so.999.88.77",
 		},
 		{
 			rootFs: "rootfs-2",
-			inputs:   []string{"libcuda.so.1", "libcuda.so.*", "libcuda.so.*.*", "libcuda.so.999.88.77"},
+			inputs: []string{
+				"libcuda.so.1",
+				"libcuda.so.*",
+				"libcuda.so.*.*",
+				"libcuda.so.999.88.77",
+				"/var/lib/nvidia/lib64/libcuda.so.1",
+				"/var/lib/nvidia/lib64/libcuda.so.*",
+				"/var/lib/nvidia/lib64/libcuda.so.*.*",
+				"/var/lib/nvidia/lib64/libcuda.so.999.88.77",
+			},
 			expected: "/var/lib/nvidia/lib64/libcuda.so.999.88.77",
 		},
 	}
 
 	for _, tc := range testCases {
 		for _, input := range tc.inputs {
-			t.Run(tc.rootFs+input, func(t *testing.T) {
+			t.Run(tc.rootFs+" "+input, func(t *testing.T) {
 				rootfs := filepath.Join(moduleRoot, "testdata", "lookup", tc.rootFs)
-				l := newLdcacheLocator(
+				l := NewLdcacheLocator(
 					WithLogger(logger),
 					WithRoot(rootfs),
 				)

internal/lookup/library.go

@@ -16,20 +16,6 @@
 
 package lookup
 
-import (
-	"fmt"
-
-	"github.com/NVIDIA/nvidia-container-toolkit/internal/ldcache"
-	"github.com/NVIDIA/nvidia-container-toolkit/internal/logger"
-)
-
-type ldcacheLocator struct {
-	logger logger.Interface
-	cache  ldcache.LDCache
-}
-
-var _ Locator = (*ldcacheLocator)(nil)
-
 // NewLibraryLocator creates a library locator using the specified options.
 func NewLibraryLocator(opts ...Option) Locator {
 	b := newBuilder(opts...)
@@ -63,39 +49,7 @@ func NewLibraryLocator(opts ...Option) Locator {
 
 	l := First(
 		symlinkLocator,
-		newLdcacheLocator(opts...),
+		NewLdcacheLocator(opts...),
 	)
 	return l
 }
-
-func newLdcacheLocator(opts ...Option) Locator {
-	b := newBuilder(opts...)
-
-	cache, err := ldcache.New(b.logger, b.root)
-	if err != nil {
-		// If we failed to open the LDCache, we default to a symlink locator.
-		b.logger.Warningf("Failed to load ldcache: %v", err)
-		return nil
-	}
-
-	return &ldcacheLocator{
-		logger: b.logger,
-		cache:  cache,
-	}
-}
-
-// Locate finds the specified libraryname.
-// If the input is a library name, the ldcache is searched otherwise the
-// provided path is resolved as a symlink.
-func (l ldcacheLocator) Locate(libname string) ([]string, error) {
-	paths32, paths64 := l.cache.Lookup(libname)
-	if len(paths32) > 0 {
-		l.logger.Warningf("Ignoring 32-bit libraries for %v: %v", libname, paths32)
-	}
-
-	if len(paths64) == 0 {
-		return nil, fmt.Errorf("64-bit library %v: %w", libname, ErrNotFound)
-	}
-
-	return paths64, nil
-}

internal/lookup/library_test.go

@@ -24,82 +24,8 @@ import (
 
 	testlog "github.com/sirupsen/logrus/hooks/test"
 	"github.com/stretchr/testify/require"
-
-	"github.com/NVIDIA/nvidia-container-toolkit/internal/ldcache"
 )
 
-func TestLDCacheLocator(t *testing.T) {
-	logger, _ := testlog.NewNullLogger()
-
-	testDir := t.TempDir()
-	symlinkDir := filepath.Join(testDir, "/lib/symlink")
-	require.NoError(t, os.MkdirAll(symlinkDir, 0755))
-
-	versionLib := filepath.Join(symlinkDir, "libcuda.so.1.2.3")
-	soLink := filepath.Join(symlinkDir, "libcuda.so")
-	sonameLink := filepath.Join(symlinkDir, "libcuda.so.1")
-
-	_, err := os.Create(versionLib)
-	require.NoError(t, err)
-	require.NoError(t, os.Symlink(versionLib, sonameLink))
-	require.NoError(t, os.Symlink(sonameLink, soLink))
-
-	lut := newLdcacheLocator(
-		WithLogger(logger),
-		WithRoot(testDir),
-	)
-
-	testCases := []struct {
-		description   string
-		libname       string
-		ldcacheMap    map[string]string
-		expected      []string
-		expectedError error
-	}{
-		{
-			description: "lib only resolves in LDCache",
-			libname:     "libcuda.so",
-			ldcacheMap: map[string]string{
-				"libcuda.so": "/lib/from/ldcache/libcuda.so.4.5.6",
-			},
-			expected: []string{"/lib/from/ldcache/libcuda.so.4.5.6"},
-		},
-		{
-			description:   "lib only not in LDCache returns error",
-			libname:       "libnotcuda.so",
-			expectedError: ErrNotFound,
-		},
-	}
-
-	for _, tc := range testCases {
-		t.Run(tc.description, func(t *testing.T) {
-			// We override the LDCache with a mock implementation
-			l := lut.(*ldcacheLocator)
-			l.cache = &ldcache.LDCacheMock{
-				LookupFunc: func(strings ...string) ([]string, []string) {
-					var result []string
-					for _, s := range strings {
-						if v, ok := tc.ldcacheMap[s]; ok {
-							result = append(result, v)
-						}
-					}
-					return nil, result
-				},
-			}
-
-			candidates, err := lut.Locate(tc.libname)
-			require.ErrorIs(t, err, tc.expectedError)
-
-			var cleanedCandidates []string
-			for _, c := range candidates {
-				// On MacOS /var and /tmp symlink to /private/var and /private/tmp which is included in the resolved path.
-				cleanedCandidates = append(cleanedCandidates, strings.TrimPrefix(c, "/private"))
-			}
-			require.EqualValues(t, tc.expected, cleanedCandidates)
-		})
-	}
-}
-
 func TestLibraryLocator(t *testing.T) {
 	logger, _ := testlog.NewNullLogger()
 

internal/lookup/null.go

@@ -1,5 +1,5 @@
 /**
-# Copyright (c) NVIDIA CORPORATION.  All rights reserved.
+# Copyright 2024 NVIDIA CORPORATION
 #
 # Licensed under the Apache License, Version 2.0 (the "License");
 # you may not use this file except in compliance with the License.
@@ -14,24 +14,23 @@
 # limitations under the License.
 **/
 
-package ldcache
+package lookup
 
-import "github.com/NVIDIA/nvidia-container-toolkit/internal/logger"
+import "fmt"
 
-type empty struct {
-	logger logger.Interface
-	path   string
+// A null locator always returns an empty response.
+type null struct {
 }
 
-var _ LDCache = (*empty)(nil)
-
-// List always returns nil for an empty ldcache
-func (e *empty) List() ([]string, []string) {
+// Locate always returns empty for a null locator.
+func (l *null) Locate(string) ([]string, error) {
 	return nil, nil
 }
 
-// Lookup logs a debug message and returns nil for an empty ldcache
-func (e *empty) Lookup(prefixes ...string) ([]string, []string) {
-	e.logger.Debugf("Calling Lookup(%v) on empty ldcache: %v", prefixes, e.path)
-	return nil, nil
+// A notFound locator always returns an ErrNotFound error.
+type notFound struct {
+}
+
+func (l *notFound) Locate(s string) ([]string, error) {
+	return nil, fmt.Errorf("%s: %w", s, ErrNotFound)
 }