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 <[email protected]>

Author: elezar

cmd/nvidia-ctk/system/print-ldcache/print-ldcache.go

@@ -18,11 +18,12 @@ package createdevicenodes
 
 import (
 	"fmt"
+	"strings"
 
 	"github.com/urfave/cli/v2"
 
-	"github.com/NVIDIA/nvidia-container-toolkit/internal/ldcache"
 	"github.com/NVIDIA/nvidia-container-toolkit/internal/logger"
+	"github.com/NVIDIA/nvidia-container-toolkit/internal/lookup"
 )
 
 type command struct {
@@ -74,27 +75,24 @@ func (m command) validateFlags(r *cli.Context, opts *options) error {
 }
 
 func (m command) run(c *cli.Context, opts *options) error {
-	cache, err := ldcache.New(m.logger, opts.driverRoot)
-	if err != nil {
-		return fmt.Errorf("failed to create ldcache: %v", err)
-	}
+	l := lookup.NewLdcacheLocator(
+		lookup.WithLogger(m.logger),
+		lookup.WithRoot(opts.driverRoot),
+	)
 
-	lib32, lib64 := cache.List()
+	libs64, _ := l.Locate("*")
 
-	if len(lib32) == 0 {
-		m.logger.Info("No 32-bit libraries found")
-	} else {
-		m.logger.Infof("%d 32-bit libraries found", len(lib32))
-		for _, lib := range lib32 {
-			m.logger.Infof("%v", lib)
-		}
-	}
-	if len(lib64) == 0 {
+	if len(libs64) == 0 {
 		m.logger.Info("No 64-bit libraries found")
 	} else {
-		m.logger.Infof("%d 64-bit libraries found", len(lib64))
-		for _, lib := range lib64 {
-			m.logger.Infof("%v", lib)
+		chain := lookup.NewSymlinkChainLocator()
+		m.logger.Infof("%d 64-bit libraries found", len(libs64))
+		for _, lib := range libs64 {
+			links, err := chain.Locate(lib)
+			if err != nil {
+				m.logger.Errorf("falied to locate %s: %v", lib, err)
+			}
+			fmt.Println(strings.Join(append([]string{lib}, links[1:]...), " => "))
 		}
 	}
 

internal/ldcache/ldcache.go

@@ -105,14 +105,7 @@ 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()
@@ -248,7 +241,20 @@ func (c *ldcache) getEntries(selected func(string) bool) []entry {
 func (c *ldcache) List() ([]string, []string) {
 	all := func(s string) bool { return true }
 
-	return c.resolveSelected(all)
+	paths := make(map[int][]string)
+	processed := make(map[string]bool)
+
+	entries := c.getEntries(all)
+	for _, e := range entries {
+		path := filepath.Join(c.root, e.value)
+		if processed[path] {
+			continue
+		}
+		paths[e.bits] = append(paths[e.bits], path)
+		processed[path] = true
+	}
+
+	return paths[32], paths[64]
 }
 
 // Lookup searches the ldcache for the specified prefixes.
@@ -275,7 +281,8 @@ func (c *ldcache) resolveSelected(selected func(string) bool) ([]string, []strin
 	paths := make(map[int][]string)
 	processed := make(map[string]bool)
 
-	for _, e := range c.getEntries(selected) {
+	entries := c.getEntries(selected)
+	for _, e := range entries {
 		path, err := c.resolve(e.value)
 		if err != nil {
 			c.logger.Debugf("Could not resolve entry: %v", err)

internal/lookup/library-ldcache.go

@@ -1,63 +1,98 @@
-/**
-# 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"
 	"github.com/NVIDIA/nvidia-container-toolkit/internal/logger"
 )
 
 type ldcacheLocator struct {
-	logger logger.Interface
-	cache  ldcache.LDCache
+	logger     logger.Interface
+	resolvesTo map[string]string
 }
 
 var _ Locator = (*ldcacheLocator)(nil)
 
-func newLdcacheLocator(opts ...Option) Locator {
+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
+		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{
-		logger: b.logger,
-		cache:  cache,
+		logger:     b.logger,
+		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) {
-	paths32, paths64 := l.cache.Lookup(libname)
-	if len(paths32) > 0 {
-		l.logger.Warningf("Ignoring 32-bit libraries for %v: %v", libname, paths32)
+	var matcher func(string, string) bool
+
+	if filepath.IsAbs(libname) {
+		matcher = func(p string, c string) bool {
+			m, _ := filepath.Match(p, c)
+			return m
+		}
+	} else {
+		matcher = func(p string, c string) bool {
+			m, _ := filepath.Match(p, filepath.Base(c))
+			return m
+		}
 	}
 
-	if len(paths64) == 0 {
-		return nil, fmt.Errorf("64-bit library %v: %w", libname, ErrNotFound)
+	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)
 	}
 
-	return paths64, nil
+	slices.Sort(matches)
+
+	return matches, nil
 }

internal/lookup/library-ldcache_test.go

@@ -43,7 +43,7 @@ func TestLDCacheLookup(t *testing.T) {
 		for _, input := range tc.inputs {
 			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

@@ -49,7 +49,7 @@ func NewLibraryLocator(opts ...Option) Locator {
 
 	l := First(
 		symlinkLocator,
-		newLdcacheLocator(opts...),
+		NewLdcacheLocator(opts...),
 	)
 	return l
 }