Create individual links instead of processing CSV

This change switches to generating a OCI runtime hook to create
individual symlinks instead of processing a CSV file in the hook.
This allows for better reuse of the logic generating CDI
specifications, for example.

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

internal/discover/symlinks.go

@@ -21,12 +21,16 @@ import (
 	"path/filepath"
 	"strings"
 
+	"github.com/NVIDIA/nvidia-container-toolkit/internal/discover/csv"
+	"github.com/NVIDIA/nvidia-container-toolkit/internal/lookup"
+	"github.com/NVIDIA/nvidia-container-toolkit/internal/lookup/symlinks"
 	"github.com/sirupsen/logrus"
 )
 
-type symlinks struct {
+type symlinkHook struct {
 	None
 	logger        *logrus.Logger
+	driverRoot    string
 	nvidiaCTKPath string
 	csvFiles      []string
 	mountsFrom    Discover
@@ -34,7 +38,7 @@ type symlinks struct {
 
 // NewCreateSymlinksHook creates a discoverer for a hook that creates required symlinks in the container
 func NewCreateSymlinksHook(logger *logrus.Logger, csvFiles []string, mounts Discover, nvidiaCTKPath string) (Discover, error) {
-	d := symlinks{
+	d := symlinkHook{
 		logger:        logger,
 		nvidiaCTKPath: nvidiaCTKPath,
 		csvFiles:      csvFiles,
@@ -45,17 +49,17 @@ func NewCreateSymlinksHook(logger *logrus.Logger, csvFiles []string, mounts Disc
 }
 
 // Hooks returns a hook to create the symlinks from the required CSV files
-func (d symlinks) Hooks() ([]Hook, error) {
-	var args []string
-	for _, f := range d.csvFiles {
-		args = append(args, "--csv-filename", f)
-	}
-
-	links, err := d.getSpecificLinkArgs()
+func (d symlinkHook) Hooks() ([]Hook, error) {
+	specificLinks, err := d.getSpecificLinks()
 	if err != nil {
 		return nil, fmt.Errorf("failed to determine specific links: %v", err)
 	}
-	args = append(args, links...)
+
+	csvSymlinks := d.getCSVFileSymlinks()
+	var args []string
+	for _, link := range append(csvSymlinks, specificLinks...) {
+		args = append(args, "--link", link)
+	}
 
 	hook := CreateNvidiaCTKHook(
 		d.nvidiaCTKPath,
@@ -66,8 +70,8 @@ func (d symlinks) Hooks() ([]Hook, error) {
 	return []Hook{hook}, nil
 }
 
-// getSpecificLinkArgs returns the required specic links that need to be created
-func (d symlinks) getSpecificLinkArgs() ([]string, error) {
+// getSpecificLinks returns the required specic links that need to be created
+func (d symlinkHook) getSpecificLinks() ([]string, error) {
 	mounts, err := d.mountsFrom.Mounts()
 	if err != nil {
 		return nil, fmt.Errorf("failed to discover mounts for ldcache update: %v", err)
@@ -99,11 +103,60 @@ func (d symlinks) getSpecificLinkArgs() ([]string, error) {
 		if linkProcessed[link] {
 			continue
 		}
+		linkProcessed[link] = true
 
 		linkPath := filepath.Join(filepath.Dir(m.Path), link)
-		links = append(links, "--link", fmt.Sprintf("%v::%v", target, linkPath))
-		linkProcessed[link] = true
+		links = append(links, fmt.Sprintf("%v::%v", target, linkPath))
 	}
 
 	return links, nil
 }
+
+func (d symlinkHook) getCSVFileSymlinks() []string {
+	chainLocator := lookup.NewSymlinkChainLocator(d.logger, d.driverRoot)
+
+	var candidates []string
+	for _, file := range d.csvFiles {
+		mountSpecs, err := csv.NewCSVFileParser(d.logger, file).Parse()
+		if err != nil {
+			d.logger.Debugf("Skipping CSV file %v: %v", file, err)
+			continue
+		}
+
+		for _, ms := range mountSpecs {
+			if ms.Type != csv.MountSpecSym {
+				continue
+			}
+			targets, err := chainLocator.Locate(ms.Path)
+			if err != nil {
+				d.logger.Warnf("Failed to locate symlink %v", ms.Path)
+			}
+			candidates = append(candidates, targets...)
+		}
+	}
+
+	var links []string
+	created := make(map[string]bool)
+	// candidates is a list of absolute paths to symlinks in a chain, or the final target of the chain.
+	for _, candidate := range candidates {
+		target, err := symlinks.Resolve(candidate)
+		if err != nil {
+			d.logger.Debugf("Skipping invalid link: %v", err)
+			continue
+		} else if target == candidate {
+			d.logger.Debugf("%v is not a symlink", candidate)
+			continue
+		}
+
+		link := fmt.Sprintf("%v::%v", target, candidate)
+		if created[link] {
+			d.logger.Debugf("skipping duplicate link: %v", link)
+			continue
+		}
+		created[link] = true
+
+		links = append(links, link)
+	}
+
+	return links
+}