Add processor package with path normalization and deduplication

pkg/processor/normalize.go

@@ -0,0 +1,93 @@
+package processor
+
+import (
+	"fmt"
+	"os"
+	"path/filepath"
+	"strings"
+)
+
+// NormalizePath normalizes a file path by:
+// - Resolving . and .. components
+// - Converting relative paths to absolute using the provided working directory
+// - Preserving symlinks (not following them)
+//
+// The pid parameter is used to look up the process's working directory
+// via /proc/<pid>/cwd when the path is relative and cwd is empty.
+func NormalizePath(path string, pid uint32, cwd string) string {
+	if path == "" {
+		return ""
+	}
+
+	// Handle absolute paths: just clean them
+	if filepath.IsAbs(path) {
+		return cleanPath(path)
+	}
+
+	// For relative paths, we need a working directory
+	workDir := cwd
+	if workDir == "" && pid > 0 {
+		// Try to read the process's cwd from /proc
+		workDir = getProcessCwd(pid)
+	}
+	if workDir == "" {
+		// Fallback: return cleaned relative path prefixed with /
+		// This is a best-effort when we can't determine the cwd
+		return "/" + cleanPath(path)
+	}
+
+	// Join with working directory and clean
+	return cleanPath(filepath.Join(workDir, path))
+}
+
+// cleanPath removes . and .. components without following symlinks.
+// Unlike filepath.Clean, this preserves trailing slashes and handles
+// edge cases more carefully for our use case.
+func cleanPath(path string) string {
+	if path == "" {
+		return ""
+	}
+
+	// filepath.Clean handles ., .., and multiple slashes
+	cleaned := filepath.Clean(path)
+
+	// Ensure absolute paths start with /
+	if !strings.HasPrefix(cleaned, "/") && strings.HasPrefix(path, "/") {
+		cleaned = "/" + cleaned
+	}
+
+	return cleaned
+}
+
+// getProcessCwd reads the working directory of a process from /proc.
+// Returns empty string if the process doesn't exist or cwd can't be read.
+func getProcessCwd(pid uint32) string {
+	// Read the symlink target of /proc/<pid>/cwd
+	cwdPath := fmt.Sprintf("/proc/%d/cwd", pid)
+	cwd, err := os.Readlink(cwdPath)
+	if err != nil {
+		return ""
+	}
+	return cwd
+}
+
+// IsExcluded checks if a path should be excluded based on the provided prefixes.
+// Paths starting with any prefix in the exclusion list are excluded.
+func IsExcluded(path string, excludePrefixes []string) bool {
+	for _, prefix := range excludePrefixes {
+		if strings.HasPrefix(path, prefix) {
+			return true
+		}
+	}
+	return false
+}
+
+// DefaultExclusions returns the default path prefixes to exclude from tracing.
+// These are system paths that are not relevant for image slimming.
+func DefaultExclusions() []string {
+	return []string{
+		"/proc/",
+		"/sys/",
+		"/dev/",
+	}
+}