From d7c32db93de62bade0339dd311ff71f61e339beb Mon Sep 17 00:00:00 2001
From: Cole Faust <colefaust@google.com>
Date: Mon, 5 Feb 2024 14:51:11 -0800
Subject: [PATCH] Enforce that soong config variables are identifiers

I want to be able to use certain characters to separate a namespace
from a variable, but currently it's possible for soong config namespaces
and variables to have any character in them.

Restrict them to just identifiers, which should cover all of our
existing usages.

Bug: 323382414
Test: Presubmits
Change-Id: I6d55dd3378ac4d257efde450189b81a4aa3932c3
---
 android/config.go | 27 +++++++++++++++++++++++++++
 1 file changed, 27 insertions(+)

diff --git a/android/config.go b/android/config.go
index d94a86f71..f2dedad0b 100644
--- a/android/config.go
+++ b/android/config.go
@@ -28,6 +28,7 @@ import (
 	"strconv"
 	"strings"
 	"sync"
+	"unicode"
 
 	"github.com/google/blueprint"
 	"github.com/google/blueprint/bootstrap"
@@ -320,6 +321,18 @@ func loadConfig(config *config) error {
 	return loadFromConfigFile(&config.productVariables, absolutePath(config.ProductVariablesFileName))
 }
 
+// Checks if the string is a valid go identifier. This is equivalent to blueprint's definition
+// of an identifier, so it will match the same identifiers as those that can be used in bp files.
+func isGoIdentifier(ident string) bool {
+	for i, r := range ident {
+		valid := r == '_' || unicode.IsLetter(r) || unicode.IsDigit(r) && i > 0
+		if !valid {
+			return false
+		}
+	}
+	return len(ident) > 0
+}
+
 // loadFromConfigFile loads and decodes configuration options from a JSON file
 // in the current working directory.
 func loadFromConfigFile(configurable *ProductVariables, filename string) error {
@@ -355,6 +368,20 @@ func loadFromConfigFile(configurable *ProductVariables, filename string) error {
 		Bool(configurable.GcovCoverage) ||
 			Bool(configurable.ClangCoverage))
 
+	// The go scanner's definition of identifiers is c-style identifiers, but allowing unicode's
+	// definition of letters and digits. This is the same scanner that blueprint uses, so it
+	// will allow the same identifiers as are valid in bp files.
+	for namespace := range configurable.VendorVars {
+		if !isGoIdentifier(namespace) {
+			return fmt.Errorf("soong config namespaces must be valid identifiers: %q", namespace)
+		}
+		for variable := range configurable.VendorVars[namespace] {
+			if !isGoIdentifier(variable) {
+				return fmt.Errorf("soong config variables must be valid identifiers: %q", variable)
+			}
+		}
+	}
+
 	// when Platform_sdk_final is true (or PLATFORM_VERSION_CODENAME is REL), use Platform_sdk_version;
 	// if false (pre-released version, for example), use Platform_sdk_codename.
 	if Bool(configurable.Platform_sdk_final) {