For #21084: add Config.getGitHash.

buildSrc/src/main/java/Config.kt

@@ -1,14 +1,14 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
 import org.gradle.api.Project
+import org.mozilla.fenix.gradle.ext.execReadStandardOutOrThrow
 import java.text.SimpleDateFormat
 import java.time.LocalDateTime
-import java.time.format.DateTimeFormatter
 import java.util.Date
 import java.util.Locale
 
-/* This Source Code Form is subject to the terms of the Mozilla Public
- * License, v. 2.0. If a copy of the MPL was not distributed with this
- * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
-
 object Config {
     // Synchronized build configuration for all modules
     const val compileSdkVersion = 31
@@ -147,4 +147,22 @@ object Config {
 
         return version
     }
+
+    /**
+     * Returns the git hash of the currently checked out revision. If there are uncommitted changes,
+     * a "+" will be appended to the hash, e.g. "c8ba05ad0+".
+     */
+    @JvmStatic
+    fun getGitHash(): String {
+        val revisionCmd = arrayOf("git", "rev-parse", "--short", "HEAD")
+        val revision = Runtime.getRuntime().execReadStandardOutOrThrow(revisionCmd)
+
+        // Append "+" if there are uncommitted changes in the working directory.
+        val statusCmd = arrayOf("git", "status", "--porcelain=v2")
+        val status = Runtime.getRuntime().execReadStandardOutOrThrow(statusCmd)
+        val hasUnstagedChanges = status.isNotBlank()
+        val statusSuffix = if (hasUnstagedChanges) "+" else ""
+
+        return "${revision}${statusSuffix}"
+    }
 }