Truncate (but keep unique-ish) the names of very long file declarations

smowton · igfoo · commit 1b91a35df03c · 2022-05-10T19:51:23.000+01:00
diff --git a/java/kotlin-extractor/src/main/kotlin/KotlinUsesExtractor.kt b/java/kotlin-extractor/src/main/kotlin/KotlinUsesExtractor.kt
@@ -2,6 +2,7 @@ package com.github.codeql
 
 import com.github.codeql.utils.*
 import com.semmle.extractor.java.OdasaOutput
+import com.semmle.util.data.StringDigestor
 import org.jetbrains.kotlin.backend.common.extensions.IrPluginContext
 import org.jetbrains.kotlin.backend.common.lower.parentsWithSelf
 import org.jetbrains.kotlin.backend.jvm.codegen.isRawType
@@ -257,7 +258,12 @@ open class KotlinUsesExtractor(
             }
 
             val paramTypes = parameters.map { useType(erase(it.type)) }
-            val signature = paramTypes.joinToString(separator = ",", prefix = "(", postfix = ")") { it.javaResult.signature!! }
+            val possiblyLongSignature = paramTypes.joinToString(separator = ",", prefix = "(", postfix = ")") { it.javaResult.signature!! }
+            // In order to avoid excessively long signatures which can lead to trap file names longer than the filesystem
+            // limit, we truncate and add a hash to preserve uniqueness if necessary.
+            val signature = if (possiblyLongSignature.length > 100) {
+                possiblyLongSignature.substring(0, 42) + "#" + StringDigestor.digest(possiblyLongSignature).substring(0, 8)
+            } else { possiblyLongSignature }
             dependencyCollector?.addDependency(f, signature)
             externalClassExtractor.extractLater(f, signature)
         }
