From 352c0c4f20ed734a6205ed2ad7a8b1bd4e33e2e1 Mon Sep 17 00:00:00 2001
From: Paul Dingemans <paul-dingemans@users.noreply.github.com>
Date: Sun, 26 Nov 2023 15:19:07 +0100
Subject: [PATCH] Prevent stack overflow exception when code provided vis stdin
 can not be parsed as Kotlin, nor Kotlin script (#2380)

Closes #2379
---
 .../ktlint/cli/internal/KtlintCommandLine.kt  | 72 +++++++++++++------
 .../com/pinterest/ktlint/cli/SimpleCLITest.kt | 22 ++++++
 2 files changed, 72 insertions(+), 22 deletions(-)

diff --git a/ktlint-cli/src/main/kotlin/com/pinterest/ktlint/cli/internal/KtlintCommandLine.kt b/ktlint-cli/src/main/kotlin/com/pinterest/ktlint/cli/internal/KtlintCommandLine.kt
index 0364a055c1..0d13311624 100644
--- a/ktlint-cli/src/main/kotlin/com/pinterest/ktlint/cli/internal/KtlintCommandLine.kt
+++ b/ktlint-cli/src/main/kotlin/com/pinterest/ktlint/cli/internal/KtlintCommandLine.kt
@@ -538,18 +538,32 @@ internal class KtlintCommandLine {
                 }
         } catch (e: Exception) {
             if (code.isStdIn && e is KtLintParseException) {
-                logger.warn {
-                    """
-                    Can not parse input from <stdin> as Kotlin, due to error below:
-                        ${e.toKtlintCliError(code).detail}
-                    Now, trying to read the input as Kotlin Script.
-                    """.trimIndent()
+                if (code.script) {
+                    // When reading from stdin, code is only parsed as Kotlint script, if it could not be parsed as pure Kotlin. Now parsing
+                    // of the code has failed for both, the file has to be ignored.
+                    logger.error {
+                        """
+                        Can not parse input from <stdin> as Kotlin, due to error below:
+                            ${e.toKtlintCliError(code).detail}
+                        """.trimIndent()
+                    }
+                    ktlintCliErrors.add(e.toKtlintCliError(code))
+                } else {
+                    // When reading from stdin, it is first assumed that the provided code is pure Kotlin instead of Kotlin script. If
+                    // parsing fails, retry parsing at Kotlin script.
+                    logger.warn {
+                        """
+                        Can not parse input from <stdin> as Kotlin, due to error below:
+                            ${e.toKtlintCliError(code).detail}
+                        Now, trying to read the input as Kotlin Script.
+                        """.trimIndent()
+                    }
+                    return format(
+                        ktLintRuleEngine = ktLintRuleEngine,
+                        code = Code.fromSnippet(code.content, script = true),
+                        baselineLintErrors = baselineLintErrors,
+                    )
                 }
-                return format(
-                    ktLintRuleEngine = ktLintRuleEngine,
-                    code = Code.fromSnippet(code.content, script = true),
-                    baselineLintErrors = baselineLintErrors,
-                )
             } else {
                 ktlintCliErrors.add(e.toKtlintCliError(code))
                 tripped.set(true)
@@ -587,18 +601,32 @@ internal class KtlintCommandLine {
             }
         } catch (e: Exception) {
             if (code.isStdIn && e is KtLintParseException) {
-                logger.warn {
-                    """
-                    Can not parse input from <stdin> as Kotlin, due to error below:
-                        ${e.toKtlintCliError(code).detail}
-                    Now, trying to read the input as Kotlin Script.
-                    """.trimIndent()
+                if (code.script) {
+                    // When reading from stdin, code is only parsed as Kotlint script, if it could not be parsed as pure Kotlin. Now parsing
+                    // of the code has failed for both, the file has to be ignored.
+                    logger.error {
+                        """
+                        Can not parse input from <stdin> as Kotlin, due to error below:
+                            ${e.toKtlintCliError(code).detail}
+                        """.trimIndent()
+                    }
+                    ktlintCliErrors.add(e.toKtlintCliError(code))
+                } else {
+                    // When reading from stdin, it is first assumed that the provided code is pure Kotlin instead of Kotlin script. If
+                    // parsing fails, retry parsing at Kotlin script.
+                    logger.warn {
+                        """
+                        Can not parse input from <stdin> as Kotlin, due to error below:
+                            ${e.toKtlintCliError(code).detail}
+                        Now, trying to read the input as Kotlin Script.
+                        """.trimIndent()
+                    }
+                    return lint(
+                        ktLintRuleEngine = ktLintRuleEngine,
+                        code = Code.fromSnippet(code.content, script = true),
+                        baselineLintErrors = baselineLintErrors,
+                    )
                 }
-                return lint(
-                    ktLintRuleEngine = ktLintRuleEngine,
-                    code = Code.fromSnippet(code.content, script = true),
-                    baselineLintErrors = baselineLintErrors,
-                )
             } else {
                 ktlintCliErrors.add(e.toKtlintCliError(code))
                 tripped.set(true)
diff --git a/ktlint-cli/src/test/kotlin/com/pinterest/ktlint/cli/SimpleCLITest.kt b/ktlint-cli/src/test/kotlin/com/pinterest/ktlint/cli/SimpleCLITest.kt
index 9474f49e5b..60f4eab3ac 100644
--- a/ktlint-cli/src/test/kotlin/com/pinterest/ktlint/cli/SimpleCLITest.kt
+++ b/ktlint-cli/src/test/kotlin/com/pinterest/ktlint/cli/SimpleCLITest.kt
@@ -515,6 +515,28 @@ class SimpleCLITest {
             }
     }
 
+    @Test
+    fun `Issue 2379 - Given stdin input resulting in a KtLintParseException when formatted as Kotlin Script code`(
+        @TempDir
+        tempDir: Path,
+    ) {
+        CommandLineTestRunner(tempDir)
+            .run(
+                testProjectName = "too-many-empty-lines",
+                arguments = listOf("--stdin", "--format"),
+                stdin =
+                    ByteArrayInputStream(
+                        """
+                        fun foo() =
+                        """.trimIndent().toByteArray(),
+                    ),
+            ) {
+                assertThat(errorOutput)
+                    .containsLineMatching(Regex(".*Not a valid Kotlin file.*"))
+                    .doesNotContainLineMatching(Regex(".*Now, trying to read the input as Kotlin Script.*"))
+            }
+    }
+
     @Test
     fun `Enable android code style via parameter --code-style=android_studio`(
         @TempDir