From d6dd082adfb93716c31e5093b189fdedb64e5efe Mon Sep 17 00:00:00 2001
From: Mostyn Bramley-Moore <mostyn@antipode.se>
Date: Mon, 7 Oct 2024 05:35:28 +0200
Subject: [PATCH] Add absolute path test for bsdtar (#2370)

Check that extracting archive entries with absolute paths uses mangled
relative paths unless -P / --absolute-paths is specified.
---
 Makefile.am              |  1 +
 tar/test/CMakeLists.txt  |  1 +
 tar/test/test_option_P.c | 82 ++++++++++++++++++++++++++++++++++++++++
 3 files changed, 84 insertions(+)
 create mode 100644 tar/test/test_option_P.c

diff --git a/Makefile.am b/Makefile.am
index 64af9afd9..53f47bb0c 100644
--- a/Makefile.am
+++ b/Makefile.am
@@ -1117,6 +1117,7 @@ bsdtar_test_SOURCES= \
 	tar/test/test_option_H_upper.c \
 	tar/test/test_option_L_upper.c \
 	tar/test/test_option_O_upper.c \
+	tar/test/test_option_P.c \
 	tar/test/test_option_T_upper.c \
 	tar/test/test_option_U_upper.c \
 	tar/test/test_option_X_upper.c \
diff --git a/tar/test/CMakeLists.txt b/tar/test/CMakeLists.txt
index 7808a8d1f..09ad68015 100644
--- a/tar/test/CMakeLists.txt
+++ b/tar/test/CMakeLists.txt
@@ -32,6 +32,7 @@ IF(ENABLE_TAR AND ENABLE_TEST)
     test_option_H_upper.c
     test_option_L_upper.c
     test_option_O_upper.c
+    test_option_P.c
     test_option_T_upper.c
     test_option_U_upper.c
     test_option_X_upper.c
diff --git a/tar/test/test_option_P.c b/tar/test/test_option_P.c
new file mode 100644
index 000000000..e63da3e08
--- /dev/null
+++ b/tar/test/test_option_P.c
@@ -0,0 +1,82 @@
+/*-
+ * SPDX-License-Identifier: BSD-2-Clause
+ *
+ * Copyright (c) 2024 Mostyn Bramley-Moore <mostyn@antipode.se>
+ */
+
+#include "test.h"
+
+#include <stdlib.h>
+#include <string.h>
+
+#if defined(_WIN32) && !defined(__CYGWIN__)
+#define UNLINK _unlink
+#else
+#define UNLINK unlink
+#endif
+
+DEFINE_TEST(test_extract_tar_absolute_paths)
+{
+	int r;
+
+	// Create an absolute path for a test file inside testworkdir.
+	char *entry_suffix = "/tar-noabs";
+	size_t entry_suffix_length = strlen(entry_suffix);
+	size_t testworkdir_length = strlen(testworkdir);
+	size_t temp_absolute_file_name_length = testworkdir_length + entry_suffix_length;
+	char *temp_absolute_file_name = calloc(1, temp_absolute_file_name_length + 1); // +1 for null character.
+	assertEqualInt(snprintf(temp_absolute_file_name, temp_absolute_file_name_length + 1, "%s%s", testworkdir, entry_suffix),
+		temp_absolute_file_name_length);
+
+#if defined(_WIN32) && !defined(__CYGWIN__)
+	// I'm unsure how to specify paths with spaces for the test invocation on windows.
+	// Adding quotes doesn't seem to work. We should find a way to escape these paths,
+	// but for now let's fail in a place that's obviously related to the test setup if
+	// testworkdir contains spaces.
+	for (char *p = temp_absolute_file_name; *p != '\0'; p++)
+	{
+		assert(*p != ' ');
+		if (*p == ' ') break;
+	}
+#endif
+
+	// Create the file.
+	const char *sample_data = "test file from test_extract_tar_absolute_paths";
+	assertMakeFile(temp_absolute_file_name, 0644, sample_data);
+
+	// Create an archive with the test file, using an absolute path.
+#if defined(_WIN32) && !defined(__CYGWIN__)
+	r = systemf("%s --absolute-paths -cf test.tar %s", testprog, temp_absolute_file_name);
+#else
+	r = systemf("%s --absolute-paths -cf test.tar \"%s\"", testprog, temp_absolute_file_name);
+#endif
+	assertEqualInt(r, 0);
+
+	UNLINK(temp_absolute_file_name);
+
+	// Extracting the archive without -P / --absolute-paths should strip leading drive letter or slash
+	r = systemf("%s -xf test.tar", testprog);
+	assertEqualInt(r, 0);
+	assertFileNotExists(temp_absolute_file_name);
+
+	// Check that the mangled path exists.
+#if defined(_WIN32) && !defined(__CYGWIN__)
+	assertFileExists(temp_absolute_file_name + 3); // Skip the drive letter, colon and slash.
+	UNLINK(temp_absolute_file_name + 3);
+#else
+	assertFileExists(temp_absolute_file_name + 1); // Skip the slash.
+	UNLINK(temp_absolute_file_name + 1);
+#endif
+
+	// Extracting the archive with -P / --absolute-paths should create the file.
+	r = systemf("%s --absolute-paths -xf test.tar", testprog);
+	assertEqualInt(r, 0);
+	assertFileExists(temp_absolute_file_name);
+
+	// Check that the mangled path wasn't created.
+#if defined(_WIN32) && !defined(__CYGWIN__)
+	assertFileNotExists(temp_absolute_file_name + 3); // Skip the drive letter, colon and slash.
+#else
+	assertFileNotExists(temp_absolute_file_name + 1); // Skip the slash.
+#endif
+}
-- 
2.47.2