From: Martin Matuska <martin@matuska.org>
Date: Tue, 29 Nov 2016 15:55:41 +0000 (+0100)
Subject: Fix extracting hardlinks over symlinks
X-Git-Tag: v3.3.0~110
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=256e52f073765a4ddad1e86fd4d0eda2a18147bf;p=thirdparty%2Flibarchive.git

Fix extracting hardlinks over symlinks

Closes #821
---

diff --git a/libarchive/archive_write_disk_posix.c b/libarchive/archive_write_disk_posix.c
index b717ae0dc..afcadbbe2 100644
--- a/libarchive/archive_write_disk_posix.c
+++ b/libarchive/archive_write_disk_posix.c
@@ -2590,6 +2590,49 @@ check_symlinks_fsobj(char *path, int *a_eno, struct archive_string *a_estr,
 					break;
 				}
 				tail[0] = c;
+			} else if ((flags &
+			    ARCHIVE_EXTRACT_SECURE_SYMLINKS) == 0) {
+				/*
+				 * We are not the last element and we want to
+				 * follow symlinks if they are a directory.
+				 * 
+				 * This is needed to extract hardlinks over
+				 * symlinks.
+				 */
+				r = stat(head, &st);
+				if (r != 0) {
+					tail[0] = c;
+					if (errno == ENOENT) {
+						break;
+					} else {
+						fsobj_error(a_eno, a_estr,
+						    errno,
+						    "Could not stat %s", path);
+						res = (ARCHIVE_FAILED);
+						break;
+					}
+				} else if (S_ISDIR(st.st_mode)) {
+					if (chdir(head) != 0) {
+						tail[0] = c;
+						fsobj_error(a_eno, a_estr,
+						    errno,
+						    "Could not chdir %s", path);
+						res = (ARCHIVE_FATAL);
+						break;
+					}
+					/*
+					 * Our view is now from inside
+					 * this dir:
+					 */
+					head = tail + 1;
+				} else {
+					tail[0] = c;
+					fsobj_error(a_eno, a_estr, 0,
+					    "Cannot extract through "
+					    "symlink %s", path);
+					res = ARCHIVE_FAILED;
+					break;
+				}
 			} else {
 				tail[0] = c;
 				fsobj_error(a_eno, a_estr, 0,
diff --git a/tar/test/test_symlink_dir.c b/tar/test/test_symlink_dir.c
index 25bd8b162..852e00b37 100644
--- a/tar/test/test_symlink_dir.c
+++ b/tar/test/test_symlink_dir.c
@@ -47,11 +47,18 @@ DEFINE_TEST(test_symlink_dir)
 	assertMakeDir("source/dir3", 0755);
 	assertMakeDir("source/dir3/d3", 0755);
 	assertMakeFile("source/dir3/f3", 0755, "abcde");
+	assertMakeDir("source/dir4", 0755);
+	assertMakeFile("source/dir4/file3", 0755, "abcdef");
+	assertMakeHardlink("source/dir4/file4", "source/dir4/file3");
 
 	assertEqualInt(0,
 	    systemf("%s -cf test.tar -C source dir dir2 dir3 file file2",
 		testprog));
 
+	/* Second archive with hardlinks */
+	assertEqualInt(0,
+	    systemf("%s -cf test2.tar -C source dir4", testprog));
+
 	/*
 	 * Extract with -x and without -P.
 	 */
@@ -118,9 +125,15 @@ DEFINE_TEST(test_symlink_dir)
 		assertMakeSymlink("dest2/file2", "real_file2");
 	assertEqualInt(0, systemf("%s -xPf test.tar -C dest2", testprog));
 
-	/* dest2/dir symlink should be followed */
+	/* "dir4" is a symlink to existing "real_dir" */
+	if (canSymlink())
+		assertMakeSymlink("dest2/dir4", "real_dir");
+	assertEqualInt(0, systemf("%s -xPf test2.tar -C dest2", testprog));
+
+	/* dest2/dir and dest2/dir4 symlinks should be followed */
 	if (canSymlink()) {
 		assertIsSymlink("dest2/dir", "real_dir");
+		assertIsSymlink("dest2/dir4", "real_dir");
 		assertIsDir("dest2/real_dir", -1);
 	}
 
@@ -141,4 +154,7 @@ DEFINE_TEST(test_symlink_dir)
 	/* dest2/file2 symlink should be removed */
 	failure("Symlink to non-existing file should be removed");
 	assertIsReg("dest2/file2", -1);
+
+	/* dest2/dir4/file3 and dest2/dir4/file4 should be hard links */
+	assertIsHardlink("dest2/dir4/file3", "dest2/dir4/file4");
 }