From 0e3bb2104a8e3fd07e201e6ba99f8d017fdc72a8 Mon Sep 17 00:00:00 2001
From: David Oberhollenzer <david.oberhollenzer@sigma-star.at>
Date: Tue, 29 Dec 2020 12:10:46 +0100
Subject: Fix normalization of slashes in filenames

All paths were canonicalized internally, which includes filtering
sequences of slashes and converting backslashes to slashes.
Furthermore, when unpacking files, filenames are sanity checked
and rejected if they contain forward OR backward slashes.

This is a problem on Unix-like systems, where files containing
backslashes are a legitimate use case (*cough* SystemD *cough*).

This patch removes the backslash conversion from the canonicalization
and modifies the sanity check to reject backslashes only on Windows.

Signed-off-by: David Oberhollenzer <david.oberhollenzer@sigma-star.at>
---
 lib/fstree/canonicalize_name.c |  6 +++---
 lib/fstree/filename_sane.c     |  4 ++--
 tests/canonicalize_name.c      | 10 +++++-----
 tests/filename_sane.c          |  7 ++++---
 4 files changed, 14 insertions(+), 13 deletions(-)

diff --git a/lib/fstree/canonicalize_name.c b/lib/fstree/canonicalize_name.c
index f35307f..7fbd5a7 100644
--- a/lib/fstree/canonicalize_name.c
+++ b/lib/fstree/canonicalize_name.c
@@ -11,12 +11,12 @@ static void normalize_slashes(char *filename)
 {
 	char *dst = filename, *src = filename;
 
-	while (*src == '/' || *src == '\\')
+	while (*src == '/')
 		++src;
 
 	while (*src != '\0') {
-		if (*src == '/' || *src == '\\') {
-			while (*src == '/' || *src == '\\')
+		if (*src == '/') {
+			while (*src == '/')
 				++src;
 			if (*src == '\0')
 				break;
diff --git a/lib/fstree/filename_sane.c b/lib/fstree/filename_sane.c
index b0f8c90..91c15da 100644
--- a/lib/fstree/filename_sane.c
+++ b/lib/fstree/filename_sane.c
@@ -57,7 +57,7 @@ bool is_filename_sane(const char *name, bool check_os_specific)
 		return false;
 
 	while (*name != '\0') {
-		if (*name == '/' || *name == '\\')
+		if (*name == '/')
 			return false;
 
 #if defined(_WIN32) || defined(__WINDOWS__) || defined(TEST_WIN32)
@@ -66,7 +66,7 @@ bool is_filename_sane(const char *name, bool check_os_specific)
 				return false;
 			if (*name == '"' || *name == '|' || *name == '?')
 				return false;
-			if (*name == '*' || *name <= 31)
+			if (*name == '*' || *name == '\\' || *name <= 31)
 				return false;
 		}
 #endif
diff --git a/tests/canonicalize_name.c b/tests/canonicalize_name.c
index 679cd06..2ab73a0 100644
--- a/tests/canonicalize_name.c
+++ b/tests/canonicalize_name.c
@@ -14,14 +14,14 @@ static const struct {
 } must_work[] = {
 	{ "", "" },
 	{ "/", "" },
-	{ "\\", "" },
+	{ "\\", "\\" },
 	{ "///", "" },
-	{ "\\\\\\", "" },
-	{ "/\\//\\\\/", "" },
+	{ "\\\\\\", "\\\\\\" },
+	{ "/\\//\\\\/", "\\/\\\\" },
 	{ "foo/bar/test", "foo/bar/test" },
-	{ "foo\\bar\\test", "foo/bar/test" },
+	{ "foo\\bar\\test", "foo\\bar\\test" },
 	{ "/foo/bar/test/", "foo/bar/test" },
-	{ "\\foo\\bar\\test\\", "foo/bar/test" },
+	{ "\\foo\\bar\\test\\", "\\foo\\bar\\test\\" },
 	{ "///foo//bar//test///", "foo/bar/test" },
 	{ "./foo/././bar/test/./.", "foo/bar/test" },
 	{ "./foo/././", "foo" },
diff --git a/tests/filename_sane.c b/tests/filename_sane.c
index 3c1fd4f..86270b3 100644
--- a/tests/filename_sane.c
+++ b/tests/filename_sane.c
@@ -11,6 +11,9 @@
 static const char *must_work[] = {
 	"foobar",
 	"test.txt",
+#if !defined(_WIN32) && !defined(__WINDOWS__) && !defined(TEST_WIN32)
+	"\\foo", "foo\\", "foo\\bar",
+#endif
 	NULL,
 };
 
@@ -18,16 +21,14 @@ static const char *must_not_work[] = {
 	".",
 	"..",
 	"/foo",
-	"\\foo",
 	"foo/",
-	"foo\\",
 	"foo/bar",
-	"foo\\bar",
 	NULL,
 };
 
 static const char *must_not_work_here[] = {
 #if defined(_WIN32) || defined(__WINDOWS__) || defined(TEST_WIN32)
+	"\\foo", "foo\\", "foo\\bar",
 	"fo<o", "fo>o", "fo:o", "fo\"o",
 	"fo|o", "fo?o", "fo*o", "fo\ro",
 	"CON", "PRN", "AUX", "NUL",
-- 
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