libmwaw: fix infinite loop in findCentralDirectoryEnd

Change-Id: I36ec7ad735fa15cfda88167b11a922883ef2bb72
(cherry picked from commit e3e2cf30373446e5511b12467e3b8008311c81c2)

2 files changed, 33 insertions, 0 deletions

diff --git a/libmwaw/UnpackedTarball_libmwaw.mk b/libmwaw/UnpackedTarball_libmwaw.mk
index 8e3be68d7e96..a17961d7d2bf 100644
--- a/libmwaw/UnpackedTarball_libmwaw.mk
+++ b/libmwaw/UnpackedTarball_libmwaw.mk
@@ -13,6 +13,7 @@ $(eval $(call gb_UnpackedTarball_set_tarball,libmwaw,$(MWAW_TARBALL)))
 
 $(eval $(call gb_UnpackedTarball_add_patches,libmwaw,\
        libmwaw/libmwaw-0.1.9.patch.1 \
+       libmwaw/libmwaw-infinite-loop.patch.1 \
 ))
 
 # vim: set noet sw=4 ts=4:
diff --git a/libmwaw/libmwaw-infinite-loop.patch.1 b/libmwaw/libmwaw-infinite-loop.patch.1
new file mode 100644
index 000000000000..9c8e3a8b413e
--- /dev/null
+++ b/libmwaw/libmwaw-infinite-loop.patch.1
@@ -0,0 +1,32 @@
+fix infinite loop in findCentralDirectoryEnd
+
+WPXSvInputStreamImpl::seek returns -1 if it catches an exception
+
+--- libmwaw/src/lib/MWAWZipStream.cxx	2013-06-18 00:37:57.208657845 +0200
++++ libmwaw/src/lib/MWAWZipStream.cxx	2013-06-18 00:48:20.971665257 +0200
+@@ -258,18 +258,20 @@
+ 
+ static bool findCentralDirectoryEnd(WPXInputStream *input)
+ {
+-  input->seek(0, WPX_SEEK_SET);
++  // seek returns -1 both on error and on seek to position post-the-end
++  int ret = input->seek(0, WPX_SEEK_SET);
+   try {
+-    while (!input->atEOS())
+-      input->seek(1024, WPX_SEEK_CUR);
++    while (-1 != ret && !input->atEOS())
++      ret = input->seek(1024, WPX_SEEK_CUR);
+     input->seek(-1024, WPX_SEEK_CUR);
+-    while (!input->atEOS()) {
++    ret = 0; // perhaps it's smaller than 1024?
++    while (-1 != ret && !input->atEOS()) {
+       unsigned signature = getInt(input);
+       if (signature == CDIR_END_SIG) {
+         input->seek(-4, WPX_SEEK_CUR);
+         return true;
+       } else
+-        input->seek(-3, WPX_SEEK_CUR);
++        ret = input->seek(-3, WPX_SEEK_CUR);
+     }
+   } catch (...) {
+     return false;