From 700e5fff8b40ca228a5d45a8f0116ec68636ab80 Mon Sep 17 00:00:00 2001
From: lurchi <lurchi@strangeplace.net>
Date: Wed, 7 Sep 2016 15:14:35 +0200
Subject: [PATCH] slice::from_raw_parts must not be called on null pointer

---
 rust/src/packet_types.rs | 20 ++++++++++----------
 rust/src/parser.rs       |  9 ++++++---
 rust/src/util.rs         | 14 ++++++++++++--
 3 files changed, 28 insertions(+), 15 deletions(-)

diff --git a/rust/src/packet_types.rs b/rust/src/packet_types.rs
index a316609..3ab9d11 100644
--- a/rust/src/packet_types.rs
+++ b/rust/src/packet_types.rs
@@ -33,6 +33,16 @@ pub enum PsycPacketFlag {
     PSYC_PACKET_NO_LENGTH = 2,
 }
 
+#[repr(C)]
+pub enum PsycPacketId {
+    PSYC_PACKET_ID_CONTEXT = 0,
+    PSYC_PACKET_ID_SOURCE = 1,
+    PSYC_PACKET_ID_TARGET = 2,
+    PSYC_PACKET_ID_COUNTER = 3,
+    PSYC_PACKET_ID_FRAGMENT = 4,
+    PSYC_PACKET_ID_ELEMS = 5,
+}
+
 #[derive(Copy, Clone)]
 #[repr(C)]
 pub enum PsycOperator {
@@ -51,16 +61,6 @@ pub enum PsycStateOp {
     PSYC_STATE_RESYNC = '?' as _,
 }
 
-#[repr(C)]
-pub enum PsycPacketId {
-    PSYC_PACKET_ID_CONTEXT = 0,
-    PSYC_PACKET_ID_SOURCE = 1,
-    PSYC_PACKET_ID_TARGET = 2,
-    PSYC_PACKET_ID_COUNTER = 3,
-    PSYC_PACKET_ID_FRAGMENT = 4,
-    PSYC_PACKET_ID_ELEMS = 5,
-}
-
 #[repr(C)]
 pub struct PsycElem {
     pub elem_type: PsycString,
diff --git a/rust/src/parser.rs b/rust/src/parser.rs
index ffe3963..eba4a5c 100644
--- a/rust/src/parser.rs
+++ b/rust/src/parser.rs
@@ -300,21 +300,24 @@ impl PsycListParser {
 
                     PsycParseListRC::PSYC_PARSE_LIST_ELEM_START => {
                         let result = PsycListParserResult::ListElementStart {
-                            value_part: util::cstring_to_slice(element.data, element.length)
+                            value_part: util::cstring_to_slice(element.data,
+                                                               element.length)
                         };
                         return Ok(result)
                     },
 
                     PsycParseListRC::PSYC_PARSE_LIST_ELEM_CONT => {
                         let result = PsycListParserResult::ListElementCont {
-                            value_part: util::cstring_to_slice(element.data, element.length)
+                            value_part: util::cstring_to_slice(element.data,
+                                                               element.length)
                         };
                         return Ok(result)
                     },
 
                     PsycParseListRC::PSYC_PARSE_LIST_ELEM_END => {
                         let result = PsycListParserResult::ListElementEnd {
-                            value_part: util::cstring_to_slice(element.data, element.length)
+                            value_part: util::cstring_to_slice(element.data,
+                                                               element.length)
                         };
                         return Ok(result)
                     },
diff --git a/rust/src/util.rs b/rust/src/util.rs
index e40f84c..3cd4fcb 100644
--- a/rust/src/util.rs
+++ b/rust/src/util.rs
@@ -1,13 +1,23 @@
 use packet_types::{RawPsycList, PsycRenderRC};
 use std::slice;
 use std::os::raw::c_char;
+use std::str;
 
 extern "C" {
     fn psyc_render_list(list: *const RawPsycList, buffer: *mut c_char, buflen: usize) -> PsycRenderRC;
 }
 
-pub unsafe fn cstring_to_slice<'a>(cstring: *const c_char, length: usize) -> &'a[u8] {
-    slice::from_raw_parts(cstring as *const u8, length)
+pub unsafe fn cstring_to_slice<'a>(cstring: *const c_char, length: usize)
+                                   -> &'a[u8] {
+    match cstring {
+        p if p.is_null() => &[],
+        _ => slice::from_raw_parts(cstring as *const u8, length)
+    }
+}
+
+pub unsafe fn cstring_to_str<'a>(cstring: *const c_char, length: usize)
+                                 -> &'a str {
+    str::from_utf8_unchecked(cstring_to_slice(cstring, length))
 }
 
 pub unsafe fn render_list(list: &RawPsycList) -> Vec<u8> {