serialize string input robustness

[ust.git] / libust / buffers.c

diff --git a/libust/buffers.c b/libust/buffers.c
index c27b78877df625c33a23af1ff8f6af2f4277ad1b..5d9bb8ec87ab566bdf58fe476e2b8a20f58407de 100644 (file)
--- a/libust/buffers.c
+++ b/libust/buffers.c
@@ -70,28 +70,68 @@ static int get_n_cpus(void)
        return n_cpus;
 }
 
-/* _ust_buffers_write()
+/**
+ * _ust_buffers_strncpy_fixup - Fix an incomplete string in a ltt_relay buffer.
+ * @buf : buffer
+ * @offset : offset within the buffer
+ * @len : length to write
+ * @copied: string actually copied
+ * @terminated: does string end with \0
  *
- * @buf: destination buffer
- * @offset: offset in destination
- * @src: source buffer
- * @len: length of source
- * @cpy: already copied
+ * Fills string with "X" if incomplete.
  */
-
-void _ust_buffers_write(struct ust_buffer *buf, size_t offset,
-        const void *src, size_t len, ssize_t cpy)
+void _ust_buffers_strncpy_fixup(struct ust_buffer *buf, size_t offset,
+                               size_t len, size_t copied, int terminated)
 {
-       do {
-               len -= cpy;
-               src += cpy;
-               offset += cpy;
+       size_t buf_offset, cpy;
+
+       if (copied == len) {
+               /*
+                * Deal with non-terminated string.
+                */
+               assert(!terminated);
+               offset += copied - 1;
+               buf_offset = BUFFER_OFFSET(offset, buf->chan);
+               /*
+                * Underlying layer should never ask for writes across
+                * subbuffers.
+                */
+               assert(buf_offset
+                      < buf->chan->subbuf_size*buf->chan->subbuf_cnt);
+               ust_buffers_do_memset(buf->buf_data + buf_offset, '\0', 1);
+               return;
+       }
 
-               WARN_ON(offset >= buf->buf_size);
+       /*
+        * Deal with incomplete string.
+        * Overwrite string's \0 with X too.
+        */
+       cpy = copied - 1;
+       assert(terminated);
+       len -= cpy;
+       offset += cpy;
+       buf_offset = BUFFER_OFFSET(offset, buf->chan);
+
+       /*
+        * Underlying layer should never ask for writes across subbuffers.
+        */
+       assert(buf_offset
+              < buf->chan->subbuf_size*buf->chan->subbuf_cnt);
 
-               cpy = min_t(size_t, len, buf->buf_size - offset);
-               ust_buffers_do_copy(buf->buf_data + offset, src, cpy);
-       } while (unlikely(len != cpy));
+       ust_buffers_do_memset(buf->buf_data + buf_offset,
+                             'X', len);
+
+       /*
+        * Overwrite last 'X' with '\0'.
+        */
+       offset += len - 1;
+       buf_offset = BUFFER_OFFSET(offset, buf->chan);
+       /*
+        * Underlying layer should never ask for writes across subbuffers.
+        */
+       assert(buf_offset
+              < buf->chan->subbuf_size*buf->chan->subbuf_cnt);
+       ust_buffers_do_memset(buf->buf_data + buf_offset, '\0', 1);
 }
 
 static int ust_buffers_init_buffer(struct ust_trace *trace,