X-Git-Url: https://pintos-os.org/cgi-bin/gitweb.cgi?a=blobdiff_plain;f=src%2Flanguage%2Flexer%2Flexer.c;h=1caadac1de9854433d499122686d1ffa052d9704;hb=0838c7ce8528a241fd6bb422767e187af4b5d9a7;hp=e72a3e47bc9637d93ad3c1f764b7099686df6d3d;hpb=6fb50290892e920da3af95489bafe74541e55198;p=pspp

diff --git a/src/language/lexer/lexer.c b/src/language/lexer/lexer.c
index e72a3e47bc..1caadac1de 100644
--- a/src/language/lexer/lexer.c
+++ b/src/language/lexer/lexer.c
@@ -1209,14 +1209,18 @@ lex_source_read__ (struct lex_source *src)
   do
     {
       size_t head_ofs;
+      size_t space;
       size_t n;
 
       lex_source_expand__ (src);
 
       head_ofs = src->head - src->tail;
+      space = src->allocated - head_ofs;
       n = src->reader->class->read (src->reader, &src->buffer[head_ofs],
-                                    src->allocated - head_ofs,
+                                    space,
                                     segmenter_get_prompt (&src->segmenter));
+      assert (n <= space);
+
       if (n == 0)
         {
           /* End of input.