Rewrote .incbin's parsing and checks for position and size to increase robustness

diff --git a/direct.c b/direct.c
index 65a119d3211e5063fb9a58d05b957dd86f17a54f..24c3d93d4f1d029941c600019861fc908ff3cdd7 100644 (file)
--- a/direct.c
+++ b/direct.c
@@ -621,32 +621,40 @@ allright:
 
        tok += 2;
 
+       size = lseek(fd, 0L, SEEK_END);
+       pos = lseek(fd, 0L, SEEK_SET);
+
        if (*tok != EOL)
        {
-               // Check size parameter (can be omitted)
-               if (*tok++ == ',')
+               // Parse size and position parameters
+               uint64_t requested_size = -1;   // -1 means "not set" for these two
+               if (*tok++ != ',')
+               {
+                       close(fd);
+                       return error("expected comma after incbin filename");
+               }
+               if (tok != EOL)
                {
                        if (*tok != ',')
                        {
-                               if (abs_expr(&size) != OK)
+                               if (abs_expr(&requested_size) != OK)
                                {
                                        close(fd);
                                        return ERROR;
                                }
-                               if ((int64_t)size <= 0)
+                               if ((int64_t)requested_size <= 0 || requested_size > size)
                                {
+                                       close(fd);
                                        return error("invalid incbin size requested");
                                }
                        }
-                       else
-                               size = lseek(fd, 0L, SEEK_END);
-               }
-
-               // Check offset parameter (can be omitted)
-               if (*tok != EOL)
-               {
-                       if (*tok++ == ',')
+                       if (*tok != EOL)
                        {
+                               if (*tok++ != ',')
+                               {
+                                       close(fd);
+                                       return error("expected comma after size parameter");
+                               }
                                if (*tok != EOL)
                                {
                                        if (abs_expr(&pos) != OK)
@@ -654,30 +662,37 @@ allright:
                                                close(fd);
                                                return ERROR;
                                        }
-
-                                       lseek(fd, pos, SEEK_SET);
-                                       if ((int64_t)(size - pos) < 0)
+                                       if ((int64_t)pos <= 0 || pos > size)
                                        {
-                                               return error("requested incbin size out of range");
+                                               close(fd);
+                                               return error("invalid incbin position requested");
                                        }
                                }
-                               else
-                               {
-                                       // offset parameter omitted, so it's 0
-                                       pos = lseek(fd, 0L, SEEK_SET);
-                               }
                        }
-                       else
-                               return error(comma_error);
+
+                       if (*tok != EOL)
+                       {
+                               close(fd);
+                               return error("extra characters following incbin");
+                       }
                }
-               else
-                       pos = lseek(fd, 0L, SEEK_SET);
-       }
-       else
-       {
-               // size & pos not given, so assume offset of 0 and all of the binary
-               size = lseek(fd, 0L, SEEK_END);
-               pos = lseek(fd, 0L, SEEK_SET);
+
+               // Adjust size if the user didn't specify it via the parameter
+               if (requested_size == -1)
+               {
+                       requested_size = size - pos;
+               }
+               
+               // Are we going to read past the end of the file?
+               if (pos + requested_size > size)
+               {
+                       close(fd);
+                       return error("invalid combination of incbin position and size");
+               }
+               size = requested_size;
+
+               // All checks passed, let's seek to where the user requested, otherwise at file start
+               lseek(fd, pos, SEEK_SET);
        }
 
        chcheck(size);