fix buffer printer overflowing buffer

[r27173]

diff --git a/printer.c b/printer.c
index 29705e6..71d48f8 100644 (file)
--- a/printer.c
+++ b/printer.c
@@ -112,28 +112,25 @@ void print_to_obstack(struct obstack *new_obst)
 static char *buffer_pos;
 static char *buffer_end;
 
+static inline void buffer_add_char(int c)
+{
+       if (buffer_pos == buffer_end)
+               return;
+       *buffer_pos++ = c;
+}
+
 static void print_string_buffer(const char *str)
 {
        for (const char *c = str; *c != '\0'; ++c) {
-               if (buffer_pos == buffer_end) {
-                       return;
-               }
-               *buffer_pos++ = *c;
+               buffer_add_char(*c);
        }
 }
 
 static void print_vformat_buffer(const char *format, va_list ap)
 {
-       size_t size    = buffer_end - buffer_pos + 1;
-       int    written = vsnprintf(buffer_pos, size, format, ap);
-       buffer_pos    += written;
-}
-
-static inline void buffer_add_char(int c)
-{
-       if (buffer_pos == buffer_end)
-               return;
-       *buffer_pos++ = c;
+       size_t size    = buffer_end - buffer_pos;
+       size_t written = (size_t) vsnprintf(buffer_pos, size, format, ap);
+       buffer_pos    += written < size ? written : size;
 }
 
 static void print_char_buffer(wchar_rep_t c)
@@ -159,7 +156,7 @@ static void print_char_buffer(wchar_rep_t c)
 void print_to_buffer(char *buffer, size_t buffer_size)
 {
        buffer_pos = buffer;
-       buffer_end = buffer + buffer_size - 1;
+       buffer_end = buffer + buffer_size - 2;
 
        print_string  = print_string_buffer;
        print_vformat = print_vformat_buffer;