Replace all snprintf() calls with M_snprintf().

The Windows API has an _snprintf function that is not the same as
Unix's snprintf(): if the string is truncated then no trailing NUL
character is appended. This makes the function unsafe. Define a
replacement/wrapper called M_snprintf that works the same but always
appends a trailing NUL, for safety on Windows and other OSes that
behave like this.

Do the same thing for vsnprintf(), and update HACKING to list
snprintf/vsnprintf as forbidden functions. This fixes #375;
thanks to Quasar for pointing out the different behavior of these
functions.

1 files changed, 3 insertions, 2 deletions

diff --git a/src/doom/am_map.c b/src/doom/am_map.c
index b7bfd3bd..d920823f 100644
--- a/src/doom/am_map.c
+++ b/src/doom/am_map.c
@@ -38,6 +38,7 @@
 
 #include "m_cheat.h"
 #include "m_controls.h"
+#include "m_misc.h"
 #include "i_system.h"
 
 // Needs access to LFB.
@@ -689,8 +690,8 @@ AM_Responder
         }
         else if (key == key_map_mark)
         {
-            snprintf(buffer, sizeof(buffer), "%s %d",
-                     DEH_String(AMSTR_MARKEDSPOT), markpointnum);
+            M_snprintf(buffer, sizeof(buffer), "%s %d",
+                       DEH_String(AMSTR_MARKEDSPOT), markpointnum);
             plr->message = buffer;
             AM_addMark();
         }