From a9d9335b20a0b708fae1b978f70348aec998356a Mon Sep 17 00:00:00 2001
From: Simon Howard
Date: Tue, 1 Apr 2014 21:49:16 -0400
Subject: textscreen: Use safe string functions.

Define TXT_{StringCopy,StringConcat,snprintf,vsnprintf} as analogs of
the m_misc.c versions so that the textscreen library does not need a
dependency on the Doom code, and change all textscreen code to use
these instead of unsafe functions. This fixes #372.
---
 textscreen/txt_sdl.c | 67 ++++++++++++++++++++++++++++++++++++++++++++++++----
 1 file changed, 63 insertions(+), 4 deletions(-)

(limited to 'textscreen/txt_sdl.c')

diff --git a/textscreen/txt_sdl.c b/textscreen/txt_sdl.c
index 0fb8d722..860adfa6 100644
--- a/textscreen/txt_sdl.c
+++ b/textscreen/txt_sdl.c
@@ -751,7 +751,7 @@ static const char *SpecialKeyName(int key)
     }
 }
 
-void TXT_GetKeyDescription(int key, char *buf)
+void TXT_GetKeyDescription(int key, char *buf, size_t buf_len)
 {
     const char *keyname;
 
@@ -759,15 +759,15 @@ void TXT_GetKeyDescription(int key, char *buf)
 
     if (keyname != NULL)
     {
-        strcpy(buf, keyname);
+        TXT_StringCopy(buf, keyname, buf_len);
     }
     else if (isprint(key))
     {
-        sprintf(buf, "%c", toupper(key));
+        TXT_snprintf(buf, buf_len, "%c", toupper(key));
     }
     else
     {
-        sprintf(buf, "??%i", key);
+        TXT_snprintf(buf, buf_len, "??%i", key);
     }
 }
 
@@ -870,3 +870,62 @@ void TXT_SDL_SetEventCallback(TxtSDLEventCallbackFunc callback, void *user_data)
     event_callback_data = user_data;
 }
 
+// Safe string functions.
+
+void TXT_StringCopy(char *dest, const char *src, size_t dest_len)
+{
+    if (dest_len < 1)
+    {
+        return;
+    }
+
+    dest[dest_len - 1] = '\0';
+    strncpy(dest, src, dest_len - 1);
+}
+
+void TXT_StringConcat(char *dest, const char *src, size_t dest_len)
+{
+    size_t offset;
+
+    offset = strlen(dest);
+    if (offset > dest_len)
+    {
+        offset = dest_len;
+    }
+
+    TXT_StringCopy(dest + offset, src, dest_len - offset);
+}
+
+// On Windows, vsnprintf() is _vsnprintf().
+#ifdef _WIN32
+#if _MSC_VER < 1400 /* not needed for Visual Studio 2008 */
+#define vsnprintf _vsnprintf
+#endif
+#endif
+
+// Safe, portable vsnprintf().
+int TXT_vsnprintf(char *buf, size_t buf_len, const char *s, va_list args)
+{
+    if (buf_len < 1)
+    {
+        return 0;
+    }
+
+    // Windows (and other OSes?) has a vsnprintf() that doesn't always
+    // append a trailing \0. So we must do it, and write into a buffer
+    // that is one byte shorter; otherwise this function is unsafe.
+    buf[buf_len - 1] = '\0';
+    return vsnprintf(buf, buf_len - 1, s, args);
+}
+
+// Safe, portable snprintf().
+int TXT_snprintf(char *buf, size_t buf_len, const char *s, ...)
+{
+    va_list args;
+    int result;
+    va_start(args, s);
+    result = TXT_vsnprintf(buf, buf_len, s, args);
+    va_end(args);
+    return result;
+}
+
-- 
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